African disturbance 92L chugs west; California fires generating significant pollution

By: Dr. Jeff Masters , 1:40 PM GMT on July 02, 2008

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A strong tropical wave (Invest 92L) is a few hundred miles off the coast of Africa, south of the Cape Verde Islands. This low has the potential to develop into a tropical depression later this week as it moves westwards at 15-20 mph. The low is under about 5-10 knots of wind shear, which is favorable for development. Sea Surface Temperatures are about 28°C, which is about 2-3°C above average for this date, and well above the 26°C threshold for tropical storm formation. There is not much African dust or dry air near the storm, but the low appears much as it did yesterday, with little heavy thunderstorm activity. The low has plenty of spin, as seen on this morning's QuikSCAT pass (Figure 1). One 35 mph (30 knot) wind vector was noted to the southwest of the storm's center in the QuikSCAT data, so 92L is kicking up some strong winds. There aren't really any negatives for development, except for climatology--there has never been a tropical depression that has formed east of 34° longitude in the first half of July (see the first image I posted in my July Atlantic hurricane outlook). NHC is giving a medium (20-50% chance) that 92L will develop into a tropical depression by Friday afternoon. All the models are developing this system into a tropical depression by Saturday. Wind shear is forecast by the SHIPS model to remain below 10 knots for the next four days, and the waters will stay warm (above 26°C) for the next 2-3 days of 92L's life. None of the computer models foresee that 92L will become a threat to land, and it currently appears that the storm will recurve in the middle of the Atlantic Ocean, east of Bermuda.


Figure 1. QuikSCAT image of 92L from 3:12am EDT Wed July 2, 2008. Image credit: Paul Chang, NOAA/NESDIS/ORA.

California fires cause significant air pollution
It was a destructive April, May, and June for fires in California, with 889,000 acres burned (71% of this acreage since June 20!) This is over five times the acreage burned during the same months in 2007. Satellite-detected fires from April through June this year totaled over 13,000, compared to only 1,200 during the same time period in 2007. These fires have caused many cities in the state to exceed the EPA's daily standard of 35 µg/m3 for particulate air pollution (Figure 2).


Figure 2. Location of all satellite-detected fires from last year (left panel) and this year (right panel) for the months of April through June, along with the number of days when surface particle pollution exceeded EPA's daily standard in several major cities in California. Image credit: Environmental Protection Agency (EPA), National Aeronautics and Space Administration (NASA).

Air quality is improving this week in California due to the onset of west-southwesterly winds aloft that have enhanced mixing and dispersion in the atmosphere. The moist flow of air off the ocean has brought fog and raised humidity levels, aiding firefighting efforts. However, with fire season's peak still months away, expect many more fires and significant pollution episodes later this summer.

Jeff Masters

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1407. TheWeatherMan504
3:18 AM GMT on July 03, 2008



1402. IKE 3:17 AM GMT on July 03, 2008
1398. Levi32 10:15 PM CDT on July 02, 2008
1391. IKE 7:12 PM AKDT on July 02, 2008

I'm not convinced either....in fact I really don't like the look of the latest model runs. If it survives the shear I think we will have to keep an eye on it.

I agree....see how it does tomorrow...by dinner time....my guess....it'll still be around...


im not yet either however things appear to start going for 93l because of the retreating TUTT.

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1406. STORMTTOP
3:18 AM GMT on July 03, 2008
July 23rd
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1405. KEEPEROFTHEGATE (Mod)
3:15 AM GMT on July 03, 2008
be back in a few hrs around 5 am edt to check out big bertha later all
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1404. HurricaneGeek
11:17 PM EDT on July 02, 2008
1399. Sadly, New Orleans got a "faceDROP".
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1403. FLWeatherFreak91
11:16 PM EDT on July 02, 2008
Re 1399;

Yeah, I think that's what it was. I dunno- it was some kind of tour. Went to Hell and such... then to swim with the rays.
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1402. IKE
10:15 PM CDT on July 02, 2008
1398. Levi32 10:15 PM CDT on July 02, 2008
1391. IKE 7:12 PM AKDT on July 02, 2008

I'm not convinced either....in fact I really don't like the look of the latest model runs. If it survives the shear I think we will have to keep an eye on it.


I agree....see how it does tomorrow...by dinner time....my guess....it'll still be around...
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1400. FLWeatherFreak91
11:15 PM EDT on July 02, 2008
Re 1397:

Wow! I would never have expected that. And like I said before, the island doesn't look like it's been hit by anything at all. I remember hearing about some hotels that were gutted by surge but that's about it. I was just there in January and it was truly breathtaking.
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1399. 786
3:13 AM GMT on July 03, 2008
oh yeah lol, did you go on the Trolley Roger? some really nice houses here, I am so impressed at how fast the island came back after Ivan, it got a facelift...wish we could say the same about New Orleans
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1398. Levi32
7:13 PM AKDT on July 02, 2008
1391. IKE 7:12 PM AKDT on July 02, 2008

I'm not convinced either....in fact I really don't like the look of the latest model runs. If it survives the shear I think we will have to keep an eye on it.
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1397. kmanislander
3:13 AM GMT on July 03, 2008
1386. FLWeatherFreak91 3:08 AM GMT on July 03, 2008

Actually, from 1932 we never had a direct strike hurricane until 2004. Gilbert gave us a glancing blow in 1988.
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1396. StormJunkie
3:09 AM GMT on July 03, 2008
Dmax helping out some...

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1395. 786
3:13 AM GMT on July 03, 2008
Just in time for the long weekend
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1393. FLWeatherFreak91
11:10 PM EDT on July 02, 2008
Re 1389:

Do they really? That's good. I'm actually very surprised every time I go there how great the island looks despite the fact that so many storms have come through. There's that one little house that's over 100 years old that they show you on every tour... in perfect condition. I would like to visit there by other means besides a cruise. 7-8 hours isn't enough to see much at all.
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1392. kmanislander
3:09 AM GMT on July 03, 2008
786

Soonest would be Saturday night/ Sunday morning

Given its current disorganised state and the existing shear conditions the worst would be somewhere between a rainmaker and a TD or minimal TS IMO.

That's assuming it comes this way at all
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1391. IKE
10:10 PM CDT on July 02, 2008
1382. Levi32 10:07 PM CDT on July 02, 2008
1381. IKE 7:06 PM AKDT on July 02, 2008 Hide this comment.
1372. 786 10:02 PM CDT on July 02, 2008
Kman: when do you think it may effect us, Saturday? what do you think we'll be dealing with?

StormW was on earlier...said it would go "bye-bye" in about 3 days after some organization. I should have asked him why...

He meant that it will likely pass over Hispaniola, which will definitely kill it if the shear doesn't.



It's suppose to pass mainly south of PR..."Tropical wave moving across the Windward Islands late this
afternoon will continue to propagate west through Thursday and
pass mainly south of the area."...from their discussion.

I'm not convinced it's gonna go over Hispaniola...yeah, if it does...it's probably history.
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1390. 786
3:11 AM GMT on July 03, 2008
actually don't take that as fact, I have no idea what the % is, but its not common
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1389. 786
3:09 AM GMT on July 03, 2008
lol ,funnily enough we are so small (22 miles long) that the hurricane force winds miss us over 95% of the time
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1388. ajcamsmom2
10:07 PM CDT on July 02, 2008
Wow, thanks, it is a lot easier to follow things when you post the numbers you are responding to... :)
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1387. TheWeatherMan504
3:07 AM GMT on July 03, 2008
92Lisawsome, YOU ARE A TROLLCASTER!
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1386. FLWeatherFreak91
11:06 PM EDT on July 02, 2008
The Cayman Islands- what a most unfortunate place for such a beautiful group of islands to be located. There's just no way for a large Hurricane to ever get by w/o a collision. It's kinda' like trying to pass a garbage truck on a small, back country road.. (excuse that horrible simile lol)
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1385. atmoaggie
3:04 AM GMT on July 03, 2008
maybe alot of miles difference..this makes it even more scary for me in the Eastern Caribbean Islands

The point behind the models is that they are estimating solutions to equations that have no real solution (calculus refresher, anyone?). The error in location simply grows with every time step. If the beginning is off, the forecasted location will likely be progressively worse.
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1384. 786
3:06 AM GMT on July 03, 2008
Thanks Ike, so many surprises has made me skeptical - just about anything can happen, but I would be surprised if it became anything more than a depression in the next few days
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1383. TheWeatherMan504
3:04 AM GMT on July 03, 2008

1372. 786 3:02 AM GMT on July 03, 2008
Kman: when do you think it may effect us, Saturday? what do you think we'll be dealing with?

maybe
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1382. Levi32
7:06 PM AKDT on July 02, 2008
1381. IKE 7:06 PM AKDT on July 02, 2008 Hide this comment.
1372. 786 10:02 PM CDT on July 02, 2008
Kman: when do you think it may effect us, Saturday? what do you think we'll be dealing with?

StormW was on earlier...said it would go "bye-bye" in about 3 days after some organization. I should have asked him why...


He meant that it will likely pass over Hispaniola, which will definitely kill it if the shear doesn't.
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1381. IKE
10:03 PM CDT on July 02, 2008
1372. 786 10:02 PM CDT on July 02, 2008
Kman: when do you think it may effect us, Saturday? what do you think we'll be dealing with?


StormW was on earlier...said it would go "bye-bye" in about 3 days after some organization. I should have asked him why...
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1380. HadesGodWyvern (Mod)
3:04 AM GMT on July 03, 2008
National Hurricane Center
Tropical Cyclone Warning Number FIVE
03:00 AM UTC July 3 2008
=====================================

At 0:00 AM UTC, Tropical Storm Douglas (1004 hPa) located near 18.8N 109.1W or 252 NM south of Caba Lucas, Mexico has sustained winds of 35 knots with gusts up to 45 knots. The cyclone is reported as moving northwest at 8 knots.

Gale-Force Winds
=================
60 NM from the center

Forecast Position and Intensity
=================================
24 HRS: 20.0N 110.9W - 40 knots (Cyclone)
48 HRS: 20.7N 112.8W - 25 knots (Low Pressure Area
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1379. 786
3:04 AM GMT on July 03, 2008
Kman, Grand Cayman - Red Bay = low lying
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1378. HadesGodWyvern (Mod)
3:02 AM GMT on July 03, 2008
National Hurricane Center
Tropical Cyclone Warning Number TWENTY-FIVE
03:00 AM UTC July 3 2008

==========================================
At 0:00 AM UTC, Tropical Storm Boris (995 hPa) located near 17.7N 128.3W or 1081 NM west-southwest of the tip of Baja California Peninsula has sustained winds of 50 knots with gusts up to 60 knots. The cyclone is reported moving northwest at 7 knots.

Storm Force Winds
==================
60 NM from the center

Forecast and Intensity
=======================
24 HRS: 18.2N 130.1W - 35 knots (Cyclone)
48 HRS: 17.9N 132.2W - 20 knots (Low Pressure Area)
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1377. TheWeatherMan504
3:02 AM GMT on July 03, 2008
its 11pm and the NHC hasnt said a bloody thing.
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1376. kmanislander
3:03 AM GMT on July 03, 2008
786

Where are you ?
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1375. Littleninjagrl
3:02 AM GMT on July 03, 2008
1371 i never heard of that but it doesn't sound very good to me!
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1374. svgweather
3:00 AM GMT on July 03, 2008
thanks atmoaggie.. rather interesting to note this because we all look at models taking this out to see but we hardly look at each model's initialization to where the system actually is at this point in time..maybe alot of miles difference..this makes it even more scary for me in the Eastern Caribbean Islands
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1373. FLWeatherFreak91
11:03 PM EDT on July 02, 2008
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1372. 786
3:01 AM GMT on July 03, 2008
Kman: when do you think it may effect us, Saturday? what do you think we'll be dealing with?
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1371. pottery
10:55 PM AST on July 02, 2008
I notice that there are no large areas of weather behind 92L. For the first time in several weeks. As an Island boy,I know, ( and surfers will confirm ) the last wave in a set is the biggest, baddest, meanest of all.
Just to put another spin on this...
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1370. Levi32
6:57 PM AKDT on July 02, 2008
1357. svgweather 6:57 PM AKDT on July 02, 2008 Hide this comment.
question to StormW, Drak or any other experienced Mets in here, With the Models does the point of Model initialization and actual location difference matter in potential track or path? if so with these models initiating at different locations (some north of where it is actually now) wouldn't this mean they can be wrong?


Well I am nowhere close to being an experienced met at all.....but....I don't think that the small differences we are seeing in model initialization matter that much at this point. In some situations they do matter a huge deal, but not here. If the models are wrong it's because they either intensify 92L too rapidly or overestimate the weakness in the ridge.
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1369. HurricaneGeek
10:59 PM EDT on July 02, 2008
1362. I think either I don't understand, Weather456, or you made a mistake. If it's -3 hours for the West, then that means -0 for us here in the Eastern Time. We are three hours ahead of you, (Florida). hmm?
And we are not on the same time zone as CV islands! lol
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1368. kmanislander
2:58 AM GMT on July 03, 2008
JFV

Yes I agree in part. The retreat of the TUTT is an opportunity for 93L to hold on for more favourable conditions.

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1367. FLWeatherFreak91
10:59 PM EDT on July 02, 2008
Well, I've heard it straight from 2 different meteos today that 92 could actually go straight to TS status. It isn't all that uncommon if I'm remembering correctly.
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1366. presslord
10:47 PM EDT on July 02, 2008
stormw..thanks for your report...we're all provisioned and ready to head out about two tomorrow... I'm cross the Gulf Stream...and jsut knock around out thee...shaking down the new boat....
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1365. atmoaggie
2:57 AM GMT on July 03, 2008
question to StormW, Drak or any other experienced Mets in here, With the Models does the point of Model initialization and actual location difference matter in potential track or path? if so with these models initiating at different locations (some north of where it is actually now) wouldn't this mean they can be wrong?

Heck yes! GIGO = garbage in...garbage out.

Initial conditions are so important that GFS runs a 3 hour data assimilation (collecting obs a correcting solutions) at the beginning of every run. A 1 day forecast off of half-fast initial conditions is worthless.

If you see a model's analysis (0 hour forecast) with the system in the wrong spot, throwing out the forecasted result is my personal MO (and I am sure I am not alone in that).
Member Since: August 16, 2007 Posts: 6 Comments: 12461
1364. TheWeatherMan504
2:57 AM GMT on July 03, 2008
1355. JFV 2:56 AM GMT on July 03, 2008
Holla KMan! Carib TUTT is retreating noticeably towards the west, this is not a good sign, wouldn't you agree kman?


Im not kman but this isnt a good sign. Farmers Almanac has a hurricane in the GOM on the 16th.
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1363. kmanislander
2:55 AM GMT on July 03, 2008
Hi there MLC

The TUTT seems to be degenerating into a cut off low in the ATL and another low lifting out N of the Caribbean. Either way the shear map now has much reduced shear in the E Caribbean.

93L is like the " little train that could "
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1362. Weather456
10:57 PM AST on July 02, 2008
DMAX is around 6 am cape verde time, which -3 hrs or 3 am for us here in the West.
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1361. ajcamsmom2
9:50 PM CDT on July 02, 2008
Maybe we could start adding the post number we are responding to when we talk about one...It would make it a lot easier to follow...especially when we have a lot of posts to go thru...I get so lost on here sometimes...
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1360. KEEPEROFTHEGATE (Mod)
2:55 AM GMT on July 03, 2008
dmax 2am edt 92l fl weatherfreak
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1359. TheWeatherMan504
2:56 AM GMT on July 03, 2008
lol 1554
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1358. HurricaneGeek
10:56 PM EDT on July 02, 2008
1354. MONTY PYTHON!!!!?
I love it! =)
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1357. svgweather
2:53 AM GMT on July 03, 2008
question to StormW, Drak or any other experienced Mets in here, With the Models does the point of Model initialization and actual location difference matter in potential track or path? if so with these models initiating at different locations (some north of where it is actually now) wouldn't this mean they can be wrong?
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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.