[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201203
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC

...SPECIAL FEATURES...

TROPICAL STORM HARVEY IS CENTERED NEAR 16.6N 87.0W OR ABOUT 55
KM WNW OF ISLA ROATAN HONDURAS... OR ABOUT 105 MI...170 KM SE OF
BELIZE CITY MOVING W 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
994 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60
KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER
AWIPS/WMO HEADER MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/
ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT22 KNHC FOR MORE
DETAILS. SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS
COVER THE AREA S OF 22N TO INLAND OVER HONDURAS BETWEEN 80W-90W.
T.S. HARVEY IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS
OF 3-6 INCHES ACROSS HONDURAS...GUATEMALA...BELIZE AND THE
YUCATAN PENINSULA OF MEXICO WITH POSSIBLE ISOLATED MAXIMUM
AMOUNTS OF 10 INCHES. THESE RAINS WILL PRODUCE LIFE-THREATENING
FLASH FLOODS AND MUDSLIDES...ESPECIALLY OVER HIGHER TERRAIN.

A LARGE TROPICAL WAVE IS HEADING TO THE LESSER ANTILLES ANALYZED
ALONG 53W FROM 11N-18N WITH A 1007 MB LOW CENTERED NEAR 14N.
SCATTERED HEAVY SHOWERS AND THUNDERSTORMS COVER THE AREA FROM
11N-18N BETWEEN 51W-58W. THE SYSTEM IS MOVING INTO AN
ENVIRONMENT THAT IS MORE CONDUCIVE FOR DEVELOPMENT...AND A
TROPICAL DEPRESSION COULD FORM OVER THE NEXT COUPLE OF DAYS.
THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS AS IT MOVES GENERALLY WESTWARD NEAR 17
KT. INTERESTS IN THE LEEWARD ISLANDS AND PUERTO RICO SHOULD
MONITOR THE PROGRESS OF THIS DISTURBANCE. LOCALLY HEAVY RAIN AND
GUSTY WINDS ARE LIKELY OVER THE LEEWARD ISLANDS LATER TODAY
THROUGH SUNDAY AND OVER PUERTO RICO BY SUNDAY NIGHT. AN AIR
FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO
INVESTIGATE THIS SYSTEM LATER THIS AFTERNOON.

A BROAD 1007 MB LOW IS CENTERED IN THE VICINITY OF THE CAPE
VERDE ISLANDS NEAR 16N23W. SCATTERED HEAVY SHOWERS AND
THUNDERSTORMS ARE OVER THE CAPE VERDE ISLANDS AND SURROUNDING
WATERS FROM 12N-18N BETWEEN 20W-28W. UPPER-LEVEL WINDS ARE
CURRENTLY CONDUCIVE FOR DEVELOPMENT BUT ARE EXPECTED TO INCREASE
DURING THE NEXT COUPLE OF DAYS AS THIS SYSTEM MOVES WNW AT ABOUT
10 KT INTO A DRIER AND MORE STABLE ENVIRONMENT. THIS SYSTEM HAS
A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT
48 HOURS. LOCALLY HEAVY RAINS AND GUSTY WINDS SHOULD CONTINUE TO
AFFECT PARTS OF THE CAPE VERDE ISLANDS THROUGH THE REST OF TODAY.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF MAURITANIA NEAR
18N16W ALONG THE SPECIAL FEATURE LOW ALONG 16N23W TO 11N31W TO
12N40W. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 210 NM ON
EITHER SIDE OF THE MONSOON TROUGH E OF 30W...AND WITHIN 180 NM S
OF THE AXIS W OF 30W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE ANCHORED OVER CENTRAL TEXAS CONTINUES TO
DOMINATE THE GULF THIS MORNING PROVIDING A DRY SUBSIDENT AIRMASS
ALOFT ACROSS THE AREA. HOWEVER...THE SOUTHERN EXTENSION OF AN
UPPER TROUGH CURRENTLY MOVING OFF THE EASTERN CONUS SEABOARD
SWINGS OVER THE NE GULF...SUPPORTING A WEAK SURFACE TROUGH AXIS
ANALYZED FROM 30N83W TO 24N84W. THIS FEATURE IS GENERATING
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS IN THE FAR EAST
GULF E OF 84W TO THE FLORIDA COAST. THE REMAINDER OF THE GULF IS
UNDER MOSTLY CLEAR SKIES WITH A FEW ISOLATED WEAK SHOWERS
DOTTING THE BASIN. THE WEAK SURFACE RIDGE IS EXPECTED TO PREVAIL
ACROSS THE N GULF THROUGH WEDNESDAY.

CARIBBEAN SEA...
THE PRIMARY CONCERN THIS EVENING IS T.S. HARVEY MOVING WEST
PARALLEL TO THE COAST OF HONDURAS AND GENERATING A BROAD AREA OF
CONVECTION THAT COVERS THE NW CARIBBEAN BASIN...SEE SPECIAL
FEATURES ABOVE. A FEW SCATTERED SHOWERS REMAIN IN THE SW BASIN
NEAR THE COAST OF COLOMBIA AND PANAMA E OF 80W ASSOCIATED TO THE
MONSOON TROUGH EXTENDING INLAND ACROSS COSTA RICA AND PANAMA.
THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES WITH A
FEW ISOLATED SHOWERS EMBEDDED IN THE 5-15 KT EASTERLY TRADE WIND
FLOW. THE 1007 MB LOW ALONG THE TROPICAL WAVE IN THE SPECIAL
FEATURES WILL REACH THE LESSER ANTILLES EARLY SUN...POSSIBLY AS
A TROPICAL CYCLONE...AND NEAR PUERTO RICO EARLY MON.

ATLANTIC OCEAN...
AN UPPER TROUGH MOVES OFF THE EASTERN CONUS SEABOARD GENERATING
CLUSTERS OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS W OF A
LINE ALONG 30N70W TO THE COAST OF CUBA NEAR 22N78W. THE OUTER
CONVECTION ASSOCIATED TO T.S. HARVEY EXTENDS INTO THE FLORIDA
STRAITS W OF 79W. FARTHER EAST...AN ELONGATED UPPER LEVEL LOW
SPINS NEAR 27N61W SUPPORTING A WEAK SURFACE TROUGH ANALYZED FROM
32N57W TO 26N63W GENERATING ISOLATED SHOWERS WITHIN 120 NM ON
EITHER SIDE OF THE AXIS. LOW LEVEL MOISTURE IS ADVECTING ACROSS
THE NORTHERN COASTAL WATERS OF HISPANIOLA NOTICED ON TOTAL
PRECIPITABLE WATER IMAGERY S OF 23N BETWEEN 67W-72W PROVIDING
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS IN THIS
REGION. THE REMAINDER OF THE ATLC BASIN IS DOMINATED BY A
SURFACE RIDGE ANCHORED BY A 1026 MB HIGH W OF THE AZORES NEAR
37N34W LEAVING THE DISCUSSION AREA N OF 20N UNDER FAIR
CONDITIONS THIS EVENING. SAHARAN DRY AIR IN THE MID AND UPPER
LEVELS CONTINUES TO DOMINATE THE E AND CENTRAL ATLC. THE 1007 MB
LOW ALONG A TROPICAL WAVE IN THE SPECIAL FEATURES WILL REACH THE
W ATLC EARLY MONDAY...POSSIBLY AS A TROPICAL CYCLONE...AND
CONTINUE NW THROUGH WEDNESDAY.

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

$$

GARCIA




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