[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170006
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 16 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 IS CENTERED NEAR 19.3N 75.8W OR OR ABOUT 175
NM...320 KM...SOUTHEAST OF CAMAGUEY CUBA AND ABOUT 50 NM...100
KM...SOUTHWEST OF GUANTANAMO CUBA AT 17/0000 UTC. A GRADUAL TURN
TOWARD THE WEST-NORTHWEST AND NORTHWEST WITH A DECREASE IN
FORWARD SPEED IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ON
THIS TRACK...THE CENTER OF FAY WILL BE MOVING NEAR OR OVER THE
SOUTHERN COAST OF EASTERN AND CENTRAL CUBA TONIGHT AND SUNDAY...
AND NEAR OR OVER WESTERN CUBA SUNDAY NIGHT OR MONDAY. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1005 MB. REPORTS FROM AN AIR FORCE
RESERVE HURRICANE HUNTER AIRCRAFT INDICATE THAT THE MAXIMUM
SUSTAINED WINDS ARE NEAR 40 KT...70KM/HR...WITH HIGHER GUSTS.
THESE WINDS ARE CONFINED TO A SMALL AREA TO THE EAST OF THE
CENTER. SATELLITE IMAGES INDICATE THAT FAY IS BECOMING A LITTLE
BETTER ORGANIZED. STRENGTHENING COULD BEGIN TONIGHT OR SUNDAY
AND FAY COULD BE APPROACHING HURRICANE STRENGTH AS IT NEARS
WESTERN CUBA. 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. FAY IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS
OF 4 TO 8 INCHES OVER HISPANIOLA...EASTERN AND CENTRAL
CUBA...JAMAICA...AND THE NORTHERN CAYMAN ISLANDS...WITH ISOLATED
MAXIMUM AMOUNTS OF 15 INCHES. THESE RAINS COULD PRODUCE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. RAINFALL
ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE OVER JAMAICA AND THE
NORTHERN CAYMAN ISLANDS...WHILE RAINFALL ACCUMULATIONS OF 1 TO 3
INCHES ARE POSSIBLE OVER THE SOUTHEASTERN BAHAMAS. A NEW CLUSTER
OF STRONG CONVECTION IS DEVELOPING IN THE SOUTHEASTERN QUADRANT
OF FAY. THIS ACTIVITY IS AFFECTING THE SOUTHERN PENINSULA OF
HAITI. OUTER RAIN BANDS ARE OVER THE BAHAMAS AND EASTERN CUBA.
INTERESTS IN WESTERN CUBA...THE FLORIDA KEYS...AND THE FLORIDA
PENINSULA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

...TROPICAL WAVES...
A TROPICAL WAVE IS IN THE E TROPICAL ATLC ALONG 28W S OF 17N
MOVING W 10-15 KT. SOME CYCLONIC TURNING IS NOTED NEAR THE
NORTHERN END OF THE WAVE AXIS WITH A BAND OF MODERATE CONVECTION
ALONG 15N27W 14N28W 14N31W. THE WAVE SHOWS UP VERY WELL ON THE
TPW PRODUCT WITH A BROAD AREA OF DEEP LAYERED MOISTURE. STRONG
ELY UPPER LEVEL WINDS ARE PRESENTLY OVER THIS FEATURE.

A TROPICAL WAVE IS IN THE CENTRAL TROPICAL ATLC MOVING W 10-15
KT AND EXTENDS FROM FROM 28N51W TO 12N54W. A CLUSTER OF MODERATE
TO ISOLATED STRONG CONVECTION IS WITHIN 245 NM E OF THE WAVE
AXIS FROM 21N TO 24N. THIS TROPICAL WAVE IS INTERACTING WITH AN
UPPER-LEVEL LOW LOCATED NEAR 24N57W. THE N PART OF THE WAVE IS
EXPECTED TO SHEAR OFF AND MOVE NW AT 15 KT AS A SFC TROUGH OVER
THE ATLANTIC OCEAN WHILE THE REMAINDER OF THE WAVE WILL CONTINUE
TO MOVE WWD APPROACHING THE LESSER ANTILLES LATE SUNDAY.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 15N17W 10N27W 8N35W 11N51W. A LARGE
CLUSTER OF MODERATE TO STRONG CONVECTION IS JUST MOVING OFF THE
WEST AFRICAN COAST AND COVERS THE AREA FROM FROM 11.5N-15N
BETWEEN 16.5W-19W. SCATTERED MODERATE CONVECTION IS WITHIN 80 NM
SE OF LINE 10N22W 9N25W 7N27W. SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS OVER GUYANA.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL HIGH CENTERED OVER N-CENTRAL MEXICO EXTENDS A
RIDGE EWD OVER MOST OF THE GULF REGION AND THE YUCATAN PENINSULA
GIVING THE AREA NLY UPPER WINDS. A SHORT-WAVE TROUGH IS OVER THE
SE CONUS AND THE NE PORTION OF THE GULF. A BAND OF SHOWERS WITH
EMBEDDED TSTMS REMAINS OVER THE NORTHERN GULF WATERS N OF 26N
AHEAD OF A FRONTAL BOUNDARY LOCATED JUST INLAND OVER THE NORTH
GULF STATES. THE REMAINDER OF THE GULF REMAINS RATHER CLEAR THIS
EVENING WITH ISOLATED SHOWERS/THUNDERSTORMS OVER S FLORIDA AND
THE FLORIDA STRAITS ASSOCIATED WITH AN UPPER-LEVEL LOW OVER W
CUBA. AT THE SURFACE...A RIDGE ANCHORED ON A 1017 MB HIGH
SITUATED NEAR 28N86W AT 2100 UTC DOMINATES THE AREA PRODUCING
SLY RETURN FLOW OF 10 TO 15 KT OVER THE WESTERN HALF OF THE
GULF.

CARIBBEAN SEA...
ALL THE ATTENTION REMAINS FOCUSED ON TROPICAL STORM FAY THAT IS
RE-ORGANIZING SOUTH OF EASTERN CUBA. NEW WATCHES AND WARNINGS
WERE ISSUED FOR CUBA AT 2100 UTC. RAIN BANDS ASSOCIATED WITH FAY
ARE AFFECTING HISPANIOLA...E CUBA AND JAMAICA. SEE SPECIAL
FEATURES ABOVE. ELONGATED UPPER LOW IS OVER W CUBA NEAR THE ISLE
OF YOUTH EXTENDING AN UPPER TROUGH SW TO THE N COAST OF HONDURAS
NEAR ROATAN ISLAND. THIS LOW IS FORECAST BY THE COMPUTER MODELS
TO MOVE TOWARD THE YUCATAN PENINSULA ON MON. FAY REMAINS ON THE
SOUTH SIDE OF A LOW/MID-LEVEL RIDGE ANCHORED ON A HIGH CURRENTLY
OVER THE SOUTH-CENTRAL BAHAMAS. THIS RIDGE EXTENDS OVER THE EAST
AND CENTRAL CARIBBEAN. THE COLOMBIAN LOW COMBINED WITH THE EPAC
ITCZ IS GENERATING SCATTERED MODERATE CONVECTION BETWEEN WESTERN
VENEZUELA AND COSTA RICA.  ACCORDING TO THE OFFICIAL FORECAST
TRACK...FAY IS FORECAST TO REMAIN IN THE CARIBBEAN SEA THIS SUN
AND POSSIBLE PART OF MONDAY.

ATLANTIC OCEAN...
THE MAIN CONCERN FOR THE W ATLC THIS EVENING IS TROPICAL STORM
FAY WITH OUTER RAINBANDS CURRENTLY OVER THE CENTRAL AND SE
BAHAMAS. SEE SPECIAL FEATURES ABOVE. AN UPPER-LEVEL TROUGH IS
OVER THE E U.S. INTO THE W ATLC WITH THE ASSOCIATED FRONTAL
BOUNDARY N OF THE REGION. AN ELONGATED UPPER LOW IS OVER W CUBA
EXTENDING AN UPPER TROUGH NE TO OVER SE FLORIDA. LARGE UPPER LOW
IS IN THE CENTRAL ATLC NEAR 24N58W AND IS PRODUCING STRONG SLY
WINDS OVER THE TROPICAL WAVE IN THE CENTRAL TROPICAL ATLC. A
BENIGN UPPER LOW IS IN THE E ATLC JUST W OF THE CANARY ISLANDS
NEAR 28N20W WITH AN UPPER HIGH TO THE SW NEAR 24N40W. MODERATE
TO STRONG SUBSIDENCE/DRY STABLE AIR IS ON THE SOUTH SIDE OF THIS
UPPER HIGH. A SURFACE RIDGE CONTINUES TO DOMINATE THE ATLC
ANCHORED BY A 1024 MB HIGH SW OF THE AZORES. THE RIDGE EXTENDS
WWD AND ENVELOPS THE STATE OF FLORIDA AND THE E GULF WHERE THERE
IS A 1017 MB HIGH.

$$
GR




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