[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU MAY 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 13N17W
TO 9N21W. THE ITCZ BEGINS NEAR 9N21W AND CONTINUES ALONG 7N34W
4N46W 5N53W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 4N-8N BETWEEN 30W-46W. SIMILAR ACTIVITY IS FROM 6N-11N
BETWEEN 52W-60W.

...DISCUSSION...

GULF OF MEXICO...
SE RETURN FLOW OF 15-20 KT SPREADS ACROSS THE GULF OF MEXICO
AROUND BROAD SURFACE RIDGING DOMINATING THE EASTERN CONUS. UPPER
LEVEL RIDGING ALONG 86W SUPPORTS THE SURFACE RIDGE. UPPER LEVEL
TROUGHING IS TO EITHER SIDE. THE UPPER TROUGH TO THE WEST ALONG
THE EASTERN MEXICO COAST IS ONLY SUPPORTING A FEW UPPER LEVEL
CLOUDS ACROSS THE BASIN. HOWEVER...THE UPPER TROUGH TO THE EAST
NEAR 79W IS PROVIDING DIFFLUENT FLOW ALOFT ACROSS THE SW NORTH
ATLC AND COMBINING WITH THE EFFECTS OF LOW LEVEL TROPICAL
MOISTURE STREAMING FROM THE SOUTHEAST. THIS LOW-LEVEL MOISTURE
CONTINUES OVER MUCH OF THE FLORIDA PENINSULA SUPPORTING
SCATTERED SHOWERS SOUTH OF 29N. IN THE SW GULF...THE EAST
PACIFIC SYSTEM T.D. BARBARA IS JUST ALONG THE MEXICO COAST NEAR
18.5N 95.0W. ONLY A FEW ISOLATED SHOWERS ARE OVER GULF WATERS
FROM 18N-20N BETWEEN 92W-96W. THE SYSTEM IS EXPECTED TO MOVE NW
ALONG THE COASTLINE AND MAY CONTINUE TO PRODUCE
SHOWERS/THUNDERSTORMS IN THE SW GULF.

CARIBBEAN SEA...
ABUNDANT DEEP LAYER MOISTURE IS THROUGHOUT THE WESTERN CARIBBEAN
EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. THIS IS DUE TO BOTH
LOW-LEVEL MOISTURE CONVERGENCE AND UPPER LEVEL DIFFLUENT FLOW
AROUND THE BASE OF AN UPPER TROUGH OVER CENTRAL CUBA...AND
AROUND AN UPPER RIDGE OVER CENTRAL AMERICA. THE COMBINATION IS
SUPPORTING A LARGE CLUSTER OF STRONG SHOWERS AND SCATTERED
THUNDERSTORMS FROM 11N-15N BETWEEN 76W-80W...AND SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS FROM 12N-20N BETWEEN 80W-85W. A
WEAK 1010 MB SURFACE LOW IS ALSO ANALYZED OFF THE COAST OF
NICARAGUA NEAR 12N83W NEAR THE END OF THE MONSOON TROUGH THAT
EXTENDS FROM THE EPAC THROUGH COSTA RICA TO THE LOW. ISOLATED
SHOWERS ARE MOVING THROUGH PORTIONS OF THE EASTERN AND CENTRAL
CARIBBEAN EMBEDDED WITHIN TRADEWIND FLOW OF 20 KT. THE UPPER
TROUGH OVER CENTRAL CUBA IS ALSO SUPPORTING SHOWERS AND
THUNDERSTORMS OVER EASTERN CUBA...JAMAICA...AND HISPANIOLA.
LITTLE CHANGE IS EXPECTED WITH DEEP MOISTURE REMAINING OVER MUCH
OF THE CENTRAL AND WESTERN CARIBBEAN.

HISPANIOLA...
AN UPPER LEVEL TROUGH NEAR 78W CONTINUES TO PROVIDE MOIST AND
DIFFLUENT FLOW ALOFT OVER HISPANIOLA. CURRENTLY...SCATTERED LOW-
LEVEL SHOWERS ARE PRESENT. AS THE DAY CONTINUES...DEEP
CONVECTION IS MORE LIKELY TO FORM DUE TO DAYTIME HEATING. THIS
PATTERN IS EXPECTED TO CONTINUE AS THE UPPER TROUGH DRIFTS EAST
AND WILL CONTINUE TO PROVIDE A FAVORABLE UPPER LEVEL ENVIRONMENT
FOR CONVECTIVE ACTIVITY...ESPECIALLY IN THE AFTERNOON AND
EVENING HOURS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH NEAR 77W/78W CONTINUES TO PROVIDE A LARGE
AREA OF DIFFLUENCE ALOFT ACROSS THE WEST ATLC SUPPORTING
WIDESPREAD SHOWERS/THUNDERSTORMS FROM 21N-29N BETWEEN 70W-76W.
SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS CONTINUE WESTWARD FROM
24N-28N WEST OF 76W AND OVER THE FLORIDA PENINSULA. AN UPPER
LEVEL RIDGE TO THE EAST ALONG 69W SUPPORTS BROAD SURFACE RIDGING
ACROSS THE WEST ATLC EXTENDING FROM A 1031 MB HIGH CENTERED TO
THE NORTH NEAR 38N56W. A COUPLE OF WEAK SURFACE TROUGHS PROVIDE
A WEAKNESS IN THE RIDGE. THE FIRST IS ALONG 32N50W TO 27N56W.
THE SECOND IS ALONG 30N46W 26N46W. ISOLATED SHOWERS ARE WITHIN
60 NM EAST OF BOTH AXIS. THE TROUGHS ARE SUPPORTED BY AN UPPER
LEVEL TROUGH EXTENDING ALONG 44N44W 26N50W 15N61W. THE REMAINDER
OF THE EAST ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1035
MB HIGH NEAR 41N27W. VISIBLE SATELLITE IMAGERY INDICATES AN AREA
OF DUST EXTENDS FROM THE COAST OF AFRICA TO NEAR 60W SOUTH OF
22N. ALOFT...BROAD UPPER LEVEL RIDGING COVERS THE EASTERN ATLC
NEAR 35N25W...AS WELL AS THE TROPICAL ATLC NEAR 13N31W.

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

$$
WALTON


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