Monday, June 8, 2015

Tropical Storm Blanca Landfall Is Record Earliest in Baja California; Moisture to Fuel Early Desert Southwest Storms (FORECAST)

Jon Erdman
Published: June 8,2015




 

Highlights

  • Tropical Storm Blanca made landfall near Puerto Cortes, Mexico around 5 a.m. PDT Monday, the earliest tropical cyclone landfall date on record in Baja California.
  • Blanca was downgraded to a tropical depression early Monday afternoon; all coastal watches and warnings have been discontinued.
  • Although the center of circulation is now inland, pockets of heavy rain will persist into Tuesday in portions of Baja California.
  • Blanca is expected to degenerate into a remnant area of low pressure early Tuesday.
  • Moisture from Blanca will push into parts of the U.S. Desert Southwest in earnest beginning Tuesday.

Latest Status

Projected Path

Water Vapor Satellite














































Tropical Storm Blanca's center made landfall in the southern Baja California peninsula near the town of Puerto Cortes early Monday with maximum sustained winds estimated at 45 mph.
(INTERACTIVE: Latest Satellite Loop)
Blanca became the earliest-in-season tropical cyclone to make landfall in the Baja peninsula. According to NOAA's database, only one other pre-July 1 tropical cyclone tracked within 150 nautical miles of the southern Baja peninsula, a Jun. 14, 1958 Category 1 hurricane whose center passed just south of Los Cabos.
Blanca was downgraded to a depression Monday afternoon, and all watches and warnings along the coast were dropped at that time.
(MORE: Hurricane Season Outlook | Hurricane Central | Tropical Update)
Sustained winds reached 46 mph in Cabo San Lucas International Airport late Sunday afternoon. Winds gusted to 40 mph in La Paz, Mexico on the eastern edge of the Baja peninsula early Monday.
As of late Monday morning, up to 5.18 inches of rain was measured unofficially in Loreto, Mexico.
Overnight Saturday night, as Blanca made its closest approach, an automated station on Socorro Island recorded a peak sustained wind of 74 mph and gust to 101 mph. Socorro Island is a volcanic island about 290 miles south-southwest of Cabo San Lucas.

A Desert Southwest Moisture Surge

The story does not end in Baja California.
A somewhat strange early June pattern will deliver some early-season leftover moisture to parts of the Desert Southwest.

Rainfall Forecast
A closed area of low pressure aloft off the California coast, together with a dome of high pressure aloft over northern Mexico will set up a pipeline of moisture from the Gulf of California, Baja, and eastern Pacific into parts of the Desert Southwest and Rockies early this week.
The upshot of all this is an increasing threat of rain and thunderstorms in the Desert Southwest and southern Rockies, along with a more humid air mass than one would normally expect in early June.
(MORE: How Eastern Pacific Hurricanes Can Impact the U.S.)
Given the potential tropical moisture feed, locally heavy rain and flooding of normally dry washes and arroyos are possible.
(FORECASTS: Phoenix | Tucson | Grand Canyon)
This enhanced thunderstorm threat appears to kick in starting Tuesday in parts of Arizona and New Mexico, then spreads northward into the Great Basin, central and southern Rockies Wednesday. A few thunderstorms are even possible over the mountains and high desert of Southern California, as well as the Sierra.
That moisture may linger and fuel additional scattered thunderstorms Thursday in the Wasatch, Tetons and high country of Colorado and northern New Mexico.
(MAPS: Weekly Planner 7-Day Forecast)
In most years, the wet phase of the North American monsoon, a much weaker version of the more famous Indian/Asian monsoon, imports increasing moisture into the Desert Southwest and northwest Mexico by mid-July.
As a result, thunderstorms fire up most afternoons and evenings, particularly over the higher terrain of the Desert Southwest.
Prior to that, it is typically extremely hot and dry in June.
June is the driest month, on average, in Phoenix, where a paltry 0.02 inches is typically measured at Sky Harbor Airport. The record daily rainfall during the first 11 days of June is only 0.41 inches, recorded 100 years ago on June 3, 1915.
But thanks to that moisture plume from former Hurricane Andres, Phoenix recorded 0.16 inch of rain Friday – the first time Arizona's capital has ever recorded measurable precipitation on June 5 since records began in 1895.
Average rainfall increases by a factor of 52 in July, their average wettest month (1.05 inches).

Blanca's History

Blanca's intensity has fluctuated up and down over the past week, at times allowing it to strengthen into a formidable hurricane.
Blanca rapidly morphed into a major hurricane off the Mexican Pacific Coast, reaching Category 4 status on June 3. This made Blanca the earliest-in-season second major hurricane – Category 3 or stronger – of record in the eastern Pacific basin dating to 1971.


View image on Twitter
has rapidly intensified into a Category 4 off the Mexico coast. Details: http://wxch.nl/1ANNxF1 

Blanca then weakened to a Category 1 hurricane late in the week due to the storm's ingesting of dry air to its north, as well as replacing its eyewall - known as an eyewall replacement cycle, which all intense tropical cyclones do - and churning up slightly cooler water while essentially standing still for 3 days.
Blanca was then able to take advantage of an environment that featured low wind shear and deep, warm waters which fueled the system again on Saturday as it moved to the northwest. As a result, Blanca strengthened to Category 4 status once again.
Late Saturday into early Sunday, Blanca began its final weakening phase as it encountered cooler water temperatures and unfavorable winds aloft along its path, and the cyclone eventually weakened into a Category 1 hurricane Sunday morning before diminishing to a tropical storm Sunday afternoon.
Less than nine months ago, Category 3 Hurricane Odile plowed into Mexico's southern Baja peninsula, including popular tourist destinations in Los Cabos.
Odile was the strongest hurricane strike the region had taken since 1989 and tied the strongest landfall of record, there. Over $1 billion (12 billion pesos) in insured losses was attributed to Odile.

MORE: Hurricanes By the Numbers (PHOTOS)

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