Forecast for 92L: dissipation by Friday

By: Dr. Jeff Masters , 2:17 PM GMT on June 16, 2010

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A low pressure system about 700 miles east of the Lesser Antilles Islands, Invest 92L, was near tropical depression status early this morning, but is currently weakening. Infrared satellite loops show the disturbance's heavy thunderstorm activity has decreased markedly in the past few hours, with the cloud top temperatures warming noticeably, indicating that 92L's thunderstorms are no longer pushing as high into the atmosphere. Water vapor satellite loops show that the storm is surrounded on all sides by dry air, though there is a region of moister air in front of it that 92L will encounter on Thursday. Wind shear as diagnosed by the University of Wisconsin is near 20 knots, though the SHIPS model is diagnosing the shear at a higher 25 - 30 knots. This high shear is pushing 92L's heavy thunderstorm activity to the east side of the center of circulation, and the center will probably become exposed to view late this morning. Had 92L been able to maintain the heavy thunderstorm activity it had early this morning for 12 or so hours, it could have been classified as a tropical depression. However, classification as a TD requires persistent heavy thunderstorm activity, typically interpreted to mean 12 hours of consistent heavy thunderstorm activity, and 92L did not meet that criterion.


Figure 1. Morning satellite image of Invest 92L. Image credit: NOAA.

The forecast for 92L: dissipation
Wind shear is the main story in the forecast for 92L, as a band of very high wind shear of 20 - 50 knots lies to the northwest of the storm. The current expected track of 92L carries it into this band of high wind shear, and the SHIPS model (based on the GFS model) is predicting that the shear will remain in the 25 - 30 knot range through Friday. Other models predict higher shear levels. It is likely that the high shear, combined with the dry air surrounding the storm, will destroy 92L by Friday. The National Hurricane Center is giving 92L a low (10% chance) of developing into a tropical depression by Friday morning, and this is a reasonable forecast. It is likely that 92L will bring heavy rain showers and wind gusts up to 35 mph on Friday to the Lesser Antilles Islands. I don't expect 92L to be organized enough to cause flooding problems to any of the islands in its path. None of our reliable global computer models develop 92L into a tropical depression. The rest of the tropical Atlantic is quiet, and none of the reliable computer models is calling for tropical cyclone development in the Atlantic over the next seven days.

Is the formation of 92L a harbinger of an active hurricane season?
According to the Hurricane FAQ, Goldenberg (2000) found that during the period 1944 - 1999, formation of a named storm in the tropical Atlantic south of 22°N and east of 77°W during June and July was a harbinger of at least an average season, and in many cases an above average season. The formation of a storm in this region during June or July is one factor the NOAA and Colorado State University seasonal hurricane forecast teams have used in the past as a predictor for an active season in their early August forecasts. Now, 92L didn't make it to named storm status, though it was pretty close to being a tropical depression. However, the near-formation of 92L into a tropical depression, is, in my mind, a clear harbinger that we can expect a severe hurricane season this year. It's very rare to have a development like 92L in that portion of the tropical Atlantic this early in the season. The lower than average wind shear and higher than average SSTs that helped 92L get organized are more likely than not to carry over into the main portion of hurricane season, giving us a much more active hurricane season than normal.


Figure 2. Synthetic Aperture Radar (SAR) image of the oil spill taken at 7:51 am EDT Tuesday June 15, 2010, by the Canadian Radarsat-1 satellite, operated by MDA GeospatialServices of Richmond, Canada. A large amount of oil was present on the Florida Panhandle coast near Pensacola, and was headed east towards Panama City. Image credit: Center for Southeastern Tropical Advanced Remote Sensing, University of Miami Rosenstiel School of Marine and Atmospheric Science. SAR images have a resolution of 8 - 50 meters, and can be taken through clouds and precipitation.

Oil spill wind and ocean current forecast
Light and variable winds less than 10 knots will blow in the northern Gulf of Mexico for the next five days, according to the latest marine forecast from NOAA. The winds will tend to have a westerly component for the most part, which will maintain a slow (1/4 mph) eastward-moving surface ocean current that will transport oil eastwards along the Florida Panhandle coast, according to the latest ocean current forecast from NOAA's HYCOM model. These winds and currents may be capable of transporting oil east past Panama City, Florida to Cape San Blas by Monday. Oil will continue to threaten the coasts of Louisiana, Alabama, and Mississippi for the remainder of the week as well, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range 8 - 16 day forecast from the GFS model indicates a typical summertime light wind regime, with winds mostly blowing out of the south or southeast. This wind regime will likely keep oil close to the coastal areas that have already seen oil impacts over the past two weeks.

NOAA has lauched a great new interactive mapping tool that allows one to overlay wind forecasts, ocean current forecasts, oil location, etc.

Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA has lauched a great new interactive mapping tool that allows one to overlay forecasts and oil location observations
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

I'll have an update on Thursday.

Jeff Masters

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Quoting YourCommonSense:
I don't expect any tropical development in the Atlantic for the next 2 years. Have a great day!


YourCommonSense
maybe a screen name change
to NoCommonSense
would be better
Member Since: July 15, 2006 Posts: 178 Comments: 56141
466. xcool
Levi32 .how about joe b new
videos >?
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HI StormW

I love the pic #453---what site is that from?
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Quoting KEEPEROFTHEGATE:
levi its 73 here heat index 87 dewpoints of 70 just had a recent thunderstorm beginning to clear sun comes out temps should spike a little more maybe to high 70's low 80's with heat index of 95 could still see another passing storm before end of day


Yuck yuck.
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Since the Atlantic is dead for the time being, I'm going to focus of the eastern Pacific.

TD 1-E

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Never seen a Caribbean red pool this big in June. In fact it's rare to get them this big in any month.

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Quoting YourCommonSense:
I don't expect any tropical development in the Atlantic for the next 2 years. Have a great day!


That can't be good for the blog.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
levi its 73 here heat index 87 dewpoints of 70 just had a recent thunderstorm beginning to clear sun comes out temps should spike a little more maybe to high 70's low 80's with heat index of 95 could still see another passing storm before end of day
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Destin, feel kind of bad now since this blog only has one Doctor.
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456. IKE
Quoting YourCommonSense:
I don't expect any tropical development in the Atlantic for the next 2 years. Have a great day!


WOOHOO!
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Quoting DestinJeff:
LOL. all the "hey"s and "hi"s and "good afternoon"s remind me of this:


LMAO
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Quoting leo305:
for a supposed extreemely active season, we have yet to have 1 named storm, and we are heading for late june
don't worry still lots of time for an ass whipping yet
Member Since: July 15, 2006 Posts: 178 Comments: 56141
*Sigh*...that satellite image of the oil just sucked the spirit out of me. Ninety percent of my memories growing up are on Pensacola Beach. Just never imagined it would be an oil spill that did us all in.
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Quoting MiamiHurricanes09:
Here its 96F with a feels like of 118F. How about that.


We're 97 with 113 HI. Rain rain come today!
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448. IKE
From the latest discussion...

"A 1011 MB SURFACE LOW IS
CENTERED E OF THE TROPICAL WAVE APPROACHING THE LESSER ANTILLES
NEAR 14N51W. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS
NEAR AND N OF THE CENTER FROM 13N-18N BETWEEN 47W-51W. THIS LOW
IS FORECAST TO BECOME AN OPEN TROUGH DURING THE NEXT 24 HRS."
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Quoting Levi32:


A single closed isobar doesn't necessarily guarantee a closed surface circulation. A closed isobar means that the low pressure center is surrounded completely all around by higher pressures. This will naturally make the surface wind want to rush towards the low from all directions, but when it is only one isobar and the system is weak, the air flow drawn into the system will not always be strong enough to form a closed circulation, as we saw in the WindSat pass earlier, which was barely open to the southwest. I'd post it again but their site is down.


Nice explanation Levi, as usual.
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000
ABNT20 KNHC 161730
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED JUN 16 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE LOW PRESSURE SYSTEM
LOCATED ABOUT 625 MILES EAST OF THE LESSER ANTILLES ARE POORLY
ORGANIZED. UPPER-LEVEL WINDS ARE EXPECTED TO REMAIN UNFAVORABLE
FOR TROPICAL CYCLONE FORMATION. THERE IS A LOW CHANCE...10
PERCENT
... OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD NEAR 15 MPH.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER KIMBERLAIN/BROWN

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Quoting extreme236:


All the way in SW Ohio. Good 'ol Midwest lol
WOW. Far away.
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Quoting stillwaiting:
maybe some seabreeze storms along sarasota's coastline over the next 2-3hrs....
Sea breeze very evident around Tampa Bay. I'm watching the line blow up from Odessa, north of tpa.
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Quoting leo305:
for a supposed extreemely active season, we have yet to have 1 named storm, and we are heading for late june


and?

June is a very inactive month no matter how active the season is
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maybe some seabreeze storms along sarasota's coastline over the next 2-3hrs....
Member Since: October 5, 2007 Posts: 20 Comments: 4970
Quoting MiamiHurricanes09:
Where are you? The TWO is 20 minutes late.


All the way in SW Ohio. Good 'ol Midwest lol
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Quoting extreme236:


80 degrees and sunny here.
Where are you?

The TWO is 20 minutes late.
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438. xcool
Hurricanes101 .so sad.
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for a supposed extreemely active season, we have yet to have 1 named storm, and we are heading for late june
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Quoting xcool:
so sad ep get first name Storm.


They usually do. They had it back in May.
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Quoting MiamiHurricanes09:
Here its 96F with a feels like of 118F. How about that.


80 degrees and sunny here.
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Quoting xcool:
so sad ep get first name Storm.


EPAC always gets the first named storm
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433. xcool
so sad ep get first name Storm.
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432. MTWX
Levi, I would gladly trade you locations!! I have always wanted to live in Alaska!!
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Quoting stillwaiting:




better than 94!!!,lol;)
Here its 96F with a feels like of 118F. How about that.
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Quoting Levi32:


Sounds like it's past my melting point lol. I've never experienced a dewpoint above 50 or an ambient temperature above 85.


Actually no I've seen dewpoints up to 60....but never above 50 when the air temperature is 70+
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Quoting Levi32:


Pretty good, a bit on the chilly side....how does 44 degrees sound?




better than 94!!!,lol;)
Member Since: October 5, 2007 Posts: 20 Comments: 4970
428. xcool
hope this season becomes more interesting than the last one.


look all wind shear now wt===== iknow june
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Quoting StormW:


COLD! How does 96 with a heat index of 114 sound?


Sounds like it's past my melting point lol. I've never experienced a dewpoint above 50 or an ambient temperature above 85.
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Quoting StSimonsIslandGAGuy:
Closed isobar.

So I have a question, doesn't a closed isobar define a tropical depression? Or is it also subjective, such as if the NHC doesn't think it has much of a chance, they will not call it a tropical depression even if it meets the requirements (unless it strengthened and organized in defiance of predictions)


A single closed isobar doesn't necessarily guarantee a closed surface circulation. A closed isobar means that the low pressure center is surrounded completely all around by higher pressures. This will naturally make the surface wind want to rush towards the low from all directions, but when it is only one isobar and the system is weak, the air flow drawn into the system will not always be strong enough to form a closed circulation, as we saw in the WindSat pass earlier, which was barely open to the southwest. I'd post it again but their site is down.
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425. MTWX
Quoting Levi32:


Pretty good, a bit on the chilly side....how does 44 degrees sound?

Sounds very refreshing to me!! Our heat index yesterday reached 125 degrees!!!!
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Quoting StSimonsIslandGAGuy:
Closed isobar.

So I have a question, doesn't a closed isobar define a tropical depression? Or is it also subjective, such as if the NHC doesn't think it has much of a chance, they will not call it a tropical depression even if it meets the requirements (unless it strengthened and organized in defiance of predictions)


It just means it is a closed low.
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Quoting StormW:


How goes it out Alaska way?


Pretty good, a bit on the chilly side....how does 44 degrees sound?
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419. MTWX
Quoting StormW:


How goes it out Alaska way?


I was curious too. Hows the weather up there Levi??
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Nice low-mid level turning with this ITCZ disturbance.

Loop

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Very late TWO...
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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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