California fires and global warming; 90L lashes Puerto Rico

By: Dr. Jeff Masters , 2:38 PM GMT on October 26, 2007

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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

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396. InTheCone
4:50 PM EDT on October 26, 2007
When the tropics are slow - as they have been for quite awhile now - I think that we all may get a bit over zealous in our analysis of what there is out there to look at.

It is kind of the point of the blog - tropics and all.

Most of us are known to eat large servings of black feathered critters when the naked swirls don't develop!! Then we start looking for the next one - lol!!
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395. Floodman
3:45 PM CDT on October 26, 2007
388. NRAamy 3:40 PM CDT on October 26, 2007
367. ShenValleyFlyFish 1:08 PM PDT on October 26, 2007

Just stepped outside to get mail. Still raining steadily. Got cussed at by a damp crow. Wonder what that means?

he was saying, "Bring Felix back!"



LOL...
Amy's Cat,
bring back
Amy's Cat
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394. NEwxguy
8:54 PM GMT on October 26, 2007
good job Drak
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393. TampaSpin
8:53 PM GMT on October 26, 2007
Is crow good.....never tried it.
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392. Drakoen
8:51 PM GMT on October 26, 2007
I just updated my blog. If you have any questions feel free to ask them there.
Link
Member Since: October 28, 2006 Posts: 57 Comments: 30833
391. NEwxguy
8:43 PM GMT on October 26, 2007
389. FLSWEDE 8:42 PM GMT on October 26, 2007
26/1515 UTC 16.7N 68.8W TOO WEAK 90L
latest reading on 90L only modle that shows something to S FL is the NOGAPS even EU modle backing off, seems you people use wish casting more then forecasting seen this over and over on here the last few years.

sound of ignore buttons clicking furiously
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390. InTheCone
4:44 PM EDT on October 26, 2007
Hey Shen -

He heard about Flood's cookbook!!
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389. FLSWEDE
8:39 PM GMT on October 26, 2007
26/1515 UTC 16.7N 68.8W TOO WEAK 90L
latest reading on 90L only modle that shows something to S FL is the NOGAPS even EU modle backing off, seems you people use wish casting more then forecasting seen this over and over on here the last few years.
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388. NRAamy
1:39 PM PDT on October 26, 2007
367. ShenValleyFlyFish 1:08 PM PDT on October 26, 2007

Just stepped outside to get mail. Still raining steadily. Got cussed at by a damp crow. Wonder what that means?


he was saying, "Bring Felix back!"
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387. IKE
3:39 PM CDT on October 26, 2007
sporteguy03 3:38 PM CDT on October 26, 2007
The Ike storm will be a treat for you Ike to follow :) .


Yo bud :)
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386. NEwxguy
8:39 PM GMT on October 26, 2007
382. IKE 8:35 PM GMT on October 26, 2007
Can't wait for the 2008 season and the "I" storm....with IKE!

Cat 5 probably
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385. sporteguy03
8:37 PM GMT on October 26, 2007
The Ike storm will be a treat for you Ike to follow :) .
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384. Patrap
3:35 PM CDT on October 26, 2007
End season Doldrums with invest to nowhere . Thats all. It'll pass if we get a depression.
Member Since: July 3, 2005 Posts: 428 Comments: 129903
382. IKE
3:34 PM CDT on October 26, 2007
Can't wait for the 2008 season and the "I" storm....with IKE!
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381. IKE
3:33 PM CDT on October 26, 2007
12Z ECMWF doesn't do much with 90L...

Link
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380. extreme236
8:33 PM GMT on October 26, 2007
BBL for the TWO
Member Since: August 2, 2007 Posts: 19 Comments: 19234
379. Patrap
3:31 PM CDT on October 26, 2007
I just so freaking confused now..LOL

Goes-12 WV loop Link
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378. stormybil
8:28 PM GMT on October 26, 2007
anyone interested joe says the two lows will join forces and get ready fla. see below

Link
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376. extreme236
8:22 PM GMT on October 26, 2007
Considering how 90L is moving at around 15 mph, and one degree of longitude is about 70 miles, then 90L would reach 70W in about 6 hours or so, and that is where conditions are more favorable, so some slow development may begin to occur overnight and tomorrow
Member Since: August 2, 2007 Posts: 19 Comments: 19234
375. extreme236
8:16 PM GMT on October 26, 2007
Anyway, conditions should become more favorable tonight and overnight as 20 knot shear is at 70W, and only decreases farther westward...will be an interesting weekend
Member Since: August 2, 2007 Posts: 19 Comments: 19234
374. extreme236
8:15 PM GMT on October 26, 2007
Well if conditions were favorable then I think that 90L would have developed in the "dead zone" as it was almost a depression near the zone before the shear effected it too much
Member Since: August 2, 2007 Posts: 19 Comments: 19234
373. extreme236
8:14 PM GMT on October 26, 2007
Ok im back...just noticed that the JTWC is reissuing advisories of Faxai in the wpac...estimated winds are 35 knots/pressure is 996mb
Member Since: August 2, 2007 Posts: 19 Comments: 19234
372. kmanislander
8:03 PM GMT on October 26, 2007
Good afternoon everyone

90L continues to dive to the WSW and is now near 16N. Once it passes 75W it will be beyond the infamous " dead zone" in the E Caribbean that historically has impeded or destroyed numerous developing systems.

It should come as no surprise that 90L has not developed so far as weak developing systems traversing the E Caribbean have in large part been unable to do so even when conditions aloft have been far more favourable than those now in place.

By late tonight 90L will be transitioning to a more climatologically favourable part of the Caribbean and the overnight hours will probably see a renewed burst of convection close to or over the COC for the first time
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370. FloridaScuba
8:10 PM GMT on October 26, 2007
When the cyclones approach each other, their centers will begin orbiting cyclonically about a point between the two systems. The two vortices will be attracted to each other, and eventually spiral into the center point and merge. When the two vortices are of unequal size, the larger vortex will tend to dominate the interaction, and the smaller vortex will orbit around it.

that's something called 'fujiwara' effect isn't it? (not sure how it's spelled)
369. TampaSpin
8:01 PM GMT on October 26, 2007
A little twist starting.

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367. ShenValleyFlyFish
4:05 PM EDT on October 26, 2007
Just stepped outside to get mail. Still raining steadily. Got cussed at by a damp crow. Wonder what that means?
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366. extreme236
8:06 PM GMT on October 26, 2007
And before I go, in case anyone doenst know what the fujiwara effect is, this is the definition(from wikipedia):

When the cyclones approach each other, their centers will begin orbiting cyclonically about a point between the two systems. The two vortices will be attracted to each other, and eventually spiral into the center point and merge. When the two vortices are of unequal size, the larger vortex will tend to dominate the interaction, and the smaller vortex will orbit around it.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
365. hurricane23
4:05 PM EDT on October 26, 2007
361. StormW 4:04 PM EDT on October 26, 2007
359. JFV 4:01 PM EDT on October 26, 2007
Stormw your thoughts on 90L this afternoon?


May see some improvement tomorrow...should still get some slow development.

Improving conditions could be ahead...Agreed.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
364. extreme236
8:05 PM GMT on October 26, 2007
363. Sfloridacat5 8:05 PM GMT on October 26, 2007
Yes, Extreme236
TWC said they could possibly merge. The low near the Caymans is supposed to remain nearly stationary for right now.

They also mentioned both lows could form. Wouldn't that be interesting.

But wouldn't the dominant low eventually take over?


Yes, but a guess a fujiwara (if thats how you spell it) effect could occur. But its highly uncertain right now...something to watch...BBL
Member Since: August 2, 2007 Posts: 19 Comments: 19234
363. Sfloridacat5
8:00 PM GMT on October 26, 2007
Yes, Extreme236
TWC said they could possibly merge. The low near the Caymans is supposed to remain nearly stationary for right now.

They also mentioned both lows could form. Wouldn't that be interesting.

But wouldn't the dominant low eventually take over?
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362. extreme236
8:04 PM GMT on October 26, 2007
BBL
Member Since: August 2, 2007 Posts: 19 Comments: 19234
360. extreme236
8:00 PM GMT on October 26, 2007
From TWC:

An area of low pressure currently spinning south of the Mona Passage (between Hispanola and Puerto Rico) has not generated sufficient convection near its center to organize any further today. Despite this, it is forecast to continue westward over the next few days and could organize into a tropical depression once it gets into the western Caribbean Sea. Widespread cloudiness and scattered showers will continue to plague areas well to the east of this low in the Antilles, Virgin Islands, and, at times, Puerto Rico through the weekend.

A second area of low pressure is spinning just to the west of Grand Cayman. While a north-south area of rain showers & squalls is quite evident from Cuba's Isle of Youth due southward west of Grand Cayman, no organization is evident at this time. However, occasional showers may plague Grand Cayman over the next day or so.

Member Since: August 2, 2007 Posts: 19 Comments: 19234
357. extreme236
7:59 PM GMT on October 26, 2007
It will be interesting to see how the low in the cayman area and 90L develop. Perhaps they may end up merging on monday
Member Since: August 2, 2007 Posts: 19 Comments: 19234
355. Sfloridacat5
7:57 PM GMT on October 26, 2007
TWC just mentioned the low near the Cayman Islands.
They said it could become a T.D.

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353. extreme236
7:54 PM GMT on October 26, 2007
GFS shows unfavorable conditions in the west caribbean, however the other global models suggest favorable or even very favorable conditions throughout the run. I guess the NHC is going with the favorable solution right now in terms of development for 90L
Member Since: August 2, 2007 Posts: 19 Comments: 19234
352. extreme236
7:52 PM GMT on October 26, 2007
Also StormW I wanted to ask you briefly about the non tropical low west of 40W south of 40N...this low is under favorable condtions according to the CIMSS shear map as of 18Z with some light anticyclonic flow over the center. QS shows a closed LLC, albeit small. The weather channel says it could gain some subtropical characteristics and I wanted to know your opinion. thanks
Member Since: August 2, 2007 Posts: 19 Comments: 19234
351. NEwxguy
7:52 PM GMT on October 26, 2007
well,you can't help getting the feeling something is going to get going down there,the question is where does it go.
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349. extreme236
7:51 PM GMT on October 26, 2007
Actually, the GFS shows unfavorable conditions in the west caribbean for the passage of 90L, however its the outlier right now
Member Since: August 2, 2007 Posts: 19 Comments: 19234
348. NEwxguy
7:50 PM GMT on October 26, 2007
lol,close enough,nobody cares about February anyway.

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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347. TampaSpin
7:47 PM GMT on October 26, 2007
339. StormW 7:47 PM GMT on October 26, 2007
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.

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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