[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 250603
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT AUG 25 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0545 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM ISAAC AT 25/0600 UTC WAS LOCATED
NEAR 18.0N 72.8W. THIS POSITION IS ABOUT 55 MI...85 KM SW OF
PORT AU PRINCE HAITI ABOUT 220 MI...AND 350 KM SE OF GUANTANAMO
CUBA. ISAAC IS MOVING NW AT 11 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 990 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 60 KT
WITH GUSTS TO 70 KT. PLEASE READ THE FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC
ADVISORY...MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS.

A 1008 MB LOW AND ASSOCIATED TROPICAL WAVE AXIS IS LOCATED SW OF
CAPE VERDE ISLANDS NEAR 13N26W MOVING WNW AT ABOUT 12 KT. THIS
FEATURE IS EMBEDDED IN THE BROAD SCALE MONSOON GYRE ON SATELLITE
IMAGERY... WITHIN A LARGE SURGE OF DEEP LAYER MOISTURE PRESENT
ACROSS MUCH OF THE EASTERN TROPICAL ATLC. A THICK LAYER OF
SAHARAN DUST SURROUNDS THE WAVE AND ASSOCIATED LOW...INHIBITING
THIS SYSTEM TO GENERATE CONVECTION NEAR THE CENTER. THEREFORE...
THE SYSTEM REMAINS FAIRLY DISORGANIZED WITH THE MAJORITY OF THE
CONVECTION WELL TO THE WEST AND SW OF THE LOW CENTER. SCATTERED
MODERATE CONVECTION IS FROM 14N-17N BETWEEN 26W-31W...AND FORM
7N-11N BETWEEN 31W-39W. ENVIRONMENTAL CONDITIONS ARE MARGINALLY
CONDUCIVE FOR DEVELOPMENT. THIS SYSTEM HAS A MEDIUM CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

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

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA...ENTERING THE ERN
TROPICAL ATLC OVER THE COAST OF MAURITANIA AT 20N16W CONTINUING
SW TO THE SPECIAL FEATURE 1008 MB SURFACE LOW AND ASSOCIATED
TROPICAL WAVE AT 13N26W AND ALONG 11N33W TO 12N42W. A SMALL
PORTION OF THE ITCZ BEGINS NEAR 10N54W TO NEAR TRINIDAD AND
TOBAGO. NO CONVECTION IS NOTED AROUND THE ITCZ. THE CONVECTION
NEAR THE MONSOON TROUGH IS DISCUSSED IN THE SPECIAL FEATURES
SECTION ABOVE.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL NORTHERLY FLOW COVERS THE BASIN...BEHIND THE BASE OF
AN UPPER TROUGH THAT MOVES ACROSS THE FAR ERN REGION OF THE
GULF. THIS FEATURE IS PROVIDING SOME WEAK TO MODERATE DIFFLUENCE
ALOFT OVER THE NW QUADRANT OF THE BASIN...GENERATING AN AREA OF
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 24N BETWEEN
90W-95W. DRY AIR AND STRONG SUBSIDENCE IS SINKING ACROSS THE ERN
BASIN PROVIDING FAIR CONDITIONS E OF 90W. HOWEVER...LOW-LEVEL
MOISTURE IS BEING BROUGHT FROM THE EAST ACROSS THE FAR ERN GULF
AND STRAITS OF FLORIDA DUE TO THE LARGE CYCLONIC WIND FIELD OF
TROPICAL STORM ISAAC. SOME OF THIS ACTIVITY HAS ENTERED THE AREA
NOTED ON DOPPLER RADAR AS A FEW SQUALL LINES S OF 27N E OF 84W.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO REMAIN OVER THE NW
GULF. SIMILAR CONVECTION WILL ALSO CONTINUE ACROSS THE SE GULF
AS TROPICAL STORM ISAAC MOVES CLOSER. WINDS WILL ALSO BEGIN TO
INCREASE OVER THE SE GULF THROUGHOUT THE WEEKEND. ALL INTERESTS
IN THE EASTERN GULF SHOULD MONITOR THE PROGRESS OF ISAAC.

CARIBBEAN SEA...
TROPICAL STORM ISAAC CONTINUES TO BE THE MAIN WEATHER CONCERN IN
THE CARIBBEAN SEA...GENERATING CONSIDERABLE CONVECTION OVER THE
CENTRAL AND ERN BASIN. ALL INTERESTS IN THE NORTHERN CARIBBEAN
SHOULD MONITOR THE PROGRESS ON ISAAC. FLOODING AND MUDSLIDES ARE
DEFINITE HAZARDS ACROSS THE ISLANDS IMPACTED. THE WESTERN
CARIBBEAN IS STILL UNDER FAIR CONDITIONS DUE TO TO DRY AIR ALOFT
COVERING MUCH OF THE AREA WEST OF 80W. THE LARGE CIRCULATION OF
ISAAC IS PROVIDING CYCLONIC SURFACE FLOW ACROSS THE ENTIRE BASIN
WITH LIGHT WINDS ONLY ACROSS THE SW CARIBBEAN. ISAAC WILL
CONTINUE TO DOMINATE THE WEATHER PATTERN ACROSS THE CARIBBEAN AS
IT CONTINUES TO MOVE NW ACROSS HAITI AND THEN CUBA BEFORE
HEADING INTO THE FLORIDA STRAITS.

ATLANTIC OCEAN...
THE COMBINATION OF LOW-LEVEL MOISTURE BEING DRAWN ACROSS THE NW
BAHAMAS DUE TO TROPICAL STORM ISAAC AND DIFFLUENCE ALOFT AROUND
AN UPPER TROUGH OVER THE EASTERN GULF IS HELPING PRODUCE
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE NW BAHAMAS AND
STRAITS OF FLORIDA S OF 28N W OF 76W. THE OUTER CONVECTION BANDS
ASSOCIATED TO ISAAC ARE ALSO AFFECTING THE NRN COASTAL WATERS OF
HISPANIOLA...TURKS AND CAICOS...AND SE BAHAMAS. TO THE ENE OF
THESE AREAS OF CONVECTION...A WEAK SURFACE TROUGH IS ANALYZED
ALONG 32N60W TO 24N61W WITH MINIMAL ACTIVITY IN THE WRN VICINITY
OF ITS AXIS. AN ELONGATED UPPER LEVEL LOW IS CENTERED NEAR
24N57W. THIS FEATURE HAS TAKEN OVER THE REMNANTS OF FORMER
TROPICAL STORM JOYCE...NOW ANALYZED AS A SURFACE TROUGH FROM
25N53W TO 19N51W. SCATTERED SHOWERS AND THUNDERSTORMS ARE FROM
20N-27N BETWEEN 48W-54W. THE REMAINDER OF THE ATLC BASIN
DISCUSSION AREA IS DOMINATED BY A BROAD SURFACE RIDGE ANCHORED
BY A 1022 MB HIGH NEAR 34N46W. THE FAIR WEATHER IS ENHANCED
ALOFT BY SAHARAN DUST NOTED ON METEOSAT-9 IMAGERY. EMBEDDED IN
THIS DRY ENVIRONMENT...AN UPPER LOW WOBBLES NEAR 30N21W.
ALSO...EXPECT WEATHER CONDITIONS TO DETERIORATE OVER THE NRN
COASTAL WATERS OF HISPANIOLA...TURKS AND CAICOS...AND THE
BAHAMAS DURING THE NEXT FEW DAYS AS TROPICAL STORM ISAAC MOVES
OVER HAITI AND CUBA BEFORE HEADING INTO THE FLORIDA STRAITS.

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

$$

GARCIA




This weather bulletin was brought to you by:
www.nashvilleweather.net