[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192358
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE JUL 19 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM BRET IS CENTERED NEAR 30.4N 75.5W AT 19/2100 UTC
OR 285 NM S OF CAPE HATTERAS NORTH CAROLINA MOVING NE AT 7 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 999 MB. MAXIMUM SUSTAINED
WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SCATTERED MODERATE
CONVECTION IS LIMITED TO WITHIN 120 NM SW QUADRANT AND BRET IS
FORECAST TO TRACK NE OVER THE NEXT 2 TO 3 DAYS. NORTH AND
NORTHWESTERLY MIDDLE TO UPPER LEVEL SHEAR IS EXPECTED TO IMPART
A GRADUAL WEAKENING TREND TO THE SYSTEM THROUGH EARLY FRIDAY.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 10N37W TO 18N36W MOVING W AT 20
KT. THE WAVE IS LOCATED ON THE LEADING EDGE OF A RATHER LARGE
AND BROAD AREA OF LOW-LEVEL MOISTURE TO THE EAST OF THE WAVE
AXIS AS NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. THIS ALONG
WITH OVERALL BROAD CYCLONIC FLOW S OF 15N BETWEEN 30W-40W
ACCOMPANY THE WAVE WHICH CONTINUES TO PERTURB THE MONSOON TROUGH
AXIS. ISOLATED MODERATE CONVECTION IS FROM 10N-15N BETWEEN
29W-35W.

TROPICAL WAVE IS ANALYZED FROM 13N71W TO 22N67W MOVING W AT 20
KT. THE WAVE APPEARS VERY BROAD ON SATELLITE IMAGERY AND
CONTINUES TO INTERACT ALOFT WITH AN UPPER LEVEL LOW CENTERED
NEAR 18N70W. BOTH THE LOW-LEVEL CONVERGENCE AND UPPER LEVEL
DIFFLUENCE ARE GENERATING AN AREA OF WIDELY SCATTERED MODERATE
CONVECTION FROM 20N-23N BETWEEN 62W-68W. TOTAL PRECIPITABLE
WATER IMAGERY ALSO SHOWS A HIGH CONTENT OF VERTICAL ATMOSPHERIC
MOISTURE ALONG 60W AND THE ASSOCIATED SCATTERED SHOWERS AND
ISOLATED TSTMS OCCURRING FROM 10N-20N BETWEEN 58W-61W.

TROPICAL WAVE IS ANALYZED FROM 14N TO 21N ALONG 87W MOVING W AT
20 KT. THE WAVE EXHIBITS CYCLONIC TURNING OF THE LOW-LEVEL CLOUD
FIELD WHICH HAS MOVED ONSHORE ACROSS THE YUCATAN THIS EVENING.
PEAK DAYTIME HEATING AND INSTABILITY HAS GENERATED SCATTERED
MODERATE CONVECTION OVER THE SW YUCATAN PENINSULA AND NORTHERN
GUATEMALA FROM 16N-20N BETWEEN 89W-92W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N13W TO
08N20W TO 13N31W 06N45W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 06N45W TO 09N61W. ISOLATED MODERATE CONVECTION IS
FROM 06N-13N BETWEEN 15W-18W. SCATTERED MODERATE CONVECTION IS
FROM 05N-08N BETWEEN 32W-40W...AND FROM 09N-12N BETWEEN 59W-62W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL LOW IS CENTERED
OVER THE CENTRAL GULF NEAR 27N88W WHICH IS PROVIDING FOR AMPLE
MIDDLE TO UPPER LEVEL LIFT ACROSS MUCH OF THE GULF BASIN THIS
EVENING. WHILE A RELATIVELY WEAK SURFACE RIDGE EXTENDS ACROSS
THE NE GULF ANCHORED BY A 1017 MB HIGH CENTERED OVER SOUTHERN
ALABAMA...SOUTHERLY MOISTURE TRANSPORT AND INSTABILITY ACROSS
PORTIONS OF THE WESTERN GULF ARE GENERATING ISOLATED SHOWERS AND
TSTMS FROM 23N-29N BETWEEN 86W-97W. THE SURFACE HIGH IS EXPECTED
TO SHIFT SOUTHEASTWARD OVER THE NEXT 24-36 HOURS AS AN AREA OF
LOW PRESSURE DEVELOPS ACROSS THE WESTERN HIGH PLAINS OF THE U.S.

CARIBBEAN SEA...
AS MENTIONED ABOVE...A TROPICAL WAVE IS MOVING INTO THE CENTRAL
CARIBBEAN AND CONTINUES TO INTERACT WITH AN UPPER LEVEL LOW
CENTERED NEAR 18N70W. WHILE MOST OF THE ACTIVE CONVECTION IS
LOCATED N OF 20N...SCATTERED SHOWERS AND ISOLATED TSTMS LOCATED
WELL TO THE EAST OF THE WAVE AXIS ALONG 60W ARE EXPECTED TO
IMPACT THE LESSER ANTILLES THIS EVENING INTO EARLY WEDNESDAY.
FARTHER WEST...AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER
WESTERN CUBA NEAR 22N80W AND EXTENDS AN UPPER LEVEL RIDGE AXIS
SOUTHWARD TO OVER PANAMA NEAR 10N80W. MOSTLY FAIR CONDITIONS ARE
NOTED OVER MUCH OF THE WESTERN CARIBBEAN THIS EVENING...HOWEVER
WITH AMPLE UPPER LEVEL DIFFLUENCE IN PLACE AND PEAK DAYTIME
HEATING ACROSS CUBA...SCATTERED SHOWERS AND TSTMS ARE OCCURRING
OVER MUCH OF INTERIOR CUBA BETWEEN 76W-84W. OTHERWISE...THE
TROPICAL WAVE ALONG 87W IS FORECAST TO MOVE INLAND ACROSS
BELIZE...THE YUCATAN PENINSULA...AND GUATEMALA DURING THE NEXT
12-24 HOURS.

ATLANTIC OCEAN...
TROPICAL STORM BRET CONTINUES TO RESIDE WITHIN A WEAKNESS OF THE
SUBTROPICAL RIDGE ACROSS THE W ATLC THIS EVENING. AS BRET TRACKS
NE OVER THE NEXT FEW DAYS THE SURFACE RIDGE AXIS IS EXPECTED TO
RE-ESTABLISH ITSELF ALONG 26N THROUGH THE REMAINDER OF THE WEEK
AND GRADUALLY SHIFT NORTHWARD TO 29N BY SATURDAY. FARTHER TO THE
E-NE OF BRET THIS EVENING WATER VAPOR IMAGERY SHOWS A SHORTWAVE
UPPER LEVEL TROUGH EAST OF BERMUDA ALONG 64W THAT SUPPORTS A
1013 MB LOW CENTERED NEAR 33N63W. THE LOW CONTINUES TO RAPIDLY
PROGRESS EASTWARD WITH SCATTERED SHOWERS AND ISOLATED TSTMS
OCCURRING OVER THE AREA FROM 30N-35N BETWEEN 53W-62W. THIS LOW
IS FORECAST TO MOVE NE THEN MORE NORTH OVER THE NEXT 24 HOURS AS
A STRONG 1034 MB AZORES HIGH IS CENTERED NEAR 39N29W. THIS HIGH
CARRIES INFLUENCE ACROSS THE REMAINDER OF THE CENTRAL AND
EASTERN TROPICAL ATLC N OF 18N WITH MOSTLY FAIR CONDITIONS AND A
LARGE AREA OF NE TO E WINDS OF 15 TO 20 KT.

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

$$
HUFFMAN




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