[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...SPECIAL FEATURES...
TROPICAL STORM FAY IS CENTERED NEAR 24.3N 81.6W OR ABOUT 20 NM
SOUTHEAST OF KEY WEST FLORIDA AT 18/1800 UTC MOVING NNW AT 12
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. MAXIMUM
SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. 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. BROAD UPPER
HIGH ASSOCIATED WITH FAY COVERS THE CENTRAL CARIBBEAN AND W ATLC
FROM 12N-32N BETWEEN 61W ACROSS FLORIDA TO 82W INCLUDING THE
BAHAMA ISLANDS. SCATTERED MODERATE/STRONG CONVECTION IS
PRIMARILY LOCATED IN THE NORTHERN AND EASTERN SEMICIRCLE WITHIN
200 NM OF THE CENTER. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE OVER THE REMAINDER OF THE AREA FROM 19N-28N BETWEEN 76W-83W
INCLUDING THE NW BAHAMA ISLANDS...SRN FLORIDA...THE FLORIDA KEYS
AND THE STRAITS OF FLORIDA. FAY IS EXPECTED TO PRODUCE TOTAL
RAINFALL ACCUMULATIONS OF 4 TO 8 INCHES OVER MUCH OF CUBA...WITH
ISOLATED MAXIMUM AMOUNTS OF 12 INCHES. THESE RAINS COULD PRODUCE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. HEAVY RAINS WILL
CONTINUE TO SPREAD ACROSS SOUTH AND CENTRAL FLORIDA. STORM TOTAL
AMOUNTS OF 4 TO 8 INCHES...WITH MAXIMUM AMOUNTS OF 10 INCHES ARE
POSSIBLE FOR THE FLORIDA KEYS AND SOUTH FLORIDA. RAINFALL
ACCUMULATIONS OF 3 TO 5 INCHES ARE POSSIBLE IN THE NORTHWESTERN
BAHAMAS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS
AND FAY IS FORECAST TO BECOME A HURRICANE AS IT NEARS THE
SOUTHWESTERN FLORIDA COAST ON TUESDAY.

...TROPICAL WAVES...
TROPICAL WAVE IN THE E TROPICAL ATLC IS ALONG 34W/35W S OF 17N
MOVING W NEAR 7-10 KT. A 1010 MB LOW IS ANALYZED ALONG THE WAVE
AXIS NEAR 13N. THIS WAVE REMAINS EMBEDDED AS A SMALL PERTURBATION
WITHIN THE ITCZ. A BROAD AREA OF DEEP LAYERED MOISTURE IS
OBSERVED ON THE MIMIC-TPW PRODUCT FROM CIMSS. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 11N-14N BETWEEN 33W-39W.

TROPICAL WAVE IN THE W TROPICAL ATLC AND FAR SERN CARIBBEAN SEA
REMAINS TILTED FROM 21N58W THROUGH MARTINIQUE TO 10N63W OVER NE
VENEZUELA MOVING WNW AT 10-15 KT. WAVE REMAINS DISTORTED DUE TO
AN UPPER LOW TO THE N OF THE WAVE AXIS AND AN UPPER RIDGE AXIS
TO THE E. SCATTERED SHALLOW SHOWERS ARE WITHIN 90 NM NORTHWEST
OF THE WAVE AXIS.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 14N16W 13N32W 12N37W 9N42W 6N58W.
SCATTERED MODERATE CONVECTION IS WITHIN FROM 6N-12N BETWEEN
25W-31W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
7N-12N BETWEEN 53W-55W.

...DISCUSSION...

GULF OF MEXICO...
THE PRIMARY CONCERN FOR THE GULF IS TROPICAL STORM FAY. SEE
SPECIAL FEATURES ABOVE. A BROAD UPPER TROUGH IS OVER THE ERN
U.S. TO THE N GULF COAST STATES AND FAR NE GULF WATERS WITH
ASSOCIATED FRONTAL BOUNDARY REMAINING INLAND EXTENDING FROM THE
W ATLC ACROSS S GEORGIA TO E TEXAS. DOPPLER RADAR AND LIGHTNING
DATA INDICATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE NORTH
AND WEST OF A LINE FROM THE FLORIDA BIG BEND REGION TO
BROWNSVILLE TEXAS. AN UPPER LEVEL RIDGE IS ACROSS THE WRN GULF
ANCHORED OVER NW MEXICO EXTENDING AN AXIS ALONG 24N TO 88W. A
WEAK 1014 MB HIGH IS LOCATED NEAR 27N90W. THE REMAINDER OF THE
GULF S OF 24N AND W OF 86W REMAINS CLEAR. CONDITIONS OVER THE
FAR ERN GULF... INCLUDING THE FLORIDA PENINSULA WILL CONTINUE TO
DETERIORATE AS T.S. FAY MOVES ACROSS THE STRAITS OF FLORIDA THIS
AFTERNOON AND OVER THE FAR SE GULF WATERS BY LATE MONDAY
EVENING.

CARIBBEAN SEA...
AS T.S. FAY CONTINUES TO TRACK NORTHWARD ACROSS THE STRAITS OF
FLORIDA AND INTO THE FAR SE GULF OF MEXICO THE PRIMARY FOCUS
CONTINUES TO BE CONVECTIVE BANDS OF SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS CUBA WHICH EXTEND SOUTHWARD INTO THE N
CENTRAL CARIBBEAN. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS
ON T.S. FAY. A BROAD UPPER HIGH IS CENTERED NE OF THE BAHAMA
ISLANDS AND EXTENDS RIDGING THROUGH ERN CUBA TO JAMAICA. THIS
UPPER DIFFLUENT PATTERN IS SUPPORTING SCATTERED MODERATE TO
STRONG CONVECTION ASSOCIATED WITH T.S. FAY ACROSS CENTRAL CUBA
AND THE N CENTRAL CARIBBEAN SEA FROM 19N-23N BETWEEN 77W-82W. AN
UPPER LOW IN THE W/CENTRAL ATLC EXTENDS WEAK UPPER TROUGHING
OVER THE NE CARIBBEAN WITH AXIS ALONG 65W. THE ENTIRE ERN
CARIBBEAN IS DOMINATED BY MODERATE/STRONG SUBSIDENCE AND DRY
STABLE AIR AND THEREFORE CLEAR SKIES PREVAIL FOR THE CARIBBEAN E
OF 75W WITH THE EXCEPTION OF A SMALL AREA OF SHALLOW SHOWERS
MOVING ACROSS DOMINICA AND GUADELOUPE WHICH ARE ASSOCIATED WITH
THE TROPICAL WAVE. THE ITCZ AXIS EXTENDS FROM COLOMBIA INTO THE
ERN PACIFIC REGION NEAR THE PANAMA/COSTA RICA BORDER GENERATING
ISOLATED SHOWERS OVER THE FAR SW CARIBBEAN S OF 10N BETWEEN
COLOMBIA AND COSTA RICA.

ATLANTIC OCEAN...
THE MAIN CONCERN FOR THE SW ATLC IS T.S. FAY...SEE SPECIAL
FEATURES ABOVE. THE FRONTAL BOUNDARY OVER THE SE U.S. EXTENDS
FROM THE W ATLC N OF THE REGION...AND ALONG WITH T.S. FAY OVER
THE STRAITS OF FLORIDA... IS GENERATING SCATTERED SHOWERS AND
THUNDERSTORMS N OF A LINE FROM 32N69W TO 22N77W INCLUDING OVER
THE FLORIDA PENINSULA. AN UPPER HIGH CENTERED NEAR 26N71W IS
PROVIDING AMPLE UPPER DIFFLUENCE TO SUSTAIN THIS CONVECTIVE
ACTIVITY. A LARGE UPPER LOW IS LOCATED IN THE W/CENTRAL ATLC
NEAR 25N61W EXTENDING UPPER TROUGHING OVER THE NE CARIBBEAN. A
SURFACE TROUGH IS TO THE E OF THE UPPER LOW EXTENDING FROM
31N55W TO 24N58W GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH. AN
UPPER HIGH IS TO THE E NEAR 30N49W. A PAIR OF BENIGN UPPER LOWS
ARE IN THE E ATLC WITH ONE NEAR 25N38W AND A SECOND W OF THE
CANARY ISLANDS NEAR 32N18W. MODERATE SUBSIDENCE AND SOMEWHAT DRY
STABLE AIR COVERS THE ATLC E OF 50W GIVING THE AREA FAIR WEATHER
CONDITIONS. A SURFACE RIDGE COVERS THE ATLC E OF 50W ANCHORED BY
A SERIES OF HIGHS N OF THE REGION. RIDGE AXES EXTEND FROM THE
SURFACE HIGHS...ONE E OF THE SURFACE TROUGH THROUGH 32N45W S TO
20N50W AND A SECOND SW THROUGH BERMUDA TO NE OF THE T.S. FAY
NEAR 28N71W.

$$
HUFFMAN




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