[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 241759
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUN 24 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...SPECIAL FEATURES...

AS OF 1800 UTC...TROPICAL STORM DEBBY IS CENTERED NEAR 28.3N
85.9W...OR ABOUT 175 NM ESE OF THE MOUTH OF MISSISSIPPI
RIVER...MOVING NE AT 5 KT. THE ESTIMATED MINIMUM PRESSURE IS 993
MB. THE MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60
KT. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM
26N-31N BETWEEN 79W-85W INCLUDING MUCH OF THE FLORIDA
PENINSULA...WHICH IS CONFIRMED BY RADAR IMAGERY. SIMILAR
ACTIVITY IS ALSO N OF THE STORM CENTER FROM 29N-31N BETWEEN
85W-88W. A LINE OF SHOWERS/THUNDERSTORMS ALSO EXTENDS FROM THE
MAIN AREA OF CONVECTION TOWARDS THE SW GULF ALONG 26N85W TO
21N95W. ANOTHER AREA OF NUMEROUS MODERATE/SCATTERED STRONG
CONVECTION IS IN THE NW CARIBBEAN FROM 17N-23N BETWEEN 84W-88W.
EVEN THOUGH THIS AREA OF CONVECTION IS REMOVED FROM THE STORM
CENTER...IT IS STILL WITHIN THE LARGE AREA OF CYCLONIC FLOW
PRESENT AROUND THE STORM WHICH SPREADS ACROSS THE ENTIRE GULF OF
MEXICO AND THE FAR NW CARIBBEAN. THERE IS A LOT OF UNCERTAINTY
IN THE TRACK FORECAST...AND ALL AREAS OF THE GULF COAST SHOULD
CONTINUE TO MONITOR THE PROGRESS OF DEBBY. PLEASE READ THE
LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT43/WTNT24 KNHC AND THE PUBLIC ADVISORY MIATCPAT4/WTNT34
KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE HAS MOVED OFF THE COAST OF AFRICA AND IS ALONG
16N20W TO 8N24W MOVING W NEAR 10-15 KT. UPPER AIR SOUNDINGS FROM
DAKAR SENEGAL INDICATE THAT THE WAVE PASSED THE STATION BETWEEN
23/0000 UTC AND 23/1200 UTC. THERE IS ALSO A CLEARING IN THE
SAHARAN AIR LAYER AROUND THE WAVE ALONG WITH A SURGE OF DEEP
LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY.
SCATTERED MODERATE CONVECTION IS FROM 4N-11N BETWEEN 21W-28W.

A TROPICAL WAVE IS ALONG 17N46W TO 8N47W MOVING W NEAR 20 KT.
THE WAVE LIES ON THE WRN SIDE OF A NARROW SURGE IN DEEP LAYER
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. VISIBLE
SATELLITE IMAGERY ALSO INDICATES A CLEARING IN A LARGE AREA OF
SAHARAN DUST THAT EXISTS BOTH E AND W OF THE WAVE AXIS. NO DEEP
CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE DUE TO THE DRY
AIR SURROUNDING IT.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF AFRICA NEAR 19N16W
ALONG 13N23W 6N29W. THE ITCZ CONTINUES FROM 6N29W ALONG 4N38W
6N46W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
8N-14N BETWEEN 15W-17W. SIMILAR ACTIVITY IS FROM 5N-8N BETWEEN
28W-36W.

...DISCUSSION...

THE GULF OF MEXICO...

TROPICAL STORM DEBBY IS DOMINATING THE WEATHER PATTERN ACROSS
THE GULF OF MEXICO TODAY. SEE SPECIAL FEATURES ABOVE FOR MORE
DETAILS. MOST OF THE SHOWER/THUNDERSTORM ACTIVITY IS E AND N OF
THE STORM CENTER LEAVING MUCH OF THE WRN GULF DRY AND CLEAR. DRY
AIR ALOFT AROUND AN UPPER LEVEL TROUGH OVER THE WRN GULF ALONG
93W IS HELPING MAINTAIN THESE FAIR CONDITIONS. AN UPPER LEVEL
RIDGE IS ALONG THE FLORIDA PENINSULA AND ACROSS MUCH OF THE
CARIBBEAN. THE FUTURE TRACK OF DEBBY IS SOMEWHAT UNCERTAIN AS
MODEL GUIDANCE HAS BEEN YIELDING CONFLICTING TRACK FORECASTS.
THE ENTIRE GULF COAST SHOULD MONITOR THE PROGRESS OF DEBBY DUE
TO THE LOW CONFIDENCE IN TRACK FORECAST.

THE CARIBBEAN SEA...

SHOWERS/THUNDERSTORMS ARE ACROSS THE FAR NW CARIBBEAN IN
ASSOCIATION WITH THE CIRCULATION AROUND TROPICAL STORM DEBBY IN
THE GULF OF MEXICO. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS.
THE REMAINDER OF THE CARIBBEAN IS UNDER MOSTLY CLEAR SKIES DUE
TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE COVERING FLORIDA
AND THE CENTRAL AND WRN CARIBBEAN. A WEAK UPPER TROUGH COVERS
THE ERN CARIBBEAN ALSO ACCOMPANIED BY DRY AIR. TRADEWIND FLOW OF
15-20 KT IS ACROSS MUCH OF THE BASIN. SURFACE OBSERVATIONS
INDICATE THE PRESENCE OF DUST ACROSS BOTH THE LESSER ANTILLES
AND THE NRN CARIBBEAN ISLANDS INCLUDING HISPANIOLA POSSIBLY ALL
THE WAY TO CUBA. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS.

THE ATLANTIC OCEAN...

SHOWERS/THUNDERSTORMS ASSOCIATED WITH TROPICAL STORM DEBBY
SPREAD ACROSS FLORIDA AND INTO THE WRN ATLC TO 79W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO FARTHER E FROM 23N-29N
BETWEEN 69W-75W...AND FROM 24N-26N BETWEEN 63W-65W. ALOFT...AN
UPPER LEVEL RIDGE COVERS THE W ATLC W OF 69W SUPPORTING A WEAK
1021 MB SURFACE HIGH NEAR 26N62W. AN UPPER TROUGH IS ALONG 64W
LIKELY SUPPORTING SOME OF THE SHOWERS/THUNDERSTORMS NEAR THE
SURFACE HIGH CENTER. A SECOND UPPER RIDGE IS ALONG 52W WITH A
BROAD UPPER TROUGH COVERS THE N CENTRAL ATLC ALONG 40W. THIS
UPPER RIDGE SUPPORTS A STATIONARY FRONT ALONG 31N40W 28N47W
DISSIPATING TO 28N58W. A PRE-FRONTAL SURFACE TROUGH IS ALONG
31N38W 26N46W 24N55W. ISOLATED SHOWERS ARE ALONG THE FRONTAL
BOUNDARY WHILE SCATTERED SHOWERS ARE ALONG THE TROUGH AXIS.
UPPER LEVEL RIDGING COVERS BOTH THE TROPICAL ATLC AND ERN ATLC
AROUND TWO ANTI-CYCLONIC CENTERS NEAR 17N43W AND 31N21W. VISIBLE
SATELLITE IMAGERY INDICATES A LARGE AREA OF SAHARAN DUST EXTENDS
FROM THE COAST OF AFRICA ALL THE WAY TO THE ERN CARIBBEAN.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON





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