[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200557
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0545 UTC

...SPECIAL FEATURE...
TROPICAL STORM HARVEY IS CENTERED NEAR 116.3N 85.6W OR ABOUT
ABOUT 50 NM E OF ISLA ROATAN HONDURAS AND ABOUT 170 NM ESE 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 IN THE W TROPICAL ATLC IS ALONG 52W
FROM 10N-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 15N22W. 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
WEST-NORTHWESTWARD AT ABOUT 9-13 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
19N16W ALONG THE SPECIAL FEATURE LOW ALONG 15N22W TO 11N30W TO
12N40W. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 210 NM ON
EITHER SIDE OF THE MONSOON TROUGH E OF 33W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE ANCHORED OVER CENTRAL TEXAS CONTINUES TO
DOMINATE THE GULF THIS EVENING. 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 29N84W TO 24N84W. THIS FEATURE IS
GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS IN THE
FAR EAST GULF E OF 84W. ALSO WITHIN THIS REGION...THE OUTER
CONVECTION ASSOCIATED TO T.S. HARVEY EXTENDS ACROSS THE FLORIDA
STRAITS. THE REMAINDER OF THE GULF IS UNDER MOSTLY CLEAR SKIES
WITH A FEW ISOLATED WEAK SHOWERS DOTTING THE BASIN. THE WEAK
SURFACE RIDGE WILL PREVAIL ACROSS THE N GULF THROUGH WED.

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. 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 22N79W. THE OUTER
CONVECTION ASSOCIATED TO T.S. HARVEY EXTENDS ACROSS THE FLORIDA
STRAITS W OF 79W. FARTHER EAST...AN ELONGATED UPPER LEVEL LOW
SPINS NEAR 27N61W SUPPORTING A WEAK SURFACE TROUGH ANALYZED FROM
32N56W TO 25N62W GENERATING ISOLATED SHOWERS WITHIN 120 NM ON
EITHER SIDE OF THE AXIS. THE REMAINDER OF THE ATLC BASIN IS
DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH W OF THE
AZORES NEAR 37N37W LEAVING THE DISCUSSION AREA N OF 20N UNDER
FAIR CONDITIONS THIS EVENING. SAHARAN DRY AIR 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 MON...POSSIBLY AS A TROPICAL CYCLONE...AND CONTINUE NW
THROUGH WED.

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

$$

GARCIA



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