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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756. Floodman
4:01 PM CDT on July 02, 2008
Howdy, SJ...yep, things are getting a little more interesting, at the least
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755. blueranch1
9:01 PM GMT on July 02, 2008
746. RIP...that was quick.
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754. OUSHAWN
8:59 PM GMT on July 02, 2008
735...

True...however, I have seen too many times where theses systems have everything in their favor as far as them developing and yet we end up sitting back and scratching our heads wondering why they didn't. The large circulation and the dry air I feel will eventually be its downfall.
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753. kmanislander
8:58 PM GMT on July 02, 2008
93L is a shallow system with good vorticity at 850 mb but hardly any at 700 mb

As such it will be driven by the low level flow and not so much by the flow around the TUTT. This would account for the WNW track from the models.

Shear maps show decreasing shear ahead but shear values are still quite high. I am not sure why the models conclude that it will survive to make the run to the NW Caribbean or points further afield unless they see shear relaxing ahead of it as it progresses
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752. Nolehead
9:00 PM GMT on July 02, 2008
guys keep up the good work and i'll bbl..who knows by then there could 94L & 95L before dark..
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750. TerraNova
3:58 PM EST on July 02, 2008
736. JFV 3:58 PM EST on July 02, 2008
Drak, when will the model runs be released for 93L?


Afternoon JFV! SFWMD just posted preliminary models on their website. Other than shear, it looks like 93L may encounter difficulty with proximity to land in the future based on these track models.

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749. Drakoen
9:01 PM GMT on July 02, 2008
93L models:
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748. stoormfury
8:56 PM GMT on July 02, 2008
456
Well my ball of convection i brought to your attention last night 600 miles east of barbados has come into the limelight.
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747. Floodman
3:59 PM CDT on July 02, 2008
739. Drakoen

Those damned custom keyboards again...LOL
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746. Tazmanian
1:58 PM PDT on July 02, 2008
93L is RIP
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745. StormJunkie
9:00 PM GMT on July 02, 2008
92, 93, chance of 94 off the E coast???

Things are heating up.

Afternoon all :~)
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744. blueranch1
8:59 PM GMT on July 02, 2008
Ha HA Taz..this blog would go insane.
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743. HurricaneTracker01
8:59 PM GMT on July 02, 2008
wow... out for a few hours and now there are two more invests, 93L and 97E
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742. sporteguy03
8:58 PM GMT on July 02, 2008
JP the trolls would choose A of course lol
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741. OUSHAWN
8:58 PM GMT on July 02, 2008
and is also because of the stalled out front...
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740. weathermanwannabe
4:57 PM EDT on July 02, 2008
726. JFV 4:54 PM EDT on July 02, 2008
Guys, we have 93L? When in God's green earth did that appear?


It's a damn "sleeper" cell, that's what it is......
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739. Drakoen
8:58 PM GMT on July 02, 2008
732. blueranch1 8:57 PM GMT on July 02, 2008
If 93L doesnt have a chance then why did they tag it. Just to get people worked up...doubt it.


somebody's finger slipped and pushed the "93L.INVEST" button.
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738. Tazmanian
1:54 PM PDT on July 02, 2008
may be wil get 94L in the gulf of MX and 95L off the E coast of FL later today
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737. Weather456
4:58 PM AST on July 02, 2008
731. Nolehead 4:57 PM AST on July 02, 2008
hey why not...were on a roll now..


lol lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
735. Drakoen
8:56 PM GMT on July 02, 2008
725. OUSHAWN 8:54 PM GMT on July 02, 2008
93L doesn't stand a chance IMO. There is way too much shear in the Caribbean and there will be plenty more in the GOM if it were to continue on that path. Honestly, I feel both our Atlantic invests will be busts. Maybe in about 3 weeks or so the pattern may be change to allow these systems to start getting their act together but for right now they will struggle to get going. Again...IMO.


92L definitely has a chance. Its just the circulation is so large it has a hard time consolidating. All conditions are favorable for additional development of the system. This is the same thing we saw with Dean and even Felix. They take time to get their act together.
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734. OUSHAWN
8:56 PM GMT on July 02, 2008
What you are seeing off the Texas coast is being caused by the ULL sitting over the central part of the state...it looks a lot more impressive than it really is. Shear is way too high for anything to happen with it.
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733. atmoaggie
8:56 PM GMT on July 02, 2008
728. Tazmanian 8:54 PM GMT on July 02, 2008 Hide this comment.
what is that this off the TX coast???


Stalled cold front.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
732. blueranch1
8:55 PM GMT on July 02, 2008
If 93L doesnt have a chance then why did they tag it. Just to get people worked up...doubt it.
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731. Nolehead
8:56 PM GMT on July 02, 2008
hey why not...were on a roll now..
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730. Thundercloud01221991
8:55 PM GMT on July 02, 2008
what are you trying to do -- get us another invest???
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729. Nolehead
8:55 PM GMT on July 02, 2008
yeah taz, that's what i'm wondering..
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728. Tazmanian
1:33 PM PDT on July 02, 2008
what is that this off the TX coast???
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727. Weather456
4:53 PM AST on July 02, 2008
719. JFV 4:52 PM AST on July 02, 2008
And we all know where we want 93L to go....lol lol lol

Now, let me guess where that might be, dare I say Florida perhaps, Weather456? LOL!!!


BINGO!!! and we have a winner.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
725. OUSHAWN
8:48 PM GMT on July 02, 2008
93L doesn't stand a chance IMO. There is way too much shear in the Caribbean and there will be plenty more in the GOM if it were to continue on that path. Honestly, I feel both our Atlantic invests will be busts. Maybe in about 3 weeks or so the pattern may be change to allow these systems to start getting their act together but for right now they will struggle to get going. Again...IMO.
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724. Nolehead
8:52 PM GMT on July 02, 2008
anyone notice the spin in the GOM just south of tex/la border?? is that a low trying to develope?
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723. sky1989
8:51 PM GMT on July 02, 2008
I just don't see how 93L can survive. 30 to 40 knots of shear in its path will surely rip it apart, especially since it's so tiny.
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722. kmanislander
8:50 PM GMT on July 02, 2008
What ?? 93L, and a straight line from one of the models to the Caymans !!!

Say it aint so, puleeeze
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721. TerraNova
3:48 PM EST on July 02, 2008
TUTT
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720. JRRP
8:49 PM GMT on Julio 02, 2008
what model predict this system?
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718. Nolehead
8:51 PM GMT on July 02, 2008
things happen rather quik it seems these days..
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717. Thundercloud01221991
8:51 PM GMT on July 02, 2008
i think that the navy and NHC watches us and what we think will happen is what they forecast against
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715. Weather456
4:50 PM AST on July 02, 2008
Ok...who's the wiseguy that said activity would pick up these two weeks?

h23, drak, u, myself and a few others who saw de MJO and GFS long-range outlook.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
714. atmoaggie
8:49 PM GMT on July 02, 2008
I'll stick it out there and pick option A. I see a better chance than even that neither will develop into a TS. One simply doesn't want to and the other is would say isn't in the right environment.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
713. cchsweatherman
8:49 PM GMT on July 02, 2008
Right now, I'm going to be preparing a special update on my site regarding both features.
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712. Floodman
3:49 PM CDT on July 02, 2008
Man, walk away for half an hour and you guys get us another invest...
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711. Weather456
4:48 PM AST on July 02, 2008
Dont give a system 0% chance of develop....the only thing that definite is death. If shear is high, SSTs must be high, or vice versa....give it a low chance but not no chance.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
710. 7544
8:49 PM GMT on July 02, 2008
who thinks 93l will be a td before 92l hands up
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708. JRRP
8:44 PM GMT on Julio 02, 2008
93L?????
What is happening here ?
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707. Drakoen
8:47 PM GMT on July 02, 2008
697. StormW 8:45 PM GMT on July 02, 2008
Ok...who's the wiseguy that said activity would pick up these two weeks?


I thought activity would pick up around the beginning of July. I even went out to say I couldn't see how we couldn't have 1 or 2 tropical storms forming in July.
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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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