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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1057. HurricaneTracker01
12:35 AM GMT on July 03, 2008
im vacationing near daytona this week.. until the 15th... will i be affected by one of these storms?
Member Since: August 1, 2006 Posts: 6 Comments: 126
1056. extreme236
12:34 AM GMT on July 03, 2008
Its interesting that the SHIPS/DSHPS takes 93L to minimal Tropical storm status (with the DSHPS being slightly weaker than SHIPS due probably to some land interaction.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1055. NorthxCakalaky
12:33 AM GMT on July 03, 2008
1037


Models are pointing around southern Florida.Probaly will change every update though.I think the East Coast of Florida and ALL of the Gulf Of Mexico States have the chance to be at risk.
1054. pearlandaggie
12:33 AM GMT on July 03, 2008
atmo, wait 'til i tell your wife! LOL
Member Since: September 14, 2007 Posts: 3 Comments: 3963
1053. extreme236
12:32 AM GMT on July 03, 2008
1047.

Oh your referring to the Gabby pre-cursor! Sorry, I thought you were referring to when it was a cyclone. I was gonna say, I don't remember 40 knots of shear over it as a cyclone lol
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1052. IKE
12:32 AM GMT on July 03, 2008
1043. TheWeatherMan504 7:30 PM CDT on July 02, 2008
Jp my magic 8 ball predicted 93l.


If I'm not mistaken, 93L is the CATL wave w/a circulation...it's survived up til now.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1051. GeoffreyWPB
12:32 AM GMT on July 03, 2008
1035. JFV 8:26 PM EDT on July 02, 2008
Guys, I'll be right back. My fiance is throwing up again! Be back in 5 or 10 minutes from now.

JFV is going to be a daddy...Congrats dude. I am just finally happy that he ended a post with a period (.)
Member Since: September 10, 2007 Posts: 0 Comments: 11401
1050. bluenosedave
12:31 AM GMT on July 03, 2008
1015. I got it, too, p&a. Nice image. :-)
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1049. pearlandaggie
12:31 AM GMT on July 03, 2008
1043. well, give it a job, then! :)
Member Since: September 14, 2007 Posts: 3 Comments: 3963
1048. Levi32
4:29 PM AKDT on July 02, 2008
93L's LLC is already fighting to stay underneath the southern edge of the convective burst as the southerly shear starts pushing the thunderstorms to the north. Link
Member Since: November 24, 2005 Posts: 635 Comments: 26682
1045. yamil20
12:29 AM GMT on Julio 03, 2008
Link

woo the tropics are heating up and the shear around this wave seems to be decreasing
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1044. atmoaggie
12:30 AM GMT on July 03, 2008
would never STFU! LOL

Yeah, got a wife like that...jk ;^)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
1043. TheWeatherMan504
12:29 AM GMT on July 03, 2008
Jp my magic 8 ball predicted 93l.
Member Since: May 18, 2008 Posts: 2 Comments: 1042
1042. Levi32
4:26 PM AKDT on July 02, 2008
1029. TerraNova 4:22 PM AKDT on July 02, 2008 Hide this comment.
1025. Levi32 7:20 PM EST on July 02, 2008

Isn't there a longwave associated with the possible future weakness in the high?


We're talking about 2 different weaknesses. The ULL will pull on 92L first. Assuming 92L doesn't recurve here.....it will turn back to the west as the ridge rebuilds when the ULL lifts out and move on until it encounters the long-wave trough which will pull on it once again. That's way too far out to really get an idea of how strong the trough will be, but it will be influencing the high after the ULL is long gone, they're too different things at two different times.
Member Since: November 24, 2005 Posts: 635 Comments: 26682
1041. pearlandaggie
12:28 AM GMT on July 03, 2008
i had a parrot named Gabby...would never STFU! LOL
Member Since: September 14, 2007 Posts: 3 Comments: 3963
1040. IKE
7:28 PM CDT on July 02, 2008
1035. JFV 7:26 PM CDT on July 02, 2008
Guys, I'll be right back. My fiance is throwing up again! Be back in 5 or 10 minutes from now.


Too much info.......
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1039. extreme236
12:26 AM GMT on July 03, 2008
Well Gabby was also a developed cyclone, and 93L is far from that. I just don't see how 93L will survive the shear, but the shear does seem to be dropping so it could get lucky.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1038. TheWeatherMan504
12:23 AM GMT on July 03, 2008
1031. extreme236 12:23 AM GMT on July 03, 2008
Well Ingrid was fairly shallow too but it didn't get very far once it reached the shear lol


lol 93l had probaly met its demise however if shear was low 93l would have been a hurricane.
Member Since: May 18, 2008 Posts: 2 Comments: 1042
1037. caribbeansurvivor1
12:24 AM GMT on July 03, 2008
agree with u north. But about 93L...someone tell me more....it will move more to wnw...?
Member Since: July 29, 2007 Posts: 0 Comments: 170
1034. Levi32
4:22 PM AKDT on July 02, 2008
1026. jphurricane2006 4:21 PM AKDT on July 02, 2008

Well yeah.....I dunno.....I'm going back and forth with 93L lol. I don't like the look of the model tracks being run on it. I'm leaning towards the shear severely hampering or reversing any progress for the next couple days....but if anything remains of the system I think we'll have something to watch.
Member Since: November 24, 2005 Posts: 635 Comments: 26682
1031. extreme236
12:22 AM GMT on July 03, 2008
Well Ingrid was fairly shallow too but it didn't get very far once it reached the shear lol
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1030. NorthxCakalaky
12:19 AM GMT on July 03, 2008
93L is alot closer to the U.S than 92, we realy need to watch it more.
1029. TerraNova
7:21 PM EST on July 02, 2008
1025. Levi32 7:20 PM EST on July 02, 2008

Isn't there a longwave associated with the possible future weakness in the high?
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1028. TheWeatherMan504
12:18 AM GMT on July 03, 2008
93l is now arriveing in its final desination.
Member Since: May 18, 2008 Posts: 2 Comments: 1042
1027. pearlandaggie
12:20 AM GMT on July 03, 2008
1024. relax, dawg! LOL
Member Since: September 14, 2007 Posts: 3 Comments: 3963
1025. Levi32
4:18 PM AKDT on July 02, 2008
1013. caribbeansurvivor1 4:13 PM AKDT on July 02, 2008 Hide this comment.
92L are moving at 25mph, really fast...
About the B/A high i were reading can not get weak so soon...but is my impression and i still learning about it...


The high itself is not going to weaken anytime soon, it is very strong this year. The issue is the ULL sitting in the central Atlantic in the middle of the high, and will provide a weakness that will pull on 92L. How much it pulls is the million dollar question, and again it all depends on how strong 92L is when it tries to cross that area.
Member Since: November 24, 2005 Posts: 635 Comments: 26682
1024. gulfcoastdweller
12:18 AM GMT on July 03, 2008
92 & 93? Oh lord, Thanks God it isn't Aug/Sept
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1023. reedzone
12:18 AM GMT on July 03, 2008
1020.

Ohh ok, cool... I'm a 2006 graduate!
Member Since: July 1, 2008 Posts: 13 Comments: 7416
1022. Levi32
4:12 PM AKDT on July 02, 2008
92L looks to be getting better organized. The system is now far enough from the African coast that the eastern rain bands can start setting up. Expect only gradual development with this system, as it is quite large. Again the weaker 92L stays, the more dangerous it is, as a weaker system has a much greater chance of slipping under the high and getting further west.

93L is a valiant little system, but it has very little time left before it begins feeling the strong effects of wind shear provided by the TUTT in the Caribbean. This TUTT is forecast to lift out by 48 hours, but by that time 93L will have been under its influence for at least 24 hours, and that's probably all it will take to rip the system apart. We'll see how it all plays out.
Member Since: November 24, 2005 Posts: 635 Comments: 26682
1021. extreme236
12:17 AM GMT on July 03, 2008
Well 93L was trying to get more organized but its heading into Shear City. It already looks to be getting hit by some increasing shear.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1019. TerraNova
7:16 PM EST on July 02, 2008
Confirmed tornado/waterspout in Staten Island.

EDIT: This actually happened last Sunday.
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1018. atmoaggie
12:06 AM GMT on July 03, 2008
FORECASTER BEVEN/LANDSEA

what a great name for a meteorologist! it's almost as good as the goalie that played for the Dallas Stars...Tugnut!


Whoa, I didn't notice Landsea was involved the TWO. That's odd. Landsea is a Hurricane Research Division guy. I did hear they would integrate different departments some, but didn't expect that.

Landsea got his PhD 10 years or so ago under Bill Gray. Very sharp guy and very cool to talk to at conferences. Show any interest in his work and he will make time to answer questions and likely will be armed with prints of his published works to give to you.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
1017. moonlightcowboy
7:15 PM CDT on July 02, 2008
1015. ;P
Member Since: July 9, 2006 Posts: 184 Comments: 29610
1016. TerraNova
7:13 PM EST on July 02, 2008
1012. extreme236 7:13 PM EST on July 02, 2008
One think to watch for with 92L is the Dvorak number. If you see it go up, that would indicate an increase in organization and could be enough for the NHC to classify it.


It's remained at T1.0/1.0 for most of today (even during the Navy's hiccup) but I would expect an increase in Dvorak classifications to T1.5/1.5 on the next update, if the current convective round continues.
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1015. pearlandaggie
12:13 AM GMT on July 03, 2008
MLC, i wonder if i'm the only one that'll get your joke! LMAO!

how long have you had that one in storage waiting for the appropriate time to use it? LOL
Member Since: September 14, 2007 Posts: 3 Comments: 3963
1013. caribbeansurvivor1
12:12 AM GMT on July 03, 2008
92L are moving at 25mph, really fast...
About the B/A high i were reading can not get weak so soon...but is my impression and i still learning about it...
Member Since: July 29, 2007 Posts: 0 Comments: 170
1012. extreme236
12:12 AM GMT on July 03, 2008
One think to watch for with 92L is the Dvorak number. If you see it go up, that would indicate an increase in organization and could be enough for the NHC to classify it.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1011. TerraNova
7:10 PM EST on July 02, 2008
1001. FLWeatherFreak91 7:07 PM EST on July 02, 2008
ok terra thanks. so basically, if one trough can't get 92 out of the way, there's a backup


Most likely, yes. It depends on whether the GFS is correct in taking it that far north, though, so we'll just have to wait and see.
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1010. moonlightcowboy
7:08 PM CDT on July 02, 2008
PhD's? Yeah, we've got quite a few on WU! Good group of folks! hehe

Member Since: July 9, 2006 Posts: 184 Comments: 29610
1009. tropicfreak
8:10 PM EDT on July 02, 2008
1007 you already said that
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1008. pearlandaggie
12:09 AM GMT on July 03, 2008
Winter in the high Rockies finally gets plowed
Member Since: September 14, 2007 Posts: 3 Comments: 3963
1007. caribbeansurvivor1
12:09 AM GMT on July 03, 2008
Gentlemen/ladies do u think that 92L will stay in wnw track??
Member Since: July 29, 2007 Posts: 0 Comments: 170

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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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