[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 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 FEATURES...

TROPICAL STORM DON IS CENTERED NEAR 26.5N 95.6W AT 29/1800 UTC
OR 125 NM SE OF CORPUS CHRISTI TEXAS OR ABOUT 105 NM ENE OF
BROWNSVILLE TEXAS MOVING W-NW AT 13 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 45
KT WITH GUSTS TO 55 KT. DON IS LOCATED ON THE SOUTHERN PERIPHERY
OF A MIDDLE TO UPPER LEVEL RIDGE CENTERED OVER SOUTHEASTERN
ARKANSAS. THE DEEP LAYERED RIDGING CONTINUES TO PROVIDE AMPLE
MIDDLE TO UPPER LEVEL DIFFLUENCE AND ENHANCEMENT TO THE ONGOING
SCATTERED MODERATE TO STRONG CONVECTION FROM 23N-27N BETWEEN
94W-97W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT4/ WTNT34 KNHC AND THE FULL FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS.

TROPICAL WAVE IS ANALYZED FROM 09N41W TO 19N41W MOVING W AT
15-20 KT. A 1008 MB LOW IS CENTERED NEAR THE SOUTHERN EXTENT OF
THE WAVE NEAR 09N41W AND CONTINUES TO BE LOCATED BENEATH THE
SOUTHERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION
OVER THE CENTRAL TROPICAL ATLC CENTERED NEAR 15N41W. AN AREA OF
INCREASED TOTAL PRECIPITABLE WATER ALSO COINCIDES WITH THE WAVE
AXIS FROM 06N-15N BETWEEN 37W-46W WITH WIDELY SCATTERED MODERATE
CONVECTION OCCURRING FROM 06N-13N BETWEEN 37W-44W.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 11N25W TO 21N25W MOVING W AT 15
KT. THE WAVE HAS SUFFICIENTLY MOVED OFF THE WESTERN COAST OF
AFRICA OVER THE PAST 24 HOURS AND TOTAL PRECIPITABLE WATER
IMAGERY SHOWS A VERY DISTINCT CURL TO THE DISTRIBUTION OF THE
LOW-LEVEL MOISTURE IN THE VICINITY OF THE CAPE VERDE ISLANDS. NO
SIGNIFICANT CONVECTION IS NOTED WITH THE WAVE AT THIS TIME.

TROPICAL WAVE IS ANALYZED FROM 11N75W TO 23N73W MOVING W AT
15-20 KT. BOTH LOWER LEVEL STREAMLINE ANALYSIS AND NEAR 700 MB
MODEL EVALUATION INDICATES THE WAVE REMAINS BROAD AS IT MOVES
ACROSS THE CENTRAL CARIBBEAN SEA. THIS IS CONFIRMED IN TOTAL
PRECIPITABLE WATER IMAGERY AS VALUES OF LOW-LEVEL MOISTURE ARE
MAXIMIZED S OF 20N BETWEEN 67W-85W. THE WAVE IS ALSO QUICKLY
BECOMING EMBEDDED WITHIN THE MONSOON TROUGH AND THE ASSOCIATED
LOW-LEVEL CYCLONIC GYRE CENTERED OVER THE SW CARIBBEAN NEAR
11N82W. SCATTERED MODERATE CONVECTION IS FROM 14N-18N BETWEEN
71W-78W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N17W TO
11N22W THEN RESUMES NEAR 09N26W TO 08N30W TO 10N40W AND FROM
08N43W TO 07N46W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 07N46W TO 06N57W. ISOLATED MODERATE CONVECTION IS
FROM 06N-10N BETWEEN 26W-30W...FROM THE EQUATOR TO 04N BETWEEN
36W-40W...AND WITHIN 120 NM NORTH OF THE ITCZ AXIS BETWEEN
45W-56W.

...DISCUSSION...

GULF OF MEXICO...
TROPICAL STORM DON CONTINUES TO TRACK NW TOWARDS THE SOUTHERN
TEXAS COASTLINE REMAINING ON THE SOUTHERN PERIPHERY OF AN UPPER
LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER SE ARKANSAS. THE
RIDGE AXIS EXTENDS OVER NORTH TEXAS TO NE MEXICO NEAR 22N102W.
AT THE SURFACE...DON CONTINUES TO GENERATE A STRONG PRESSURE
GRADIENT BETWEEN ITS CENTER AND A SURFACE RIDGE WITH AXIS
EXTENDING FROM THE W ATLC AND ACROSS THE FLORIDA PENINSULA TO A
1021 MB HIGH CENTERED OVER SW GEORGIA. STRONG SE WINDS ARE
FORECAST OVER THE MIDDLE AND WESTERN GULF PRIMARILY N OF 25N W
OF 90W THROUGH THE AFTERNOON AND EVENING PERIOD AS DON NEARS THE
TEXAS COAST LATE TONIGHT INTO SATURDAY MORNING. BROWNSVILLE AND
WIDER MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATE
SCATTERED MODERATE CONVECTION N OF 25N BETWEEN 87W-93W...AND THE
REMAINDER OF THE GULF W OF 93W. BY EARLY SATURDAY...THE SURFACE
RIDGE AXIS WILL RE-ESTABLISH ITSELF ALONG 30N THROUGH THE
REMAINDER OF THE WEEKEND.

CARIBBEAN SEA...
AS THE TROPICAL WAVE ALONG 75W TRACKS WESTWARD...WATER VAPOR
IMAGERY INDICATES IT CONTINUES TO INTERACT WITH AN UPPER LEVEL
TROUGH AXIS OVER THE WESTERN CARIBBEAN ALONG 82W THAT EXTENDS
FROM WEST OF JAMAICA TO SOUTHERN COSTA RICA. LOW-LEVEL
CONVERGENCE IN THE VICINITY OF THE WAVE AXIS AND OVERALL LIFT IN
THE MIDDLE TO UPPER LEVELS OF THE ATMOSPHERE ARE GENERATING
SCATTERED MODERATE CONVECTION OVER A LARGE PORTION OF THE
CENTRAL AND SW CARIBBEAN W OF 70W AND S OF A LINE FROM 18N74W TO
15N85W. MOST OF THE ONGOING INTENSE CONVECTION AND HEAVIER
PRECIPITATION IS FOCUSED ALONG AND NORTH OF THE MONSOON TROUGH
AXIS WHICH EXTENDS FROM THE EASTERN PACIFIC REGION ALONG 10N TO
76W. THE NW CARIBBEAN HOWEVER REMAINS MOSTLY INFLUENCED BY
SURFACE RIDGING AND A FEW PASSING ISOLATED SHOWERS N OF 17N W OF
78W.

ATLANTIC OCEAN...
A MAJORITY OF THE ATLC BASIN REMAINS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1029 MB HIGH CENTERED NEAR 38N39W.
THE RIDGE AXIS EXTENDS SW FROM THE HIGH TO 30N56W THEN WESTWARD
ALONG 30N TO THE FLORIDA PENINSULA. ASIDE FROM THE TROPICAL
WAVES LOCATED PRIMARILY S OF 22N ACROSS THE TROPICAL NORTH
ATLC...A WEAK FRONTAL TROUGH EXTENDS TO 30N70W FROM A 1014 MB
LOW CENTERED NEAR 34N65W. A FEW ISOLATED SHOWERS ARE OCCURRING N
OF 27N BETWEEN 66W-73W. OTHERWISE...NE TO E WINDS PREVAIL IN THE
RANGE FROM 15 TO 25 KT ACROSS MUCH OF THE BASIN THIS AFTERNOON.

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

$$
HUFFMAN


WWWW
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