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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696. extreme236
12:23 AM GMT on October 27, 2007
I counted 67 links however I dont use some of them or I rarely use some, and a few others were just links to go back to and read about some past seasons.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
695. BahaHurican
8:15 PM EDT on October 26, 2007
236,

I think, unfortunately, that the Cuba crossing is a lot more likely with this storm than with just about any other this year. Climatology supports this. On the other hand, right now that high is looking to build in fairly strongly for a while. If whatever comes of this doesn't head off to the NW by Tuesday, I wouldn't be surprised by a Cuba crossing then a landfall on either W FL coast or Central Bahamas somewhere. A lot depends on what happens with that high.
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693. extreme236
12:22 AM GMT on October 27, 2007
691. Drakoen 12:22 AM GMT on October 27, 2007
extreme236 30-40 links LOL???


LOL Yes...any tropical site I find that has been useful I have linked...some I use more than others.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
692. Patrap
7:22 PM CDT on October 26, 2007
Thats almost as many webcams Taz has..Wow.Thats a lotta Links.
Member Since: July 3, 2005 Posts: 421 Comments: 127702
691. Drakoen
12:22 AM GMT on October 27, 2007
extreme236 30-40 links LOL???
Member Since: October 28, 2006 Posts: 57 Comments: 29942
690. extreme236
12:22 AM GMT on October 27, 2007
T1.5/1.5 90A -- Arabian Sea
Member Since: August 2, 2007 Posts: 19 Comments: 19234
689. Drakoen
12:20 AM GMT on October 27, 2007
90L has taken a bit of a SW jog on the last few frames of the visible loop. That better for its development because it gets far enough away from the upper level low to its north, to provide ventilation for itself.
Member Since: October 28, 2006 Posts: 57 Comments: 29942
688. Patrap
7:21 PM CDT on October 26, 2007
Surface analysis Link
Member Since: July 3, 2005 Posts: 421 Comments: 127702
687. extreme236
12:19 AM GMT on October 27, 2007
Yes, the tropics are only a hobby of mine and Im definatly no professional met. However I have learned a lot from the people on here and with all (about 30-40 links) in my favorites list, I have been able to put together some of the data to get as much info on a system.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
686. Patrap
7:19 PM CDT on October 26, 2007
8:05 Atlantic TWD Link
Member Since: July 3, 2005 Posts: 421 Comments: 127702
685. Patrap
7:18 PM CDT on October 26, 2007
All the Tropical Stuff can be found on the Wunderground tropical Page.
From the NHC to Models to CIMMS forecasts...
here...Link
Member Since: July 3, 2005 Posts: 421 Comments: 127702
683. Patrap
7:16 PM CDT on October 26, 2007
Im a Hobbyist only. Theres no such thing as a amateur Met. Period.
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682. extreme236
12:16 AM GMT on October 27, 2007
Just tell me when you finish Koritheman I will read it :)
Member Since: August 2, 2007 Posts: 19 Comments: 19234
681. KoritheMan
12:14 AM GMT on October 27, 2007
I will try to make a blog entry sometime tonight or tomorrow...havent had much time to do so recently.

I blog all the time. I just absolutely love it! I will post another one tommorow if you wanna read it. It'll be my synopsis of the entire tropics, from Atlantic to West Pacific. I just have a sore throat today, and thus this weather forecaster won't be blogging today!
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680. extreme236
12:15 AM GMT on October 27, 2007
Your welcome KoritheMan :)

I will BBL, going to eat something real quick.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
679. BahaHurican
8:10 PM EDT on October 26, 2007
660. Stormy2day 8:07 PM EDT on October 26, 2007
Dear Dr. Masters, can we go just one week without finding some way to stretch weather news into a GW event?


Ya'll do realize that on his blog today Dr. M actually said the fires were NOT likely a GW result? I'm not sure what the problem is with that?
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678. KoritheMan
12:13 AM GMT on October 27, 2007
Thanks, extreme. I pretty much agree with everything you said there.
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677. extreme236
12:14 AM GMT on October 27, 2007
I will try to make a blog entry sometime tonight or tomorrow...havent had much time to do so recently.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
676. extreme236
12:13 AM GMT on October 27, 2007
Sorry it took so long koritheman...took a while to type all of that lol...and I agree, the global circulation pattern seems to be at work
Member Since: August 2, 2007 Posts: 19 Comments: 19234
675. CaneAddict
12:11 AM GMT on October 27, 2007
666. KoritheMan 12:08 AM GMT on October 27, 2007
extreme, what do you think of 90L's development? Can you give me a quick run down on it, please? You're one of the ones I really trust here.
Action: | Ignore User


I know im not extreme but i like to spread my knowledge to others. Go to my blog and you can get my take on it also. Thanks. Post a comment and let me know what you think. My Blog
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674. extreme236
12:09 AM GMT on October 27, 2007
666. KoritheMan 12:08 AM GMT on October 27, 2007
extreme, what do you think of 90L's development? Can you give me a quick run down on it, please? You're one of the ones I really trust here.


Ok I will give you the run down. Right now, I am estimating the center to be around 70W or so (not quite sure so Im waiting for the NHC cordinates). According to the CIMSS shear map, shear becomes increasingly more favorable west of this longitude line. And as seen on the microwave pass Drak showed below, some spiral banding is already evident and the circulation is fairly well defined. I expect gradual development tomorrow and perhaps on Sunday we could see a tropical depression (all depends on how fast it organizes assuming it does so). Shear forecasts for the most part predict favorable conditions (GFS is the outlier predicting heavy shear). A lot of things are uncertain to say the least. I wont even speculate on a track right now lol, but I know some of the models want to take it to Cuba.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
673. nash28
12:11 AM GMT on October 27, 2007
Ok guys... Gotta make an ice cream run to Publix for the wife and myself:-)

I'll try to get back on, but if not, have a wonderful evening and I am sure we'll have plenty of 90L to discuss this weekend.
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672. KoritheMan
12:11 AM GMT on October 27, 2007
extreme, still waiting to hear your take on 90L.

Thanks.
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671. Patrap
7:09 PM CDT on October 26, 2007
Im feeling fine Now Nash..thanks. When I get the nip tuck Nov 7th. It'll be smooth sailing.

I like the chimney reference..I throw in sometimes that the Low Pressure is the Fire/convection underneath the Chimney. Seems to help with the perspective some.
Member Since: July 3, 2005 Posts: 421 Comments: 127702
670. KoritheMan
12:08 AM GMT on October 27, 2007
Also it's amazing to note that we STILL have yet to have seen Noel, a storm we expected to have formed and disappated weeks ago . . .

I'm telling you, it's because of a global circulation pattern, similar to the one in 1977. Only this year, the basins have more storms than 1977 had, but it seems that all the storms this year, or at least 80% of them worldwide, are short-lived. With La Niña present, the Atlantic should be active (it has been active, but it should've still saw at least one October storm, and not just a TD), but it's not. This leads me to believe that a global circulation pattern is at work which is shortening the longevity of tropical cyclones worldwide this year. The South Pacific hasn't had much of anything this year, the West Pacific has had some powerful, but fairly short-lived storms. The EPAC has sucked because of La Niña, but that doesn't explain why the storms have been so short-lived. Finally, the Atlantic has had some very short-lived storms, which leads me to believe that a global circulation pattern unfavorable for tropical cyclones is at work here.
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669. BahaHurican
8:07 PM EDT on October 26, 2007
644. FloridaScuba 7:58 PM EDT on October 26, 2007
BahaHurican, thanks! i'm glad you see what i am saying and yeah, awesome diving in the b'hamas

can you put me up for a few days? lol. i just want to do the shark feed. :)

i won't eat much.. just a few cold ones afterwards and a dry cot to pass out on will be fine.


Hey, have u dived here before?? LOL I've heard the shark dive (I'm assuming u mean Divi Bahamas off New Providence) is awesome.
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668. extreme236
12:08 AM GMT on October 27, 2007
Well its La Nina so I expect this season to not end until November, if not the end of november
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667. nash28
12:07 AM GMT on October 27, 2007
Hey Pat. Nice concise way to put it:-)

How are you feeling?
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666. KoritheMan
12:07 AM GMT on October 27, 2007
extreme, what do you think of 90L's development? Can you give me a quick run down on it, please? You're one of the ones I really trust here.
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665. Patrap
7:06 PM CDT on October 26, 2007
psst!..the Upper High opens the Chimney flue. (translated)
Member Since: July 3, 2005 Posts: 421 Comments: 127702
664. MrSea
12:05 AM GMT on October 27, 2007
Guys I gotta go...it seems that the W Carib low is a vertically stacked low that has an upper level Anticylone to the south and a general anticyclonic flow over it....good enough..good night and have a great weekend
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663. BahaHurican
7:51 PM EDT on October 26, 2007
Just looked at Noe's video, and I thought he did a good job of explaining what is likely to happen with 90L.

I also think it's interesting that all 3 areas that caught my eye this morning look like they may have something to contribute to whatever forms next week.

Also it's amazing to note that we STILL have yet to have seen Noel, a storm we expected to have formed and disappated weeks ago . . .
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662. KoritheMan
12:06 AM GMT on October 27, 2007
90L looks disorganized on that radar image Pat posted. Even so, I can see convection slowly increasing near the center.
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661. extreme236
12:06 AM GMT on October 27, 2007
Well 90L is gradually moving into that more favorable enviroment shown on shear maps (I like to use the color CIMSS shear maps to be able to read the data better)
Member Since: August 2, 2007 Posts: 19 Comments: 19234
660. Stormy2day
7:52 PM EDT on October 26, 2007
Dear Dr. Masters, can we go just one week without finding some way to stretch weather news into a GW event?

I realize that every decade must have its "sky is falling" theory but do you really want to be immortalized 40 years from now on a VH1 spoof about the masses, led by Dr. Masters, who stock piled Freon in anticipation of GW coming to take them away?

And on a serious note, because I am serious – I signed up and paid my dues because I want a good website to go to for weather news.
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659. nash28
12:04 AM GMT on October 27, 2007
An Anticyclone rotates in a clockwise fashion, much like a High pressure system, which it actually is. Tropical cyclones rotate conterclockwise. This anticyclone acts as a ventilation system for a tropical cyclone, while bring lower shear over the cyclone.
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658. KoritheMan
12:05 AM GMT on October 27, 2007
oh man... this i gotta ask. wouldn't an anticyclone kill it? how does it getting underneath it make us want to "watch out"?

gosh, i got a lot to learn about this anti stuff


An anticyclone is a high pressure area aloft. If a tropical cyclone gets under that, then its clockwise circulation combined with the tropical cyclone's COUNTER-clockwise circulation provides a favorable outflow regime for any convection that fires up around the cyclone.
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656. KoritheMan
12:03 AM GMT on October 27, 2007
After seeing how Felix, humberto, dean, and lorenzo all intensified Ive just about given up on intensity forecasts lol

Might as well, LOL.

But since there is lots of shear over 90L, at least for now, I have no choice but to forecast only slow strengthening. However, it would not be a surprise if for some reason 90L rapidly intensified, even in the face of such adversity. Unlikely to happen yes, but possible, given how unpredictable weather is, and how the tropical cyclones of 2007 have been.
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655. Patrap
7:04 PM CDT on October 26, 2007
40 Frame Radar Loop from Puerto Rico

Link
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654. MrSea
12:03 AM GMT on October 27, 2007
aaa whatever I cant post the pic
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653. KoritheMan
12:01 AM GMT on October 27, 2007
No. that surface area of low pressure is vertically stacked with an upper level low. If you want to see upper level highs it is best you use the cimss wind shear product imagery and look for a clockwise flow. There is current an anticyclone in the southern Caribbean.

Really? I could've sworn that was an anticyclone. Shows I still have much to learn.

Dvorak numbers being run on the one system in the indian ocean...90A invest dvorak was run earlier giving a number of 1.5 as well

T1.5/1.5 99B -- Bay of Bengal


Interesting. I'll be monitoring these over the next few days. It's interesting when a cyclone develops in the Arabian Sea.
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652. FloridaScuba
12:01 AM GMT on October 27, 2007
645. nash28 11:58 PM GMT on October 26, 2007

90L needs to get underneath the anticyclone.

If it can, look out.


oh man... this i gotta ask. wouldn't an anticyclone kill it? how does it getting underneath it make us want to "watch out"?

gosh, i got a lot to learn about this anti stuff
651. extreme236
12:02 AM GMT on October 27, 2007
After seeing how Felix, humberto, dean, and lorenzo all intensified Ive just about given up on intensity forecasts lol
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650. Drakoen
12:01 AM GMT on October 27, 2007
JFV too early to tell...wait and see...
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648. Drakoen
11:57 PM GMT on October 26, 2007
MrSea use the wind shear product not the upper level divergence product.
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647. extreme236
11:59 PM GMT on October 26, 2007
IR imagery as of 23:15 UTC continues to show an increase of convection over/near the center of 90L
Member Since: August 2, 2007 Posts: 19 Comments: 19234
646. extreme236
11:58 PM GMT on October 26, 2007
Dvorak numbers being run on the one system in the indian ocean...90A invest dvorak was run earlier giving a number of 1.5 as well

T1.5/1.5 99B -- Bay of Bengal
Member Since: August 2, 2007 Posts: 19 Comments: 19234

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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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