[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132334
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI APR 13 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
2300 UTC.

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

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
SIERRA LEONE AT 9N13W TO 3N20W. THE ITCZ CONTINUES FROM 3N20W TO
THE EQUATOR AT 31W TO 2N40W TO 1N44W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N BETWEEN
13W-20W. SIMILAR ACTIVITY IS FROM EQ-3N BETWEEN 28W-42W...AND
FROM 3N-5N BETWEEN 42W-51W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL RIDGE IS MOVING ACROSS THE GULF OF MEXICO ALONG
90W SUPPORTING A SURFACE RIDGE ACROSS THE ERN CONUS WITH AXIS
ACROSS THE GULF FROM ALABAMA TO THE YUCATAN PENINSULA. DRY AIR
ALOFT IS HELPING MAINTAIN FAIR CONDITIONS AND MOSTLY CLEAR
SKIES. LIGHT ANTI-CYCLONIC SURFACE FLOW IS AROUND THE ERN SIDE
OF THE RIDGE AS SE RETURN FLOW INCREASES OVER THE WRN GULF.
WINDS UP TO 20 KTS ARE CURRENTLY OBSERVED ALONG THE TEXAS AND
LOUISIANA COASTS. A SURFACE TROUGH EXTENDS UP THE FLORIDA
PENINSULA ASSOCIATED WITH A DISSIPATING FRONTAL BOUNDARY IN THE
W ATLC AND THE DIURNAL SEABREEZE EFFECT. THIS IS HELPING PRODUCE
SCATTERED SHOWERS ACROSS S FLORIDA. EXPECT SURFACE RIDGING TO
REMAIN OVER THE GULF AS THE SURFACE HIGH TO THE N SHIFTS EWD.
RETURN FLOW OVER THE WRN GULF IS ALSO EXPECTED TO SPREAD EWD.

THE CARIBBEAN SEA...
DRY AIR ALOFT IN SW-W FLOW AROUND AN UPPER LEVEL RIDGE CENTERED
N OF ERN SOUTH AMERICA IS PROVIDING FAIR CONDITIONS ACROSS MUCH
OF THE CARIBBEAN WATERS. HOWEVER...A SURFACE TROUGH IS ANALYZED
IN THE ERN CARIBBEAN FROM THE MONA PASSAGE AT 19N68W TO 14N71W
...WHICH IS PRODUCING SCATTERED SHOWERS WITHIN 180 NM E
INCLUDING PUERTO RICO. A FRONTAL BOUNDARY N OF THE ISLANDS IS
ALSO PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER
HISPANIOLA. THE REMAINDER OF THE AREA IS UNDER MOSTLY CLEAR
SKIES WITH LIGHT TRADEWIND FLOW OF 10-15 KTS. EXPECT
SHOWERS/POSSIBLE THUNDERSTORMS TO REMAIN OVER THE NE CARIBBEAN
AS THE FRONTAL BOUNDARY TO THE N CONTINUES TO DIP S.

THE ATLANTIC OCEAN...
A BROAD UPPER TROUGH COVERS THE W ATLC ALONG 65W SUPPORTING A
COLD FRONT ENTERING THE DISCUSSION AREA AT 32N56W ALONG 25N61W
TO 21N65W WHERE IT CONTINUES AS A DISSIPATING COLD FRONT ALONG
20N70W TO 21N73W...AND AS A DISSIPATING STATIONARY FRONT TO THE
FLORIDA COAST AT 26N80W. A SURFACE TROUGH CONTINUES UP THE
CENTER OF THE FLORIDA PENINSULA ALSO ASSOCIATED WITH THE DIURNAL
SEABREEZE TROUGH. A PRE-FRONTAL SURFACE TROUGH IS ALSO E OF THE
COLD FRONT FROM 24N59W TO 20N64W. THE STRONGEST SHOWER ACTIVITY
IS MAINLY E OF THE FRONT AND SURFACE TROUGH DUE TO THE AREA OF
STRONGEST DIFFLUENCE ALOFT AROUND THE E SIDE OF THE UPPER
TROUGH. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 250
NM E OF THE COLD FRONT N OF 25N...AND WITHIN 130 NM SE OF THE
SURFACE TROUGH. ISOLATED SHOWERS ARE WITHIN 75 NM EITHER SIDE OF
THE FRONT AXIS ELSEWHERE BESIDES NEAR THE BAHAMAS WHERE
SCATTERED ACTIVITY IS NOTED FROM 23N-27N BETWEEN 73W-78W...AS
WELL AS FROM 28N-31N BETWEEN 78W-81W. A NARROW UPPER LEVEL RIDGE
COVERS THE CENTRAL ATLC EXTENDING FROM N OF ERN SOUTH AMERICA AT
11N55W TO W OF THE AZORES ISLANDS AT 45N35W. THIS UPPER RIDGE
SUPPORTS A STRONG SURFACE RIDGE AROUND A 1030 MB HIGH NEAR
36N34W...WHICH IS DOMINATING THE ERN ATLC AND PROVIDING MOSTLY
FAIR CONDITIONS ACROSS THIS AREA. AN UPPER LEVEL TROUGH COVERS
THE ERN ATLC ALONG 30W...BUT IS CAUSING NO SIGNIFICANT WEATHER
OVER THE DISCUSSION AREA.

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

$$
WALTON





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