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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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
645. nash28
11:57 PM GMT on October 26, 2007
90L needs to get underneath the anticyclone.

If it can, look out.
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644. FloridaScuba
11:54 PM GMT 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.
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643. MrSea
11:57 PM GMT on October 26, 2007
Not really an anticyclone but upper divergence that seems to go all along that trough along the east coast
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642. UYA
11:56 PM GMT on October 26, 2007
Got ya Drak.
641. MrSea
11:55 PM GMT on October 26, 2007

Looks like an upper high to me on this map
http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8shr.html
Ok I see the upper Anticyclone in the S Carrib but over the swirl in the W Carrib there seems to be an anticyclonic flow that could allow for ventilation
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640. MrSea
11:52 PM GMT on October 26, 2007
Hold on...looks like we have different answers...
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639. Drakoen
11:54 PM GMT on October 26, 2007
UYA, 90L has a better chance at winning. You ask for a reason how so i told you LOL.
Member Since: October 28, 2006 Posts: 57 Comments: 30687
638. UYA
11:53 PM GMT on October 26, 2007
That weak area of low pressure in the W Carib is not strong....or do you mean 90L winning out? I'm confused.
637. UYA
11:51 PM GMT on October 26, 2007
I wouldn't choose to agree with that Drak.
636. Drakoen
11:50 PM GMT on October 26, 2007
633. UYA 11:49 PM GMT on October 26, 2007 Hide this comment.
How can we have an anticyclone, an ULL and a surface low all in the same place and expect anything?


The upper level low is weakening. The upper level high is helping for low wind shear. The stronger surface low will win.
Member Since: October 28, 2006 Posts: 57 Comments: 30687
635. BahaHurican
7:45 PM EDT on October 26, 2007
614. FloridaScuba 11:36 PM GMT on October 26, 2007
607. BahaHurican 11:34 PM GMT on October 26, 2007
I'm sure the Bahamas would greatly appreciate some death, destruction and general mayhem to break up the November monotony . . .

man, don't quote me like that. i would never mean something like the way you put that. i don't wish bad on anybody

LOL Sorry, Scuba. ;o) I was trying to keep a straight face on that one. I knew u didn't mean it that way.

However, I do want to remind u that the Exuma Cays, where the diving is EXCELLENT, would likely be affected by a 'cane passing north from Cuba. (Actually, the diving in much of the Bahamas is excellent.) My point is that if this storm doesn't peter out in the central Caribbean, SOMEbody's scuba weekend is likely to be messed up. So I understand where u are coming from . . . .
lol
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634. MrSea
11:47 PM GMT on October 26, 2007
ok thanks KoritheMan... Ill be gone this weekend up in Syracuse (where believe it or not it might snow Sunday night, right after I leave :-( I'll be back some time next week. Good night.
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633. UYA
11:48 PM GMT on October 26, 2007
How can we have an anticyclone, an ULL and a surface low all in the same place and expect anything?
632. Drakoen
11:46 PM GMT on October 26, 2007
626. MrSea 11:45 PM GMT on October 26, 2007 Hide this comment.
I have just one question tonight... is there an upper level anticyclone over that swirl in the western Carribean? I thought I saw one on the satelite...looked like good ventilation.


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.
Member Since: October 28, 2006 Posts: 57 Comments: 30687
631. KoritheMan
11:47 PM GMT on October 26, 2007
Theres currently only an Invest..Plenty of time to see what 90L brings. Enjoy the weekend.

Agreed. No need to lose sleep over something that has plenty of time left before it dies.
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630. KoritheMan
11:46 PM GMT on October 26, 2007
I have just one question tonight... is there an upper level anticyclone over that swirl in the western Carribean? I thought I saw one on the satelite...looked like good ventilation

You are correct.
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629. Patrap
6:45 PM CDT on October 26, 2007
Theres currently only an Invest..Plenty of time to see what 90L brings. Enjoy the weekend.
Member Since: July 3, 2005 Posts: 427 Comments: 129411
628. Drakoen
11:45 PM GMT on October 26, 2007
a take that back..some good spiral banding occurring...Noticeable on that microwave image i posted.
Member Since: October 28, 2006 Posts: 57 Comments: 30687
627. KoritheMan
11:43 PM GMT on October 26, 2007
Still doenst have much consistancy correct? With the conditions that could be in play I see no reason for it to dissapate at least that quickly. What does the HWRF do?

Yeah extreme, I agree with you. 90L has been notorious for holding in its own in both the diurnal minimum and against 30 knots of westerly shear, no less. Do I think it will develop today or tommorow? No. But do I think it will develop Sunday or Monday? Yeah, most definitely. I'm going to go out on a whim and say what Dr. Masters said, and that is that a hurricane might be in the western Carribean Sea next week from this system.

I don't see it threatening the U.S. though as anything stronger than a Category 1 if it were to do that, seeing as how SSTs and TCHP have decreased dramatically in the Gulf over the past couple weeks.
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626. MrSea
11:42 PM GMT on October 26, 2007
I have just one question tonight... is there an upper level anticyclone over that swirl in the western Carribean? I thought I saw one on the satelite...looked like good ventilation.
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625. zoomiami
11:43 PM GMT on October 26, 2007
That sounds great, as you know, we aren't even allowed to talk about something coming from Cuba!
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624. Drakoen
11:43 PM GMT on October 26, 2007
616. extreme236 11:40 PM GMT on October 26, 2007
612. Drakoen 11:38 PM GMT on October 26, 2007
18z GFDL dissapates 90L in 48 hours...

Still doenst have much consistancy correct? With the conditions that could be in play I see no reason for it to dissapate at least that quickly. What does the HWRF do?


Still waiting for the HWRF 18z. The last run didn't initialize the system properly.
Member Since: October 28, 2006 Posts: 57 Comments: 30687
622. BahaHurican
7:34 PM EDT on October 26, 2007
591. zoomiami 11:26 PM GMT on October 26, 2007
Hi Baha: has it been raining over there today?


Hey zoo,

Actually, after our "5-minute tropical storm" this morning, it was basically dry all day. First goodly dry day in a while. I'm afraid to speak too soon, though. I am supposed to be going out tonight, and the spot we are likely to hang out at is an outdoor Cuban cafe where they sometimes have live bands from Cuba. And always Cuban rum and cigars . . .
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621. Drakoen
11:40 PM GMT on October 26, 2007
spiral banding beginning to occur.
Member Since: October 28, 2006 Posts: 57 Comments: 30687
620. Patrap
6:37 PM CDT on October 26, 2007
Thus the development continues. Thats just an example of one way to Determine scale. But A Cat 4..Like Rita or Katrina at Landfall..due to size..force mechanism's. Dont carry the urgency say as a CAT-5 would.
A Cat 3-4 pushing a Cat-5 surge dont weigh in the argument that Katrina was a 3,4 at Landfall. The effects over time and area were way greater than the Cat size. As so Obviously stated and verified since then.
Member Since: July 3, 2005 Posts: 427 Comments: 129411
619. UYA
11:40 PM GMT on October 26, 2007
The only TV Met in Miami that really understands the tropics is Brian Norcross.
617. UYA
11:37 PM GMT on October 26, 2007
Don Noe learned anything he might think he knows about tropical systems from former NHC director Dr. Neil Frank and Walter Cronise.
I remember when Don Noe first started at WPLG in Miami. He didn't know a lot.
616. extreme236
11:39 PM GMT on October 26, 2007
612. Drakoen 11:38 PM GMT on October 26, 2007
18z GFDL dissapates 90L in 48 hours...


Still doenst have much consistancy correct? With the conditions that could be in play I see no reason for it to dissapate at least that quickly. What does the HWRF do?
Member Since: August 2, 2007 Posts: 19 Comments: 19234
615. zoomiami
11:37 PM GMT on October 26, 2007
JFV: ok - watched the video. I think it is very interesting, and something to watch. A couple of things - Don Noe really dislikes people who play up the hype of a system, where it can go, etc. So, when he does believe that something may happen there is a good chance. The second thing is that he uses all the tools, but he also uses the "gut", knowing what is possible by watching the conditions, not just the models.
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614. FloridaScuba
11:36 PM GMT on October 26, 2007
607. BahaHurican 11:34 PM GMT on October 26, 2007 Hide this comment.
541. FloridaScuba 6:46 PM EDT on October 26, 2007
thanks drak. that anticyclonic high looks like it would steer 90l straight to key largo... barring wherever it moves in the next X days. maybe it'll turn n and ne next week and burn through the bahamas, away from fla

I'm sure the Bahamas would greatly appreciate some death, distruction and general mayhem to break up the November monotony . . .


man, don't quote me like that. i would never mean something like the way you put that. i don't wish bad on anybody
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613. extreme236
11:38 PM GMT on October 26, 2007
But how would that work for a hurricane out to sea, since it wouldnt have a category as high, wouldnt that make the cyclone appear much weaker? Or would it just take into consideration the strength and size an create a number for it
Member Since: August 2, 2007 Posts: 19 Comments: 19234
612. Drakoen
11:38 PM GMT on October 26, 2007
18z GFDL dissapates 90L in 48 hours...
Member Since: October 28, 2006 Posts: 57 Comments: 30687
611. Patrap
6:34 PM CDT on October 26, 2007
Hope that clarifies the problem some. Its not all Cat-1 thru 5 anymore.
The current Scale dosent take Overall Storm Size..to task along with Surge,inland Flooding..and just as important. Storm single point duration.
Member Since: July 3, 2005 Posts: 427 Comments: 129411
610. extreme236
11:36 PM GMT on October 26, 2007
That scale seems reasonable. But to me it makes me wonder if a cat 4 was heading somewhere and lets say it was only a ranking of 6, while some weaker storm was a 8, then they make think its less of a threat and then they suffer the consequences, however I think some of that already happens with our current scale.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
608. Patrap
6:33 PM CDT on October 26, 2007
The idea for a new Hurricane Impact Scale (HIS) emphasizing coastal impact at landfall evolved from several field studies and discussions with Orrin Pilkey. The well-known Saffir-Simpson Scale (SSS) is a good representation of hurricane strength over open water and of damage potential over land, but lacks an indicator of size of the storm. The proposed HIS uses three parameters to rank hurricanes: (1) maximum elevation of storm surge, (2) storm surge spread (coastal length impacted by higher water level), and (3) wind speed (SSS category). A ranking of 1-5 is given for each of the 3 criteria, making the possible range of HIS values 3-15. The HIS provides a broader range of categories than the Saffir-Simpson Scale (15 versus 5) and allows more precise classification for predictive (prestorm) and comparative (poststorm) modes.

Other investigators have suggested new hurricane scales. Balsillie (1999) uses the event longevity parameter (ELP—storm surge height and duration) as a measure of volumetric beach and coast erosion from hurricanes, but does not include length of shoreline impacted (size of the hurricane). A storm impact scale for barrier islands (Sallenger, 2000) compares water level versus barrier island elevation at landfall, but it also does not include a measure of length of shoreline impacted. The National Hurricane Center is working to include inland winds and rainfall potential as part of a revised hurricane scale, but those are inland effects.

The ultimate goal of the proposed HIS is a tool for hurricane/weather forecasters to give coastal residents more information for preparing for a storm’s potential impact. As an example, Hurricane Andrew (1992) was one of the strongest storms on record (SSS category 4) but it was also a relatively small storm. Opal (1995) was a weaker storm (category 3) but it was much larger. Although Andrew caused a tremendous amount of inland wind damage, Opal actually caused more shoreline erosion and overwash. The HIS rankings reflect this (Andrew-8, Opal-11). Inclusion of the SSS in the HIS reflects the critical nature of storm strength in any such scale. Two storm surge parameters are justified because storm surge is the best measure of a hurricane’s energy flux at the shoreline, and thus the potential for erosion, overwash, and property damage at and near the shore.
Member Since: July 3, 2005 Posts: 427 Comments: 129411
607. BahaHurican
7:25 PM EDT on October 26, 2007
541. FloridaScuba 6:46 PM EDT on October 26, 2007
thanks drak. that anticyclonic high looks like it would steer 90l straight to key largo... barring wherever it moves in the next X days. maybe it'll turn n and ne next week and burn through the bahamas, away from fla


I'm sure the Bahamas would greatly appreciate some death, destruction and general mayhem to break up the November monotony . . .
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606. extreme236
11:32 PM GMT on October 26, 2007
So Patrap the new scale would give more detail as to the specific threats of certain strength hurricanes?
Member Since: August 2, 2007 Posts: 19 Comments: 19234
605. Patrap
6:30 PM CDT on October 26, 2007
But I wouldnt expect the New Scale to come out till at Least 2012.At earliest.
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604. extreme236
11:31 PM GMT on October 26, 2007
And if they wanted to raise oil prices more, they could probably do so anyway without a cyclone threat
Member Since: August 2, 2007 Posts: 19 Comments: 19234
601. extreme236
11:29 PM GMT on October 26, 2007
598. Tazmanian 11:29 PM GMT on October 26, 2007
236 we dont need higher gas then what they are now send 90L to MX


but Taz the point is some people in Mexico cant handle storms well. Certain areas can. A storm they may only kill 1-2 people here could kill 20 people there if it hit a bad area. An anyway, if Im not mistaken, the majority of oil areas in the gulf arent in the far SE part
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600. Patrap
6:26 PM CDT on October 26, 2007
As far as a New Scale coming out in 08.Thats not the aim of the Projects. The aim is to come up with a Newer scale that will encompass a lot more info as to a Landfalling event. The Saffir -Simpson scale,..although used for many years..it is lacking in critical Exponential qualities.
It was designed only for Wind Force loading on Structures. The next Gen scale will have a better Overall Size to Surge to Wind Loading..than what we have currently.
Member Since: July 3, 2005 Posts: 427 Comments: 129411
599. UYA
11:28 PM GMT on October 26, 2007
Taz....are you the blog commodity broker now?
598. Tazmanian
4:28 PM PDT on October 26, 2007
236 we dont need higher gas then what they are now send 90L to MX
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596. extreme236
11:28 PM GMT on October 26, 2007
90L though could be a problem for Cuba, and we cant rule out a possible threat to Florida
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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