African disturbance 92L chugs west; California fires generating significant pollution
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
Reader Comments
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Any how, shear should remain high in the Caribbean even as the TUTT moves out, due to the current anticyclone (ULH/Upper Level High) and the possible development of several new highs in the Eastern Pacific and over Central America, according to the GFS.
Here's the Link.. at the bottom you can animate it.
Link
Gee, go to work early this am and come home to a 93L. Anyone ELSE got a hunch this is going to be an interesting season?
I will just sit back read and learn.
Drak, can 93L survive despite so much overwhelming shear in the Carib right now
read what you just said over again.
Ok... I'm gettign all confused. Who wants to be a dear and update me (quickly/simply) on 92L, 93L and is there something in the GOM? I'm losing it...
92L = Africa Wave
93L = Eastern Caribbean wave near Barbados.
Blob of thunderstorms in the SW GOM.
Didn't honestly think you were calling me that, but don't actually care all that much if you did.
And you are right, somewhat. Most of our trolls will say that 4 cat 5s will come out of 2 invests, all 4 of them will meet at Memphis, and the storm surge will go around NOLA and totally inundate everything from Tulsa to Asheville, NC because they are real smart like that.
Models backing up on significant development with 92L could mean it might try to track westward a bit futher.I still think the odds are slim though it ever threatens the U.S.
Even with model consensus I don't think 92L will pull north without a fight. It will eventually re curve though.
Ok... I'm gettign all confused. Who wants to be a dear and update me (quickly/simply) on 92L, 93L and is there something in the GOM? I'm losing it...
LOL.....alright here's the scoop.
92L is holding its own in the diurnal min southeast of the Cape Verde Islands. Models continue to call for recurvature with a couple outliers forecasting westward movement and a weaker system. The major determining factor in 92L's future track is its strength during the next week, as a weaker system is more likely to slip under the high and make it further west. For now gradual development into a tropical depression is expected over the next 3 days.
93L is a tiny little beastly spin east of the Antilles islands kicking up some thunderstorm activity over the center of the tiny circulation. Unfortunately for this tiny creature there is a big monster TUTT squarely ahead that I expect will rip this thing apart within 48 hours. There is a small window of oppertunity for this system to become a TD before upper-air conditions become too hostile.
The GOM is quiet......by next week we will have to watch that area as the waves in the eastern Pacific are nudging northeast with each passing wave, and the MJO pulse will eventually move these waves into the Caribbean and GOM, and by that time upper-air conditions will be improving and those areas will have to be watched for development in the 1-2 week time-frame.
93L: 13%
African wave: 99%
Does anyone know if the MJO pulse has reached the Caribbean Basin yet?....The EPAC is still very active right now and I wonder about significant development in the Caribean until Boris, and particularly Douglas and the good looking system just west of Central America, move a little further way......
Still mostly in the eastern pacific/eastern atlantic but eventually will slip into the gulf/caribbean during the next 2 weeks.
Could be the intensity models are getting impatient waiting for the system to do something. Dropped some wind speed.
Hey Shawn
Levi - Thank you so much!!
The intensity forecasts for 92L:
The 12z models were all predicting a tropical storm to form at one or another; now I see NOGAPS wants to keep at at depression strength, and GFDL barely has it as a tropical storm.
Thanks for your thoughts. I will keep a close eye on this one, as it's a lot closer to home.
92L to me has a 60 %
The 12z models were all predicting a tropical storm to form at one or another; now I see NOGAPS wants to keep at at depression strength, and GFDL barely has it as a tropical storm.
Hah! Modified my comment sometime before I refreshed and saw yours. I dunno...NOGAPS isn't the best tropical model out there, but I have a lot of respect for GFDL and if it is trending down...
(I see that I might be up late waiting for the 06 UTC runs tonight)
Whoever said 92L WILL be a cane (with conviction) must be seeing something most of the models are not.
CCHS, you may be looking at something different than I am, perhaps 48 hrs or more out, but clearly, here on this shear tendency map, shear in the eCarib is 30 kts and better. It does show a relaxing of about 10 kts within 24 hrs. That's strong enough to still likely prevent further development. Let's hope so.
Not even a smidgen of rot. in the GOM. Is shear forcast to relax any? I khow storms can form on the tail ends of these frontal boundries.
You can click here for the latest GFS wind shear forecast. Shear should remain at unfavorable levels in the most of the Gulf of Mexico as well as the Western Caribbean for the next week or so, as a series of upper level high pressure systems develop over Central America and head west into the East Pacific. The clockwise flow over the GOM/Western Caribbean at the higher levels coupled with different winds at the mid and lower levels will keep shear up.
MLC, that plot is only what happened in the LAST 24 hours of measurements...it tells you nothing about the future. You can assume that some persistence will occur and you may or may not be correct. (That assumption has bitten me more than once, though.)
MLC....compare:
GFS 12z analysis 200mb winds
GFS 12z 48-hour forecast 200mb winds
It's bookin' it out of there pretty fast.....we'll see if 93L survives until it does. Another very interesting situation developing here.
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