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000
AXNT20 KNHC 211152
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE MAY 21 2013

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
1015 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 8N38W TO EQ40W MOVING W AT 10-15 KT.
WAVE COINCIDES WITH A LOW AMPLITUDE MOISTURE MAXIMUM ON THE
TOTAL PRECIPITABLE WATER IMAGERY WITH CURVATURE EVIDENT ON THE
700 MB STREAMLINES AND SATELLITE DERIVED WINDS. WAVE ALSO
DISRUPTS THE ITCZ.

TROPICAL WAVE EXTENDS FROM 15N63W TO INLAND OVER SOUTH AMERICA
TO NEAR 8N65W MOVING W NEAR 5 KT. WAVE COINCIDES WITH A WEAK
MOISTURE MAXIMUM ON THE TOTAL PRECIPITABLE WATER IMAGERY THAT
CONTINUES TO SHIFT NORTHWARD OVER THE E CARIBBEAN WITH A WEAK
CURVATURE ON THE 700 MB STREAMLINES. SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS DOT THE W TROPICAL ATLC/E
CARIBBEAN FROM 10N-18N BETWEEN 58W-66W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 11N15W CONTINUING ALONG 5N21W TO 3N26W WHERE THE ITCZ
BEGINS AND CONTINUES ALONG 4N34W TO 2N38W. SCATTERED MODERATE/
STRONG CONVECTION IS WITHIN 60 NM OF LINE FROM 4N6W TO 5N12W.
CLUSTERS OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE OFF
THE COAST OF SW AFRICA FROM 3N-9N E OF 17W TO THE PRIME
MERIDIAN. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 2N-
5N BETWEEN 19W-30W. CLUSTERS OF ISOLATED MODERATE CONVECTION ARE
FROM 2N-6N BETWEEN 30W-38W AND FROM 2N TO THE EQUATOR BETWEEN
41W-46W.

...DISCUSSION...

GULF OF MEXICO...
A SHORTWAVE UPPER TROUGH EXTENDS FROM SE GEORGIA OVER THE
FLORIDA PENINSULA TO NEAR 24N80W IN THE STRAITS OF FLORIDA. A
BROAD UPPER RIDGE AXIS EXTENDS OVER THE W GULF ACROSS S MEXICO
NEAR VERACRUZ TO OVER THE SE CONUS NEAR THE LOUISIANA/TEXAS
BORDER COVERING THE REMAINDER OF THE GULF. A SURFACE RIDGE
EXTENDS FROM THE W ATLC ACROSS CENTRAL FLORIDA TO OVER THE E
GULF WITH SOUTHERLY RETURN FLOW COVERING THE REMAINDER OF THE
GULF. WATER VAPOR IMAGERY INDICATES MOSTLY STRONG SUBSIDENCE AND
DRY STABLE AIR ALOFT DOMINATING THE GULF THIS MORNING...THUS
CLEAR SKIES FOR ALL BUT THE FAR W GULF WHERE LOW LEVEL CLOUDS
ARE N OF 23N W OF 94W. MODEL GUIDANCE CONTINUES TO SHOW HIGH
MOISTURE AND PRECIPITATION POTENTIAL OVER THE FAR E GULF AND
OVER THE FLORIDA PENINSULA THROUGH EARLY WED BEFORE THE UPPER
TROUGH IS EXPECTED TO MOVE E OF FLORIDA. A COLD FRONT MAY MOVE
INTO THE NE GULF FRI THEN DRIFT S THROUGH SAT.

CARIBBEAN SEA...
AN UPPER RIDGE AXIS EXTENDS ALONG THE N COAST OF SOUTH AMERICA
GIVING THE CARIBBEAN S OF 17N SW FLOW ALOFT. THE AREA N OF 17N
IS UNDER NEAR ZONAL WESTERLY FLOW ALOFT. THE UPPER FLOW IS
DRAWING TROPICAL MOISTURE ALOFT OVER THE S CARIBBEAN AND COUPLED
WITH THE MONSOON TROUGH THAT EXTENDS FROM COLOMBIA NEAR 10N75W
ALONG 11N80W TO ACROSS COSTA RICA NEAR 10N84W ARE GENERATING
SCATTERED SHOWERS/THUNDERSTORMS S OF 12N BETWEEN 74W-84W.
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS CONTINUE
OVER PORTIONS OF E CUBA AND FROM 16N-20N BETWEEN 74W-80W. THE E
CARIBBEAN IS COVERED IN THE TROPICAL WAVE SECTION ABOVE. SURFACE
RIDGE OVER THE W ATLC WILL MAINTAIN MODERATE TO FRESH TRADE
WINDS OVER THE REGION WITH STRONGER WINDS AT TIMES OFF THE COAST
OF COLOMBIA AND IN THE GULF OF HONDURAS THROUGH MID WEEK.

HISPANIOLA...
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60 NM ALONG
THE S COAST OF THE DOMINICAN REPUBLIC BETWEEN BAHIA DE YUMA TO
BAHIA DE OCOA. MODEL GUIDANCE INDICATES A SIMILAR PATTERN WILL
PERSIST TODAY WITH THE MOST LIKELY PRECIPITATION TO BE DURING
THE AFTERNOON AND EARLY EVENING HOURS ACROSS THE ISLAND WHEN
PEAK DAYTIME HEATING AND INSTABILITY OCCUR. ANY AREAS THAT
RECEIVE MEASURABLE AMOUNTS OF RAINFALL WILL LIKELY BE PRONE TO
LOCALIZED FLOODING. MOISTURE FROM A TROPICAL WAVE MAY INCREASE
ACTIVITY OVER THE ISLAND TONIGHT INTO WED.

ATLANTIC OCEAN...
A SHORTWAVE UPPER TROUGH OVER THE FLORIDA PENINSULA TO NEAR
24N80W IN THE STRAITS OF FLORIDA AND IS AMPLIFYING AN UPPER
RIDGE OVER THE FAR W ATLC THAT EXTENDS FROM THE TURKS AND CAICOS
NEAR 21N72W TO BEYOND 32N77W AND IS ENHANCING THE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS FROM 24N-32N W OF 78W TO THE
FLORIDA COAST. A SURFACE RIDGE EXTENDS FROM A 1024 MB HIGH NEAR
33N62W ACROSS CENTRAL FLORIDA INTO THE GULF OF MEXICO. CLUSTERS
OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 75 NM
ALONG THE N COAST OF CUBA E OF 79W. A BROAD UPPER TROUGH COVERS
THE REMAINDER OF THE W ATLC INTO THE CENTRAL ATLC SUPPORTING A
COLD FRONT THAT ENTERS THE REGION NEAR 32N47W TO 28N54W WHERE IT
DISSIPATES TO 27N60W. SCATTERED SHOWERS ARE WITHIN 90 NM E OF
THE FRONT N OF 29N. A WEAK SURFACE TROUGH IS TO THE SE EXTENDING
FROM 29N48W THROUGH AN EQUALLY WEAK 1019 MB SURFACE LOW NEAR
27N48W TO 25N49W. THIS FEATURE IS NOT PRODUCING ANY SIGNIFICANT
WEATHER. A BROAD SURFACE RIDGE COVERS THE E ATLC ANCHORED BY A
1035 MB HIGH N OF THE AZORES. A COLD FRONT MAY MOVE INTO THE NW
PORTION FRI SLOWLY MOVING E ACROSS THE WATERS N OF 27N THROUGH
SAT.

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

$$
PAW