[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 142359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 14 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 OMAR IS CENTERED NEAR 14.1N 68.3W AT 15/0000 UTC
OR ABOUT 290 NM SOUTH-SOUTHWEST OF SAN JUAN PUERTO RICO MOVING
E-NE AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 MB.
MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT.
PLEASE SEE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT5/WTNT35 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.
NUMEROUS STRONG CONVECTION IS WITHIN 150 NM OF THE CENTER WITH
SCATTERED MODERATE/STRONG CONVECTION COVERING THE REMAINDER OF
THE AREA FROM 10N-19N BETWEEN 61W-73W...INCLUDING AN OUTER
CONVECTIVE BAND INLAND OVER NE VENEZUELA. OMAR IS FORECAST TO
TRACK NE BY EARLY WEDNESDAY WITH A GRADUAL INCREASE IN FORWARD
SPEED BRINGING THE CYCLONE OVER OR NEAR THE NRN LEEWARD ISLANDS
BY WEDNESDAY NIGHT.

TROPICAL DEPRESSION SIXTEEN IS CENTERED NEAR 16.2N AND 83.5W AT
15/0000 UTC OR ABOUT 140 NM NORTH-NORTHWEST OF CABO GRACIAS A
DIOS ON THE NICARAGUA/HONDURAS BORDER MOVING W-NW AT 6 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED
WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. PLEASE SEE LATEST NHC
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC
AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION COVER A LARGE AREA OF THE
WRN CARIBBEAN FROM 12N-21N BETWEEN 77W-88W. A SIMILAR AREA OF
CONVECTION IS ACROSS THE YUCATAN PENINSULA N OF 17N. T.D.
SIXTEEN IS FORECAST TO TRACK TOWARD THE WEST WITH A GENERAL
WESTWARD MOTION EXPECTED DURING THE NEXT COUPLE OF DAYS AS THE
CENTER OF THE DEPRESSION PARALLELS THE NRN HONDURAS COAST.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 36W S OF 14N MOVING W NEAR 10-15 KT.
THIS LOW AMPLITUDE WEAK PERTURBATION EMBEDDED WITHIN THE ITCZ IS
GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM
5N-11N BETWEEN 34W-41W.

A WEAK TROPICAL WAVE IS ALONG 54W/55W S OF 17N MOVING W NEAR 10
KT. THE WAVE IS EMBEDDED IN AN AREA OF MODERATE TO STRONG
SUBSIDENCE THUS NO SIGNIFICANT DEEP CONVECTION SURROUNDS THE
WAVE AXIS. HOWEVER...LAST VISIBLE SATELLITE IMAGES DEPICT A WEAK
LOW-LEVEL INVERTED-V CLOUD SIGNATURE ASSOCIATED WITH THE WAVE.

A TROPICAL WAVE IS IN THE FAR ERN CARIBBEAN ALONG 62W S OF 18N
MOVING W NEAR 5-10 KT. LOW-LEVEL CYCLONIC CURVATURE IS NOTED
ACROSS THE ERN CARIBBEAN AS THE WAVE IS BECOMING EMBEDDED WITHIN
THE LARGER CYCLONIC SURFACE FLOW AROUND T.S. OMAR. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION...MOST LIKELY ASSOCIATED
WITH THE OUTER CONVECTIVE BANDS OF OMAR...ARE FROM 12N-19N
BETWEEN 58W-65W BRINGING HEAVY RAINFALL TO THE LESSER
ANTILLES.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 8N34W 8N38W 7N42W 9N52W 9N56W
10N61W. IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...SCATTERED MODERATE/STRONG CONVECTION IS ALONG COASTAL W
AFRICA FROM 5N-14N BETWEEN 9W-18W. ELSEWHERE...SCATTERED
MODERATE CONVECTION IS FROM 7N-10N BETWEEN 25W-32W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL LOW IS CENTERED OVER ERN MEXICO NEAR 19N98W AND
EXTENDS CYCLONIC FLOW NWD TO ACROSS DEEP SRN TEXAS AND THE WRN
GULF W OF 91W. LOW-LEVEL INSTABILITY AND MOIST SOUTHERLY
MID-HIGH LEVEL FLOW EAST OF THIS FEATURE IS HELPING TO INDUCE
SCATTERED SHOWERS AND TSTMS OVER THE WRN GULF THIS EVENING FROM
25N-29N W OF 92W. A SURFACE TROUGH...LIKELY A REFLECTION OF THE
UPPER FEATURE...IS ANALYZED ALONG 93W S OF 26N. SHIP AND BUOY
OBSERVATIONS FROM THE PAST 6-12 HOURS CONFIRM THE WIND SHIFT
ASSOCIATED WITH THIS SURFACE TROUGH. SCATTERED SHOWERS AND TSTMS
ARE ALSO ACROSS THE YUCATAN PENINSULA AND EXTEND INTO THE
S/CENTRAL GULF WATERS S OF 22N BETWEEN 86W-92W. THESE ARE BEING
GENERATED DUE TO THE UPPER LEVEL RIDGE ASSOCIATED WITH T.D.
SIXTEEN IN THE WRN CARIBBEAN. A HIGH PRESSURE CENTER OVER THE SE
CONUS DOMINATES MUCH OF THE GULF E OF 90W...INCLUDING THE
FLORIDA PENINSULA AND STRAITS OF FLORIDA. THE PRESSURE GRADIENT
BETWEEN THIS HIGH AND T.D. SIXTEEN IS GENERATING MODERATE TO
STRONG ELY WINDS OVER THE CENTRAL AND ERN GULF.

CARIBBEAN SEA...
A TROPICAL WAVE AND TWO TROPICAL CYCLONES ARE IN THE CARIBBEAN
SEA...SEE THE SPECIAL FEATURES AND TROPICAL WAVES SECTION FOR
MORE DETAILS. AN UPPER-LEVEL RIDGE IS CENTERED OVER T.D. SIXTEEN
COVERING MUCH OF THE CARIBBEAN W OF 73W. THIS UPPER RIDGE IS
PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE THE CONVECTIVE
ACTIVITY ASSOCIATED WITH T.D. SIXTEEN. WATER VAPOR IMAGERY
REVEALS A DEEP LAYERED TROUGH ACROSS THE W ATLC DIGGING SWD INTO
THE NRN CARIBBEAN. THIS TROUGH WILL PLAY A ROLE IN TRACKING OMAR
TO THE NE OVER THE NEXT FEW DAYS. UPPER DIFFLUENCE E OF THE
UPPER TROUGH ACROSS THE ERN CARIBBEAN IS PROVIDING AMPLE OUTFLOW
FOR THE CONVECTIVE ACTIVITY ASSOCIATED WITH OMAR E OF 71W.
SCATTERED SHOWERS AND TSTMS EXTEND NEWD FROM OMAR ACROSS PUERTO
RICO...THE US/UK VIRGIN ISLANDS AND MUCH OF THE LESSER ANTILLES
THIS EVENING.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE IS ACROSS THE SE CONUS EXTENDING ACROSS THE
W ATLC WATERS W OF 71W. MODERATE TO STRONG SUBSIDENCE IS
ASSOCIATED WITH THIS UPPER RIDGE BRINGING DRY AIR ACROSS THE
FLORIDA PENINSULA...NRN CUBA AND THE BAHAMAS. A DEEP LAYERED
TROUGH IS ACROSS THE REMAINDER OF THE W ATLC EXTENDING EWD INTO
THE CENTRAL ATLC W OF 50W. A SURFACE TROUGH EXTENDS INTO THE
DISCUSSION AREA NEAR 32N47W SW TO 20N67W. A LARGE AREA OF
DEEP-LAYERED MOISTURE CONTINUES TO STREAM NE ACROSS THE CENTRAL
ATLC WITH EMBEDDED SHOWERS FROM 20N-32N BETWEEN 51W-62W. ANOTHER
SURFACE TROUGH CLIPS THE REGION NEAR 31N58W. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS ALSO MOVING NE ACROSS PUERTO RICO
AND THE LEEWARD ISLANDS IN ASSOCIATION WITH OMAR. A 1008 MB
LOW...REMNANTS OF NANA...CENTERED NEAR 19N45W IS DRIFTING N-NW
INTO THE DEEP LAYERED TROUGH ACROSS THE CENTRAL ATLC. SCATTERED
SHOWERS AND TSTMS ARE FROM 19N-22N BETWEEN 43W-46W. TO THE SE...
A 1009 MB LOW IS GENERATING LITTLE SENSIBLE WEATHER UNDER DRIER
AIR ALOFT. THE E ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED ON A 1026 MB HIGH CENTERED SOUTH OF THE AZORES NEAR
35N26W. A BROAD UPPER-LEVEL RIDGE ANCHORED ON AN HIGH NEAR
10N25W DOMINATES THE TROPICAL ATLC E OF 50W AND IS ENHANCING
CONVECTION ALONG THE ITCZ.

$$
HUFFMAN


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