[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 21 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM ISAAC CENTERED NEAR 15.4N 53.9W AT 21/2100 UTC OR
ABOUT 435 NM E OF GUADELOUPE MOVING W AT 15 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND
SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
AND THE PUBLIC ADVISORY...MIATCPAT4/ WTNT34 KNHC FOR MORE
DETAILS. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
NEAR THE CENTER FROM 13N TO 16N BETWEEN 54W -57W. TROPICAL STORM
WARNINGS HAVE BEEN INITIATED BY THE INDIVIDUAL GOVERNMENTS OF
THE EASTERN CARIBBEAN SEA ISLANDS FROM MARTINIQUE TO ST MARTIN
AND ANGUILLA.

AN ATLANTIC OCEAN TROPICAL WAVE EXTENDS FROM 18N30W TO AN
EMBEDDED 1010 MB LOW AT 10N32W. THE SYSTEM IS MOVING W AT 1O TO
15 KT AND HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE
WITHIN THE NEXT 48 HOURS. SCATTERED MODERATE CONVECTION IS OVER
A LARGE AREA FROM 07N TO 14N BETWEEN 32W AND 38W.

...TROPICAL WAVES...

A POORLY DEFINED TROPICAL WAVE EXTENDS OVER THE EASTERN
CARIBBEAN FROM 19N65W TO 10N65W MOVING W AT 20-25 KT...BRINGING
A FEW SHOWERS TO THE NE CARIBBEAN. THE WAVE WILL PUSH INTO THE
CENTRAL CARIBBEAN WED.

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

THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 14N17W
THE 1010 MB LOW NEAR 10N32W TO 07N36W AND 10N43W. SCATTERED
MODERATE CONVECTION IS OVER A LARGE AREA FROM 07N TO 14N BETWEEN
32W AND 38W ASSOCIATED WITH THE LOW NEAR 10N32W. OTHERWISE NO
SIGNIFICANT CONVECTION NOTED..

...DISCUSSION...

THE GULF OF MEXICO...
A 1010 MB LOW IS CENTERED OVER THE W GULF OF MEXICO NEAR 23N97W.
A SURFACE TROUGH EXTENDS FROM 26N96W TO THE LOW CENTER TO
22N97W. THIS SYSTEM IS DRIFTING W AND WILL LIKELY PUSH ONSHORE
OVERNIGHT. THIS SYSTEM HAS A LOW CHANCE OF BECOMING A TROPICAL
CYCLONE WITHIN THE NEXT 48 HOURS. NO SIGNIFICANT CONVECTION IS
NOTED WITH THE LOW CENTER. SURFACE TROUGH EXTENDS FROM THE
FLORIDA PANHANDLE AT 30N86W TO 28N93W MOVING E. THE SURFACE
TROUGH IS SUPPORTED BY AN UPPER LEVEL TROUGH DIGGING THROUGH THE
LOWER MISSISSIPPI VALLEY INTO THE SOUTHEAST UNITED STATES AND NE
GULF. A LINE OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
PERSISTS OVER THE EASTERN GULF AHEAD OF THE UPPER TROUGH WITHIN
60 NM EITHER SIDE OF A LINE FROM ROUGHLY TAMPA BAY TO NEAR
25N87W.

THE CARIBBEAN SEA...
A TROPICAL WAVE THAT HAD BEEN OVER THE GULF OF HONDURAS HAS
SHIFTED W INTO THE YUCATAN PENINSULA AND THROUGH BELIZE. ASIDE
FROM THE TROPICAL WAVE IN THE EASTERN CARIBBEAN...A 1009 MB LOW
PERSISTS OVER N COLOMBIA AT 07N74W. SURFACE RIDGING EXTENDS FROM
THE NW ATLC THROUGH CUBA. A SOMEWHAT TIGHT PRES GRADIENT BETWEEN
THE RIDGE AND LOW PRES OVER THE SE CARIBBEAN IS TRADE WIND
CONVERGENCE IS ALLOWING FRESH TO STRONG TRADE WINDS OVER THE SW
CARIBBEAN. LOW LEVEL CONVERGENCE FROM THESE ENHANCED TRADES HAD
GENERATED CLUSTERS OF CONVECTION OVER THE SW CARIBBEAN FROM
PROVIDENCIA ISLAND TO THE NICARAGUAN COAST. MUCH OF THIS HAS
DIMINISHED OVER THE PAST COUPLE OF HOURS. FAIRLY DRY CONDITIONS
ELSEWHERE IS INHIBITING MUCH IN THE WAY OF CONVECTION IN MOST
AREAS OF THE CARIBBEAN. THE NOTABLE EXCEPTION WILL BE THE
WINDWARD AND LEEWARD ISLANDS WHERE THE FIRST OUTER SHOWERS FROM
THE NEWLY NAMED TROPICAL STORM ISAAC ARE JUST REACHING THE AREA.
RESIDENTS IN THESE AREAS SHOULD KEEP ABREAST OF THE LATEST
FORECASTS AND ADVISORIES FROM NHC AND INFORMATION FROM LOCAL
AUTHORITIES AND MEDIA ON THIS DEVELOPING STORM.

THE ATLANTIC OCEAN...
A 1023 MB HIGH IS ANCHORED OVER THE W ATLANTIC NEAR 29N65W. A
1022 MB HIGH IS CENTERED OVER THE CENTRAL ATLANTIC NEAR 33N49W.
A SURFACE TROUGH IS OVER THE CENTRAL ATLANTIC FROM 32N32W TO
26N38W. AFRICAN DUST EXTENDS FROM 10N-33N E OF 30W...AND FROM
10N-26N BETWEEN 25W-65W. IN THE UPPER LEVELS...AN UPPER LEVEL
LOW IS CENTERED OVER THE BAHAMAS NEAR 22N75W. UPPER LEVEL
DIFFLUENCE N OF THE CENTER AND AHEAD OF A MID TO UPPER LEVEL
TROUGH OVER THE EASTERN UNITED STATES IS PRODUCING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS MAINLY N OF 25N AND W OF 75W.

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

$$
CHRISTENSEN





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