[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 300547
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON SEP 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0315 UTC.

...SPECIAL FEATURES...

SUBTROPICAL STORM LAURA IS CENTERED NEAR 39.0N 48.4W AT 30/0300
UTC OR ABOUT 510 NM SSE OF CAPE RACE NEWFOUNDLAND MOVING N AT
8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM
SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. PLEASE SEE
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT2/ WTNT32 KNHC FOR MORE DETAILS. LAURA IS EXPECTED TO
TURN TOWARD THE NNE WITH AN INCREASE IN FORWARD SPEED DURING THE
NEXT COUPLE OF DAYS WITH LITTLE CHANGE IN STRENGTH. LAURA IS
EMBEDDED WITHIN AN UPPER LOW/TROUGH AND OVER THE NEXT DAY OR SO
THE UPPER LOW IS EXPECTED TO WEAKEN AS LAURA MOVES INTO THE
WESTERLIES...AND LAURA STILL COULD BECOME A TROPICAL CYCLONE
BEFORE MOVING INTO AN AREA OF LOWER SEA SURFACE TEMPERATURES
DURING THE NEXT 24 HOURS. IN THE REGION...CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE WITHIN 90/120 NM OF LINE FROM 22N42W
29N30W TO BEYOND 32N30W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 29W/30W S OF 15N MOVING W 15 KT. WAVE IS
WELL DEFINED INVERTED-V CURVATURE OBSERVED IN THE LOW LEVEL
CLOUDS EMBEDDED WITHIN DEEP LAYERED MOISTURE AS INDICATED BY
MIMIC TPW ANIMATION. SMALL CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION FROM 8N-16N BETWEEN THE WAVE AXIS AND 33W.

TROPICAL WAVE IS ALONG 43W/44W FROM 10N-20N MOVING W 5-10 KT.
WELL DEFINED BROAD SWIRL IN THE LOW LEVEL CLOUDS ALONG THE WAVE
AXIS NEAR 15N. DEEP LAYER MOISTURE IS ALSO BROADLY DISTRIBUTED
AROUND WAVE AS INDICATED BY MIMIC TPW ANIMATION. SCATTERED
MODERATE CONVECTION IS WITHIN 30/45 NM OF 18N FROM 40W TO THE
WAVE AXIS.

TROPICAL WAVE IS ALONG 57W/58W S OF 16N MOVING W 10-15 KT. WEAK
LOW AMPLITUDE INVERTED-V CURVATURE. ALTHOUGH THIS WAVE IS
EMBEDDED WITHIN DEEP LAYERED MOISTURE AS INDICATED BY MIMIC TPW
ANIMATION...WATER VAPOR SATELLITE IMAGERY INDICATES STRONG
SUBSIDENCE AND THUS DRY STABLE AIR. RESULTS IS NO ASSOCIATED
SHOWERS/CONVECTION.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 12N14W 10N26W 6N39W 8N50W
10N60W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 7N-9N
BETWEEN 36W-38W. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE FROM 2N-10N BETWEEN 30W-45W AND MOVING OFF W AFRICA WITHIN
75 NM ALONG THE COAST FROM 8N-11N.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH DOMINATES THE CENTRAL US AND THE W GULF W OF 86W
WITH A COMPLICATED SYSTEM OVER THE E GULF CONSISTING OF A 1011
MB LOW N OF THE YUCATAN NEAR 23N89W AND A SURFACE TROUGH
EXTENDING SW OVER THE E BAY OF CAMPECHE TO 19N92W AND NE ACROSS
CENTRAL FLORIDA NEAR NAPLES. BROAD UPPER RIDGE ANCHORED IN THE W
ATLC COVERS THE REMAINDER OF THE GULF DRAWING MOIST UPPER FLOW N
OVER THE E GULF PROVIDING UPPER LEVEL SUPPORT FOR HEAVY
SHOWERS/THUNDERSTORMS MAINLY ALONG THE W COAST OF FLORIDA FROM
JUST N OF TAMPA TO OVER THE FLORIDA KEYS BETWEEN 81W-84W AND
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE REMAINDER OF
THE AREA S AND E OF THE SURFACE TROUGH AS WELL AS N OF THE
SURFACE TROUGH E OF 88W. THE REMAINDER OF THE GULF IS UNDER
STRONG SUBSIDENCE AND DRY UPPER AIR BUT ENOUGH LOW LEVEL
MOISTURE TO CREATE LOW LEVEL CLOUDS WITH POSSIBLE ISOLATED
SHOWERS E OF 94W AND REMARKABLE CLEAR SKIES ALONG THE COAST OF
TEXAS AND W LOUISIANA.

CARIBBEAN SEA...
WEAK UPPER LOW IS IN THE NW CARIBBEAN JUST W OF JAMAICA EMBEDDED
WITH THE STRONGER UPPER RIDGE ANCHORED IN THE W ATLC THAT COVERS
THE REMAINDER OF THE CARIBBEAN. THE UPPER RIDGE IS BRINGING
STRONG SUBSIDENCE AND DRY STABLE AIR TO THE E CARIBBEAN E OF 75W
LEAVING THE W CARIBBEAN UNDER DEEP LAYERED MOISTURE AND MOSTLY
FAIR WEATHER WITH ONLY ISOLATED SHOWERS USHERED IN ON MODERATE
TRADE WINDS OVER THE E CARIBBEAN. MEANWHILE THE W CARIBBEAN
REMAINS MOISTURE LADEN AND WITH THE UPPER DIFFLUENCE IS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS W OF 75W
WITH THE HIGHEST CONCENTRATION OVER CENTRAL AMERICA.

ATLANTIC OCEAN...
SUBTROPICAL STORM LAURA IS LOCATED N OF THE REGION...SEE SPECIAL
FEATURES ABOVE. BROAD UPPER RIDGE COVERS THE W ATLC ANCHORED
OVER THE BAHAMAS NEAR 24N76W AND A RIDGE AXIS EXTENDING NE TO
33N54W DRAWING UPPER LEVEL MOISTURE FROM THE CARIBBEAN ACROSS
CUBA AND THE N BAHAMA ISLANDS GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS W OF 76W. THE SURFACE TROUGH IN THE GULF
OF MEXICO EXTENDS ACROSS FLORIDA FROM NAPLES TO VERO BEACH INTO
THE W ATLC TO 30N76W. BENEATH THE UPPER RIDGE IS A 1017 MB
SURFACE HIGH NEAR 26N66W AND ALONG WITH STRONG SUBSIDENCE AND
DRY AIR IS GIVING THE REMAINDER OF THE AREA FAIR WEATHER
TONIGHT. THE UPPER TROUGH ASSOCIATED WITH SUBTROPICAL STORM
LAURA EXTENDS INTO THE CENTRAL ATLC N OF 22N FROM 35W-50W AND IS
ENHANCING THE CONVECTION ASSOCIATED WITH LAURA. AN UPPER LOW IS
MOVING INLAND OVER MOROCCO JUST E OF THE CANARY ISLANDS WITH AN
UPPER TROUGH COVERING THE NE ATLC N OF 26N E OF 24W. THE TROPICS
IS DOMINATED BY THE TYPICAL E/W UPPER RIDGE ANCHORED OVER THE
CAPE VERDE ISLANDS EXTENDING W TO NEAR 50W.

$$
WALLACE




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