Thursday, April 30, 2015

NASA's Eyes on Rainstorms, Hurricanes, and Floods

By: Dr. Marshall Shepherd , 5:10PM,GMT on April 30,2015

Sunday's WxGeeks is really special for me because it is rooted in my professional legacy. Often, viewers are curious about my professional background as a meteorologist. They may know that I am a Professor at the University of Georgia or that I was 2013 President of the American Meteorological Society. But many WxGeeks viewers may not realize that I spent 12 years of my career as a Research Meteorologist at NASA's Goddard Space Flight Center. During that time, I developed a vigorous research program involving precipitation variability and extremes. I have published over 75 peer-reviewed papers on aspects of urban rainfall, flooding, tropical storms, and convective storms. I also served as Deputy Project Scientist for NASA's Global Precipitation Measurement (GPM) Mission. GPM launched last year and my good friend Dr. Gail Jackson is its Project Scientist (Link). By the way, if you haven't see the new global precipitation maps coming from the mission, take 5 seconds and click this link. It is worth it (Link).

The forerunning to GPM was the Tropical Rainfall Measuring Mission (TRMM). Both TRMM and GPM are a part of NASA's Earth Science Program (Link). Wait, doesn't NASA launch space shuttles or send rovers to Mars? Why are we wasting money studying Earth? Ummmmmmmmmmmm, because as important as learning about other planets are, we better understand this one first. We won't be visiting our "vacation planet" any time soon. You can learn about NASA's Earth Sciences program here (Link).

TRMM and GPM have advanced our knowledge of weather, climate, and hydrologic processes in so many ways scientifically. However, you may be surprised to learn that NOAA, USAID, USGS, and private stakeholders utilize the satellite data in operational or societal applications too. However, from a "geek" factor, I just think that it is cool that we figured out how to measure rainfall or snowfall from space using radars and other microwave instruments. How is that done? We'll tell you Sunday on WxGeeks.

I have invited 2 NASA colleagues, Dr. Scott Braun (TRMM Project Scientist) and Dr. Jeff Halverson (former TRMM Outreach Scientist and Professor at University of Maryland Baltimore County), to share the legacy of TRMM and the promise of GPM. We also get into a discussion of how these missions are improving weather forecasting, climate diagnosis, hurricane prediction, and more. Scott and Jeff have also been involved in some really cool field experiments using the Global Hawk UAV and other geeky technology to improve our understanding of hurricanes (Link) or (Link). I will ask them about this work and why hurricane intensity forecasts have lagged track forecasts in improvements. And as usual, NASA has provided us with some amazing visuals that you will not want to miss. Oh, I should mention that many WxGeeks viewers may recognize Dr. Halverson from his writings in Weatherwise and Capital Weather Gang (Link), respectively.

We can't wait to bring you this episode Sunday.

We have some really great shows lined up for the next couple of weeks including a look at the role of analytics in weather. It will be great to have Paul Walsh, Paul Walsh, Vice President, Weather Strategy / The Weather Company and Glen Finch , Global Leader of Big Data & Analytics / IBM join us. Also, we have a great show with Denver Broncos Tight End Owen Daniels, a degreed meteorologist and NFL football player. This show may have some other surprises too.

Please join us Sunday at Noon ET (11 CT, 10 MT, 9 PT).

Follow @WxGeeksTWC or @DrShepherd2013 on Twitter.

Find us on Facebook at WxGeeks (Link) or Dr. Marshall Shepherd (Link)

Warm Start to May

By: Steve Gregory , 7:59PM,GMT on April 30,2015

Cool Temps in the east to Warm during the Week Ahead

(Next Update MON – MAY 4)

As the upper low/TROF in the Northeast weakens and the TROF in the EPAC moves into the western US, the Ridge over the Rockies will shift eastward into the central US and amplify - bringing above normal Temps to much of the nation through next week.

The global models are in reasonably good agreement on maintaining a TROF near the west coast and broad ridging from the Rockies eastward. However, however, there are significant differences developing between the models for Week 2 on just how strong the ridge will be versus a re-amplifying downstream TROF over eastern Canada. It appears that despite the evolving pattern change to above normal heights in the east and below normal in the west, the northwesterly flow around the eastern Canadian TROF will be sufficient to bring cooler Temps back into the Great Lakes and New England during Week 2.

In the near term, the developing storm off the Carolinas coast will move slowly out to sea with its rain shield extending over the Mid Atlantic states as warmer air flows northward across the Midwest/Great Lakes starting Friday, reaching into the Northeastern states later this weekend. As the week progresses, short wave TROFs being ejected from the western TROF will bring periods of enhanced Precip chances and isolated severe T-Storms to the central US eastward to Mid Atlantic region. By the start of Week 2, the eastern Canadian TROF will likely amplify, with a cold front slipping southward across the Great Lakes on into southern New England, with Temps falling off to near normal around the Great Lakes and in the Northeast for much of the week. With above normal Precip across the Gulf coast region, Temps will likely average near to slightly below normal through mid May.

El Niño / MJO

Both SST and sub-surface anomalies have essentially stopped increasing, but remain well above normal. Anomalous surface westerlies continue across much of the west central tropical Pacific, keeping SST anomalies above normal while the generally southeasterly wind anomalies in the far eastern Pacific have begun to shift to a more southerly and even SSW direction. El Niño indices remain near moderate intensity, with an ONI value near +1.1°C – the same as for the somewhat more accurate MEI metric. The atmospheric pattern continues to reflect El Niño conditions, with above normal Precip across the central tropical Pacific and what appears to be a forcing mechanism that’s maintaining a mean upper air TROF near the US west coast.

The MJO remains weak and incoherent with model forecasts still calling for a small increase in intensity neat week. However, the latest model runs now forecast the signal to develop in the south China Sea or far western Pacific in about 10 days, in stark contract to the past weeks’ worth of forecasts that called for the emergence of a signal in the far eastern Pacific. (A classic example of how poorly model forecasts are for predicting the development of a significant MJO.) If a significant MJO does develop in the far western Pacific, an enhanced easterly wind anomaly would be expected to develop over the west-central Pacific ahead of the signal itself which will prevent further increases in SST anomalies in the central Pacific (though a westerly wind anomaly can be expected to redevelop to the west of the signal as it translates eastward).


Over the next 2 weeks, the semi-permanent Upper Low near the Aleutians will amplify some as it shifts a bit eastward leading to falling heights over central Alaska. The falling heights and increasing chances of Precip (especially across south Central Alaska) will gradually bring the well above normal Temps down closer to, but still above normal, in most areas during Week 2; though below normal readings will begin to appear over the Northwestern portions of the state along with somewhat stormier conditions in that region by the end of Week 2.

Fig 1: Animation of the overnight operational GFS forecast for 500mb (~18,000 ft) heights and Temperatures. As the last short wave digs into the eastern TROF before the entire TROF moves out to sea, the mean EPAC TROF is expected to deepen and dig into the western US next week, with a broad ridge developing over the central-eastern states by the end of Week 1. By Day 10, the western TROF will de-amplify as short wave energy heads towards the Northern Plains & upper Midwest. During the rest of Week 2, the next upstream NORPAC short wave will repeat the pattern of developing a western US TROF and to a lessor extent, the rebuilding of the broad ridge over the central US.

Fig 2: Sea Surface Temp (SST) anomalies (top panel) have changed little over the past week and remain well above normal across much of the tropical Pacific. Fairly strong westerly wind anomalies (‘arrows’) cover much of the region west of 120° West. Likewise, sub-surface Temp anomalies have changed little over the past week in location or intensity, with readings > +4.0° above normal over the eastern half of the Pacific.

Fig 3: Global SST anomalies remain much above normal across the entire eastern and northwestern Pacific with a wedge of below normal readings in the mid-latitudes of the west and central Pacific leading to a strongly positive PDO. In the Atlantic, the pool of relatively cold water in the North Atlantic to the southeast of Greenland and below normal readings across the MDR (major development region) in the tropical Atlantic persists with little change noted.

Fig 4: Temperature anomaly forecast is based STRICTLY on the GFS MOS model data output which calls for a continuation of below normal readings during the week ahead, with below normal readings confined to the Gulf coast region due to above normal Precip. Confidence for the overall anomaly Pattern and Magnitude is still excellent, with Ratings of ‘5’ on a Scale of 1 to 5.

Fig 5: The Week 2 Temperature ANOMALY forecast is based on the 12Z run of the GFS (80%) integrated with the 12Z GFS Ensemble (10%) and the 00Z ECMWF (10%) using the projected pattern, along with the explicit surface and 850mb (~5,000 FT) Temperature forecasts. Some Temp forecasts are adjusted for known or expected anomalous thermal patterns and/or projected storm system passages.Pleasantly above normal readings will persist into Week 2 except for the Great Lakes into New England where cool air and some Precip will knock temps down to near or a bit below normal, and the PAC NW. Confidence in the overall Temp anomaly pattern and magnitude is near average for Spring time Week 2 forecasts with the greatest uncertainty being in Temps from the Great Lakes to Northeast giving Confidence Ratings of ‘3’ on a Scale of 1 to 5.

Fig 6: The Temperature ANOMALY forecasts are based on the 12Z run of the Operational GFS using the GFS MOS data for Week 1, and the projected pattern, along with raw GFS surface forecast data for Week 2. Well Above normal Temps should continue into Week 2, though the anomalies will slowly drop off as upper level heights fall off and Precip chances increase during Week 2

✭ The next regular WX Update will be on MONDAY, MAY 4



1. A GENERAL Glossary of Weather Terms can be found HERE

2. Another Glossary of weather terms is available HERE

Massive Tornadic Storm Just Misses Dallas; Extreme Heat in South Florida, Cuba

By: Bob Henson , 12:09PM,GMT on April 27,2015

Near-record atmospheric moisture for late April teamed up with an extremely strong jet stream to produce a fearsome night of severe weather over north Texas, mainly south of the Dallas-Fort Worth area. The most intense storms of the day developed by early afternoon southeast of Abilene, with one large supercell emerging at the south end of the complex. After producing several brief tornadoes and hail as large as softballs from a giant stacked-plate circulation, the storm grew even larger and more threatening after dark as it moved just south of the DFW area. Slowing and reoganizing, it dumped more than 5” of rain on some areas, according to Doppler radar estimates. At one point, there were three potentially tornadic circulations evident on Doppler radar along the storm’s south edge, a pattern eerily reminiscent of the deadly storm on May 30, 2013, that killed several storm chasers near El Reno, Oklahoma. Soon after midnight, the circulations congealed into a powerful comma-shaped bow echo that swept across the prairie with high winds (see Figure 1). Nineteen preliminary tornado reports were logged by NOAA's Storm Prediction Center in Texas on Sunday.

Figure 1. National Weather Service radar imagery from 11:55 pm CDT Sunday, April 26 (left) and 12:55 am CDT Monday, April 27 (right) shows the dramatic evolution of the storm complex south of Fort Worth into a bow echo (right), with a “bookend” circulation evident on its north end. Here's an animation from NCAR showing the storm's evolution on radar. Image credit: Weather Underground Storm.

Sunday night’s storm would have been far more destructive had its track been just one county north, across Fort Worth and Dallas. Just two nights earlier, parts of the Fort Worth area were racked by a powerful downburst that brought winds estimated at 80 – 85 mph. That storm went on to produce high winds all the way to Mississippi, with three brief EF1 tornadoes reported there. Another storm complex produced an even more extensive swath of high wind on Saturday, stretching nearly 500 miles from southeast Louisiana to the Georgia coast. Also on Saturday, hail up to baseball size pounded central Kentucky, with a short-lived EF2 tornado reported northwest of the town of Brownsville.

Figure 2. A hazy sunset on Saturday night, April 26, served as a prelude to Miami’s record heat on Sunday. Upper-air analyses carried out by the National Weather Service traced a smoke layer that lay a few thousand feet above the city on Saturday back to its origin several days earlier above fires on Mexico’s Yucatan Peninsula. Image credit: NWS/Miami.

Heat wave blasts April records in South Florida and Cuba
The spring of 2015, already one of the warmest on record across southeast Florida, turned it up a notch on Sunday, as residents baked in heat that would be unusual even in midsummer. Fort Lauderdale International Airport broke its all-time April heat record with 96°F, while Miami tied its April record with the same reading. Fort Lauderdale Executive Airport sizzled at 99°F; this was just 1° short of the city’s all-time any month record of 100° achieved on Aug. 4, 1944 (records date back to 1912 in the city.) In addition, one preliminary report of 100°F came in from the Boca Raton area. The day’s heat was not only intense but persistent: Miami hit 96°F at 1:27 pm and stayed above 90°F for eight torrid hours. Strong westerly winds kept the typical afternoon cooling from the sea breeze at bay.

Figure 3. The weekly U.S. Drought Monitor issued on April 23 showed an area of severe drought (orange) across far south Florida that had grown fivefold in size from the previous week. Image credit: National Drought Mitigation Center.

The heat may have also gotten a boost from parched ground across far southern Florida, where drought conditions have intensified rapidly in the last several weeks (see Figure 3). Dry ground heats up more readily than moist ground in full-sun conditions, and Sunday’s westerly winds swept across the drought area en route to the big east-coast cities. Miami is coming off its second-warmest March on record, and April is currently running at the warmest pace on record (80.4°F). Even with slightly less brutal temperatures on tap this week, April should end up toppling the monthly record of 80.1°F set in 2011.

The heat has been even more impressive in nearby Cuba, where Havana set its all-time temperature record on Sunday with a sizzling 37.0°C (98.6°F). The day also brought the second-highest temperature ever recorded anywhere in Cuba: 38.7°C (101.6°F), at Holguin. These data were provided courtesy of Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. He notes that these records are all the more impressive since July and August are usually the hottest months in Cuba.

Bob Henson

Storm skies over Grapevine, TX (zomcap)
Just a small indication of weather to come. This was taken at 3:30pm. Severe weather is on its way in to Grapevine for the evening. Texas has cool thunderstorms!
Storm skies over Grapevine, TX
Anvil Crawler (weatherfanatic2010)
Anvil Crawler
Touchdown (Malavok)
Spider lightning from my balcony in Austin, early Saturday morning.
mammatus clouds (Stina474)
mammatus clouds

Air Pollution and Dust Credited With Weakening Hurricanes Irene and Katrina

By: Jeff Masters , 1:30PM,GMT on April 28,2015

As Hurricane Irene churned northwards out of the Bahamas towards the Northeast U.S. on August 25, 2011, residents there scrambled to prepare for the arrival of what could well be the most destructive hurricane ever to hit the United States. Irene had just devastated the northern Bahamas as a Category 3 storm with 120 mph winds, and the National Hurricane Center forecast called for the hurricane remain at Category 3 strength as it plowed over the Outer Banks of North Carolina. Irene was then expected to slowly weaken to Category 1 strength at landfall on the New York/New Jersey coast three days later. Fortunately, Irene surprised forecasters by weakening unexpectedly to a Category 1 storm at landfall in North Carolina, and further weakening to a strong tropical storm with 70 mph winds when it reached New York City on August 28. Even so, Irene did $16 billion in damage, making it the 7th costliest U.S. hurricane in history, and most expensive hurricane ever to hit the Northeast U.S. (until Hurricane Sandy in 2012.)

Figure 1. Tropical Storm Irene, with top winds of 70 mph, was centered almost directly over New York City in this image taken on August 28, 2011.

Figure 2. The European (ECMWF) model is not known for making good intensity forecasts, and is not one of the intensity models the National Hurricane Center uses to make intensity forecasts. Nevertheless, its 4-day forecast of Hurricane Irene making landfall in Delaware as a borderline Category 3/Category 4 hurricane with a central pressure of 936 mb had forecasters like me sweating a bit.

Why did Irene weaken?
Like most intense hurricanes, Irene underwent an eyewall replacement cycle, a process where the inner eyewall shrinks, becomes unstable, and collapses, and is replaced by a new outer eyewall that forms from an outer spiral band. Typically, this process results in a temporary weakening of the storm of 10 - 30 mph in peak winds and 10 - 20 mb in pressure. After about a day, though, the outer eyewall usually grows more organized and contracts, and the storm re-intensifies. Unexpectedly, Irene never completed its eyewall replacement cycle after it left the Bahamas, and the size of the new outer eyewall grew in parallel with an intensification of the hurricane’s outer rain bands. This resulted in the somewhat unusual case where the minimum pressure occurred 40 hours after the winds peaked in intensity. Research accepted for publication last week in the Journal of Atmospheric Science, led by Barry Lynn of The Hebrew University of Jerusalem, "The sensitivity of Hurricane Irene to aerosols and ocean coupling: simulations with WRF spectral bin microphysics", gives partial credit for Irene’s weakening to dust and air pollution sucked in by the storm. These particles (collectively called aerosols) invigorated the outer spiral bands and outer eyewall, and kept the outer portions of the storm strong at the expense of the inner core. Using a high-resolution model that used a 1-km grid to simulate the storm, the researchers were able to show that dust particles from the Saharan Air Layer (SAL) and air pollution particles from the Eastern U.S. could have caused a weakening of Irene’s winds of 20 - 30 mph, accompanied by an increase of 10 - 15 mb in the central pressure, and caused the observed delay of the storm’s lowest pressure occurring 40 hours after the winds peaked. Unfortunately, none of the hurricane intensity models that NHC uses include aerosol particles, or have the fine 1 km resolution used in the Hurricane Irene study. I hope that within a few years, computers will become powerful enough to run such a model in real time for use in operational forecasting.

How do aerosols weaken a hurricane?
Aerosol particles of the right size and composition (called Cloud Condensation Nuclei, CCN) provide convenient places where water vapor can condense and form cloud droplets. An increase in concentration of small aerosols increases droplet concentration and decreases droplet size. The net effect is a decrease in the collision rate to form large raindrops, and a delay in raindrop formation and rain. As a result, small droplets ascend in cloud updrafts and continue growing by condensation, leading to an increase in supercooled water content. When the moisture condenses in these updrafts, it releases extra "latent heat" (the energy it took to vaporize the water originally, which the water vapor stores). This release of energy leads to an increase in cloud updrafts and an increase in cloud top height and lightning. When this process occurs in the outer bands of a hurricane, the resulting invigoration of the thunderstorms there creates heavy rain that drags down cold air from aloft to the surface, creating pools of cold air near the surface that act to block the inflow of warm, moist air into the hurricane's core, thus weakening the storm.

Figure 3. Dry air/Saharan Air Layer (SAL) maps from the University of Wisconsin - CIMSS ( for 18 UTC 21 August 2011 (top) and 00 UTC 24 August 2011. Hurricane Irene crossed a wide band of Saharan dust during its northward movement. Figure 3 (top) shows that Saharan Air Layer dust impinged on Irene in three sectors at 18 UTC 21 August 2011. Fifty-four hours later (0000 UTC 24 August 2011) most of the dust was not observable by satellite, but it was still seen to Irene's north in a cloud-free area (Figure 3, bottom). This indicates that the dust seen at the earlier time was likely absorbed into Irene’s circulation.

Figure 4. Official NHC intensity forecasts for Irene every 6 hours from 1200 UTC 23 August to 0600 UTC 28 August. The black line is the observed intensity of Irene. NHC consistently over-predicted the strength of Irene's winds.

Aerosols are also credited with weakening Hurricane Katrina
According to Khain et al. (2010), ”Aerosol Effects on Intensity of Landfalling Hurricanes as Seen from Simulations with the WRF Model with Spectral Bin Microphysics”, ingestion of aerosols also may have been responsible for weakening Hurricane Katrina as it approached landfall in Mississippi on August 29, 2005. Katrina peaked as a monster Category 5 storm with a central pressure of 902 mb and 175 mph winds about 24 hours before landfall, but weakened to a Category 3 storm with 125 mph winds and a 923 mb central pressure when it came ashore. Up to 35 mph of the wind decrease and 15 mb of the pressure rise could have been due to the storm pulling in aerosol pollution and dust particles from Southern U.S. in the final 24 hours before landfall, the authors deduced, using a detailed computer model of the storm.

Why not use aerosols to intentionally weaken hurricanes?
Since we’re pretty sure that aerosols can help weaken hurricanes, why not intentionally introduce small particles into a hurricane to control its intensity? That was the rationale behind a $1 million study by the Department of Homeland Security between 2009 - 2011, HURRMIT (The Identification and Testing of Hurricane Mitigation Hypotheses). Scientists with the project conducted a number of computer simulations on what would happen to a hurricane by intentionally spraying small aerosol particles into the storm using aircraft. They found that in theory this approach would work, with winds decreasing 20 - 30% for Category 4 and weaker hurricanes. However, the hurricanes had to be treated during an intensification phase to get these reductions in intensity; the effect was significantly less when the simulated storm had completed an intensification cycle and was fully mature. In addition, they found that putting too much aerosol into a hurricane’s outer rain bands thrust more water substance into the thunderstorm anvils, lowering storm precipitation efficiency and short-circuiting the reduction in surface winds.

It is quite possible that seeding a hurricane with aerosol particles can actually make the storm more intense, though. The authors of the Hurricane Irene study commented that if aerosols can manage to penetrate directly to the core of a hurricane, they can act to invigorate the inner eyewall and make the storm stronger. In addition, putting aerosols into a tropical depression in its formative phase can help it, since the storm typically needs an extra boost in cloud droplets to get going (however, the dry air that often accompanies aerosols from the Saharan Air Layer often destroys a budding tropical depression.) So, we’d better be really sure we know what we’re doing if we are going to be intentionally messing with hurricanes. I am very sure that we are not really sure, and that we should leave hurricanes alone for the foreseeable future!

Related: my 2009 blog post, Bill Gates Takes on Hurricanes.

The next post will be Thursday at the latest.

Jeff Masters

California Rainy Season Ending; January-April rain in San Francisco Lowest on Record

By: Jeff Masters , 2:44PM,GMT on April 30,2015

The fourth consecutive severely dry California rainy season is drawing to a close. Rain-bearing low pressure systems typically stop bringing heavy rains to the state by mid-April, as the jet stream shifts to the north in its usual springtime migration. With almost no rain in the forecast for the next seven days, and the 16-day GFS model forecast showing mostly light rains affecting the northern portion of the state 8 - 16 days from now, California has likely seen over 95% of the precipitation that it’s going to get this anemic rainy season. What little precipitation did fall this winter came mainly in the form of rain, thanks to record-warm ocean temperatures off of the coast. This resulted in snow falling only at very high elevations, keeping the critical Sierra snowpack--which provides one-third of the state's water--at record low levels. According to the California Department of Water Resources, snow depths in the Sierras are the lowest on record for this time of year, only 2% of average, and the Southern Sierras have no snow at all--nearly three months earlier than usual. California's eight largest reservoirs are 30% - 83% below their historical average, and the portion of the state covered by the highest level of drought--"Exceptional"--was at 47% this week. The area covered by "Exceptional" drought peaked at a record 58% during the summer of 2014, and this mark may well fall during the summer of 2015.

Figure 1. Aerial view showing recreational boats by the Bidwell Marina at Lake Oroville, California on March 2, 2015. Lake Oroville, California's 2nd largest reservoir, was at 62% of average on April 29, 2015, which was its third lowest level since 1989. Image credit: California Department of Water Resources.

Record dryness in San Francisco
According to wunderground weather historian Christopher C. Burt, with just 1.30” of precipitation in downtown San Francisco this April and no chance of any additional rain to the end of the month, the January-April period will have a total of only 2.89”--easily the lowest on record, and well below the approximately 11.5" of rain the city usually gets. San Francisco got no rain at all in January, the first January on record that has occurred. Here is a list of the top ten driest Jan-April periods on record since 1850 in San Francisco:

1.   2.89” 2015
2.   3.54” 2013
3.   3.68” 1898
4.   4.01” 1976
5.   4.43” 1851
6.   4.75” 1972
7.   4.92” 1862
8.   4.92” 1864
9.   5.08” 1984
10. 5.11” 1977

Figure 2. Predicted precipitation for the 7-day period ending on Thursday, May 7, 2015. With the exception of light rains in the Sierras, California will be dry this week. Image credit: NOAA/HPC.

The long-range forecast: hot, dry, and more intense drought
The latest 3-month outlooks from NOAA's Climate Prediction Center, private forecasting firm WSI, and Columbia University's International Research Institute for Climate and Society all call for above-average chances of hotter than usual weather in California though July, and the U.S. Seasonal Drought Outlook calls for drought to persist or intensify over California. This should be no surprise, given that ocean temperatures along the coast of California are at record or near-record levels for this time of year, and will be slow to change. These record warm ocean temperatures will drive hotter weather and more intense drought this summer than otherwise would occur, and this summer's fire season will likely be severe. Next winter, California has a decent chance of getting a better rainy season, if the current El Niño event manages to intensify into a strong one (an event predicted by several of our better El Niño models.) Still, the Sierras need 1.7 - 2.9 times more precipitation than a usual rainy season brings to bust the drought; some portions of the state need even more than that.

Figure 3. Ocean temperatures off the coast of California were at record or near-record levels for this time of year on April 29, 2015. Ocean temperatures off the coast of Los Angeles and San Diego were more than 4°C (7.2°F) above average, an astonishingly high anomaly. These high temperatures were due to a combination of effects: a very persistent ridge (the Ridiculously Resilient Ridge, or RRR) that has been in place along the West Coast much of the past three years, bringing warm air temperatures and little mixing of cool waters from the depths; a positive phase of the Pacific Decadal Oscillation (PDO), a decades-long natural pattern; and global warming, which has warmed oceans world-wide over the past century-plus. Image credit: NOAA Environmental Modeling Center.

Portlight disaster relief charity raising funds for Nepal earthquake relief
The disaster relief charity, founded and staffed by members of the wunderground community, has connected with disability stakeholders in Nepal, India and Pakistan to seek their input on how best to help our brothers and sisters affected by their devastating earthquake. Portlight has determined that they can be of the most service by raising funds to directly support the relief and recovery efforts of these and other in-country stakeholder organizations. You can donate to this effort at this link:

You can follow the progress of the relief effort on the Portlight Blog. Thanks!

FYI, we are having some technical issues with some of the blog comments disappearing, and are looking into the cause.

Jeff Masters

Nepal Earthquake Shrank Mount Everest, Lifted Areas Near Kathmandu 3 Feet

Sean Breslin
Published: April 30,2015

Nepal's massive 7.8-magnitude earthquake transformed the land that was shaken by the natural disaster, pushing areas near the city of Kathmandu higher in elevation and making Mount Everest slightly shorter.
It won't be enough to unseat Everest as the world's tallest peak, but according to studies performed after last weekend's temblor, the mountain is now an inch shorter than before the quake. On the other hand, some locations just outside Nepal's capital city of Kathmandu were lifted 3 feet higher than before the tragic event, the study also found.
These findings were discovered by Europe's Sentinel-1a radar, which passed over the affected areas and scanned the differences in terrain, compared to previous scans before the disaster. The result is a beautiful map where each 1-inch shift in the land is represented by a bright color. As you can see below, the quake caused nearly the entire region to shift.
(MORE: Baby Rescued From Rubble 22 Hours After Quake)
Kathmandu is located at the bottom-center of this scan.
(ESA SEOM InSARap Study – Norut/PPO.labs/Univ Leeds)

The colorful map that results from these scans is called an interferogram, reported. The maps will be refined in the coming days, but the initial scans give scientists a chance to map the damage and landslides created by the quake, the report added.
Tim Wright, geophysicist at the University of Leeds in the U.K., told Live Science that the region lifted by the earthquake was some 75 miles long by 30 miles wide. The biggest lift occurred just 10 miles outside of Kathmandu, he added, which contributed to the widespread damage in the city.
Geoscience research consortium UNAVCO confirmed the 1-inch shrink in Everest to Live Science, explaining that the mountain's slump occurred when the crust relaxed in areas north of the epicenter when the Earth released strain following the quake. On the other hand, the report added, the Himalayas are rising about four-tenths of an inch every year, so the deficit won't last long.
More than 6,000 people were killed and at least 11,000 were injured when the large earthquake struck on Saturday, collapsing hundreds of buildings and forever transforming poorly-built areas of Kathmandu and surrounding towns.
MORE: Images of the Nepal Quake

This Date in Weather History for April 30,2015 from

Weather History
For Thursday,April 30,2015
1852 - A tornado, following the same track as the famous "Tri-state Tornado" of 1925, struck the town of New Harmony IND. Just sixteen persons were killed by the twister, due to the sparse settlement. The "Tri-state Tornado" killed 695 persons. (David Ludlum)
1953 - A tornado 300 yards in width leveled homes on the north side of Warner-Robins GA, and barracks on the south side of the Warner-Robins Air Force Base. (The Weather Channel)
1987 - Thunderstorms developing along a cold front produced severe weather in Idaho, Utah, Wyoming and Montana. Thunderstorms produced wind gusts to 100 mph in Lincoln, Mineral and Sanders counties. Twenty-three cities in the central and southeastern U.S. reported record high temperatures for the date. Memphis TN was the hot spot in the nation with a record high of 94 degrees. (The National Weather Summary) (Storm Data)
1988 - A cold front produced high winds in the southwestern U.S. Winds gusting to 90 mph in southwestern Utah downed power lines, and damaged trees and outbuildings. The high winds also downed power lines in Nevada, completely knocking out power in the town of Henderson. (The National Weather Summary) (Storm Data)
1989 - Thunderstorms produced severe weather in central and eastern Texas. Hail three inches in diameter was reported at Cool, and thunderstorm winds gusted to 80 mph at Hillsboro. For the first time of record Oklahoma City went through the entire month of April without a single thunderstorm. (The National Weather Summary) (Storm Data) (The Weather Channel)
1990 - Late afternoon and evening thunderstorms produced severe weather in southern Virginia and the Carolinas, with tennis ball size hail reported southeast of Chesnee SC. Thunderstorms moving over the Chesapeake Bay flooded U.S. Highway 50 on Kent Island MD with several inches of water resulting in a seventeen-mile long traffic jam. (The National Weather Summary) (Storm Data)

'Eruptive Pulse' of Chile's Calbuco Volcano Forces Evacuations

By Miguel Perez, AccuWeather En Español Staff Writer
April 30,2015; 10:57PM,EDT
Following back-to-back, major eruptions of the Calbuco volcano in southern Chile, which occurred for the first time in 42 years on April 22, the volcano registered a third eruptive pulse, or an explosive eruptive plume, Thursday.
According to CIMAT - Early Warning Monitoring Information Center, Calbuco registered the third pulse of the eruption and forced preventive evacuations in the affected area.
"Unlike eruptions last week, winds above the volcano will not direct the ashes to Buenos Aires or Santiago after the current eruption," Meteorologist Jim Andrews said.
"On the contrary, winds lead the ash to the east and southeast of the volcano through Friday morning."

Through a new report issued this afternoon, the National Emergency Office (Onemi) gave details on the number of evacuees and the effects the new eruptive pulse produced.
Solid activity increased at 1:09 p.m., Chilean time, according to the National Service of Geology and Mining (Sernageomin).
From a central mass of the volcano, a column of gas, consisting of steam and pyroclastic material was expelled.
Due to increased Calbuco's volcanic activity, Onemi said it was necessary to evacuate people who were in an exclusion zone around 20 kilometers.
Evacuees are residents of areas including Correntoso, Chapo Lake, Inlet, Colonia Tres Puentes and Waterfall. All were away from high-risk areas, according to the report.
"If the volcano is still spewing ash on Friday night and on the weekend, a change in wind direction could then carry the ashes to Buenos Aires and thus cause flight delays." Andrews added.
According to recent information from the National Geology and Mining (Sernageomin) of Chile, the plume of Calbuco Volcano is low.
Likewise, with respect to weather conditions in the area, Senior Meteorologist Kristina Pydynowski said the situation could change as some showers passengers will be presented later Thursday night and shaping a stable band of rain during the first part of Friday.
In this Thursday, April 23, 2015 photo, the Calbuco volcano erupts near Puerto Varas, Chile. The volcano erupted for the first time in more than 42 years, billowing a huge ash cloud over a sparsely populated, mountainous area in southern Chile. (AP Photo/David Cortes Serey/ Agencia Uno)
"Rainfall amounts are about 0.50 of an inch (12 mm) and may be extended until the afternoon," she said.

Showers, Spotty Storms to End Week From Pittsburgh to DC

By Jordan Root, Meteorologist
April 30,2015; 10:54PM,EDT
Two storms will combine to bring clouds, areas of rain and thunderstorms to the mid-Atlantic into the end of the week.
A storm aloft dropping in from the Midwest and a surface storm near the North Carolina coast will combine forces.
Temperatures in the upper 60s and 70s and the sunshine that was experienced at midweek across the region will be replaced with clouds, showers and highs only in the 50s to low 60s by Friday.
"The weather has certainly been up and down in the Northeast this April, and that trend is expected to continue," said Meteorologist Evan Duffey.
As typical this time of the year, a roller-coaster weather pattern can bring large swings in the weather over the course of a few days.

Pittsburgh, Washington, D.C., Baltimore, Philadelphia, and Allentown, Pennsylvania, will experience a sharp turnaround in weather conditions as the end of the week approaches.
The coastal storm will cause a stiff wind to develop from northeastern North Carolina to southeastern Virginia and Delmarva by Friday. Seas will build offshore with locally rough surf possible on the beaches.
The heaviest and steadiest rain with this surface storm will remain off the coast, eliminating the threat of a washout either day. However, clouds, showers, and pockets of drizzle will occur across the region into Friday.
Farther inland across the eastern part of the Ohio Valley, Appalachians and mid-Atlantic, the storm aloft will bring the risk for heavier showers and thunderstorms into Thursday night.
These storms are not expected to be severe but could bring drenching downpours and even small hail in some cases.
Interactive Radar
AccuWeather MinuteCast® For Your Exact Location
US Summer Forecast: Northeast to Endure More 90-Degree Days Than in 2014

According to Meteorologist Elliot Abrams, "little or no rain should reach Philadelphia or New York City, but an increase in cloudiness [and] a decrease in temperature appear likely."
The majority of the showers will stay south and west of New England during the dual storm event.
Any outdoor activities such as baseball games or outdoor picnics from southern and western Pennsylvania and southern New Jersey to Virginia and northeastern North Carolina could be disrupted.
Folks will want have sweatshirts and jackets handy along with an umbrella for Friday. A thick cloud cover will help to bring the coolest day across the region this week. There will also be a risk for a few showers across the region.
High temperatures will likely remain in the 50s across New England with 60s near the Appalachians.
"Temperatures on Friday will be around 10 degrees below normal," said Duffey.
While Friday will be the worst of the two days along part of the mid-Atlantic coast, the weather will begin to improve farther west. In fact some sunshine is in the offing for the Ohio Valley to part of the lower Great Lakes region.
If possible, outdoor activities in the mid-Atlantic should be put on hold until the weekend. The coastal disturbance is expected to pull away from the coast on Saturday.
"The clouds will give way to sunshine and it will start to turn warmer," added Abrams.
Chilly mornings over the weekend will give way to comfortable afternoons. Those heading outside later in the day Saturday or Sunday across New England will feel temperatures in the mid to upper 60s while people farther south in the mid-Atlantic will have temperatures in the 70s.

A warming trend is in store for next week.

Severe Storms to Ramp Up in Central US Next Week

By , Senior Meteorologist
April 30,2015; 10:51PM,EDT
After a several-day lull in severe weather, the risk of damaging and dangerous storms is forecast to ramp up in the Midwest and northern Plains and return to Texas and the southern Plains early next week.
The expanding risk of severe weather could not only bring disruptions to ballgames and agriculture in the region, but could have significant consequences for travel and pose risks to lives and property.
Almost summerlike warmth will build over much of the Central and Eastern states ahead of an approaching storm system this weekend into early next week.
A cool front dropping in from Canada will lift that warm air over part of the northern Plains and the Upper Midwest, leading to showers and thunderstorms Sunday into Monday.
AccuWeather Summer 2015 Forecast
Sunshine, Warmth to Prevail for 2015 Kentucky Derby
AccuWeather Allergy Forecast Maps

The storms can first become severe from parts of central and southern Minnesota to central and northern Wisconsin later Sunday afternoon. The storms will bring the potential for large hail and damaging wind gusts. The risk of severe weather may include the Minneapolis area.

As the front sags southward, the threat of severe thunderstorms will dip into portions of Iowa, southern Wisconsin and perhaps part of the lower Michigan Peninsula Sunday night into Monday. Locally severe storms are possible in Des Moines, Iowa, and Milwaukee, Wisconsin. Storms could reach as far south as Chicago and as far east as Detroit.
The main event of severe weather next week will begin over parts of western Texas and the southern High Plains on Monday.

According to Paul Pastelok, chief long-range meteorologist, "Unlike the last severe weather event which pushed eastward over the Deep South, the severe weather next week will expand northward and northeastward over the Plains and part of the Midwest."
Weather systems will not progress quickly from west to east across the nation next week.
"A potential tropical or sub-tropical system along the east coast of Florida could help create an atmospheric traffic jam, forcing warmth to build from the Mississippi Valley to the Ohio Valley and much of the Northeast," Pastelok said.
Severe storms may fire on the rim of the warmth from west-central Texas to as far north as Illinois on Tuesday.
The atmospheric traffic jam could result in a large south-to-north swath of severe weather by Wednesday.
According to Meteorologist Becky Elliot, as a storm system attempts to move out of the Rockies and into a zone of building warmth and humidity, severe weather could become very extensive on Wednesday.
"Strong to locally severe storms could fire from Texas all the way to North Dakota and Minnesota," Elliot said.
Just as the development of the tropical system have to be monitored for impact on Florida and part of the southern Atlantic Seaboard, so will the expanding risk of severe weather next week for Texas, the Plains and Midwest. The severe weather threat next week could encompass an area of more than 1,000 miles.
It is too early to say if the outbreak of severe weather will include a significant number of tornadoes, but there are likely to be a number of storms with strong wind gusts and hail. Where storms repeat, there will be the potential for flash flooding.

PHOTOS: People Flock to See Kilauea Lava Lake as it Rises to Record Heights

By Michael Kuhne, Staff Writer
April 30,2015; 10:49PM,EDT
Earlier this week, a lava lake churning within a crater near the summit of Hawaii's Kilauea Volcano rose to record heights, offering visitors a rare glimpse of molten lava splattering above the vent rim before it overflowed late Tuesday night.
Visitors have been flocking to see the breathtaking spectacle, according to the Hawaii Tribune Herald.
"The lava lake has existed since 2008, but has been deep within the Overlook crater and not visible from overlooks in Hawai'i Volcanoes National Park," USGS Hawaiian Volcano Observatory Spokeswoman Janet Babb said.
Visitors to Hawai'i Volcanoes National Park can see the lake surface, and molten lava spattering above the vent rim for the first time since its formation, according to USGS.
Place your cursor over the image to see the lava lake rise. Kīlauea Volcano's summit lava lake, which was about 40 feet below the vent rim on April 25, overflowed for the first time at about 9:40 p.m., HST (Photos/USGS Hawaii Volcano Observatory)
The lava lake, which is located within the Overlook crater, one of Kilauea's two active vents, has risen about 25 meters (82 feet) since April 22. On Tuesday April 28, the lava lake overflowed the vent rim for the first time at about 9:40 p.m. HST, USGS reported.
As of noon on Wednesday, the lava lake had overflowed the vent rim several more times.
While the lava has fluctuated since the lake formed, for much of the past year, the level was approximately 30-60 meters below the vent rim.
It had risen to about three to four meters, or 10 feet, below the vent rim as of Tuesday, which was the highest level USGS has measured since the summit eruption began in March 2008, according to Babb.
First Calbuco Eruption in 42 Years Suspends Flights in Buenos Aires
WATCH: Explorers Dangle Over Volcano's Molten Lake of Lava
WATCH: Increased Activity Recorded From Nevado Del Ruiz Volcano

Place your cursor over the image to see the lava lake rise. The Overlook crater lava lake level was 55 m (180 ft) below the vent rim on March 18. On April 26 the lava lake level had risen to 3 m (10 ft) below the vent rim. (Photos/USGS Hawaii Volcano Observatory)
"Now that the lake has risen, it can be seen from park overlooks, such as the one at Jaggar Museum," Babb said.
"Overflow of lava will remain in Halema`uma`u Crater and will not pose a threat to people."
It is possible the lake will return to lower levels in the near future.
(Photo/USGS Hawaii Volcano Observatory)
"We identified paths of steepest descent for the lava flows on Kilauea's East Rift Zone, which helped us forecast where the active lava might go."
The summit lava lake is not connected to the East Rift Zone lava flow that moved toward Pahoa in 2014.
Lava flowed almost 14 miles toward the community of Pahoa, which is located in the Puna District on the Island of Hawaii.
(Photo/USGS Hawaii Volcano Observatory)
A rockfall from the wall of Halema'uma'u Crater impacted the lava lake Tuesday, triggering an explosion of spatter and smaller particles.(Photo/USGS Hawaii Volcano Observatory)
(Photo/USGS Hawaii Volcano Observatory)
(Photo/USGS Hawaii Volcano Observatory)
(Photo/USGS Hawaii Volcano Observatory)
(Photo/USGS Hawaii Volcano Observatory)

Global Saskatoon
Whoa, talk about a hot tub! A lava lake has risen to record heights at Hawaii's Kilauea Volcano
Bill Nigh
MT @CNNJason: The lava lake at Kilauea Volcano in Hawaii is overflowing for 1st time in a century #CNN
@CBSThisMorning WATCH: Amazing #video of a lava lake on #Hawaii's Big Island where bubbling molten rock has risen to its rim.
Kilauea Volcano's Lava Lake Overflows |
😃Sweet RT@APP VIDEO A lake of lava at Hawaii's Kilauea volcano overflows, providing viewers with a spectacular show
Kilauea Volcano's Lava Lake Overflows 6.8 magnitude earthquake hits near Kokopo, Papua New Guinea 5.8 magnitude...
Yikes, glad I saw this lava before today's news! Kilauea Volcano's Lava Lake Overflows (Video)… via @YahooNews
Marioto? RT @AP A lake of lava at Hawaii's Kilauea volcano overflows, providing viewers with a spectacular show:
Incredible lava lake puts on a show at the summit of Kilauea Volcano in Hawaii:
For volcano buffs and Big Island residents: Kilauea lava lake spills over Halema'uma'u Crater…
#Reuters reports: Lava flows from Hawaii's Kilauea volcano - A bubbling lava lake in Hawaii overflows for the firs...