[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 011043
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE OCT 01 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...SPECIAL FEATURES...

TROPICAL STORM LAURA IS CENTERED NEAR 44.8N 47.6W AT 01/0900 UTC
OR ABOUT 260 NM ESE OF CAPE RACE NEWFOUNDLAND MOVING NNE AT 14
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. PLEASE SEE
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. LAURA IS EXPECTED TO
LOSE ITS TROPICAL CHARACTERISTICS AND FULLY BECOME BE
EXTRATROPICAL LATER THIS AFTERNOON. AN INCREASE IN FORWARD SPEED
IS EXPECTED TODAY WITH A TURN TOWARD THE NE FORECAST ON THU. NO
ACTIVITY REMAINS IN THE REGION ASSOCIATED WITH LAURA.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 36W/37W S OF 19N MOVING W 10-15 KT. THIS
WAVE REMAINS EMBEDDED WITHIN DEEP LAYERED MOISTURE AS INDICATED
ON THE MIMIC TPW ANIMATION WITH SCATTERED MODERATE/ISOLATED
STRONG CONVECTION FROM 13N-16N BETWEEN 35W-40W.

TROPICAL WAVE IS ALONG 48W/49W FROM 12N-21N MOVING W 5-10 KT AND
BECOMING MORE TILTED ALONG NE/SW IN TIME. WELL DEFINED
INVERTED-V CLOUD PATTERN IS OBSERVED ON SATELLITE IMAGERY.
SCATTERED MODERATE IS CONVECTION IS FROM 20N-21N BETWEEN
46W-48W.

TROPICAL WAVE IS ALONG 64W S OF 16N MOVING W 10-15 KT. WEAK WAVE
SIGNATURE WITH NO ASSOCIATED CONVECTION.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 12N15W 6N27W 8N40W 7N50W 9N61W.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 4N-11N
BETWEEN 29W-42W AND FROM 6N-10N BETWEEN 46W-53W.

...DISCUSSION...

GULF OF MEXICO...
DEEP UPPER TROUGH OVER THE E US EXTENDS OVER THE GULF WITH
MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR COVERING MUCH OF
THE GULF WITH THE EXCEPTION OF THE FLORIDA STRAITS. A SURFACE
TROUGH EXTENDS FROM THE W ATLC ACROSS EXTREME S FLORIDA/FLORIDA
KEYS ALONG 25N81W TO OVER THE NE YUCATAN PENINSULA NEAR 21N87W.
A RE-ENFORCING COLD FRONT EXTENDS INTO THE N GULF THROUGH
PENSACOLA FLORIDA W ACROSS THE TIP OF THE MISSISSIPPI DELTA TO
INLAND OVER TEXAS NEAR MATAGORDA BAY. THE STRONG AND MOIST SW
FLOW ALOFT IS E OF THE SURFACE TROUGH PROVIDING UPPER SUPPORT
FOR SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE FLORIDA
STRAITS AND EXTREME S FLORIDA. SCATTERED LOW CLOUDS WITH
POSSIBLE ISOLATED SHOWERS DOT THE REMAINDER OF THE S GULF S OF
24N WHILE THE REMAINDER OF THE GULF IS CLOUD FREE THIS MORNING.

CARIBBEAN SEA...
AN UPPER RIDGE IS ANCHORED IN THE W CARIBBEAN NEAR 16N83W WITH A
RIDGE AXIS EXTENDING NE TO CENTRAL CUBA PROVIDING UPPER LEVEL
SUPPORT FOR SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 15N TO
OVER CUBA W OF 75W TO THE COAST OF CENTRAL AMERICA AND THE
YUCATAN. A SECOND UPPER RIDGE EXTENDS INTO THE N/CENTRAL
CARIBBEAN N OF 15N E OF 74W ANCHORED BY AN UPPER HIGH OVER THE W
ATLC. SOMEWHAT STABLE CONDITIONS AND DRYER AIR ARE BENEATH THIS
RIDGE WITH ONLY SOME ISOLATED SHOWERS FROM 15N-18N BETWEEN
69W-73W. A THIRD UPPER RIDGE IS OVER THE SE CARIBBEAN ANCHORED
OVER SOUTH AMERICA AND EXTENDING A RIDGE AXIS FROM VENEZUELA
NEAR BARCELONA ACROSS THE LESSER ANTILLES NEAR SAINT VINCENT
ISLAND. THE ITCZ AXIS EXTENDS ACROSS THE N PORTION OF SOUTH
AMERICA/PANAMA INTO THE E PACIFIC GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 60/75 NM ALONG THE COAST OF SOUTH
AMERICA AND PANAMA BETWEEN 67W-81W.

ATLANTIC OCEAN...
TROPICAL STORM LAURA IS LOCATED WELL N OF THE REGION...SEE
SPECIAL FEATURES ABOVE. THE DEEP UPPER TROUGH OVER THE E US AND
GULF OF MEXICO INTO THE W ATLC W OF 75W WITH THE ASSOCIATED COLD
FRONT ENTERING THE REGION THROUGH 32N71W ALONG 28N74W TO OVER
THE N BAHAMA ISLANDS NEAR 27N77W WHERE A SURFACE TROUGH
CONTINUES INTO THE GULF OF MEXICO THROUGH A 1010 MB LOW ALONG
THE COAST OF FLORIDA NEAR PALM BEACH. THE SW UPPER FLOW IS
DRAWING STRONG MOIST AIR ACROSS THE AREA PROVIDING THE UPPER
SUPPORT FOR SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120
NM E OF THE FRONT AND BETWEEN THE BAHAMAS AND CUBA. BROAD UPPER
HIGH COVERS THE REMAINDER OF THE W ATLC INTO THE CENTRAL ATLC
AND S OVER THE CENTRAL CARIBBEAN CENTERED NEAR 23N68W. STRONG
SUBSIDENCE AND DRY STABLE AIR COVER THE AREA S OF 30N BETWEEN
62W-73W RESULTING IN FAIR WEATHER OVER THAT AREA. A CUT-OFF
UPPER LOW IS IN THE W TROPICAL ATLC NEAR 18N51W JUST TO THE W OF
THE TROPICAL WAVE ALONG 48W/49W. BROAD UPPER TROUGH COVERS THE
REMAINDER OF THE ATLC N OF 23N E OF 53W WITH A WEAK EMBEDDED
RIDGE ALONG 28W. MID/HIGH CLOUDS DOT THE AREA WITH POSSIBLE
ISOLATED SHOWERS ARE N OF 24N BETWEEN 37W-60W. THE TYPICAL E/W
UPPER RIDGE THAT DOMINATES THE TROPICAL ATLC EXTENDING ALONG 15N
TO 45W ANCHORED BY AN UPPER HIGH OVER THE CAPE VERDE ISLANDS. A
SURFACE RIDGE EXTENDS FROM THE E ATLC THROUGH 32N30W SW TO NEAR
22N55W. THE FIRST VISIBLE SATELLITE IMAGES CLEARLY SHOW AFRICAN
DUST SPREADING W TO NEAR 45W WITH THE DENSEST AREA E OF 26W.

$$
WALLACE





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