[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUN 29 2011

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.

...SPECIAL FEATURE...

T.S. ARLENE IS CENTERED NEAR 21.1N 95.9W...OR ABOUT 85 NM E OF
TUXPAN...AS OF 1800 UTC. THE STORM IS MOVING W AT 7 KT. MINIMUM
CENTRAL PRESSURE IS 1000 MB WHILE MAXIMUM SUSTAINED WINDS ARE 45 KT
WITH GUSTS TO 55 KT. ARLENE IS EXPECTED MOVE SLOWLY WESTWARD TOWARDS
THE MEXICAN COAST. STRENGTHENING IS FORECAST...AND ARLENE COULD
APPROACH HURRICANE STRENGTH PRIOR TO LANDFALL. SEE NHC INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC AND THE
FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS. 20 KT WINDS EXTEND UP TO 300 NM N AND E OF THE
CENTER.  SATELLITE IMAGERY AND RADAR FROM ALVARADO MEXICO INDICATES
NUMEROUS STRONG CONVECTION IS WRAPPING AROUND ALL QUADRANTS EXCEPT TO
THE NORTH FROM 18N-23N BETWEEN 92W-98W REACHING EASTERN MEXICO.
NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS PRESENT FROM 18N-24N
BETWEEN 90W-95W.  SOME SHOWERS ASSOCIATED WITH THE OUTER RAINBANDS ARE
ARLENE ARE REACHING NE MEXICO AND EXTREME S TEXAS AS SEEN IN THE
BROWNSVILLE RADAR.

...TROPICAL WAVES...

A TROPICAL WAVE IS ACROSS THE CENTRAL ATLC ALONG 13N50W TO 7N51W
MOVING W NEAR 15-20 KT. SATELLITE IMAGERY SHOWS A VORTICITY MAXIMUM
NEAR 11N51W...THOUGH IT DOES NOT APPEAR TO BE A CLOSED LOW AT THE
SURFACE YET FROM A 1240 UTC ASCAT PASS.  THE WAVE IS EVIDENT FROM
THE TOTAL PRECIPITABLE WATER IMAGERY AS A DISTINCT BULGE IN THE
MOISTURE ON THE EAST SIDE OF THE TROUGH AXIS.  CONVECTION HAS BEEN
MINIMAL THIS SYSTEM OVER THE LAST DAY OR SO.

A TROPICAL WAVE IS S OF HAITI ALONG 73W FROM 13N-19N MOVING W
NEAR 10 KT. THIS WAVE HAS BECOME INDISTINCT DURING THE PAST
24 HOURS...POSSIBLY DUE TO THE INTERACTION WITH AN UPPER LEVEL
LOW NOW S OF HAITI NEAR 15N73W. SOME ENHANCED MOISTURE VALUES AS
SEEN IN THE TOTAL PRECIPITABLE WATER IMAGERY STILL REMAIN IN
THE VICINITY OF THE WAVE. SCATTERED MODERATE CONVECTION IS NEAR THE
WAVE AXIS FROM 16N-18N BETWEEN 71W-75WW.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA FROM THE PRIME MERIDIAN AT 24N
ALONG 18N12W 11N15W THEN OVER THE EASTERN ATLANTIC TO 8N20W. THE ITCZ
CONTINUES FROM 8N20W TO 7N33W TO 7N49W. A SEPARATE MONSOON TROUGH IN
THE SW CARIBBEAN SEA EXTENDS FROM 10N75W OVER COLOMBIA WESTWARD TO
10N83W OVER PANAMA. SCATTERED MODERATE/STRONG CONVECTION IS OCCURRING
WITHIN 180 NM N OF THE AXIS 20W-27W...FROM 32W-43W...AND AGAIN FROM
79W-83W.

...DISCUSSION...

GULF OF MEXICO...
TROPICAL STORM ARLENE IS CURRENTLY AFFECTING MUCH OF THE SW GULF OF
MEXICO. SEE SPECIAL FEATURES SECTION ABOVE FOR MORE DETAILS. ELSEWHERE
AT THE SURFACE...WINDS ARE LIGHT THROUGHOUT THE GULF WITH NO
SIGNIFICANT DEEP CONVECTION. A SURFACE TROUGH EXTENDS FROM OVER THE
FLORIDA PANHANDLE FROM 30N83W TO 29N88W.  SCATTERED SHOWERS ARE
OCCURRING WITHIN 60 NM OF THE TROUGH AXIS.  IN THE UPPER LEVELS...
ANTICYCLONIC FLOW ASSOCIATED WITH THE OUTFLOW OF T.S. ARLENE COVERS THE
LOWER TWO-THIRDS OF THE GULF AND NUMEROUS HIGH CLOUDS ARE EMBEDDED IN
THIS FLOW.  AN EAST-WEST ORIENTED TROUGH RESIDES ALONG THE NORTHERN
GULF OF MEXICO.  WITH THE EXCEPTION OF THE NW GULF...SUBSTANTIAL
MOISTURE IS PRESENT OVER ALL OF THE GULF AND FLORIDA.  EXPECT CONTINUED
MOISTURE AND SHOWER ACTIVITY TO REMAIN ACROSS THE WESTERN GULF IN
ASSOCIATION WITH ARLENE AS WELL AS IN AND AROUND FLORIDA DURING THE
NEXT 24 HOURS.

CARIBBEAN SEA...
BUOY...ISLAND...AND ASCAT OBSERVATIONS INDICATE THAT THE CENTRAL
CARIBBEAN HAS SURFACE WINDS OF 20-25 KT WHILE THE EASTERN AND WESTERN
CARIBBEAN HAVE LIGHT WINDS.  ASIDE FROM THE AFOREMENTIONED TROPICAL
WAVES PRODUCING SOME DEEP CONVECTION...THE REMAINDER OF THE CARIBBEAN
SEA IS EXHIBITING NO SIGNIFICANT CONVECTION.  IN THE UPPER LEVELS...A
NORTH-SOUTH STRETCHED UPPER LOW IS LOCATED SOUTH OF HISPANIOLA WITH
RIDGING EXTENDING OVER BOTH THE EASTERN AND WESTERN CARIBBEAN.  SOME
INCREASED CHANCE OF DEEP CONVECTION IS LIKELY OVER THE NEXT DAY IN THE
WESTERN CARIBBEAN AS THE TROPICAL WAVE MOVES WESTWARD.

ATLANTIC OCEAN...
AN ELONGATED WEST-SOUTHWEST TO EAST-NORTHEAST SURFACE RIDGE EXTENDS
ALONG 30N ACROSS THE ATLANTIC.  SURFACE WINDS ARE GENERALLY LIGHT
EXCEPT FOR JUST EAST OF THE LESSER ANTILLES WHERE E-NE TRADEWINDS OF
20-25 KT ARE OCCURRING.  A SURFACE TROUGH NEAR THE SE BAHAMAS EXTENDS
FROM 25N70W TO 21N73W WITH LITTLE SHOWER ACTIVITY.  SCATTERED MODERATE
CONVECTION IS OCCURRING EAST OF FLORIDA N OF 23N AND W OF 77W.
SCATTERED MODERATE CONVECTION ALSO RESIDES FROM 9N-13N BETWEEN THE
LESSER ANTILLES AND 55W.  IN THE UPPER LEVELS...RIDGING GENERALLY
EXTENDS ACROSS THE ATLANTIC ALONG 12N WITH A PROMINENT SUBSIDENT LOW
CENTERED NEAR 27N50W.  DURING THE NEXT DAY...SHOWERS AND DEEP
CONVECTION SHOULD CONTINUE JUST EAST OF FLORIDA AND DEEP CONVECTION MAY
BECOME MORE PREVALENT OVER THE LESSER ANTILLES AS THE TROPICAL WAVE
APPROACHES.

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

$$
LANDSEA



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