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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795. Drakoen 9:42 PM EDT on October 26, 2007
Its ok StormW we believe you anyways LOL.
Okay....I'm gonna pack up my toys and go home!
(just kidding) LOL!
How you doing Drak?
LOL. i'm doing good. Monitoring this system as it could be our next significant threat.
How rapid of a potential intensification phase would we be talking about here and for how long drak?
When i say signficantly intensify i mean from its current state into a depression or tropical storm. Lets not get ahead of ourselves. Still time to watch.
Shear, what shear it's coming into the most favorable environment we have seen in a LOOONG time. Will it take advantage??? We'll see, dang, but I do HATE shutters....
BTW.. party's at my place if the power goes out, now have an on demand gen., keeps the beer cold and the a.c. on!! YeeHaw - lol!!
Lucky you! 5 days without power in FLORIDA really BITES!! lol
Link
Between Francis, Jeanne and Wilma we spent the better part of 25 days w/out power. Francis and Jeanne were BAD - really Hot, Wilma was nice after, cool and sunny. I figured that the expense of the gen. was my ulimate insurance policy - hoped to never need it!!!
I'm not StormW, but I can help. I believe the NHC wants persistence before they classify this as a TD. No reason to call it a TD then it dies one advisory later.
Wow Extreme -
Shear, what shear it's coming into the most favorable environment we have seen in a LOOONG time. Will it take advantage??? We'll see, dang, but I do HATE shutters....
Shutters in November? Somehow I doubt you'll need them. A hurricane landfall is very rare for the U.S. this time of year, although still possible. But IMO, there's a 95% chance this won't make landfall as a major hurricane.
I just watched Frank Straights Tropical Corner on Accuweather and he was saying that 90L better get together because the uppward mechanics a not favorable. He talked about downward force. Let me know what you think.
I'd say the guy is wrong. I believe he is referring to subsidence, which is stable, sinking air. I don't see any evidence of that. The only thing keeping this at bay right now is 30 knots of westerly wind shear.
Seriously though, don't panic at that, stuff isn't real anyways.
But thanks for the link, I like it!
I'm not leaving before 11. Nothing interesting will be happening before about midnight, anyway. What can I say? It's a Cuban club . . . LOL
I'm also kinda hanging around to see if the weather looks like rain. I hate getting wet in my clothes. [like most people love it lol] If it does I'll likely pick another spot to hang out tonight.
As always a voice of reason - MJO going down, good news, I hope.
BTW - have a good weekend!!!
Now I really feel old - by 11 I like to be in my bed!
LOL I have to admit I'm usually in bed [or at least only blogging] by 11 p.m. However, I'm taking advantage of a day off from work. Dunno when I'll get this chance again, especially if we do indeed get some form of tropical weather next week / weekend . . . Also it's been so rainy here the last 5 - 6 weeks it's been hard to do much of anything . . .
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