[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192336
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAY 19 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 8N30W EQ31W MOVING WEST AT 10-15 KT.
THE WAVE SHOWS A GOOD SIGNAL IN 700 MB STREAMLINES AND SATELLITE
DERIVED WINDS. CURRENTLY NO DEEP CONVECTION IS NEAR THE WAVE
AXIS.

TROPICAL WAVE EXTENDS FROM 11N60W TO 5N61W MOVING W AT 15 KT.
THE WAVE IS PRIMARILY OVER SOUTH AMERICA...BUT THE MOISTURE
SIGNAL IN TOTAL PRECIPITABLE WATER IMAGERY EXTENDS UP TO 15N.
SCATTERED MODERATE/ISOLATE STRONG CONVECTION REMAINS OVER LAND
WITHIN 200 NM TO EITHER SIDE. MOISTURE ASSOCIATED WITH THE WAVE
HAS ALMOST REACHED THE WINDWARD ISLANDS AND WILL LIKELY PRODUCE
PRECIPITATION OVER THE ISLANDS DURING THE NEXT DAY OR SO.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF SIERRA LEONE NEAR
8N13W TO 6N14W 4N16W. THE ITCZ BEGINS AT 4N16W AND CONTINUES
ALONG 3N24W 5N28W WHERE IT BREAKS AROUND THE TROPICAL WAVE AND
PICKS UP ALONG EQ32W 1S48W. A LARGE AREA OF NUMEROUS STRONG
CONVECTION IS MOVING OFF THE AFRICAN COAST FROM 3N-12N BETWEEN
12W-17W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
2N-6N BETWEEN 21-26W.

...DISCUSSION...

GULF OF MEXICO...
MOSTLY FAIR WEATHER SPREADS ACROSS THE GULF OF MEXICO ALONG WITH
BROAD SURFACE RIDGING EXTENDING FROM THE NW ATLC. SOME UPPER
LEVEL CLOUD COVER IS MOVING EASTWARD ACROSS THE BASIN CURRENTLY
OVER THE EASTERN HALF ASSOCIATED WITH A SHORTWAVE UPPER TROUGH
ALONG 92W THAT EXTENDS SOUTHWARD TO 25N. BROAD UPPER RIDGING
COVERS THE REMAINDER OF THE BASIN. MOSTLY SOUTHEAST FLOW IS
PRESENT AT THE SURFACE RANGING FROM 10 KT IN THE EASTERN
PORTIONS TO 15-20 OVER THE WESTERN GULF. RADAR IMAGERY INDICATES
SEVERAL CLUSTERS OF STRONG LATE AFTERNOON SHOWERS AND
THUNDERSTORMS STILL CONTINUE OVER PORTIONS OF THE FLORIDA
PENINSULA MAINLY FOCUSED ON THE SW CORNER AND NORTH CENTRAL
PARTS. A FEW STORMS HAVE ALSO MOVED OFF CUBA INTO THE SE GULF.
LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
DRY AND STABLE AIR COVERS THE MAJORITY OF THE CARIBBEAN AROUND A
BROAD UPPER LEVEL TROUGH COVERING THE BASIN. THE DRY AIR IS
HELPING MAINTAIN GENERALLY FAIR WEATHER ACROSS THE AREA.
HOWEVER...AFTERNOON SHOWERS AND THUNDERSTORMS POPPED UP AND
CONTINUE ACROSS MANY OF THE NORTHERN CARIBBEAN ISLANDS INCLUDING
CUBA...JAMAICA...HISPANIOLA...AND PUERTO RICO. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO IN THE FAR SW CORNER AND OVER
COSTA RICA AND PANAMA ASSOCIATED WITH THE MONSOON TROUGH THAT
EXTENDS FROM THE E PACIFIC THROUGH BOTH COUNTRIES CONTINUING
INTO COLOMBIA. TRADEWIND FLOW OF 15-20 KT DOMINATES THROUGHOUT.A
FEW ISOLATED SHOWERS ARE MOVING WITHIN THE TRADEWIND FLOW ACROSS
THE LESSER ANTILLES. LITTLE CHANGE IS EXPECTED EXCEPT FOR AN
INCREASE IN MOISTURE ACROSS THE WINDWARD ISLANDS AS A TROPICAL
WAVE JUST EAST OF THE ISLANDS CONTINUES TO MOVE WESTWARD. THERE
WILL BE AN INCREASED CHANCE OF HEAVIER RAIN AS THE WAVE PASSES.

HISPANIOLA...
CURRENTLY AFTERNOON SHOWERS AND THUNDERSTORMS CONTINUE TO IMPACT
THE ISLAND OF HISPANIOLA MAINLY CONCENTRATED IN THE CENTRAL
PORTION. AS THE SUN GOES DOWN THIS ACTIVITY SHOULD DIE DOWN.
MODEL GUIDANCE INDICATES A SIMILAR PATTERN WILL PERSIST OVER THE
NEXT COUPLE OF DAYS 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.

ATLANTIC OCEAN... A COLD FRONT HAS SUNK SOUTH INTO THE
DISCUSSION AREA ALONG 31N60W 29N67W 31N73W. ISOLATED SHOWERS ARE
ALONG THE AXIS. A FEW ISOLATED SHOWERS ARE ALSO NOTED OVER THE
BAHAMAS. THE FRONT WRAPS AROUND A SURFACE RIDGE CENTERED WELL TO
THE NORTH. THE FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH ALONG
57W THAT EXTENDS NORTH OF 30N. BROAD UPPER TROUGHING CONTINUES
INTO THE SOUTHWEST NORTH ATLC AS WELL. IN THE CENTRAL ATLC...A
PAIR OF WEAK SURFACE TROUGHS ARE PRESENT. THE FIRST IS ALONG
30N57W TO 24N63W. IT ORIGINATED FROM A NOW DISSIPATED FRONTAL
BOUNDARY. POSSIBLE ISOLATED SHOWERS ARE ALONG IT. THE SECOND
SURFACE TROUGH IS ALONG 29N48W 24N44W. ISOLATED SHOWERS ARE
ALONG THE AXIS. AN AREA OF ISOLATED SHOWERS IS ALSO EAST OF THE
LESSER ANTILLES FROM 10N-18N BETWEEN 53W-61W. THIS ACTIVITY IS
ASSOCIATED WITH ENHANCED MOISTURE NEAR A TROPICAL WAVE TO THE
SOUTH. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS
DOMINATED BY BROAD SURFACE RIDGING AROUND A 1033 MB HIGH NEAR
42N30W. ALOFT...BROAD UPPER RIDGING COVERS THE TROPICAL ATLC
WITH AN UPPER LEVEL LOW TO THE NORTH NEAR 31N33W.

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

$$
WALTON


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