[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232358
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU SEP 23 2010

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 DEPRESSION FIFTEEN WAS UPGRADED TO TROPICAL STORM
MATTHEW AT 23/2100 UTC. TROPICAL STORM MATTHEW IS CENTERED NEAR
14.2N 77.7W AT 24/0000 UTC OR ABOUT 330 NM E OF PUERTO CABEZAS
NICARAGUA MOVING W AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO
45 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT5/WTNT35 KNHC AND THE FULL FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE
DETAILS. MATTHEW HAS A LARGE ENVELOPE OF DEEP CONVECTION WITH
THE OUTFLOW WELL DEFINED TO THE N AND THE S. SCATTERED MODERATE
WITH EMBEDDED CLUSTERS OF SCATTERED STRONG CONVECTION COVERS THE
AREA FROM 11N-17N BETWEEN 73W-81W.

TROPICAL DEPRESSION LISA WAS UPGRADED TO TROPICAL STORM AT
23/2100 UTC. TROPICAL STORM LISA IS CENTERED NEAR 17.5N 28.6W AT
23/2100 UTC OR ABOUT 280 NM WNW OF THE CAPE VERDE ISLANDS NEAR
STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB.
MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/
WTNT24 KNHC FOR MORE DETAILS. SATELLITE IMAGERY SHOWS A SMALL
BUT WELL DEFINED SYSTEM BUT THE DEEP CONVECTION IS MOSTLY TO THE
NE OF THE LOW LEVEL CENTER. CLUSTERS OF SCATTERED MODERATE/
STRONG CONVECTION ARE WITHIN 60 NM OF LINE FROM THE CENTER NE TO
20N26W.

...ITCZ...

THE ITCZ IS ANALYZED SW OF T.S. LISA NEAR 11N32W 14N49W 12N63W.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 4N-10N
BETWEEN 27W-38W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE COVERS THE NW GULF W OF A LINE FROM
VERMILION BAY LOUISIANA TO TAMPICO MEXICO ANCHORED OVER THE
MEXICO/TEXAS BORDER NEAR 30N102W AND IS PROVIDING DRY STABLE AIR
WITH NE FLOW ALOFT OVER THE NW GULF. A SECOND UPPER RIDGE COVERS
THE E GULF E OF A LINE FROM PENSACOLA FLORIDA TO THE YUCATAN
PENINSULA NEAR 21N88W ANCHORED IN THE NW CARIBBEAN. THIS UPPER
RIDGE IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED TO
HEAVY  SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS E OF A LINE
FROM 27N85W TO THE YUCATAN NEAR 21N90W INCLUDING S FLORIDA AND
THE FLORIDA STRAITS/KEYS. THESE UPPER RIDGES ARE INDUCING AN
UPPER TROUGH THAT EXTENDS FROM SE LOUISIANA THROUGH AN UPPER LOW
NEAR 27N91W TO NEAR VERACRUZ MEXICO. THIS UPPER TROUGH IS
SUPPORTING A WEAK SURFACE TROUGH THAT EXTENDS FROM 24N96W TO THE
BAY OF CAMPECHE NEAR 19N94W GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM OF LINE FROM 27N89W
TO INLAND OVER MEXICO NEAR TAMPICO. A SURFACE RIDGE COVERS THE N
GULF N OF 25N E OF 96W ANCHORED IN THE W ATLC. ISOLATED SHOWERS
ARE POSSIBLE ACROSS THE REMAINDER OF THE GULF WATERS AND MOVING
FROM THE W ATLC ACROSS THE FLORIDA PENINSULA AND N TO INLAND
OVER THE GULF COAST W OF MISSISSIPPI/ALABAMA BORDER TO TEXAS.

CARIBBEAN SEA...
THE MAIN CONCERN THIS EVENING IS NEWLY FORMED TROPICAL STORM
MATTHEW...SEE SURFACE FEATURES ABOVE. BROAD UPPER RIDGE COVERS
THE CARIBBEAN W OF 73W ANCHORED JUST S OF CUBA NEAR 20N80W
PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED TO HEAVY
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 18N W OF 82W TO
OVER CUBA AND THE YUCATAN PENINSULA INCLUDING THE YUCATAN
CHANNEL. JUST TO E IS AN UPPER LOW CENTERED ALONG THE NE COAST
OF THE DOMINICAN REPUBLIC NEAR 20N69W COVERING THE E CARIBBEAN N
OF 15N BETWEEN 65W-73W. SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS ARE ALONG THE BASE OF THE UPPER TROUGH N OF 12N
BETWEEN 65W-69W TO OVER PUERTO RICO AND THE VIRGIN ISLANDS.
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS COVER THE
REMAINDER OF THE W CARIBBEAN FROM 11N-17N W OF 81W LEAVING ONLY
A SMALL AREA OF CLEAR SKIES THIS EVENING...N OF 18N BETWEEN
73W-80W AND OVER THE LESSER ANTILLES.

ATLANTIC OCEAN...
A CONCERN FOR THE FAR E ATLC IS TROPICAL STORM LISA...SEE
SPECIAL FEATURES ABOVE. THE UPPER RIDGE ANCHORED IN THE NW
CARIBBEAN EXTENDS AN UPPER RIDGE AXIS NE ALONG 25N80W TO 30N75W
PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED TO HEAVY
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 28N W OF 78W TO
INLAND OVER THE FLORIDA PENINSULA AND THROUGH THE FLORIDA
STRAITS. JUST TO SE IS AN UPPER LOW CENTERED ALONG THE NE COAST
OF THE DOMINICAN REPUBLIC NEAR 20N69W COVERING THE W ATLC S OF
27N BETWEEN 63W-70W. BROAD UPPER RIDGE ANCHORED NEAR 26N51W
DOMINATES THE CENTRAL ATLC WITH MODERATE/STRONG SUBSIDENCE AND
DRY STABLE AIR. A CUTOFF UPPER LOW IS CENTERED NEAR 32N36W
SUPPORTING A WEAK 1012 MB SURFACE LOW NEAR 32N28W AND A SURFACE
TROUGH EXTENDING FROM 31N37W TO 25N41W WITH ISOLATED SHOWERS
WITHIN 75 NM E OF THE SURFACE TROUGH. A PAIR OF UPPER LOWS ARE
OVER THE FAR E ATLC CENTERED NEAR 31N23W AND 23N25W WITH A LARGE
UPPER RIDGE ANCHORED INLAND OVER AFRICA. THIS SCENARIO IS
DRAWING TROPICAL MOISTURE NE FROM T.S. LISA WITH ISOLATED
SHOWERS WITHIN 120 NM OF LINE FROM 20N26W TO 30N23W INCLUDING
THE WESTERN MOST CANARY ISLANDS.

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

$$
PAW





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