[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI AUG 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 FEATURE...
TROPICAL STORM HARVEY IS CENTERED NEAR 16.1W 84.6W OR ABOUT
ABOUT 115 NM E OF ISLA ROATAN HONDURAS AND ABOUT 220 NM ESE OF
BELIZE CITY MOVING W 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
998 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55
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/ISOLATED STRONG CONVECTION COVERS
THE AREA S OF 19N TO INLAND OVER HONDURAS BETWEEN 82W-87W. T.S.
HARVEY IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF
3-5 INCHES ACROSS HONDURAS...GUATEMALA...BELIZE AND THE YUCATAN
PENINSULA OF MEXICO WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 8
INCHES. THESE RAINS COULD PRODUCE LIFE-THREATENING FLASH FLOODS
AND MUDSLIDES...ESPECIALLY OVER HIGHER TERRAIN.

A LARGE TROPICAL WAVE IS IN THE W TROPICAL ATLC IS ALONG 49W
FROM 9N-17N WITH A 1007 MB LOW CENTERED NEAR 13N. SCATTERED
MODERATE WITH EMBEDDED CLUSTERS OF OF SCATTERED STRONG
CONVECTION COVERS THE AREA FROM 12N-17N BETWEEN 48W-55W.
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR A
TROPICAL DEPRESSION TO 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 SHOULD MONITOR THE PROGRESS OF
THIS DISTURBANCE. LOCALLY HEAVY RAIN AND GUSTY WINDS ARE LIKELY
OVER THE LEEWARD ISLANDS LATE SATURDAY INTO SUNDAY.

THE TROPICAL WAVE BETWEEN THE W COAST OF AFRICA AND THE CAPE
VERDE ISLANDS IS NOW A WELL DEFINED 1006 MB LOW CENTERED NEAR
14N20W. SCATTERED MODERATE/STRONG CONVECTION IS OVER THE CAPE
VERDE ISLANDS FROM 15N-17N BETWEEN 21W-24W. ALTHOUGH UPPER LEVEL
WINDS ARE CURRENTLY FAVORABLE FOR SOME DEVELOPMENT THIS SYSTEM
IS EXPECTED TO ENCOUNTER A MORE STABLE ENVIRONMENT WITH DRIER
AIR BY SUNDAY. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES TO THE
W-NW AT 9-13 KT. REGARDLESS OF ANY DEVELOPMENT...LOCALLY HEAVY
RAIN AND STRONG GUSTY WINDS ARE POSSIBLE IN THE CAPE VERDE
ISLANDS TONIGHT THROUGH SATURDAY.

...TROPICAL WAVES...

SEE SPECIAL FEATURES ABOVE.

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

THE MONSOON TROUGH EXTENDS FROM THE 1006 MB LOW IN THE SPECIAL
FEATURES NEAR 14N20W ALONG 11N36W TO THE 1007 MB LOW ALSO IN THE
SPECIAL FEATURES NEAR 13N49W. SCATTERED/NUMEROUS STRONG
CONVECTION IS WITHIN 45 NM OF 10N BETWEEN 27W-30W WITH SCATTERED
MODERATE STRONG CONVECTION COVERING THE REMAINDER OF THE AREA
WITHIN 120 NM OF LINE FROM 11N24W TO 8N32W. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS WITHIN 45/60 NM OF LINE FROM 8N45W
TO 6N49W. SCATTERED MODERATE CONVECTION DOT IS WITHIN 45 NM OF
6N BETWEEN 34W-37W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE CONTINUES TO DOMINATE THE GULF N OF 24N
ANCHORED OVER W TEXAS. AN UPPER TROUGH EXTENDS FROM TUXPAN
MEXICO E TO THE NW COAST OF THE YUCATAN PENINSULA NEAR MERIDA
GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
INLAND OVER THE YUCATAN PENINSULA AND ISOLATED SHOWERS IN THE SW
GULF FROM 21N-23N BETWEEN 93W-96W. A WEAK SURFACE TROUGH IS OVER
THE W GULF ALONG 92W FROM 23N-25N. A WEAK SURFACE RIDGE
DOMINATES THE N GULF. AN UPPER RIDGE ASSOCIATED WITH T.S. HARVEY
EXTENDS OVER THE SE GULF GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS INLAND OVER CUBA AND WITHIN 45 NM ALONG THE COAST
W OF 80W INTO THE YUCATAN CHANNEL. A SHORTWAVE UPPER TROUGH IS
OFF THE E COAST OF FLORIDA GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 24N-26N E OF 84W TO ACROSS S
FLORIDA. THIS IS LEAVING THE REMAINDER OF THE GULF UNDER MOSTLY
CLEAR SKIES THIS EVENING. THE WEAK SURFACE RIDGE WILL PREVAIL
ACROSS THE N GULF THROUGH WED.

CARIBBEAN SEA...
THE PRIMARY CONCERN THIS EVENING IS T.S. HARVEY IN THE W
CARIBBEAN...SEE SPECIAL FEATURES ABOVE. AN UPPER RIDGE
ASSOCIATED WITH T.S. HARVEY COVERS THE W CARIBBEAN N OF 12N W OF
76W GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS N OF 15N W OF 76W. THE MONSOON TROUGH EXTENDS
ACROSS THE SW CARIBBEAN FROM COLOMBIA NEAR 11N76W TO ACROSS
NICARAGUA NEAR 12N84W INTO THE E PACIFIC REGION GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 11N-14N BETWEEN
80W-82W. A LARGE UPPER TROUGH IN THE CENTRAL ATLC EXTENDS S OVER
THE E CARIBBEAN GENERATING ISOLATED SHOWERS N OF 15N BETWEEN
63W-75W LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY
CLEAR SKIES THIS EVENING. 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...
A SHORTWAVE UPPER TROUGH EXTENDS OFF THE E CONUS COAST THROUGH
32N74W TO THE BAHAMAS NEAR 25N77W GENERATING CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120/150 NM OF
LINE FROM FLORIDA NEAR FORT LAUDERDALE TO BEYOND 32N73W. A LARGE
UPPER LEVEL TROUGH COVERS THE REMAINDER OF THE W ATLC AND INTO
THE CENTRAL ATLC EXTENDING FROM BEYOND 32N56W THEN THROUGH AN
UPPER LOW NEAR 26N61W ACROSS HISPANIOLA/PUERTO RICO TO OVER THE
E CARIBBEAN SUPPORTING A SURFACE TROUGH THAT EXTENDS THROUGH
32N56W TO 28N61W. ISOLATED SHOWERS ARE WITHIN 90 NM OF LINE FROM
25N65W TO BEYOND 32N56W. THE REMAINDER OF THE ATLC BASIN IS
DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH ABOUT
350 NM W OF THE AZORES WITH A SURFACE RIDGE AXIS EXTENDING
ACROSS BERMUDA TO NEAR 29N79W WEAKENING ACROSS FLORIDA INTO THE
N GULF OF MEXICO LEAVING THE REMAINDER OF THE ATLC UNDER FAIR
CONDITIONS THIS EVENING. SAHARAN DRY AIR CONTINUES TO DOMINATE
THE E AND CENTRAL ATLC N OF BOTH SPECIAL FEATURE LOWS WITHIN 250
NM OF LINE FROM NEAR 21N17W ALONG 17N34W TO 24N53W. THE SURFACE
RIDGE EXTENDING FROM BERMUDA TO CENTRAL FLORIDA WILL GRADUALLY
WEAKEN THROUGH MON. THE 1007 MB LOW ALONG A TROPICAL WAVE IN THE
SPECIAL FEATURES WILL REACH THE W ATLC EARLY MON...POSSIBLY AS A
TROPICAL CYCLONE...AND CONTINUE NW THROUGH WED.

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

$$
PAW




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