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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NE was you playing Golf in Tampa if so where at.
No,I'm actually going south to my sisters in osprey.
296. TampaSpin 7:24 PM GMT on October 26, 2007
NE was you playing Golf in Tampa if so where at.
No,I'm actually going south to my sisters in osprey.
Heck she would understand....i got 4 sets of clubs.......lol
lol,sounds good,but my dad is living with her and haven;t seen him in a while,I'd take you up on that if I was staying longer.
Awsome, you can never spend enough time with parents. Lost my father 2 years ago and i hated myself for not spending more time with him as we grew older.
When does Hurricane season end?
Nov 30th
November 31st MP
Only 30 in November, dude
The end of November MP, how about that.
Good afternoon
On for only about 20 min. Try to be back a little later tonight.
Hey Amy, Flood, jp, and all!
Hey StormW! Looks like the new 18Z shear map shows shear will be favorable for 90L past 70W
When the weight challenged weatherperson sings.
26/0545 UTC 17.8N 65.5W T1.5/1.5 90L
25/2345 UTC 18.8N 64.9W T1.5/1.5 90L
25/1745 UTC 19.0N 64.2W T1.0/1.0 90L
25/1145 UTC 19.3N 63.1W T1.0/1.0 90L
Yes Yes! One should look at a calender first :-)
The end of November MP, how about that.
Well done, and good on you! I could never remember the mnemonic for the months, so I always use "end of such and so"
Link
30 days have september,april,june and november
...all the rest have 31
Except February...when, um, I fell on my bum?
See, I told you...
326. extreme236 3:43 PM EDT on October 26, 2007
Here Storm:
Link
That's what shear has done over the past 24 hours.
I know, but the shear color is now blue-green indicating more favorable conditions west of 70W, and center is already at 68.8W, so assuming there are no major changes, the center could reach this area by tonight
330. NEwxguy 2:44 PM CDT on October 26, 2007
30 days have september,april,june and november
...all the rest have 31
Except February...when, um, I fell on my bum?
See, I told you...
lol,close enough,nobody cares about February anyway.
StormW--Wow was it nice in Tampa today huh...
hey,keep that weather around for this weekend.
LMAO...uh huh!
12Z GFS SHEAR LOOP
StormW if i read that correct, it appeared that the nearly the entire Carribean looks very favorable for development. Was that correct.
except the groundhog!
even he wouldn;t mind Feb, disappearing then they would stop dragging him early in the morning with all those lights and cameras.
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