000
AXNT20 KNHC 130535
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE MAR 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA INTO THE E TROPICAL 
ATLC NEAR 6N11W TO 4N13W WHERE THE ITCZ AXIS CONTINUES S OF THE 
EQUATOR NEAR 20W INTO SOUTH AMERICA NEAR 3S43W. CLUSTERS OF 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 1N-6N 
BETWEEN 5W-18W AND FROM 4N TO S OF THE EQUATOR BETWEEN 21W-44W. 

...DISCUSSION...

GULF OF MEXICO...
A STRONG UPPER LOW IS MOVING OVER THE GREAT LAKES AREA WITH A 
SHORTWAVE UPPER TROUGH OVER THE LOWER MISSISSIPPI VALLEY TO THE 
GULF COAST GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N 
OF 29N TO INLAND OVER THE N GULF COAST BETWEEN 87W-91W. A 
SURFACE TROUGH IS ANALYZED OVER THE E BAY OF CAMPECHE AT 13/0300 
UTC EXTENDING FROM 22N90W TO NW GUATEMALA WITH ISOLATED SHOWERS 
WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS. A BROAD UPPER RIDGE 
AXIS EXTENDS FROM NE YUCATAN PENINSULA ACROSS CENTRAL FLORIDA 
INTO THE W ATLC GIVING THE GULF WATERS MOSTLY WESTERLY FLOW 
ALOFT. A SURFACE RIDGE EXTENDS FROM THE W ATLC AND A 1030 MB 
HIGH NW OF BERMUDA OVER THE GEORGIA COAST INTO THE GULF OF 
MEXICO TO ALONG THE N GULF COAST TO E TEXAS. S TO SE RETURN 
COVERS THE GULF PRODUCING SCATTERED SHOWERS OVER THE SE GULF S 
OF 26N E OF 88W. THIS IS LEAVING THE REMAINDER OF THE GULF UNDER 
MOSTLY CLEAR SKIES TONIGHT. SURFACE RIDGE WILL PREVAIL THROUGH 
SAT. 

CARIBBEAN SEA...
WEAK UPPER TROUGH EXTENDS FROM THE W ATLC THROUGH THE WINDWARD 
PASSAGE TO OVER JAMAICA AMPLIFYING AN UPPER RIDGE AXIS THAT 
EXTENDS FROM THE YUCATAN PENINSULA INTO THE W ATLC. A BROAD 
UPPER RIDGE OVER THE TROPICAL ATLC DOMINATES THE REMAINDER OF 
THE CARIBBEAN. MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR 
ALSO DOMINATE MOST OF THE CARIBBEAN WITH THE EXCEPTION OF THE 
FAR SE CARIBBEAN AND THE FAR NW CARIBBEAN. REMNANT LOW LEVEL 
ISOLATED SHOWERS DOT THE AREA WITHIN 60 NM OF 18N BETWEEN 
70W-80W INCLUDING PORTIONS OF HISPANIOLA AND JAMAICA. THE BROAD 
UPPER RIDGE IS DRAWING MOISTURE ALOFT AND IS GENERATING SOME 
ISOLATED SHOWERS OVER THE WINDWARD ISLANDS. THIS IS LEAVING THE 
REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES TONIGHT. THE 
TIGHT PRESSURE GRADIENT IS PRODUCING FRESH TO STRONG NE TO E 
TRADE WINDS ACROSS THE BASIN. LITTLE CHANGE IS EXPECTED THROUGH 
SAT.

ATLANTIC OCEAN...
AN UPPER RIDGE EXTENDS FROM THE YUCATAN PENINSULA ACROSS CENTRAL 
FLORIDA TO BEYOND 32N74W IN THE W ATLC. A SURFACE RIDGE COVERS 
THE W INTO THE CENTRAL ATLC W OF 55W ANCHORED BY A 1030 MB HIGH 
ABOUT 200 NM NW OF BERMUDA. A BROAD UPPER TROUGH EXTENDS INTO 
THE W ATLC THROUGH 32N58W ALONG 24N69W NARROWING AS IT ENTERS 
THE CARIBBEAN THROUGH THE WINDWARD PASSAGE SUPPORTING A COLD 
FRONT THAT ENTERS THE CENTRAL ATLC NEAR 32N44W ALONG 27N47W TO 
23N51W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS 
ARE WITHIN 180 NM E OF THE FRONT. BROAD UPPER RIDGE COVERS THE 
TROPICAL ATLC S OF 25N BETWEEN 30W-60W WITH A NARROW RIDGE AXIS 
EXTENDING FROM 25N31W TO BEYOND 32N28W. A SURFACE RIDGE 
DOMINATES THE E ATLC ANCHORED BY A 1028 MB HIGH JUST S OF THE 
AZORES. THE LAST VISIBLE SATELLITE IMAGES SHOW AN AREA OF 
AFRICAN DUST COVERING THE E TROPICAL ATLC FROM THE ITCZ TO 27N E 
OF 42W. W ATLC SURFACE RIDGE WILL REMAIN THROUGH TUE NIGHT AND 
WEAKEN WED THROUGH SAT AS RIDGE DRIFTS SE.

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

$$
PAW