[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182334
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED APR 18 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.

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

THE MONSOON TROUGH EXTENDS INLAND ACROSS WEST AFRICA INTO THE E
TROPICAL ATLC ACROSS THE COAST OF GUINEA NEAR 10N14W TO 7N14W TO
3N16W...WHERE THE ITCZ AXIS CONTINUES ALONG EQ24W 1N40W TO THE
COAST OF BRAZIL NEAR EQ48W. CLUSTERS OF SCATTERED MODERATE TO
STRONG CONVECTION ARE FROM 3S TO 4N BETWEEN 24W-35W. SIMILAR
CONVECTION IS WITHIN 170 NM N OF THE ITCZ BETWEEN 16W-24W.

...DISCUSSION...

GULF OF MEXICO...
A STRONG UPPER LEVEL SHORTWAVE MOVES ACROSS THE NE BASIN ON
WATER VAPOR IMAGERY. THIS FEATURE IS SUPPORTING A LOW PRESSURE
SYSTEM OVER THE FLORIDA PANHANDLE AND ASSOCIATED COLD FRONT THAT
EXTENDS S-SW ACROSS THE AREA FROM E OF PANAMA CITY NEAR 30N85W
INTO THE YUCATAN PENINSULA ALONG 21N88W. DOPPLER RADAR AND
INFRARED SATELLITE IMAGERY INDICATE SCATTERED MODERATE TO HEAVY
SHOWERS AND THUNDERSTORMS WITHIN 170 NM E OF THE BOUNDARY. THIS
FRONT IS FORECAST TO MOVE INLAND TO CENTRAL FLORIDA OR LAKE
OKEECHOBEE AREA ON THURSDAY...BEFORE LOOSING MOMENTUM AND
REMAINING NEARLY STATIONARY THURSDAY NIGHT INTO FRIDAY. A SECOND
STRONGER COLD FRONT WILL ENTER NW GULF FRIDAY NIGHT WITH NEAR
GALE FORCE WINDS BEHIND IT.

CARIBBEAN SEA...
SCATTERED MODERATE TO HEAVY SHOWERS ARE BEGINNING TO AFFECT THE
NW BASIN N OF 16N W OF 82W. THIS AREA OF CONVECTION IS
ASSOCIATED TO THE SRN EXTENSION OF A COLD FRONT MOVING ACROSS
THE YUCATAN PENINSULA. THIS FRONT IS FORECAST TO ENTER THE NW
BASIN BY FRIDAY NIGH AND BECOME STATIONARY WITH LIMITED
CONVECTION LASTING THROUGH THE WEEKEND. RELATIVELY DRY AIR AND
SUBSIDENCE ALOFT COVERS A GREAT PORTION OF THE CARIBBEAN
BASIN...ESPECIALLY OVER THE N-CENTRAL AND NE BASINS. CONVERGING
TRADE WIND FLOW ALONG WITH REMNANT LOW LEVEL MOISTURE IS
GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN
90/120 NM ON EITHER SIDE OF A LINE FROM 14N62W TO 13N71W. THIS
FLOW IS ALSO PUSHING LOW LOW LEVEL MOISTURE WITH SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS INLAND AND WITHIN 120 NM
ALONG THE COAST FROM ERN PANAMA TO NRN NICARAGUA. A SLOW MOVING
SURFACE TROUGH IS E OF THE LESSER ANTILLES GENERATING SCATTERED
HEAVY SHOWERS E OF THESE GROUP OF ISLANDS. SHORT RANGE COMPUTER
MODELS SUGGEST THE CONVECTION WILL REMAIN E OF THESE ISLANDS
DURING THE NEXT 24 HOURS.

ATLANTIC OCEAN...
AN AMPLIFIED UPPER RIDGE OVER THE WRN ATLC SUPPORTS A WEAK 1021
MB HIGH NEAR 30N75W MAINTAINING FAIR WEATHER CONDITIONS W OF
64W. A DEEP OCCLUDED 1006 MB LOW IS CENTERED NEAR 31N58W. THE
LOW LEVEL CENTER CONTINUES TO BE EXPOSED ON SATELLITE IMAGERY
...WITH SOME SCATTERED WEAK CONVECTION WITHIN 65 NM ON THE ERN
SEMICIRCLE OF THE LOW. THE ASSOCIATED COLD FRONT IS WELL
DISPLACED TO THE EAST ENTERING THE REGION ALONG 32N51W TO 24N55W
TO 23N63W. SCATTERED WEAK TO ISOLATED MODERATE CONVECTION IS
WITHIN 50-100 NM ON EITHER SIDE OF THE FRONT. TO THE E OF THIS
FRONT...A NEARLY STATIONARY SURFACE TROUGH EXTENDS S INTO THE
AREA ALONG 31N46W TO 22N49W. SCATTERED WEAK TO ISOLATED MODERATE
CONVECTION IS WITHIN 70-130 NM E OF THE TROUGH AXIS. THE
STRONGEST CONVECTION WITHIN THESE TWO BOUNDARIES IS FOUND N OF
27N WHERE LOW LEVEL CONVERGENCE AND UPPER LEVEL DIFFLUENCE IS
MAXIMIZED. THIS LOW PRESSURE SYSTEM IS EXPECTED TO SHIFT SSE
TONIGHT. A BROAD SURFACE RIDGE ANCHORED BY A 1031 MB HIGH W OF
THE AZORES OVERTAKES THE REMAINDER OF THE ATLC WITH FAIR WEATHER
CONDITIONS E OF 42W.

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

$$

GARCIA



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