African tropical wave 99L has potential to develop

By: Dr. Jeff Masters , 3:10 PM GMT on July 30, 2012

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The first African tropical wave of 2012 with a potential to develop is Invest 99L, located in the Eastern Atlantic near 9°N 36°W, midway between the Lesser Antilles Islands and the coast of Africa. Visible satellite loops show a large area of the surrounding atmosphere has a pronounced counter-clockwise spin, though there is no surface circulation. The disturbance's heavy thunderstorm activity is pretty sparse, but appears to be slowly increasing. Water vapor satellite loops show that 99L has a reasonably moist environment, and the latest Saharan air layer analysis shows that the dry air from the Sahara lies well to the north of 99L. WInd shear over the disturbance is a light 5 - 10 knots, and ocean temperatures are 28°C, (82°F) which is well above the 26.5°C (80°F) threshold typically needed to allow formation of a tropical depression.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
Wind shear is expected to remain light for the next five days, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. The disturbance is at 9°N, which is close enough to the Equator that the storm will have some difficultly getting spinning. Most of the models are showing some slow development of 99L, with the storm reaching the Lesser Antilles Islands on Saturday, August 3. NHC gave 99L a 20% chance of developing into a tropical depression by Wednesday morning. I expect the storm will have trouble with dry air at times this week as it crosses the Atlantic, but I give 99L a 50% chance of eventually developing into Tropical Storm Ernesto sometime in the next ten days. Residents and visitors to the Lesser Antilles Islands should anticipate heavy rains and strong winds from 99L beginning to affect the islands as early as Friday night. The long-range fate of 99L is uncertain, but a trough of low pressure is expected to be present over the Eastern U.S. early next week, which would be capable of turning 99L more to the northwest.

Hot in the Central U.S.
The heat in America's heartland continued on Sunday, with Wichita, KS hitting 111°F, just 3° short of their all-time hottest temperature of 114° set on 8/12/1936. Other notable highs on Sunday:

111° Coffeyville, KS
111° Winfield, KS
110° Chanute, KS
110° Parsons, KS
109° Joplin, MO (all-time record is 115° on July 14, 1954)

The low temperature in Tulsa, Oklahoma this Monday morning dropped to only 88°F. This is the all-time warmest low temperature in the city since record keeping began in 1905. The previous record warmest minimum temperature was 87°F set on August 2, 2011 and July 16, 1980. The high in Tulsa Monday - Wednesday is expected to reach 110° - 111°, close to the city's all-time hottest temperature of 115° set on August 10, 1936.

Jeff Masters

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No surface low? That's news to me.

A TROPICAL WAVE ACCOMPANIED BY A SURFACE LOW PRESSURE SYSTEM IS
LOCATED ABOUT 750 MILES SOUTHWEST OF THE CAPE VERDE ISLANDS.
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138 hours
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Don't tell me the GFS is again starting to back off intensity. lol
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July Cargoes On Panamax Ships Slump As China Coal Demand Falls

By Michelle Wiese Bockmann - Jul 30, 2012 10:27 AM ET

The number of cargoes booked on Panamax bulk carriers, the largest to transit the Panama Canal, slumped 33 percent in July amid slowing Chinese imports of thermal coal, used for power stations, Morgan Stanley said.

...
"Panamax fixtures continue to decline as China's thermal coal demand is softening," the U.S. investment bank said in the report, citing a slowing economy and growing hydropower output.

http://www.bloomberg.com/news/2012-07-30/july-car goes-on-panamax-ships-slump-as-china-coal-demand-f alls.html
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132 hours
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No Active Atlantic Tropical Warnings
July-30-12, 12:00:01 PM | Maritime.CDO@navy.mil (FWC-N CDO)
As of Mon, 30 Jul 2012 16:00:01 GMT
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Quoting MAweatherboy1:
Very weak this run so far:



Levi mentioned that the pressure gradient (when the storm nears that area) increases and distorts the circulation.
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126 hours, still weak, and look off of Africa.
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Quoting Pocamocca:
500-700 MB is the dry layer I'm concerned about with this system. Other than that inhibiting factor, all other components seem fairly favorable for a very strong TS to form in the long range.
dry air will work itself out of the system once the system becomes better defined, look at how well the wave over the Lesser Antilles held together with dry air surrounding it.



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Very weak this run so far:

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with that bermuda high flexing its muscles i have a hard time seeing it heading that far nw
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114 hours and 1007mb moving NW


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972 islandgirls: How far north might this system go?

As far as the northernmost model of the ensemble is concerned, and inre the LesserAntilles, it could skim Barbuda. Which means that pulling out the hurricane shutters from behind all of the junk piled in front of them would be a good idea for those who live in Antigua.

Probably won't need to put them up -- I favor the model passing south of Barbados heading toward Haiti myself -- but ya know that TropicalCyclones start getting hinky* at about 55degreesWest, or 300miles(480kilometres) east of Barbados.
Better to have those hurricane shutters within easy reach than to have to panic struggle them out of their storage space during nasty weather.

* ie Can make large and/or rapid changes in the direction of travel and/or the speed of travel and/or MaximumSustainedWinds and/or Storm-size
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108 hours and a pressure of 1009mb and definitely more north.
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we need that in the western caribbean given the environment it would just be a rainmaker...perfect need as much as we can get and some relief from the heat.
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I expect the storm will have trouble with dry air at times this week as it crosses the Atlantic, but I give 99L a 50% chance of eventually developing into Tropical Storm Ernesto sometime in the next ten days.
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108 hours, still pretty weak:

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Quoting Pocamocca:

Mid levels won't be conducive beyond 5 days it appears. Mid 50 RH at 500MB isn't exactly favorable for a developing depression.


Wasn't coming from me, that quote was from Dr. Masters himself. He strongly disagrees with your logic on the dry air.
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Quoting reedzone:


Apparently the SHIPS model takes it north of the islands?

SHIPS intensifies it into a hurricane.
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96 hours, seems to be north of previous runs again.
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Notably more north so far this run
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Quoting CaicosRetiredSailor:
Nice to see Janiel's recent sock puppet got the hammer...
Admin should keep the ban hammer handy...

He wasn't banned.
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Quoting TropicalAnalystwx13:
Dry air doesn't seem like it will be much of an inhibitor either.

700-500 MB RH 62 63 61 63 66 66 68 65 63 63 59 57 52


Apparently the SHIPS model takes it north of the islands?
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And lo...,

Admin moved her hand and the Land was free once again.


"Ohmmmm"
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Yes those storms were difficult to forecast..but Debby takes the cake.Sprawling out different centers..not wanting to go anywhere...going one way but then goes another...
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Quoting Pocamocca:

What SHIPS run is that? 06Z?

12Z.
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definitely, ugly storm
Tropical Storm Emily (2011)
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Quoting Pocamocca:

Did you expect anything to be? A prevalence of dry air and SAL will be lurking. If 99L doesn't make it to the Caribbean at least as a TD, then I don't see any development at all.


Water vapor satellite loops show that 99L has a reasonably moist environment, and the latest Saharan air layer analysis shows that the dry air from the Sahara lies well to the north of 99L.

Nice try ;)
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90 hours


Also Saola is a typhoon with 75mph winds.
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Quoting ncstorm:


a lot of people thought Emily was done for when she was crossing over those mountains but she had other plans..

She just would not stop, there was also Fay but that was a different story.
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Dry air doesn't seem like it will be much of an inhibitor either.

700-500 MB RH 62 63 61 63 66 66 68 65 63 63 59 57 52
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Nice to see Janiel's recent sock puppet got the hammer...
Admin should keep the ban hammer handy...
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Quoting TropicalAnalystwx13:

I'd rather take a well defined system, thanks. :P

If you want a well-defined system just look at Saola.
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Quoting ncstorm:


I just thought of that as well and posted it..
Quoting GTcooliebai:
Two great minds think alike, I was just about to post that. And noticed how in the last run of the GFS it kills it before reaching Haiti and then redevelops it off the southeast coast of FL.

O_O
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One thing is for sure...wind shear will not be a problem.

SHEAR (KT) 1 6 5 4 4 8 9 2 3 4 1 9 8
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Quoting ncstorm:
even if crosses over Hispanola, it still can generate..

Remember 2011 Emily that wouldnt die..

The gfs had 99L doing something similar with it re-generating south of FL and then making landfall in FL as a weak TS.
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Quoting wxchaser97:
66 hours
The Azores/Bermuda High is holding firm.
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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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