[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192350
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 19 2008

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...
TROPICAL STORM FAY MADE ITS SECOND LANDFALL EARLY THIS MORNING
NEAR CAPE ROMANO SW COAST OF FLORIDA. SINCE THEN...IT HAS BEEN
MOVING ACROSS THE SUNSHINE STATE LOOKING STRONGER THAN IT HAS
EVER BEEN SO FAR. AT 20/0000Z...THE CENTER OF FAY REMAINS INLAND
NEAR 27.5N 80.9W OR ABOUT 40 NM...75 KM...SOUTH-SOUTHWEST OF
MELBOURNE FLORIDA MOVING NORTH-NORTHEAST AT 6 KT. A GRADUAL TURN
TO THE NORTH WITH A DECREASE IN FORWARD SPEED IS ANTICIPATED ON
WEDNESDAY.  THIS TRACK SHOULD BRING FAY OVER WATER NEAR THE EAST
COAST OF NORTH FLORIDA DURING THE NEXT 24 TO 36 HOURS. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 986 MB. MAXIMUM SUSTAINED WIND SPEED
IS 55 KT WITH HIGHER GUSTS. SOME STRENGTHENING IS FORECAST
DURING THE NEXT 24 HOURS. PLEASE SEE THE LATEST NHC THE
FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/ WTNT21
KNHC AND PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. CURRENTLY FAY IS
EMBEDDED WITHIN A WEAK SOUTHERLY FLOW BETWEEN A MID-LEVEL TROUGH
THAT EXTENDS ACROSS THE EASTERN U.S. SEABOARD THROUGH CENTRAL
FLORIDA TO THE YUCATAN CHANNEL AND THE SUBTROPICAL RIDGE. THIS
UPPER TROUGH IS STEERING THE STORM N-NE. HOWEVER...THIS STEERING
PATTERN IS FORECAST TO CHANGE SOON AS A HIGH PRESSURE SYSTEM
BEGINS TO DEVELOP NORTH OF FAY. THE SPIRAL RAINBANDS ASSOCIATED
WITH FAY CONTINUE TO AFFECT MAINLY CENTRAL FLORIDA WITH THE
CENTER JUST N OF LAKE OKEECHOBEE. A COUPLE OF OUTER RAINBANDS
ARE STILL MOVING ACROSS SOUTH FLORIDA AND THE KEYS PRODUCING
HEAVY SHOWERS AT TIME. FAY IS EXPECTED TO PRODUCE RAINFALL
ACCUMULATIONS OF 5 TO 10 INCHES OVER THE SOUTHERN AND
EAST-CENTRAL FLORIDA PENINSULA..WITH MAXIMUM TOTAL AMOUNTS OF 15
INCHES. ACCUMULATIONS OF 3 TO 5 INCHES ARE POSSIBLE IN THE
NORTHWESTERN BAHAMAS. ISOLATED TORNADOES ARE ALSO POSSIBLE OVER
THE EASTERN HALF OF THE FLORIDA PENINSULA.

...TROPICAL WAVES...
TROPICAL WAVE IN THE E TROPICAL ATLC IS ALONG 38W S OF 17N WITH
A 1010 MB LOW ALONG THE WAVE AXIS NEAR 13N. THIS LOW HAS CHANGED
LITTLE IN ORGANIZATION TODAY. ALTHOUGH ENVIRONMENTAL CONDITIONS
ARE ONLY MARGINALLY FAVORABLE...SOME SLOW DEVELOPMENT OF THIS
SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS THE LOW MOVES
TO THE WEST OR WEST-NORTHWEST AT 10-15 KT. A CLUSTER OF MODERATE
TO STRONG CONVECTION HAS DEVELOPED WITHIN 120 NM SW QUADRANT OF
THE LOW. ANOTHER AREA OF CLOUDINESS REMAINS BEHIND THE WAVE AXIS
WITH THE CLOUD PATTERN EXHIBITING SOME CYCLONIC TURNING NEAR
11N29W. SCATTERED SHOWERS ARE MOVING AROUND THIS SECOND CENTER.

TROPICAL WAVE IN THE E CARIBBEAN/W TROPICAL ATLC REMAINS TILTED
FROM 20N65W ACROSS NE PUERTO RICO THROUGH THE ABC ISLANDS TO THE
COAST OF VENEZUELA NEAR 11N68W MOVING W 10-15 KT. A WEAK
INVERTED-V SIGNATURE IS NOTED ON VIS SATELLITE IMAGERY JUST
SOUTH OF PUERTO RICO. A WIND SURGE FOLLOWS THE WAVE AND IS
GENERATING SCATTERED SHOWERS OVER THE WINDWARD ISLANDS.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 13N17W 10N26W 12N36W 10N45W 8N60W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-10N
BETWEEN 23W-35W. SIMILAR CONVECTION IS OVER THE GUYANAS.

...DISCUSSION...

GULF OF MEXICO...
THE PRIMARY CONCERN FOR THE ERN GULF IS T.S. FAY AS IT MOVES
ACROSS THE FLORIDA PENINSULA THIS EVENING. SEE SPECIAL FEATURES
ABOVE. A BROAD UPPER TROUGH OVER THE ERN U.S. DIGS INTO THE
EASTERN GULF THROUGH THE FLORIDA PENINSULA. AN INVERTED TROUGH
IS SEEN OVER THE YUCATAN PENINSULA PREVIOUSLY ASSOCIATED WITH AN
UPPER-LEVEL LOW THAT WAS SPINNING OVER WESTERN CUBA DURING THE
LAST FEW DAYS. THE REMAINDER OF THE GULF REGION IS UNDER THE
INFLUENCE OF A RIDGE ANCHORED ON AN UPPER-LEVEL HIGH NOW LOCATED
OVER THE SOUTHERN BAJA PENINSULA. ANOTHER UPPER-LEVEL LOW IS
MOVING SE OVER N TEXAS AND OKLAHOMA. AT THE SURFACE...A
WEAKENING FRONTAL BOUNDARY IS INLAND ACROSS LOUISIANA AND TEXAS
GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
NW CORNER OF THE GULF. A WEAK 1013 MB HIGH REMAINS OVER THE
NORTH-CENTRAL GULF NEAR 28N90W. THE FLORIDA PENINSULA AND THE
FAR E GULF WILL CONTINUE TO FEEL THE EFFECTS OF T.S. FAY AS IT
MOVES IN A NORTHERLY DIRECTION.

CARIBBEAN SEA...
AN UPPER-LEVEL HIGH CENTERED OVER THE CENTRAL BAHAMAS EXTENDS A
RIDGE OVER CUBA AND THE NW CARIBBEAN GIVING MOST OF THE CENTRAL
AND WEST CARIBBEAN EASTERLY UPPER FLOW. HUMID SLY WINDS AT LOW
LEVELS COMBINED WITH UPPER-LEVEL DIFFLUENCE ASSOCIATED WITH THE
ABOVE MENTIONED UPPER HIGH IS PRODUCING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS PARTS OF CUBA. SIMILAR CONVECTIVE
ACTIVITY IS NOTED OVER WESTERN VENEZUELA AND NORTHERN COLOMBIA
AS WELL AS OVER COSTA RICA LIKELY DUE TO THE CLOSE PROXIMITY OF
THE ITCZ AXIS EXTENDING FROM COLOMBIA INTO THE E PACIFIC JUST N
OF PANAMA. A TROPICAL WAVE IS OVER THE E CARIBBEAN FOLLOWED BY A
WIND SURGE. SEE ABOVE. THE REMAINDER OF THE CARIBBEAN IS
DOMINATED BY MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR.

ATLANTIC OCEAN...
RAINBANDS ASSOCIATED WITH THE CYCLONIC CIRCULATION OF FAY ARE
AFFECTING THE NW BAHAMAS AND THE FAR W PORTION OF THE DISCUSSION
AREA. SEE SPECIAL FEATURES ABOVE. SCATTERED MODERATE TO STRONG
CONVECTION IS W OF 74W AND N OF 24N. AN UPPER LOW IS IN THE
W/CENTRAL ATLC NEAR 26N64W EXTENDING A NARROW UPPER TROUGH TO
THE MONA PASSAGE. ISOLATED TO SCATTERED SHOWERS ARE WITHIN 260
NM E OF THE LOW N OF 25N. AN UPPER RIDGE IS TO THE E EXTENDING
SOUTH OVER THE N TROPICAL ATLC. FURTHER EAST...A LARGE UPPER LOW
CENTERED NEAR 20N45W COVERS MOST OF THE E/CENTRAL ATLC. AN UPPER
TROUGH CONNECTS THIS LOW WITH A WEAKER UPPER LOW NW OF THE
CANARY ISLANDS NEAR 31N20W. THE AZORES HIGH DOMINATES MOST OF
THE ATLC N OF 20N E OF 55W. THIS SYSTEM IS FORECAST BY THE
COMPUTER MODELS TO SLIGHTLY STRENGTHEN DURING THE NEXT 24 TO 48
HOURS PRODUCING A SWATH OF MODERATE TO STRONG TRADE WINDS ACROSS
THE TROPICAL ATLC...PARTICULARLY FROM 15N-22N.

$$
GR




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