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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895. BajaALemt
3:25 AM GMT on October 27, 2007
Lookin like a rainmaker. Too bad GRL3 doesnt work for Puerto Rico...Nice set of storm training in towards San Juan
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894. BajaALemt
3:24 AM GMT on October 27, 2007
lol, nite InThe...sleep well
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893. UYA
3:20 AM GMT on October 27, 2007
Nice circulation...but no winds. None of the models to this point want to do much with 90L.
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.
892. BajaALemt
3:17 AM GMT on October 27, 2007
It doesnt look to be displacing to the east as bad as it was this morning.
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891. InTheCone
11:19 PM EDT on October 26, 2007
Nite - Baja - sleep well - may all of our storms stay weak!!
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890. BajaALemt
3:16 AM GMT on October 27, 2007
LOL InThe!!!
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889. BajaALemt
3:14 AM GMT on October 27, 2007
Yah. I was just looking at the shear tendencies. It'll be interesting to watch this...this weekend
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888. stormybil
3:05 AM GMT on October 27, 2007
it be interesting to see if 90l becomes a td during the dmax tonight as it heads into lower shear . ill be watching
887. InTheCone
11:04 PM EDT on October 26, 2007
Anytime Rodek - I'm just an observer - the real pros here will help w/ the tough stuff :)

BTW - Baja - there's nothing like a woman with an 850mb vorticity - lol!!! Thankx for your posts!!
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886. Rodek
3:00 AM GMT on October 27, 2007
Thank you for the answers Inthecone. :)
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885. BajaALemt
3:00 AM GMT on October 27, 2007
850mb Vorticity
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884. ShenValleyFlyFish
10:56 PM EDT on October 26, 2007
Night all
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883. BajaALemt
2:59 AM GMT on October 27, 2007
Nite BaHa
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882. BahaHurican
10:35 PM EDT on October 26, 2007
Hmmm, I was thinking the same thing about that Quckscat.

Anyway, I'm out. I'll prolly take a look-in later tonight, when I get in again.

Enjoy!
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881. InTheCone
10:51 PM EDT on October 26, 2007
Night Drak. -

Sleep well - see u tomorrow!!
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880. BajaALemt
2:51 AM GMT on October 27, 2007
Nite Drak
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879. Drakoen
2:49 AM GMT on October 27, 2007
Night everyone..of to bed.
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878. BajaALemt
2:44 AM GMT on October 27, 2007
Water's still really warm down there...

Link
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877. KEEPEROFTHEGATE (Mod)
2:39 AM GMT on October 27, 2007
sbkaren santa ann winds re-establish them selves by sunday so ya all better be quick to get all out those winds can blow up fire storms real fast with any little spots that remain
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876. UYA
2:43 AM GMT on October 27, 2007
872. UYA 2:35 AM GMT on October 27, 2007
Nice circulation....not a lot of wind.

875. Drakoen
2:43 AM GMT on October 27, 2007
High winds on the northern portion of the circulation center.
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874. KEEPEROFTHEGATE (Mod)
2:37 AM GMT on October 27, 2007
maybe instead of a treat we will get a trick for halloween
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873. InTheCone
10:36 PM EDT on October 26, 2007
catwomen -

Hope all the above answers your question...
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872. UYA
2:34 AM GMT on October 27, 2007
Nice circulation....not a lot of wind.
871. Drakoen
2:32 AM GMT on October 27, 2007
Tonights QuickSat shows a good circulation. "Large, vigorous circulation".
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870. nrtiwlnvragn
2:30 AM GMT on October 27, 2007
Tonights Quikscat

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869. hurricane23
10:29 PM EDT on October 26, 2007
If it developes it will have to watched as a strong cold front is likely to turn it towards florida the way things look as of this evening.
Member Since: May 14, 2006 Posts: 8 Comments: 13707
868. BajaALemt
2:28 AM GMT on October 27, 2007
Seems to be the story with ALOT of the invests this year...shear displacing convection to the east. Looks familiar, huh
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867. SBKaren
7:26 PM PDT on October 26, 2007
Since the doctor also discussed the CA fires in his header, I'm changing the subject only temporarily to say that I live in So CA and for us here along the coast, our air and temps feel GREAT! It's a nice cool 60 something and the sunset tonight WAS NOT RED! I only hope that conditions like this move inland so those that are more directly affected by these horrible fires can relay the same information.

We had a lot of aftermath - ashes, dirt, dust, debris, but we'll take care of that this weekend.
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866. UYA
2:25 AM GMT on October 27, 2007
EXTENDED FORECAST DISCUSSION
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.

865. hurricane23
10:26 PM EDT on October 26, 2007
ABNT20 KNHC 270225
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...
Member Since: May 14, 2006 Posts: 8 Comments: 13707
864. catwomen
10:21 PM EDT on October 26, 2007
Does anyone think a td will form by next week? if so where do you think it might track?
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863. InTheCone
10:21 PM EDT on October 26, 2007
Rodek -

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.
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862. Rodek
2:19 AM GMT on October 27, 2007
Very interesting. Does this upwelling aide in the strengthing of the storm?
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861. CaneAddict
2:20 AM GMT on October 27, 2007
858. hurricane23 2:19 AM GMT on October 27, 2007
Covection seems to have expanded to the east tonight...


In addition convection seems to be consolidating a little more.

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860. CaneAddict
2:17 AM GMT on October 27, 2007
853. Rodek 2:17 AM GMT on October 27, 2007
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.
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859. InTheCone
10:17 PM EDT on October 26, 2007
Rodek -

Indeed they do - upwelling - they pull the cooler water from below to the surface.
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858. hurricane23
10:18 PM EDT on October 26, 2007
Convection seems to have expanded to the east tonight...

Member Since: May 14, 2006 Posts: 8 Comments: 13707
856. ShenValleyFlyFish
10:05 PM EDT on October 26, 2007
You are all welcome. I can't claim a lot of credit since someone else on the blog posted it earlier in the season. If I could remember who would give them reference. It tickled me so I bookmarked it.
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855. BajaALemt
2:17 AM GMT on October 27, 2007
Take care Love2
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854. BajaALemt
2:13 AM GMT on October 27, 2007
Nite storm...enjoy
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853. Rodek
2:15 AM GMT on October 27, 2007
Alright... Have a question of the night. Does a Hurricane actually cool down the Sea Surface Temperature as it passes a given area?
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852. InTheCone
10:14 PM EDT on October 26, 2007
You got it Cruise - welcome aboard!!!
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851. Love2Cruise
2:11 AM GMT on October 27, 2007
Look forward to chatting tomorrow. I might be back late tonight as I am on the west coast. Thanks for welcoming the new guy.
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850. BahaHurican
10:07 PM EDT on October 26, 2007
842. zoomiami 10:05 PM EDT on October 26, 2007
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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847. Drakoen
2:09 AM GMT on October 27, 2007
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846. InTheCone
10:07 PM EDT on October 26, 2007
Thankx Storm -

As always a voice of reason - MJO going down, good news, I hope.

BTW - have a good weekend!!!
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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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