[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 192354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAY 19 2012

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
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM ALBERTO IS CENTERED NEAR 32.2N 77.9W AT 19/2250
UTC OR ABOUT 115 NM ESE OF CHARLESTON SOUTH CAROLINA AND ABOUT
105 NM S OF CAPE FEAR NORTH CAROLINA MOVING SW AT 03 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED
WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. THE AREAL EXTENT OF
ALBERTO IS FAIRLY SMALL WITH SCATTERED MODERATE CONVECTION
OCCURRING FROM 31N-34N BETWEEN 76W-80W. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE
DETAILS...AS WELL AS THE LATEST NHC UPDATE UNDER AWIPS/WMO
HEADERS MIATCUAT1/WTNT61 KNHC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 04N31W TO 10N27W MOVING W NEAR 20 KT.
THE WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYERED
MOISTURE AS EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. ALSO...
LOW-LEVEL CYCLONIC WIND FLOW WAS NOTED IN THE VICINITY OF THE
WAVE AXIS ON AN EARLIER MORNING OSCAT PASS AROUND 19/1400 UTC.
NO DEEP CONVECTION IS NOTED ON SATELLITE IMAGERY...HOWEVER A FEW
ISOLATED LOW-TOPPED SHOWERS ARE POSSIBLE FROM 04N-09N BETWEEN
28W-32W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 05N09W TO
02N18W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
02N18W TO 03N23W TO 07N30W TO 04N43W. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS FROM 03N-06N BETWEEN THE PRIME
MERIDIAN AND 04W.

...DISCUSSION...

GULF OF MEXICO...
WEST-NORTHWESTERLY UPPER LEVEL FLOW DOMINATES ACROSS THE GULF
BASIN THIS EVENING AS WATER VAPOR IMAGERY INDICATES VERY DRY AIR
AND OVERALL SUBSIDENCE REMAINS ALOFT. THIS IS SUPPORTIVE OF A
SURFACE RIDGE AXIS EXTENDING FROM THE SE CONUS ACROSS THE
NORTH-CENTRAL AND WESTERN GULF FROM 30N89W TO 20N97W. FARTHER
EAST...AN UPPER LEVEL LOW IS CENTERED OVER EASTERN GEORGIA NEAR
33N81W AND EXTENDS BROAD AND WEAK MIDDLE TO UPPER LEVEL
TROUGHING ACROSS THE FAR NE GULF AND FLORIDA PENINSULA. SURFACE
TROUGHING EXTENDS ACROSS MUCH OF THE SW NORTH ATLC WATERS W OF
76W SOUTHWESTWARD TO THE LOWER FLORIDA KEYS. LOW-LEVEL MOISTURE
CONVERGENCE ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE IS
PROVIDING FOR PLENTY OF MOISTURE AND INSTABILITY OVER THE SE
GULF...FLORIDA STRAITS...AND SOUTHERN FLORIDA PENINSULA THIS
EVENING. MOSAIC DOPPLER RADAR...SATELLITE IMAGERY...AND
LIGHTNING DATA INDICATE WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS CONTINUE TO OCCUR OVER THESE AREAS SE OF A LINE FROM
27N82W TO 23N88W. THE SURFACE RIDGE IS FORECAST TO REMAIN NEARLY
STATIONARY ACROSS THE CENTRAL AND WESTERN GULF THROUGH THE
WEEKEND INTO MONDAY PROVIDING NE TO E WINDS IN THE RANGE OF 10
TO 20 KT.

CARIBBEAN SEA...
MUCH OF THE CARIBBEAN BASIN IS UNDER THE INFLUENCE OF THE
EASTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION
CENTERED OVER EL SALVADOR NEAR 14N89W PROVIDING W-NW TO
NORTHERLY UPPER LEVEL FLOW THIS EVENING. W OF 75W...UPPER LEVEL
WIND SHEAR REMAINS MINIMAL AND UPPER LEVEL DIFFLUENCE CONTINUES
TO BE MAXIMIZED BETWEEN 78W-90W. ALONG WITH A SURFACE TROUGH
ANALYZED FROM WESTERN CUBA NEAR 23N84W INTO A 1009 MB LOW
CENTERED IN THE GULF OF HONDURAS NEAR 17N87W...PLENTY OF DEEP
LAYERED MOISTURE IS AVAILABLE FOR SCATTERED SHOWERS AND ISOLATED
TSTMS OCCURRING OVER PORTIONS OF THE WESTERN CARIBBEAN W OF A
LINE FROM 20N77W TO 11N84W...INCLUDING PORTIONS OF INLAND
NICARAGUA AND HONDURAS. ISOLATED SHOWERS SPREAD FARTHER INLAND
WESTWARD OVER BELIZE...EL SALVADOR...AND GUATEMALA. GLOBAL MODEL
GUIDANCE SUGGESTS THIS SURFACE TROUGHING WILL REMAIN NEARLY
STATIONARY OVER THE WESTERN CARIBBEAN THROUGH MUCH OF NEXT WEEK
AND CONTINUE TO BRING INCREASED CHANCES OF HEAVY RAINFALL AND
HIGHER PROBABILITIES OF LOCALIZED FLOODING ACROSS PORTIONS OF
CENTRAL AMERICA. THE REMAINDER OF THE CARIBBEAN E OF 75W IS
UNDER MOSTLY EAST-SOUTHEASTERLY SURFACE WINDS IN THE RANGE OF 15
TO 25 KT WITH ISOLATED SHOWERS OCCURRING N OF 16N E OF 75W. A
FEW EMBEDDED ISOLATED TSTMS ARE ALSO OCCURRING OVER HISPANIOLA
THIS EVENING.

ATLANTIC OCEAN...
TROPICAL STORM ALBERTO REMAINS JUST NORTH OF THE DISCUSSION AREA
OFF THE SOUTH CAROLINA COAST...SEE ABOVE FOR DETAILS. ELSEWHERE
OVER THE SW NORTH ATLC...WATER VAPOR IMAGERY INDICATES ADVECTION
OF DEEP LAYERED TROPICAL MOISTURE DUE TO STRONG SOUTHWESTERLY
FLOW ALOFT N OF 21N W OF 62W. BENEATH THE MIDDLE AND UPPER LEVEL
MOISTURE...A SURFACE TROUGH IS ANALYZED FROM EASTERN CUBA NEAR
21N77W TO 28N73W. WHILE LOW-LEVEL MOISTURE CONVERGENCE IS
MAXIMIZED IN THE VICINITY OF THE SURFACE TROUGH...A LARGE AREA
OF SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS IS OCCURRING
OVER THE SW NORTH ATLC FROM 18N-31N BETWEEN 62W-80W...INCLUDING
THE TURKS AND CAICOS...THE BAHAMAS...AND CUBA. THE SURFACE
TROUGHING ACROSS THE SW NORTH ATLC IS FORECAST TO PERSIST
THROUGH THE REMAINDER OF THE WEEKEND. GLOBAL MODEL GUIDANCE
DIFFERS SLIGHTLY ON WHETHER A SURFACE LOW WILL DEVELOP IN THE
VICINITY OF 30N70W BY LATE SUNDAY EAST OF TROPICAL STORM
ALBERTO. THE GFS REMAINS MOST AGGRESSIVE MOVING THE LOW
NORTH-NORTHEASTWARD THROUGH TUESDAY...WITH THE ECMWF AND UKMET
SUGGESTING A WEAK LOW OR SURFACE TROUGHING REMAINING THE
DOMINATE WEATHER FEATURE. FARTHER EAST...THE CENTRAL AND EASTERN
ATLC IS UNDER THE INFLUENCE OF A BROAD SURFACE RIDGE ANCHORED BY
A 1036 MB HIGH CENTERED W-SW OF THE AZORES NEAR 37N38W.

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

$$
HUFFMAN




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