[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 182353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE JUN 18 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.

...SPECIAL FEATURES...
TROPICAL DEPRESSION TWO IS CENTERED NEAR 18.3N 91.9W AT 18/2100
UTC OR 20 NM SSW OF CARMEN MEXICO...OR ABOUT 140 NM E OF
COATZACOALAS MEXICO MOVING WNW AT 9 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 25
KT WITH GUSTS TO 35 KT. SCATTERED MODERATE CONVECTION IS FROM
17N-23N BETWEEN 85W-89W...AND FROM 20N-22N BETWEEN 89W-93W. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 13N26W TO 6N25W MOVING WEST AT 15-20 KT.
THE WAVE LIES ON THE WESTERN SIDE OF A SURGE IN DEEP LAYER
MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. THERE IS
ALSO A CLEARING IN THE LARGE AREA OF SAHARAN DUST THAT SPREADS
ACROSS THE TROPICAL ATLC. DUE TO THE PRESENCE OF THE
DUST...CONVECTION IS LIMITED TO THE MONSOON TROUGH/ITCZ
REGION...AND IS SPARSE THERE AS WELL.

TROPICAL WAVE EXTENDS FROM 15N68W TO 8N68W MOVING W NEAR 20 KT.
THE WAVE COINCIDES WITH A SURGE OF DEEP LAYER MOISTURE PRESENT
IN TOTAL PRECIPITABLE WATER IMAGERY. AN UPPER LEVEL TROUGH TO
THE EAST OF THE WAVE AND THE LESSER ANTILLES IS ALSO ADVECTING
MOISTURE NORTHWARD CAUSING A LARGE AREA OF MOISTURE TO BE
PRESENT EAST OF THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS
FROM 12N-14N BETWEEN 61W-66W. CONVECTION CONTINUE TO THE
EAST...BUT IS MORE LIKELY CONNECTED TO THE UPPER TROUGH AND WILL
BE DISCUSSED IN THE ATLC SECTION.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 15N17W
TO 7N23W. THE ITCZ BEGINS ON THE WEST SIDE OF A TROPICAL WAVE
ALONG 7N27W 5N53W. A LARGE CLUSTER OF STRONG CONVECTION IS
MOVING OFF THE AFRICAN COAST FROM 7N-12N BETWEEN 12W-15W.
ISOLATED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 22W-
24W...FROM 6N-8N BETWEEN 34W-37W...AND FROM 5N-8N BETWEEN 42W-
45W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE RIDGING DOMINATES THE NORTHERN HALF OF THE GULF OF
MEXICO WITH AXIS ALONG 27N CONTINUING INTO THE WEST ATLC.
TROPICAL DEPRESSION TWO IS IMPACTING THE SOUTHERN GULF. SEE
SPECIAL FEATURES FOR MORE DETAILS. NORTH OF THE CIRCULATION OF
THE DEPRESSION...WINDS ARE LIGHT AND ANTI-CYCLONIC. SKIES ARE
MOSTLY CLEAR DUE TO DRY AIR ALOFT IN WESTERLY FLOW AROUND AN
UPPER LEVEL RIDGE TO THE SOUTH THAT EXTENDS INTO THE CARIBBEAN.
THE UPPER RIDGE IS ADVECTING MOISTURE OVER THE YUCATAN PENINSULA
FROM T.D. TWO. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
MAINLY SOUTH OF 23N BETWEEN 85W-94W. CLUSTERS OF
SHOWERS/THUNDERSTORMS ARE ALSO OVER THE SOUTHERN HALF OF THE
FLORIDA PENINSULA. T.D. TWO WILL CONTINUE TO IMPACT THE SW
GULF...WHILE SURFACE RIDGING REMAINS OVER THE NORTHERN GULF.

CARIBBEAN SEA...
MOISTURE ASSOCIATED WITH T.D TWO CONTINUES TO IMPACT THE FAR NW
CARIBBEAN SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
NORTH OF 14N WEST OF 84W. SEE SPECIAL FEATURES ABOVE FOR MORE
DETAILS. ALOFT...AN UPPER LEVEL RIDGE COVERS THE MAJORITY OF THE
BASIN...WHILE AN UPPER LEVEL TROUGH SINKS INTO THE EASTERN
CARIBBEAN ALONG 66W. BESIDES CONVECTION ASSOCIATED WITH THE
DEPRESSION...HEAVY SHOWERS/THUNDERSTORMS ARE SOUTH OF 11N
BETWEEN 77W-85W ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS
THROUGH COSTA RICA TO NORTHERN COLOMBIA. THE CENTRAL CARIBBEAN
IS FAIRLY CLEAR ELSEWHERE. A TROPICAL WAVE ALONG 68W IS DRAGGING
MOISTURE WESTWARD WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
SOUTH OF 16N EAST OF THE WAVE AXIS. THE UPPER TROUGH ALONG 66W
IS ALSO PROVIDING DIFFLUENT FLOW OVER THE FAR EASTERN
CARIBBEAN...WHICH IS DRAWING MOISTURE TOWARDS THE NE. AS THE
WAVE MOVES WESTWARD...A LARGE AREA OF MOISTURE WILL SPREAD OVER
THE EASTERN CARIBBEAN BEHIND THE WAVE. TRADEWIND FLOW OF 15-20
KT IS PRESENT OVER THE EASTERN CARIBBEAN INCREASING TO 25 KT
OVER THE CENTRAL PORTIONS. BESIDES THE MOISTURE EXPECTED OVER
THE EASTERN CARIBBEAN...MOIST CONDITIONS ARE EXPECTED TO REMAIN
OVER THE FAR NW CARIBBEAN AS WELL.

HISPANIOLA...
HISPANIOLA REMAINS RATHER TRANQUIL EXCEPT FOR A FEW WIDELY
ISOLATED SHOWERS/THUNDERSTORMS OVER SOUTHERN HAITI. CONSIDERABLY
LESS ACTIVITY IS OCCURRING COMPARED TO MOST AFTERNOONS. THIS IS
LIKELY TO DUE TO DRY AIR ALOFT AROUND AN UPPER TROUGH TO THE
EAST...AND THE PRESENCE OF DUST IN THE LOWER ATMOSPHERE.
MOISTURE EAST OF A TROPICAL WAVE TO THE SOUTH WILL BEGIN TO
IMPACT THE EASTERN PORTIONS OF THE ISLAND WITHIN 24 HOURS...AND
WILL SPREAD OVER THE ISLAND THROUGH 48 HOURS.

ATLANTIC OCEAN...
A BROAD RIDGE COVERS MUCH OF THE ATLC BASIN EXTENDING FROM A
1033 MB AZORES HIGH. DRY AIR ALOFT AROUND THE WEST SIDE OF AN
UPPER LOW NEAR 23N65W IS PROVIDING FAIR CONDITIONS OVER THE FAR
WEST ATLC. THE UPPER LOW IS ADVECTING MOISTURE AROUND THE EAST
SIDE EXTENDING FROM THE FAR EASTERN CARIBBEAN. SCATTERED
SHOWERS/THUNDERSTORMS ARE NOTED EAST OF THE LESSER ANTILLES FROM
11N-19N BETWEEN 55W-61W. FARTHER EAST...AN UPPER LEVEL RIDGE IS
ALONG 52W...WHILE ANOTHER UPPER LOW IS CENTERED NEAR 28N42W. THE
UPPER LOW SUPPORTS A BROAD SURFACE TROUGH ALONG 32N44W TO
27N41W. NO SHOWERS ARE ASSOCIATED WITH THE TROUGH. BROAD UPPER
RIDGING DOMINATES THE TROPICAL ATLC...WHILE A THIRD WEAK UPPER
LOW IS OVER THE EASTERN ATLC NEAR 25N23W. A SAHARAN AIR LAYER
CONTINUES TO BE PRESENT OVER MUCH OF THE TROPICAL ATLC...EXCEPT
NEAR THE TROPICAL WAVE...EXTENDING TO NEAR 55W.

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

$$
WALTON

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