[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU MAY 16 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.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 01N41W TO 08N39W MOVING W AT 15 KT.
THE WAVE REMAINS LOW-AMPLITUDE AND EMBEDDED WITHIN THE ITCZ AXIS
COINCIDING WITH A GLOBAL MODEL INDICATED AREA OF MAXIMUM
POTENTIAL VORTICITY AT 315K. TOTAL PRECIPITATABLE WATER AND
SATELLITE IMAGERY ALSO INDICATE A MAXIMUM IN LOW-LEVEL MOISTURE
CONVERGENCE AND CLOUDINESS IN THE VICINITY OF THE WAVE AXIS.
WIDELY SCATTTERED MODERATE CONVECTION IS FROM 03N-08N BETWEEN
36W-43W. THE WAVE IS EXPECTED TO CONTINUE MOVING WESTWARD WITH
PRECIPITATION PROBABILITIES INCREASING BY THE WEEKEND ACROSS THE
WINDWARD ISLANDS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO
06N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
06N20W TO 04N30W TO 05N40W TO 03N51W. SCATTERED MODERATE
CONVECTION IS FROM 02N-07N BETWEEN 01W-10W...AND FROM 05N-10N
BETWEEN 12W-18W. WIDELY SCATTERED MODERATE CONVECTION IS FROM
02N-05N BETWEEN 27W-35W...AND FROM THE EQUATOR TO 08N BETWEEN
45W-53W.

...DISCUSSION...

GULF OF MEXICO...
WEST-SOUTHWESTERLY FLOW BETWEEN A MIDDLE TO UPPER LEVEL LOW
CENTERED OVER EASTERN OKLAHOMA AND A RIDGE AXIS EXTENDING FROM
OVER SOUTHERN MEXICO NEAR 16N92W TO OVER THE SE CONUS NEAR
32N82W IS PROVIDING FOR MOSTLY FAIR CONDITIONS AND CLEAR SKIES
THIS AFTERNOON ACROSS MUCH OF THE GULF WITH THE EXCEPTION OF A
FEW ISOLATED SHOWERS OCCURRING N OF 28N E OF 90W. WHILE THE
UPPER LEVEL LOW AND ITS IMPACTS ARE EXPECTED TO REMAIN NORTH OF
THE BASIN...A SURFACE RIDGE WILL REMAIN THE PRIMARY FEATURE
ACROSS THE GULF DURING THE NEXT FEW DAYS. CURRENTLY THE RIDGE IS
ANCHORED BY A 1022 MB HIGH CENTERED IN THE SW NORTH ATLC NEAR
BERMUDA. LOOKING AHEAD...THE RIDGE IS EXPECTED TO REMAIN NEARLY
STATIONARY THROUGH THE REMAINDER OF THE WEEK WITH GENERALLY E-SE
WINDS FORECAST IN THE RANGE OF 10 TO 20 KT.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE
EASTERN PACIFIC REGION NEAR 13N92W AND IS PROVIDING MUCH OF THE
CARIBBEAN BASIN WITH DRY NORTHWESTERLY WIND ALOFT. WATER VAPOR
IMAGERY SHOWS THIS DRY AIR ALOFT GENERALLY NE OF A LINE FROM
16N84W TO 12N73W. THE ONLY EXCEPTION OF NOTE IS INCREASED MIDDLE
TO UPPER LEVEL MOISTURE OVER THE NE CARIBBEAN N OF 15N E OF 71W.
IN ADDITION...THE SW CARIBBEAN REMAINS UNDER DIFFLUENT FLOW
ALOFT WHICH ALONG WITH CLOSE PROXIMITY TO THE MONSOON TROUGH
AXIS IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 12N
BETWEEN 75W-82W. OTHERWISE...WIDELY SCATTERED SHOWERS ARE
OCCURRING ACROSS AN AREA SOUTH OF HISPANIOLA AND PUERTO RICO
FROM 15N-19N BETWEEN 65W-75W. ELSEWHERE...E-NE TRADES IN THE
RANGE OF 10 TO 20 KT ARE NOTED IN RECENT SCATTEROMETER DATA.

HISPANIOLA...
WATER VAPOR IMAGERY CURRENTLY SHOWS A NARROW SWATH OF MOISTURE
EXTENDING FROM 17N70W NE TO BEYOND 20N56W THAT IS LOCATED SE OF
A MIDDLE TO UPPER LEVEL TROUGH ACROSS THE SW NORTH ATLC.
CONVERGENT TRADE WINDS ALONG WITH ENHANCED LIFT DYNAMICS
SUPPORTED BY THE TROUGHING ALOFT IS GENERATING AN AREA OF WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS FROM 15N-19N BETWEEN 65W-
75W...MAINLY SOUTH OF THE ISLAND OF HISPANIOLA. HOWEVER...WITH
PEAK DAYTIME HEATING AND INSTABILITY THIS AFTERNOON...AND A
WEAKENING SHEAR LINE ANALYZED TO THE NORTH OF THE ISLAND FROM
21N67W TO EASTERN CUBA NEAR 20N75W...THE INCREASED PROBABILITY
OF ISOLATED SHOWERS AND TSTMS WILL PERSIST. THIS POTENTIAL IS
EXPECTED OVER THE NEXT 24 TO 36 HOURS AS THE AREA OF MOISTURE IS
SLOW TO MOVE. WITHIN THESE AREA OF PRECIPITATION...LOCALIZED
FLOODING IS POSSIBLE.

ATLANTIC OCEAN...
MIDDLE TO UPPER LEVEL RIDGING WITH AXIS CURRENTLY OVER THE FAR
WESTERN PORTION OF THE SW NORTH ATLC IS PROVIDING MOST OF THE
AREA W OF 68W WITH DRY NW FLOW ALOFT RESULTING IN MOSTLY CLEAR
SKIES AND FAIR CONDITIONS THIS AFTERNOON. FURTHERMORE...A 1022
MB HIGH IS CENTERED NEAR BERMUDA THAT IS EXPECTED TO SHIFT
SLOWLY EASTWARD OVER THE NEXT 24 TO 36 HOURS. FARTHER EAST...
WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL TROUGH
WITH AXIS EXTENDING INTO THE DISCUSSION AREA NEAR 32N54W
TRAILING SW TO 25N59W TO A BASE OVER THE EASTERN CARIBBEAN SEA.
THIS TROUGHING SUPPORTS A COLD FRONT ANALYZED FROM 32N56W TO
25N61W THEN CONTINUES AS A STATIONARY FRONT TO 23N64W THEN AS A
SHEAR LINE ALONG 21N66W TO EASTERN CUBA NEAR 20N75W. ISOLATED
SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE COLD AND
STATIONARY FRONT...WHILE MOST OTHER SHOWER ACTIVITY IS LESS THAN
ISOLATED IN ASSOCIATION WITH THE SHEAR LINE. THE REMAINDER OF
THE CENTRAL AND EASTERN ATLC ARE UNDER THE INFLUENCE OF SURFACE
RIDGING...HOWEVER TWO FEATURES ARE EMBEDDED WITHIN THE SOUTHERN
PERIPHERY OF THE RIDGE. A WEAK 1020 MB LOW IS CENTERED NEAR
28N44W WITH A SURFACE TROUGH EXTENDING FROM 26N42W TO THE LOW
CENTER THEN TO 32N46W. POSSIBLE ISOLATED SHOWERS ARE OCCURRING
FROM 27N-33N BETWEEN 38W-48W. THE OTHER FEATURE IS A SURFACE
TROUGH ANALYZED FROM NORTHERN AFRICA NEAR 28N13W ACROSS THE
CANARY ISLANDS TO 29N25W. THIS SURFACE TROUGH IS SUPPORTED ALOFT
BY A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDING FROM 30N09W TO
26N33W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE
OF THE SURFACE TROUGH AXIS.

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

$$
HUFFMAN

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