[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131753
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1745 UTC.

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

THE MONSOON TROUGH EXTENDS ACROSS THE TROPICAL REGIONS OF WEST
AFRICA INTO THE ATLC WATERS THROUGH SIERRA LEONE ALONG 8N13W TO
3N19W...WHERE THE ITCZ CONTINUES ALONG 1S29W TO THE CAST OF
BRAZIL NEAR 3S42W. SCATTERED TO NUMEROUS STRONG CONVECTIVE
PRECIPITATION IS NOTICED N OF THE EQUATOR BETWEEN THE PRIME
MERIDIAN AND 18W. SIMILAR CONVECTION IS WITHIN 90 NM ON EITHER
SIDE OF A LINE EXTENDING FROM 4S30W ALONG 2N40W TO BRAZIL NEAR
2N50W.

...DISCUSSION...

THE GULF OF MEXICO...
THE BASE OF AN ELONGATED UPPER LEVEL RIDGE MOVES ACROSS THE GULF
BRINGING DRY AIR ALOFT TO THE DISCUSSION AREA. THE STRONGEST
SUBSIDENCE IS NOTICED N OF THE AREA OVER THE ERN CONUS ANCHORED
BY A 1027 MB CENTERED OVER THE GREAT LAKES REGION. THE SURFACE
RIDGE AXIS ASSOCIATED TO THIS HIGH PRESSURE SYSTEM EXTENDS INTO
THE AREA SUPPORTING A MODERATE E-W PRESSURE GRADIENT WITH 10-20
KT ESE WINDS W OF 86W. AS THE SURFACE RIDGE MOVES OFF THE ERN
CONUS SEABOARD...SHORT RANGE COMPUTER MODELS SUGGEST THIS FLOW
COULD INCREASE UP TO 25 KT DURING THE NEXT 24 HOURS...ESPECIALLY
NEAR THE COASTAL WATERS OF TEXAS. OTHERWISE...NO OTHER
SIGNIFICANT CHANGES ARE EXPECTED DURING THE FORECAST PERIOD.

THE CARIBBEAN SEA...
MODERATE TO STRONG SUBSIDENCE AND DRY AIR ALOFT COVERS A GREAT
PORTION OF THE DISCUSSION AREA THIS AFTERNOON. THIS IS KEEPING
MOST OF THE AREA UNDER FAIR WEATHER CONDITIONS...EXCEPT OVER THE
COASTAL WATERS BETWEEN WRN PUERTO RICO AND ERN DOMINICAN
REPUBLIC N OF 15N BETWEEN 67W-71W. MODERATE TO HEAVY SHOWERS AND
ISOLATED THUNDERSTORMS ARE OBSERVED IN THIS REGION. A RECENT
SCATTEROMETER PASS REVEALED A SURFACE TROUGH IN THIS REGION.
THIS TROUGH WILL BE ANALYZED DURING THE NEXT MAP CYCLE. IN THE
MEAN TIME...A ROUGH ESTIMATE OF ITS AXIS COULD BE FROM 19N68W TO
13N71W. SIMILAR CONVECTION IS NOTICED OVER THE NE COASTAL WATERS
OF JAMAICA MORE LIKELY ASSOCIATED TO DAY-TIME HEATING...
INSTABILITY...AND OROGRAPHIC EFFECTS. AS UPPER LEVEL CIRRUS
COVER PART OF THE EXTREME SE BASIN...TOTAL PRECIPITABLE WATER
PRODUCT SHOWS A SPOT OF HIGH VALUES OF LOW LEVEL MOISTURE OFF
THE COAST OF VENEZUELA. VISIBLE SATELLITE IMAGERY DEPICTS
SCATTERED SHOWERS AND THUNDERSTORMS IN THIS REGION WITHIN 120 NM
OFF THE COAST BETWEEN 62W-70W. OTHERWISE...TRADEWIND FLOW OF
10-15 KTS IS REPORTED ACROSS THE AREA. COMPUTER MODELS SUGGEST
THE CONVECTION OVER THE NRN NRN CARIBBEAN LINGER AND SLOWLY
SPREAD WESTWARD OVER THE NEXT 24 HOURS.

THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH MOVES ACROSS THE WRN ATLC THIS AFTERNOON.
WATER VAPOR IMAGERY SHOWS A VIGOROUS SHORTWAVE EMBEDDED AT THE
SRN EXTENSION OF THE UPPER TROUGH SUPPORTING A 1008 MB LOW NEAR
33N57W. A CLOD FRONT EXTENDS SSW FROM THE LOW CENTER ALONG
25N60W TO 21N68W...WHERE THE BOUNDARY BECOMES WEAK AND NEARLY
STATIONARY AS IT EXTENDS NW ACROSS THE TURKS/CAICOS...AND THE
BAHAMAS ALONG 23N75W TO THE COAST OF FLORIDA NEAR BOCA RATON. A
PRE FRONTAL TROUGH EXTENDS FROM 24N60W TO 20N65W. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 150-300 NM
AHEAD OF THE COLD FRONT N OF 20N WHERE LOW LEVEL CONVERGENCE AND
UPPER LEVEL DIFFLUENCE IS MAXIMIZED. A REGION OF SIMILAR
CONVECTION IS FOUND WITHIN 80 NM NE OF THE STATIONARY PORTION OF
THE FRONTAL BOUNDARY AFFECTING MOSTLY THE CENTRAL AND NW BAHAMAS
N OF 23N. AS THE SOUTHERN MOST PORTION OF THE BOUNDARY BREAKS...
SOME ISOLATED MODERATE TO STRONG CONVECTION QUICKLY RUSH AGAINST
THE NRN COAST OF HISPANIOLA ON SATELLITE IMAGERY. COMPUTER
MODELS SUGGEST THE FRONT WILL CONTINUE TO TRACK E OVER THE NEXT
24 HOURS LEAVING FRESH TO STRONG NORTHERLY WINDS IN ITS WAKE.
FAIR WEATHER CONDITIONS ARE FOUND ELSEWHERE AHEAD OF THE FRONTAL
CONVECTION...ASSOCIATED TO A N-S ELONGATED CENTRAL ATLC UPPER
RIDGE SUPPORTING A 1032 MB HIGH NEAR 36N33W.

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

$$

GARCIA




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