Published: June 6,2015
Highlights
- After a quick strengthening burst Saturday morning, Blanca has since weakened yet again Saturday night, and as of the 11 p.m. EDT advisory, Blanca is a Category 3 hurricane packing 120 mph winds.
- The government of Mexico has issued watches and warnings for parts of Baja California including a hurricane watch from Cabo San Lucas to Santa Fe and a tropical storm warning from Loreto to Puerto San Andresito, including Cabo San Lucas. A tropical storm watch is also in effect from north of Puerto San Andresito to Punta Abreojos, as well as north of Loreto to Mulege.
- Blanca will track toward Mexico's Baja California peninsula, including the Los Cabos area, late this weekend.
- The exact track of the center and intensity relative to Los Cabos, which will determine impacts there, remains somewhat uncertain.
- Blanca will likely weaken to a tropical storm before it makes its closest approach to Los Cabos on Sunday.
- Moisture from Blanca may push into parts of the U.S. Desert Southwest next week.
(MORE: Hurricane Season Outlook | Hurricane Central | Tropical Update)
Latest Status
Projected Path
Current Tropical Storm Watches and Warnings
Eastern Pacific Sea-Surface Temperatures
Blanca then weakened 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.
(INTERACTIVE: Latest Satellite Loop)
Despite this weakening trend, Blanca was able to take advantage of an environment that featured low wind shear and deep, warm waters which fueled circulation. As a result, Blanca regained strength and is now a Category 4 hurricane, moving towards the northwest at 10 mph.
Blanca became the earliest-in-season second major hurricane – Category 3 or stronger – of record in the eastern Pacific basin dating to 1971.
On average, this second major hurricane of the season occurs by Aug. 19, according to the National Hurricane Center.
"By the end of this past week, the amount of energy achieved in two weeks in the eastern Pacific – Blanca and Andres – will likely exceed the amount of energy for the entire 2013 Atlantic hurricane season," said hurricane specialist Michael Lowry.
Unlike the former Hurricane Andres, Blanca isn't headed into the open waters of the eastern Pacific.
How big of a threat is this to Baja California?
Strange Early Baja Threat
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.
Now, the southern Baja peninsula lies in the forecast path for Blanca, and the storm is forecast to impact the Peninsula as early as Sunday morning.
That may sound ominous, but here are some things to keep in mind.
1) Blanca is forecast to weaken before approaching Baja California because of increasing wind shear, drier, more stable air and a track over cooler ocean water. This weakening may occur quickly.
2) The average track error of a 72-hour forecast in the eastern Pacific basin is about 115 statute miles, according to the National Hurricane Center. With a small hurricane-force wind field – one likely to vanish as Blanca eventually weakens to tropical storm strength – this can make a huge difference in impacts.
Residents and tourists in the southern Baja peninsula, including Los Cabos, should have already began preparing for Blanca, and they should continue to finalize preparations for the potential of tropical storm conditions.
Regardless of the final path, high surf and swells generated from Blanca – and leftovers from Andres – will affect the Mexican Riviera and west coast of the Baja peninsula. Dangerous rip currents are likely. These swells will likley also reach the beaches of Southern California, as well, this weekend.
Heavy rainfall is also likely with 6 to 10 inches expected over much of Baja California Sur and the southern portion of Baja California, with isolated totals up to 15 inches. The heavy rain may produce life-threatening flash floods and mudslides.
According to NOAA's database, only one other pre-July 1 tropical cyclone tracked within 65 nautical miles of Cabo San Lucas, Mexico, a Jun. 14, 1958 Category 1 hurricane whose center passed just south of Los Cabos.
A Desert Southwest Moisture Surge?
The story does not end in Baja California.A somewhat strange early June pattern may deliver some early-season leftover moisture to parts of the Desert Southwest.
Potential Setup Early Next Week
A closed area of low pressure aloft over Southern California is weakening, but building southwestward.
Together with a dome of high pressure aloft over the Rio Grande Valley of Texas, a pipeline of moisture may be pulled north from the Gulf of California, Baja, and eastern Pacific into parts of the Desert Southwest and Rockies early next week.
Interestingly, before that happens, that California low is also pulling some upper-level moisture from Andres into the Desert Southwest.
The upshot of all this is an increasing threat of thunderstorms in the Desert Southwest and southern Rockies – parts of California, Nevada, Arizona, New Mexico, Colorado, Utah – 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.
Where thunderstorms will be most numerous and areas with the highest chance of flash flooding remains uncertain, dependent on both the final path of Blanca and the exact configuration of steering winds aloft.
(FORECASTS: Phoenix | Tucson | Grand Canyon | Albuquerque)
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).
The National Weather Service in Grand Junction, Colorado, noted late Tuesday night that atmospheric moisture values this weekend over Grand Junction could be near a record for early June.
Here's climatology of precipitable water since 1948. Near-record moisture possible this weekend! #utwx #cowx
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