[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131734
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON MAY 13 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 GUINEA NEAR 10N14W
TO 6N17W. THE ITCZ BEGINS FROM 6N17W AND CONTINUES ALONG 2N30W
EQ40W 1N50W. SCATTERED MODERATE CONVECTION IS WITHIN 50 NM SE OF
LINE FROM 7N23W TO 5N28W. SIMILAR CONVECTION IS NOTED FROM 2N TO
5N W OF 45W TO THE COAST OF BRAZIL AND FRENCH GUIANA.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT CONTINUES TO MOVE SLOWLY THROUGH THE GULF OF MEXICO
CURRENTLY EXTENDING ACROSS CENTRAL FLORIDA FROM 28N81W TO
25.5N90W WHERE IT BECOMES STATIONARY ALONG 24N94W TO THE BAY OF
CAMPECHE NEAR 19N95W. A PRE-FRONTAL TROUGH PERSISTS OVER THE
EASTERN BAY OF CAMPECHE ALONG 92W FROM 19N TO 23N. SCATTERED
SHOWERS AND TSTMS ARE ASSOCIATED WITH THE STATIONARY PORTION OF
THE FRONT. ISOLATED SHOWERS ARE NOTED ELSEWHERE ALONG THE
FRONTAL BOUNDARY. THE COLD PORTION OF THE FRONT WILL CONTINUE TO
MOVE SE REACHING SOUTH FLORIDA LATER TODAY WHILE THE STATIONARY
PART IS FORECAST TO DISSIPATE OVER THE BAY OF CAMPECHE OVER THE
NEXT COUPLE OF DAYS. MODERATE TO FRESH NE WINDS FOLLOW THE
FRONT. GENTLE TO MODERATE EASTERLY WINDS ARE SEEN AHEAD OF THE
FRONT...AND SLIGHTLY INCREASE NEAR THE PRE-FRONTAL TROUGH.
MOISTURE WILL REMAIN OVER THE WESTERN GULF AND LIFT NORTH AS
RETURN FLOW BUILDS AND SURFACE RIDGING ESTABLISHES ACROSS THE
GULF WATERS. ALOFT...SOUTHWESTERLY FLOW DOMINATES BETWEEN AN
UPPER LEVEL TROUGH ACROSS CENTRAL TEXAS AND NW MEXICO AND AN
UPPER LEVEL RIDGE CENTERED ACROSS THE WESTERN CARIBBEAN.

CARIBBEAN SEA...
MOSTLY FAIR CONDITIONS PREVAIL ACROSS THE BASIN WITH THE TYPICAL
TRADE WIND SHOWERS AND SOME HIGH CLOUDS OVER THE NW CARIBBEAN
AND WEST-CENTRAL CUBA DUE TO STRONG WESTERLY WINDS ALOFT. TRADE
WIND FLOW OF 10-15 KT DOMINATES THE MAJORITY OF THE EASTERN AND
CENTRAL CARIBBEAN WITH WINDS OF 20 TO 25 KT NEAR THE COAST OF
COLOMBIA. THIS REGIMEN IS FORECAST TO PERSIST OVER THE NEXT
SEVERAL DAYS. A WEAK COLD FRONT WILL PASS E ACROSS CUBA AND THE
CARIBBEAN WATERS N OF 20N W OF HISPANIOLA TONIGHT AND TUE.
MAINLY MODERATE NE WINDS WILL FOLLOW THE FRONT. IN THE UPPER
LEVELS...AN ANTICYCLONE IS CENTERED OVER THE SW CARIBBEAN AND
EXTENDS A RIDGE NE THROUGH HISPANIOLA INTO THE WESTERN ATLANTIC.
MODERATE TO STRONG UPPER LEVEL SUBSIDENCE IS NOTED ON WATER
VAPOR IMAGERY E OF 75W...INCLUDING HISPANIOLA...PUERTO RICO...
THE VIRGIN ISLANDS AND MOST OF THE LESSER ANTILLES. THIS WEATHER
PATTERN IS LIMITING THE DEVELOPMENT OF SHOWER AND TSTM ACTIVITY
OVER THOSE ISLANDS. AN UPPER LEVEL TROUGH CROSSES THE SE
CARIBBEAN STRETCHING FROM NEAR MARTINIQUE TO NORTHERN VENEZUELA
NEAR 10N68W. ABUNDANT MID/UPPER LEVEL MOISTURE IS AHEAD OF THE
TROUGH AXIS AFFECTING NE VENEZUELA AND TRINIDAD AND TOBAGO.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE EASTERN UNITED STATES SUPPORTS A
COLD FRONT THAT EXTENDS FROM A 1013 MB LOW PRES NEAR 33N75W TO
CENTRAL FLORIDA...JUST N OF LAKE OKEECHOBEE...INTO THE GULF OF
MEXICO. THE FRONT WILL MOVE SOUTH AND THROUGH SOUTH FLORIDA THIS
AFTERNOON INTO EARLY THIS EVENING. CURRENTLY...DOPPLER RADAR
SHOWS ONLY ISOLATED SHOWERS ALONG THE FRONTAL BOUNDARY OVER
CENTRAL FLORIDA. THE LOW PRES LOCATED EAST THE BAHAMAS DURING
THE PREVIOUS DAYS IS NOW WEAKENING. CURRENTLY...IT IS CENTERED
NEAR 23N69W. A TROUGH EXTENDS FROM 28N70W TO THE LOW CENTER THEN
CONTINUES SOUTH TO THE MONA PASSAGE. A WEAK SWIRL OF LOW CLOUDS
IS RELATED TO THE LOW PRES FORECAST TO GRADUALLY DISSIPATE ALONG
THE TROUGH LATER TODAY...THEN THE TROUGH WILL MERGE WILL THE
AFOREMENTIONED COLD FRONT. UPPER LEVEL RIDGING COVERS THE AREA
IMMEDIATELY TO THE EAST OF THE UPPER TROUGH OVER U.S. EXTENDING
FROM HISPANIOLA TO BEYOND 31N62W. ANOTHER UPPER TROUGH EXTENDS
OVER THE CENTRAL ATLC FROM 31N45W TO 17N59W TO THE SE CARIBBEAN.
STRONG UPPER LEVEL SUBSIDENCE IS SEEN ON THE WEST SIDE OF THE
TROUGH WHILE SWLY WINDS AHEAD OF THE TROUGH ARE TRANSPORTING A
GOOD AMOUNT OF MID/UPPER LEVEL MOISTURE FROM NE VENEZUELA ACROSS
THE CENTRAL ATLC. VIS SATELLITE IMAGERY INDICATES A PLUME OF
HIGH CLOUDS ASSOCIATED WITH THESE WINDS. BROAD SURFACE RIDGING
DOMINATES THE REMAINDER OF THE CENTRAL AND EASTERN ATLC ANCHORED
BY A 1038 MB HIGH PRES SITUATED NW OF THE AZORES NEAR 42N36W.
THE RIDGE IS PROVIDING MOSTLY FAIR CONDITIONS ACROSS THIS AREA.
THE RIDGE IS SUPPORTED BY BROAD UPPER RIDGING COVERING THE
TROPICAL ATLC. ONCE AGAIN...AN AREA OF SAHARAN DUST IS OBSERVED
ON VIS AND SAHARAN AIR LAYER SATELLITE IMAGERY REACHING 50W. THE
REMNANTS OF A SHEAR AXIS IS STILL EVIDENT OF VIS SATELLITE
IMAGERY ACROSS THE TROPICAL ATLC JUST N OF THE AREA OF SAHARAN
DUST.

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

AT THE REQUEST OF METEO-FRANCE AND THE METEOROLOGICAL SERVICES OF
HAITI AND THE DOMINICAN REPUBLIC...THE TROPICAL ANALYSIS AND
FORECAST BRANCH (TAFB) WILL BEGIN PROVIDING...ON A TEMPORARY
BASIS...A SEPARATE DETAILED SECTION WITHIN THE ATLANTIC TROPICAL
WEATHER DISCUSSION (TWDAT). IT WILL COVER BOTH HAITI AND THE
DOMINICAN REPUBLIC DUE TO THE SHARED GEOGRAPHY OF BOTH COUNTRIES
ON THE ISLAND OF HISPANIOLA.

THE SECTION BEGINS ON MAY 15 2013 AT 1800 UTC...2 PM EDT. IT
WILL PROVIDE GUIDANCE FOR SIGNIFICANT WEATHER EVENTS THAT ARE
EXPECTED TO IMPACT THE REGION THROUGH 48 HOURS...WITH THE FOCUS
ON ASSESSING THE POTENTIAL FOR HEAVY RAINFALL.

$$
GR

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