California fires and global warming; 90L lashes Puerto Rico
A surface low pressure system (90L) moved over Puerto Rico this morning, and is now centered just west of the island. The surface low is entangled with an upper-level low pressure system that is bringing about 30 knots of wind shear, so no development is likely today. Long range radar of of Puerto Rico shows isolated bands of heavy rain that are not well-organized. Satellite loops show most of the heavy thunderstorm activity is to the east of the low's center of circulation, and the high wind shear is keeping this thunderstorm activity disorganized. This morning's QuikSCAT pass showed a large, vigorous circulation. Top winds were about 30 mph to the north of the center, and 90L is close to tropical depression status.
Figure 1. Latest satellite rainfall estimate of 90L.
The surface low is separating from the upper level low today, and will move west-southwest at about 10 mph. This will bring heavy rains and the threat of flash flooding and mudslides to Puerto Rico. Heavy rains of 2-4 inches in just two hours hit the Virgin Islands this morning (Figure 1), prompting flash flood warnings there. Heavy rains also hit many of the islands of the northern Lesser Antilles. Rain amounts as high as 3-5 inches are expected today over eastern Puerto Rico. Several mudslides have already been reported on the island.
The action shifts to the Dominican Republic on Saturday and Haiti on Sunday, as 90L tracks just south of the island of Hispaniola. These nations can expect rains of 3-6 inches, which could trigger life-threatening flash floods and mudslides. It is possible 90L could intensify into a tropical depression on Sunday, as wind shear will slowly fall to 20 knots. The Hurricane Hunters are on call to fly Sunday afternoon, if necessary. On Sunday, 90L will be approaching Jamaica, and the ECMWF and NOGAPS models predict that wind shear will drop to 10-20 knots. These models develop 90L into at least a strong tropical storm as it moves slowly into the Western Caribbean. The GFS model keeps wind shear 20-30 knots through the period, and does not develop 90L. The HWRF model also does not develop 90L. The GFDL is not keen on developing the system either, but does suggest that a weak tropical storm may form a week from now. I believe the most reasonable solution is the NOGAPS and ECMWF solution, and 90L will intensify into hurricane in the Western Caribbean late next week. The long-term path of such a storm is very uncertain, with the NOGAPS and ECMWF suggesting a track north into the Gulf of Mexico to threaten the U.S., and the GFDL predicting 90L will get trapped in the Western Caribbean and perform a counter-clockwise loop. If you have travel plans that take you to Jamaica or the Cayman Islands Sunday through Tuesday, or Cancun/Cozumel/Western Cuba Tuesday through Saturday next week, be prepared for the possibility of disruptions.
California's smoke
The worst of the air pollution hazard from California's fires has now passed. The smoke has thinned some, as seen on satellite images (Figure 2). The smoke made it yesterday to Fresno, in California's Central Valley, and is moving northward into Nevada and northwest Arizona today. Most of this smoke is aloft at altitudes of about 15,000 feet, but some mixing down to the surface has occurred, thanks to an upper-level low pressure system. Increases in particulate matter pollution due to smoke are expected to affect Las Vegas this weekend (Figure 1). However, the smoke will be dilute enough to keep pollution levels in the Moderate range--below the federal air quality standard.
Figure 2. Visible satellite image at 11:15 am PDT Thursday October 25, showing thinning smoke over the Pacific Ocean and much of California. Low stratus clouds are visible over the ocean, and these clouds have moved ashore into Los Angeles and San Diego this morning, triggering Dense Fog Advisories. Image credit: NASA and EPA.
Were the California fires worsened by global warming?
Dr. Ricky Rood points out in his latest wunderblog that the California fires were mostly a land-use and land-management issue. In a previous blog, he had this to say about the link between climate change and Western U.S. fires:
We do know that drought and floods, heat waves and cold snaps are all part of nature. Like the problem of urban heat waves, we have an event that already exists, and there should be a change associated with global warming. I have already mentioned that some studies have attributed the pinyon pine die off in the U.S. Southwest to the fact that the temperature in the recent drought years is higher than in previous droughts. Therefore, ground water is reduced; there is more stress on the plants. (And perhaps it is really the warmer nighttime temperatures that matter?)
There have also been papers which make a compelling argument that wild fires in the western U.S. are increasing in intensity and duration. In the paper of Westerling et al. (Science, 2006), the conclusion is drawn that this is directly related to snow melt occurring earlier in the year, a hotter and drier forest, and hence, a longer burning season. Plus they isolate the impact to be at mid-elevations in the Rockies, and hence, relatively free of land-use changes. While many newspapers reported that this work showed an increase of wild fires due to climate change, I quote directly from their paper: "Whether the changes observed in western hydroclimate and wildfire are the result of greenhouse gas-induced global warming or only an unusual natural fluctuation is beyond the scope of this work".
Jeff Masters
Reader Comments
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Indeed they do - upwelling - they pull the cooler water from below to the surface.
Alright... Have a question of the night. Does a Hurricane actually cool down the Sea Surface Temperature as it passes a given area?
Action: | Ignore User
Yes, But only a small area, and it doesent cool it down much. This is often called a Cold Water Trail left by obviously hurricanes. Hope i helped.
Covection seems to have expanded to the east tonight...
In addition convection seems to be consolidating a little more.
No - In fact a strong storm that sits in the same place too long can weaken because it pulls cooler water to the surface. Hurricanes must have warm water.
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1030 PM EDT FRI OCT 26 2007
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE BROAD AREA OF LOW PRESSURE OVER THE EASTERN CARIBBEAN SEA IS NOW
CENTERED ABOUT 175 MILES SOUTH-SOUTHEAST OF SANTO DOMINGO IN THE
DOMINICAN REPUBLIC. THIS SYSTEM HAS SLOWED ITS FORWARD MOTION THIS
EVENING AND IS NOW MOVING WEST-SOUTHWESTWARD AT 10 TO 15 MPH. THE
ASSOCIATED SHOWER ACTIVITY REMAINS DISORGANIZED AND UPPER-LEVEL
WINDS ARE CURRENTLY NOT FAVORABLE FOR DEVELOPMENT. THE LOW IS
EXPECTED TO MOVE GENERALLY WESTWARD AND TROPICAL CYCLONE
FORMATION...IF ANY...IS NOT EXPECTED UNTIL THE SYSTEM REACHES THE
WESTERN CARIBBEAN SEA IN A COUPLE OF DAYS. SHOWERS AND SQUALLS ARE
EXPECTED TO CONTINUE OVER PORTIONS THE VIRGIN ISLANDS...PUERTO
RICO...AND HISPANIOLA.
AN AREA OF DISTURBED WEATHER ASSOCIATED WITH A BROAD TROUGH OF LOW
PRESSURE CONTINUES OVER THE NORTHWESTERN CARIBBEAN SEA. THERE ARE
NO SIGNS OF ORGANIZATION AND DEVELOPMENT...IF ANY...SHOULD BE SLOW
TO OCCUR.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
Copy and past from 530 this afternoon...
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
255 PM EDT FRI OCT 26 2007
...FL...
WE ARE STILL EXPECTING THAT A TROPICAL SYS COULD DEVELOP IN THE NW
CARIBBEAN SEA AROUND MON. THIS SYS WILL BEGIN DRIFTING NW...THEN
GRADUALLY RECURVE TO THE NE DAYS 6-7 AS IT GETS CLOSER TO THE SRN
FRINGE OF THE POLAR WESTERLIES. PERIODS OF HEAVY PCPN LIKELY OVER
THE STATE ALONG/N OF A WAVY FRONTAL BOUNDARY...ESPECIALLY ALONG
THE E COAST AND BACK OVER THE KEYS.
We had a lot of aftermath - ashes, dirt, dust, debris, but we'll take care of that this weekend.
Hope all the above answers your question...
Nice circulation....not a lot of wind.
Link
Sleep well - see u tomorrow!!
Anyway, I'm out. I'll prolly take a look-in later tonight, when I get in again.
Enjoy!
BTW - Baja - there's nothing like a woman with an 850mb vorticity - lol!!! Thankx for your posts!!
00Z XTRP still has a SW motion. This invest is smelling like poof right now.
Let's see what the 12Z's tomorrow look like.
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1030 PM EDT FRI OCT 26 2007
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE BROAD AREA OF LOW PRESSURE OVER THE EASTERN CARIBBEAN SEA IS NOW
CENTERED ABOUT 175 MILES SOUTH-SOUTHEAST OF SANTO DOMINGO IN THE
DOMINICAN REPUBLIC. THIS SYSTEM HAS SLOWED ITS FORWARD MOTION THIS
EVENING AND IS NOW MOVING WEST-SOUTHWESTWARD AT 10 TO 15 MPH. THE
ASSOCIATED SHOWER ACTIVITY REMAINS DISORGANIZED AND UPPER-LEVEL
WINDS ARE CURRENTLY NOT FAVORABLE FOR DEVELOPMENT. THE LOW IS
EXPECTED TO MOVE GENERALLY WESTWARD AND TROPICAL CYCLONE
FORMATION...IF ANY...IS NOT EXPECTED UNTIL THE SYSTEM REACHES THE
WESTERN CARIBBEAN SEA IN A COUPLE OF DAYS. SHOWERS AND SQUALLS ARE
EXPECTED TO CONTINUE OVER PORTIONS THE VIRGIN ISLANDS...PUERTO
RICO...AND HISPANIOLA.
AN AREA OF DISTURBED WEATHER ASSOCIATED WITH A BROAD TROUGH OF LOW
PRESSURE CONTINUES OVER THE NORTHWESTERN CARIBBEAN SEA. THERE ARE
NO SIGNS OF ORGANIZATION AND DEVELOPMENT...IF ANY...SHOULD BE SLOW
TO OCCUR.
90L's circulation is strong enough to survive another night of shear IMO. It is almost out of the traditionally hostile area of the Caribbean and if it hangs on until 75W it will likely develop into a TD at least.
And, XTRP is not a model
LMAO!!
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