[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202339
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON MAY 20 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 7N34W TO EQ36W MOVING WEST AT 10-15
KT. THE WAVE SHOWS A GOOD SIGNAL IN 700 MB STREAMLINES AND
SATELLITE DERIVED WINDS. IT ALSO COINCIDES WITH A MAXIMUM IN
DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY.
ISOLATED MODERATE CONVECTION IS WITHIN 100 NM OF THE AXIS.

TROPICAL WAVE EXTENDS FROM 14N62W TO 9N63W MOVING W AT 5-10 KT.
THE WAVE IS PARTIALLY OVER SOUTH AMERICA...BUT THE MOISTURE
SIGNAL IN TOTAL PRECIPITABLE WATER IMAGERY EXTENDS UP TO 15N.
SCATTERED MODERATE CONVECTION IS WITHIN 200 NM TO EITHER SIDE
SOUTH OF 12N. THE DEEPEST MOISTURE ASSOCIATED WITH THE WAVE IS
STILL MOVING OVER THE WINDWARD ISLANDS...SO A RISK OF HEAVY
RAINFALL IS STILL PRESENT OVER THIS AREA.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR
11N15W TO ALONG 5N20W 4N30W. THE ITCZ BEGINS NEAR 4N30W AND
CONTINUES ALONG EQ38W 3S49W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 4N-8N BETWEEN 17W-20W. ISOLATED MODERATE
CONVECTION IS FROM 1N-7N BETWEEN 22W-32W.

...DISCUSSION...

GULF OF MEXICO...
MOSTLY FAIR WEATHER SPREADS ACROSS THE GULF OF MEXICO...WITH THE
EXCEPTION OF FLORIDA...ALONG WITH BROAD SURFACE RIDGING
EXTENDING FROM THE W ATLC. DRY AIR ALOFT COVERS THE MAJORITY OF
THE BASIN AROUND BROAD UPPER LEVEL RIDGING EXTENDING FROM THE
EAST PACIFIC JUST SOUTH OF GUATEMALA. HOWEVER...A SHORTWAVE
UPPER TROUGH EXTENDS DOWN THE WEST COAST OF FLORIDA PROVIDING
DIFFLUENCE ALOFT ACROSS THE PENINSULA. THIS COMBINED WITH
DAYTIME HEATING AND INSTABILITY HAS LED TO HEAVY SHOWERS AND
THUNDERSTORMS ACROSS FLORIDA WITH SOME BEING SEVERE. THE
ACTIVITY OVER SOUTH FLORIDA HAS DIED DOWN SOME...BUT HEAVY
ACTIVITY STILL SPREADS OVER MUCH OF THE WEST CENTRAL AND
NORTHERN PORTIONS. PRIMARILY SOUTHEAST WINDS SPREAD THROUGHOUT
THE BASIN RANGING FROM 10-15 KT WITH A FEW AREAS OF 20 KT WINDS
OVER THE WESTERN GULF ESPECIALLY ALONG THE TEXAS COAST. LITTLE
CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. MODEL GUIDANCE
CONTINUES TO SHOW HIGH MOISTURE AND PRECIPITATION POTENTIAL
THROUGHOUT THE FLORIDA PENINSULA.

CARIBBEAN SEA...
NORTHWEST TO WEST FLOW ALOFT COVERS THE CARIBBEAN ALONG WITH
MOSTLY DRY AIR. THE DRY AIR IS PROVIDING FAIR CONDITIONS ACROSS
MUCH OF THE BASIN. HOWEVER...DAYTIME HEATING AND INSTABILITY
HAVE LED TO WIDESPREAD SHOWERS AND THUNDERSTORMS OVER THE
NORTHERN CARIBBEAN ISLANDS INCLUDING
CUBA...HISPANIOLA...JAMAICA...AND PUERTO RICO. HEAVY SHOWERS AND
THUNDERSTORMS ARE ALSO IN THE FAR SW CARIBBEAN SOUTH OF 11N FROM
COSTA RICA TO COLOMBIA INCLUDING PANAMA. THIS ACTIVITY IS
CONNECTED TO THE MONSOON TROUGH EXTENDING THROUGH BOTH COSTA
RICA AND PANAMA. THE ACTIVITY IS ENHANCED BY DIFFLUENT FLOW
ALOFT ACROSS THAT AREA. A TROPICAL WAVE HAS MOVING INTO THE SE
CARIBBEAN JUST WEST OF THE WINDWARD ISLANDS. SCATTERED SHOWERS
ARE EAST OF 63W SOUTH OF 16N. THERE IS STILL SOME MOISTURE WITH
THE WAVE EAST OF THE WINDWARD ISLANDS...AND AS THE WAVE MOVES
WEST MORE SHOWERS AND POSSIBLE THUNDERSTORMS COULD OCCUR OVER
THE ISLANDS. ELSEWHERE...TRADEWIND FLOW OF 15-20 KT DOMINATES
WITH A FEW 25 KT WINDS OFF THE COAST OF COLOMBIA. MOIST
CONDITIONS AND LIKELY PRECIPITATION WILL REMAIN OVER THE SW
CARIBBEAN AS WELL AS THE NORTHERN CARIBBEAN ISLANDS ESPECIALLY
IN THE AFTERNOON HOURS. AS THE TROPICAL WAVE IN THE SE CORNER
MOVES WEST...MOISTURE WILL INCREASE AND WILL SUPPORT HEAVIER
THAN NORMAL AFTERNOON CONVECTION. THIS WILL LIKELY BE THE CASE
TOMORROW OVER PUERTO RICO AND SPREAD WESTWARD ON WEDNESDAY.

HISPANIOLA...
CURRENTLY AFTERNOON SHOWERS AND THUNDERSTORMS CONTINUE TO IMPACT
THE ISLAND OF HISPANIOLA MAINLY CONCENTRATED BETWEEN 70W-73W. AS
THE SUN GOES DOWN THIS ACTIVITY SHOULD DIE DOWN. MODEL GUIDANCE
INDICATES A SIMILAR PATTERN WILL PERSIST TOMORROW 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 ON
WEDNESDAY.

ATLANTIC OCEAN...
A SHORTWAVE UPPER TROUGH ALONG THE WEST COAST OF FLORIDA IS
SUPPORTING HEAVY SHOWERS AND THUNDERSTORMS ACROSS THE FLORIDA
PENINSULA...WHICH CONTINUE INTO THE ATLC TO NEAR 78W. AN UPPER
LEVEL RIDGE IS ALONG 76W SUPPORTING A SURFACE RIDGE ACROSS THE
WEST ATLC AROUND A 1026 MB HIGH NEAR 35N62W. FARTHER EAST...AN
UPPER LEVEL TROUGH ALONG 49W SUPPORTS A COLD FRONT THAT ENTERS
THE DISCUSSION AREA NEAR 32N49W AND CONTINUES ALONG 29N55W
27N59W. ISOLATED SHOWERS ARE WITHIN 30 NM OF THE AXIS. A WEAK
1019 MB SURFACE LOW IS TO THE EAST NEAR 27N48W. A SURFACE TROUGH
EXTENDS THROUGH THE LOW CENTER FROM 30N49W 24N44W. NO SHOWERS
ARE ASSOCIATED WITH THE SYSTEM. THE REMAINDER OF THE EASTERN
ATLC IS DOMINATED BY BROAD SURFACE RIDGING ANCHORED BY A 1034 MB
HIGH NEAR 44N29W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE
CENTERED NEAR 43N26W. BROAD UPPER RIDGING ALSO COVERS THE
TROPICAL ATLC.

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

$$
WALTON


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