000
AXNT20 KNHC 132347
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAY 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 
2335 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL 
ATLC ALONG THE NRN COAST OF GUINEA BISSAU NEAR 12N16W TO 6N18W 
...WHERE THE ITCZ CONTINUES ALONG 3N25W 4N35W 3N45W TO THE COAST 
OF BRAZIL NEAR 4N51W. SOME ISOLATED LOW TOP CONVECTION IS IN THE 
VICINITY OF THE ITCZ AXIS. OTHERWISE...NO SIGNIFICANT DEEP 
CONVECTION IS NOTED ELSEWHERE IN THE DEEP TROPICS. THIS IS 
LIKELY DUE TO THE SAHARAN AIR LAYER AND SUSPENDED DUST THAT 
ENCOMPASSES MUCH OF THE ATLC BASIN E OF 50W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF BASIN IS UNDER WSW FLOW ALOFT CARRYING MODERATE TO HIGH 
VALUES OF MOISTURE IN THE MID TO UPPER LEVELS OF THE ATMOSPHERE 
...EXCEPT FOR THE NW BASIN WHERE WATER VAPOR IMAGERY SHOWS AN 
UPPER LEVEL LONGWAVE PROGRESSING ENE ACROSS THIS REGION AS WELL 
AS THE N-CENTRAL GULF. THIS FEATURE SUPPORTS A LOW PRESSURE 
SYSTEM MOVING ACROSS THE SE CONUS. A SLOW MOVING COLD FRONT 
ASSOCIATED TO THIS LOW EXTENDS WSW ACROSS THE N-CENTRAL GULF 
ALONG THE WRN FLORIDA PANHANDLE NEAR 30N87W TO 26N89W...BECOMING 
STATIONARY TO 23N93W...THEN SOUTHWARD ACROSS THE BAY OF CAMPECHE 
AS A SURFACE TROUGH TO THE COAST OF MEXICO NEAR 18N93W. 
LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE FRONTAL 
BOUNDARY ALONG WITH UPPER LEVEL DIFFLUENCE IS GENERATING 
SCATTERED MODERATE TO HEAVY SHOWERS AND TSTMS WITHIN 90 NM E OF 
THE FRONTAL BOUNDARY AND SURFACE TROUGH. AS THE LOW PRESSURE 
SYSTEM DRIFTS NORTHEAST OVER THE NEXT COUPLE OF DAYS...COMPUTER 
MODELS SUGGEST THE CONVECTION WILL BE SLOW TO MOVE OVER THE NEXT 
FEW DAYS.

CARIBBEAN SEA...
A BROAD UPPER ANTICYCLONIC CIRCULATION IS CENTERED OVER EL 
SALVADOR. THE UPPER LEVEL FLOW AROUND THIS FEATURE IS 
INFLUENCING MOST OF THE CARIBBEAN SEA WITH DRY AIR AND MODERATE 
TO STRONG SUBSIDENCE ALOFT W OF 71W. SEVERAL UPPER AIR SOUNDINGS 
FROM THE NRN LESSER ANTILLES INDICATED THE CLASSIC DOUBLE 
INVERSION PATTERN ASSOCIATED TO THE SAHARAN AIR LAYER THAT HAS 
BEEN PROGRESSING WESTWARD ACROSS THE TROPICAL ATLC OVER THE PAST 
FEW DAYS. THIS IS ALSO LENDING TO THE OVERALL STABILITY OF THE 
CARIBBEAN SEA E OF 71W. GENTLE TO MODERATE TRADE WINDS ARE 
OBSERVED WITH SOME ISOLATED LOW TOP SHOWERS EMBEDDED IN THE 
FLOW. THIS FLOW IS BANKING SIMILAR CONVECTION WITHIN 90 NM ALONG 
THE COAST OF PANAMA AND COSTA RICA. OTHERWISE...NO SIGNIFICANT 
CHANGES ARE EXPECTED ACROSS THE CARIBBEAN DURING THE NEXT 24 
HOURS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH CONTINUES TO MOVE ACROSS THE N-CENTRAL 
ATLC BASIN. THIS TROUGHING SUPPORTS A WEAK LOW PRESSURE SYSTEM N 
OF THE DISCUSSION AREA THAT EXTENDS A COLD FRONT INTO THE AREA 
ANALYZED FROM 32N57W TO 29N60W...THEN STATIONARY TO 26N64W...AND 
CONTINUING W-SW AS A SHEAR LINE TO 25N72W. ISOLATED WEAK SHOWERS 
ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONTAL BOUNDARY. 
A PRE-FRONTAL TROUGH IS ANALYZED SE OF THE FRONT FROM 27N61W TO 
21N61W. ISOLATED SHOWERS ARE OCCURRING IN THE VICINITY OF THE 
TROUGH AXIS. THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE 
INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1028 MB HIGH CENTERED 
N OF THE DISCUSSION AREA NEAR 36N68W. THE FRONT IS FORECAST TO 
WEAKEN OVER THE NEXT FEW DAYS AS THE SURFACE RIDGE BUILDS 
EASTWARD THROUGH TUESDAY. A GALE 1009 MB LOW IS OVER THE E ATLC 
CENTERED NEAR 32N33W. A BROAD UPPER LEVEL LOW SITS NEAR THE SAME 
LOCATION OF THE SURFACE LOW SUPPORTING SCATTERED SHOWERS AND 
ISOLATED THUNDERSTORMS WITHIN 80 NM N OF THE LOW CENTER. 
OTHERWISE...SURFACE RIDGING COVERS THE REMAINDER OF THE CENTRAL 
AND EASTERN ATLC. AS NOTED ABOVE IN THE ITCZ/MONSOON TROUGH 
SECTION...A LARGE AREA OF SAHARAN DUST REMAINS OVER MUCH OF THE 
TROPICAL ATLC E OF 50W.

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

$$

GARCIA