[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151051
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT MAY 15 2011

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED FROM LIBERIA NEAR 6N11W ALONG 3N20W 3N30W
3N40W AND INTO NRN BRAZIL NEAR 1S50W. AN EMBEDDED SURFACE TROUGH
IS ALSO EXTENDS FROM 7N39W TO 1N41W. SCATTERED MODERATE/STRONG
CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 12W-18W...AND
WITHIN 120 NM N OF THE AXIS BETWEEN 21W-26W. SIMILAR ACTIVITY IS
W OF THE TROUGH AXIS FROM 1N-5N BETWEEN 42W-46W.

...DISCUSSION...

GULF OF MEXICO...
MAINLY NWLY FLOW ALOFT COVERS THE GULF OF MEXICO BETWEEN AN
UPPER LEVEL RIDGE ACROSS MEXICO AND AN UPPER LEVEL TROUGH WITH
AXIS NOW JUST E OF THE FLORIDA PENINSULA. THE UPPER TROUGH
CONTINUES TO SUPPORT A COLD FRONT THAT EXTENDS FROM NE FLORIDA
NEAR JACKSONVILLE TO TAMPA CONTINUING ALONG 24N86W 21N92W...AS
OF 0900 UTC. RADAR IMAGERY INDICATES A LINE OF STRONG
SHOWERS/THUNDERSTORMS WITHIN 60 NM AHEAD OF THE FRONT FROM
25N-29N. STRONG DRY AIR AND SUBSIDENCE COVER THE BASIN BEHIND
THE UPPER TROUGH SUPPRESSING CONVECTION AND SUPPORTING FAIR
WEATHER ACROSS THE REMAINDER OF THE AREA. A SMALL AREA OF UPPER
LEVEL MOISTURE IS NOTED OVER THE SW GULF SUPPORTING A FEW HIGH
CLOUDS. EXPECT THE FRONT TO DRIFT EWD AND DISSIPATE AS A
SECONDARY FRONT MOVES IN BEHIND IT MONDAY AND TUESDAY. THIS
SETUP WILL PROVIDE MOIST CONDITIONS ACROSS MUCH OF THE FAR ERN
GULF OF MEXICO.

CARIBBEAN SEA...
BROAD UPPER TROUGHING SITS ACROSS THE ENTIRE CARIBBEAN EXTENDING
FROM AN UPPER LEVEL LOW OVER THE OHIO VALLEY. WATER VAPOR
IMAGERY INDICATES MOSTLY DRY AIR ACROSS THE NW AND CENTRAL
CARIBBEAN WITH MOISTER CONDITIONS E OF 70W. THIS PATTERN IS
PROVIDING FAIR CONDITIONS ACROSS THE ENTIRE NW AND CENTRAL
PORTIONS OF THE BASIN. A SURFACE TROUGH EXTENDS ACROSS THE ERN
CARIBBEAN FROM PUERTO RICO TO COLOMBIA ALONG 18N67W 14N71W
9N75W. TOTAL PRECIPITABLE WATER IMAGERY SHOWS ENHANCED MOISTURE
VALUES E OF TROUGH AXIS WHERE SCATTERED SHOWERS/THUNDERSTORMS
COVER THE AREA. SOME OF THIS ACTIVITY IS INFLUENCED BY UPPER
LEVEL DIFFLUENCE AROUND THE ERN SIDE OF THE UPPER TROUGH. A FEW
ISOLATED SHOWERS ARE ALSO NOTED W OF THE SURFACE TROUGH AXIS
FROM 11N-14N BETWEEN 73W-78W. EXPECT SURFACE TROUGHING TO REMAIN
ACROSS THE ERN CARIBBEAN WITH ENHANCED MOISTURE LEVELS
SUPPORTING CONVECTION.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH NOW SITS JUST E OF THE FLORIDA PENINSULA
DOWN 80W SUPPORTING A COLD FRONT ACROSS THE ERN GULF OF MEXICO.
UPPER LEVEL DIFFLUENCE AROUND AROUND THE UPPER TROUGH IS
SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 26N
BETWEEN 74W-78W. ANOTHER LINE OF STORMS IS MOVING ACROSS CENTRAL
FLORIDA. THE REMAINDER OF THE W ATLC IS EXPERIENCING FAIR
CONDITIONS UNDER THE INFLUENCE OF DRY AIR ALOFT AND SURFACE
RIDGING AROUND A WEAK 1013 MB HIGH NEAR 25N61W.
HOWEVER...FARTHER E ANOTHER LOW PRESSURE SYSTEM IS IMPACTING THE
CENTRAL ATLC. AN UPPER LEVEL TROUGH IS ALONG 53W SUPPORTING A
1007 MB LOW NEAR 34N57W. A SURFACE TROUGH EXTENDS SWD FROM THE
LOW CENTER TO NEAR 28N60W DEPICTING THE MAIN WIND SHIFT. THE
ACTIVE WEATHER IS FARTHER E ASSOCIATED WITH UPPER LEVEL
DIFFLUENCE. SCATTERED SHOWERS/THUNDERSTORMS ARE BETWEEN 44W-51W
N OF 23N. A SURFACE TROUGH IS ALSO FARTHER S EXTENDING FROM NEAR
22N60W TO PUERTO RICO AND INTO THE CARIBBEAN. SCATTERED
SHOWERS/THUNDERSTORMS ARE S OF 23N BETWEEN 55W-65W. THE ERN ATLC
IS EXPERIENCING GENERALLY FAIR WEATHER UNDER AN UPPER LEVEL
RIDGE ALONG 38W SUPPORTING A SURFACE RIDGE ALONG 35W. AN UPPER
LEVEL LOW CONTINUES TO SPIN NE OF THE CANARY ISLANDS NEAR 34N20W
SUPPORTING A PAIR OF 1012 MB LOWS NEAR 30N19W AND 32N12W.
MINIMAL ACTIVE WEATHER IS ASSOCIATED WITH EITHER LOW IN THE
DISCUSSION AREA. EXPECT MOIST CONDITIONS TO REMAIN ACROSS THE
CENTRAL ATLC WITH ACTIVITY INCREASING OVER THE W ATLC AS A COLD
FRONT OVER THE GULF OF MEXICO PROGRESSES EWD INTO THE W ATLC.

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

$$
WALTON





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