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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605. CaneAddict
7:43 PM GMT on July 02, 2008
Accuweather seems to disagree with the model consensous...they seem to think it will head more westward and nto as far north..
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604. kmanislander
7:42 PM GMT on July 02, 2008
Well I'm out for now. Back later
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602. weathermanwannabe
3:32 PM EDT on July 02, 2008
593. IKE 3:25 PM EDT on July 02, 2008

Hey Ike; the GOM is a good example right now of the less than exact timing of Mother Nature; our "offical" rain pops in North Florida, from Tally NNW, are still currently in the 20% range for the next several days, but, that "front" in the Northern Gulf has stalled out already, and, starting to lift up already as a warm front; betcha they increase the rain pops again by this evening......If shear were lower in the Gulf right now, it would also be a different story perhaps.....
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601. franck
7:33 PM GMT on July 02, 2008
kman...sounds plausible.
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600. CybrTeddy
7:34 PM GMT on July 02, 2008
92L is almost exactly like pre-Hurricane Helene.
Large Circulation
Large Wave.
Everyone going nuts over it.
Member Since: July 8, 2005 Posts: 259 Comments: 24971
599. PensacolaNative
7:31 PM GMT on July 02, 2008
JP,Ike Is that a ULL forming in the NW GOM?
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598. kmanislander
7:27 PM GMT on July 02, 2008
JP

Perhaps the problem with 92L being slow to organize is that having so large a circulation takes time to tighten up ( similar to the time it takes a large fly wheel to overcome inertia if you will ).
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596. reedzone
7:26 PM GMT on July 02, 2008
Ya know something about those images Drak, the convection increased in size, but not in intensity. Again, it shows me that it will blow up later on tonight!
Member Since: July 1, 2008 Posts: 13 Comments: 7439
595. OSUWXGUY
7:20 PM GMT on July 02, 2008
Back to wait and watch mode I guess...

If it doesn't get more organized over the next day...it is unlikely that it will do much until/unless it makes it to the warmer western side of the Atlantic.

Marginal SSTs from 25W to 50W from 12N northward.

Tropical Atlantic SSTs
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593. IKE
2:23 PM CDT on July 02, 2008
590. Nolehead 2:21 PM CDT on July 02, 2008
ike

thanks!! yeah but hasn't it been going through shear from the beginning? still need to keep an eye on it..and the GOM is blowing up!! not a good day to be on a boat..


Shear has been somewhat favorable for that low until what's directly ahead of it.

Yeah...I was just looking at the GOM...that old frontal boundary is setting off some storms.
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592. NC0WX0Man
7:20 PM GMT on July 02, 2008
my local news on the tropical update the Met just said to keep an eye on the stationary front off of the southeast/east coast just said that something could or may try to spin up but no signs of it happening yet. Didn't someone say on this blog yesterday/last night that there was too much shear off the east coast/southeast for something to form so is that still the case or no?
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591. Drakoen
7:22 PM GMT on July 02, 2008
Photobucket
Photobucket
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590. Nolehead
7:19 PM GMT on July 02, 2008
ike

thanks!! yeah but hasn't it been going through shear from the beginning? still need to keep an eye on it..and the GOM is blowing up!! not a good day to be on a boat..
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588. conchygirl
3:13 PM EDT on July 02, 2008
Hey Mel:

Lived in San Diego too for 11 years (Rancho Penasquitos) - moved to FL before the fires but have many friends who lost their homes. So sad!
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587. NC0WX0Man
7:19 PM GMT on July 02, 2008
on another hurricane site a moderator said it was a mistake and it's still 92L.
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586. TheCaneWhisperer
7:19 PM GMT on July 02, 2008
Really? Sounds like politics to me, lol.
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585. NC0WX0Man
7:19 PM GMT on July 02, 2008
Oh and I'm not a downcaster I'm a wishcaster because I'm tired of drawing & ploting all these Trop. waves on my map of the ATL Basin Tracking Map. My maps is full of waves and could haves and almost and impressive waves I have to go print a new one off soon.
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583. IKE
2:15 PM CDT on July 02, 2008
575. Nolehead 2:13 PM CDT on July 02, 2008
ike, that little thing has just been hanging in there...is the shear supposed to let up anytime soon??


It's let up a little in the eastern Caribbean...it's headed for 20-30 knots of shear....CIMSS 1500UTC Shear Map
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582. TheCaneWhisperer
7:17 PM GMT on July 02, 2008
It is 02L now.
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580. NC0WX0Man
7:11 PM GMT on July 02, 2008
hello everyone on lunch and decided to pop in and see what was going on with 92L and I have to say (I'll eat crow IF I'm wrong) but I don't think 92L is going to make it to no more then possibly a TD (if that). I know it's D-min and I know these systems go through flare ups and flare downs but 92L doesn't seem to have readjusted too well from being a terrestrial(sp?) low to being an aquatic low. So this plus the broad LLC and hard time organizing and keeping convection fired/maintained over the LLC is looking & feeling kinda suspicious to me JMHO and nothing more nothing less.
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578. kmanislander
7:14 PM GMT on July 02, 2008
574. leftovers

The SW/NE flow from the TUTT ahead of it is forcing it off to the NW
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577. kmanislander
7:11 PM GMT on July 02, 2008
I guess 92L is like many of the companies being traded on the exchanges, upgraded in the morning and then downgraded soon thereafter !
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575. Nolehead
7:12 PM GMT on July 02, 2008
ike, that little thing has just been hanging in there...is the shear supposed to let up anytime soon??
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573. CybrTeddy
7:10 PM GMT on July 02, 2008
Why does the Ts say 1.0 02L? Strange.
Member Since: July 8, 2005 Posts: 259 Comments: 24971
572. pearlandaggie
7:11 PM GMT on July 02, 2008
bbl, folks. don't hold your breath too long waiting on 92L.

LOL
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571. IKE
2:10 PM CDT on July 02, 2008
That "little low" is now west of Barbados...winds have shifted to the south.....

Grantley Adams, BR (Airport)
Updated: 10 min 39 sec ago
Mostly Cloudy
82 °F
Mostly Cloudy
Humidity: 89%
Dew Point: 79 °F
Wind: 9 mph from the South
Pressure: 29.92 in (Steady)
Heat Index: 92 °F
Visibility: 5.0 miles
UV: 5 out of 16
Clouds:
Few 800 ft
Scattered Clouds 1000 ft
Mostly Cloudy 3600 ft
(Above Ground Level)
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570. Nolehead
7:10 PM GMT on July 02, 2008
lmao..same here pearl!!
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569. Nolehead
7:08 PM GMT on July 02, 2008
jp i agree...guess the NHC is just going to wait till EVERYONE except them realizes...hey there is a storm out there........DUH!!
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568. pearlandaggie
7:08 PM GMT on July 02, 2008
LOL, thanks, Ike. i thought i was missing something! :)
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567. pearlandaggie
7:07 PM GMT on July 02, 2008
LOL, jp! i'm about as close to being a millionaire without actually being one :)

/just kiddin' wif ya :)
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566. Drakoen
7:07 PM GMT on July 02, 2008
Not a tropical depression tonight:

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL922008) 20080702 1800 UTC
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565. kmanislander
7:04 PM GMT on July 02, 2008
Hi MLC

After dying down earlier that little low has fired up again. Fortunately there is a shear zone just to its West which should do a number on it.

Otherwise it would cruise all the way through the Caribbean and, like a bird that flies into a home through an open window, knock over a lot of things before finding its way out again !
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564. IKE
2:06 PM CDT on July 02, 2008
562. pearlandaggie 2:05 PM CDT on July 02, 2008
Ike, i'm just a dumb denialist...not following your post. what am i looking for?


It shows nothing much left of 92L/TD2/92L the 2nd/future TD/future TS.........
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563. Drakoen
7:06 PM GMT on July 02, 2008
It's lacking deep organized convection over the LLC.
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562. pearlandaggie
7:05 PM GMT on July 02, 2008
Ike, i'm just a dumb denialist...not following your post. what am i looking for?
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560. IKE
2:02 PM CDT on July 02, 2008
12Z ECMWF....

92L Naked?
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559. pearlandaggie
6:59 PM GMT on July 02, 2008
Archibald 2007
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558. 7544
6:57 PM GMT on July 02, 2008
92l is becoming a pretty large system right now taking up alot of realestate and maybe at dmax tonight it will show its colors and get tighter to be td 2 but looking at the sat ots quite large
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557. moonlightcowboy
1:58 PM CDT on July 02, 2008
534. Nice updates, Pearland.

543. K'man, whew, you are sooooo right about that TUTT there. That lil beast is still fighting though!
Member Since: July 9, 2006 Posts: 184 Comments: 29610

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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