[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161114
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 16 2009

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
1015 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION FOUR WAS UPGRADED AT 16/0900 UTC CENTERED
NEAR 27.7N 83.9W OR ABOUT 80 NM WEST-SOUTHWEST OF TAMPA FLORIDA
AND ABOUT 135 NM SOUTH-SOUTHEAST OF APALACHICOLA FLORIDA MOVING
NNW AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1011 MB.
MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE
LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. DEEP
CONVECTION IS TO THE EAST OF THE LOW LEVEL CENTER WITH SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 27N-28N BETWEEN
83W-84W.

TROPICAL STORM ANA IS CENTERED NEAR 14.6N 53.8W AT 16/0900 UTC
OR ABOUT 490 NM EAST-SOUTHEAST OF THE LEEWARD ISLANDS MOVING W
AT 17 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
MIATCPAT2/WTNT32 KNHC AND THE FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. SCATTERED
MODERATE CONVECTION IS TO THE SW OF THE LOW LEVEL  LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/ WTNT23 KNHC
FOR MORE DETAILS. BROAD AREA OF SCATTERED MODERATE/STRONG
CONVECTION COVERS THE AREA WITHIN 120 NM OF LINE FROM 9N41W TO
13N35W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 19W/20W S OF 19N MOVING W 10-15 KT. WAVE
IS EMBEDDED WITHIN AN AREA OF DEEP LAYERED MOISTURE THAT
CONTINUES TO MOVIE OFF THE COAST OF AFRICA AS INDICATED BY THE
TOTAL PRECIPITABLE WATER IMAGERY WITH A MID LEVEL CYCLONIC
CIRCULATION ALONG THE WAVE NEAR 15N. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE N OF THE ITCZ AXIS AND
ON EITHER SIDE OF THE WAVE AXIS FROM 10N-13N BETWEEN 15W-24W.

TROPICAL WAVE IS ALONG 86W/87W S OF 22N MOVING W NEAR 15 KT.
WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE AS
INDICATED BY THE TOTAL PRECIPITABLE WATER IMAGERY. WAVE REMAINS
ALONG THE EASTERN EDGE OF AN UPPER LOW ENHANCING THE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS THAT COVER THE NW CARIBBEAN S OF
20N W OF 80W TO INLAND OVER CENTRAL AMERICA AND PORTIONS OF THE
YUCATAN PENINSULA.

...ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 11N13W 10N21W 13N31W 9N40W 8N53W
11N62W AND OVER THE N PORTION OF SOUTH AMERICA AND SW CARIBBEAN
SEA. SCATTERED MODERATE CONVECTION S OF THE ITCZ FROM 7N-9N
BETWEEN THE COAST OF W AFRICA TO 16W AND WITHIN 120 NM ALONG THE
COAST OF VENEZUELA BETWEEN THE BORDER OF THE GUYANA AND
TRINIDAD. SMALL CLUSTERS OF SIMILAR CONVECTION ARE FROM 5N-10N
BETWEEN 40W-50W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 16/0900 UTC...SEE SPECIAL FEATURES ABOVE FOR T.D. FOUR. A
NARROWING UPPER LEVEL TROUGH EXTENDS FROM THE LOWER MISSISSIPPI
VALLEY OVER THE W GULF INTO THE W BAY OF CAMPECHE WHILE AN UPPER
RIDGE COVERS THE E GULF. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS COVERS THE LARGE PORTION OF THE GULF N OF A LINE
FROM FORT MYERS FLORIDA TO 22N90W TO ALONG THE N GULF COAST E OF
THE LOUISIANA/TEXAS BORDER. DRY AIR CLEAR SKIES DOMINATE MOST OF
THE SW GULF WITH THE EXCEPTION OF SOME ISOLATED SHOWERS MOVING
OFF THE YUCATAN PENINSULA INTO THE E BAY OF CAMPECHE AHEAD OF
THE TROPICAL WAVE CURRENTLY ALONG 86W/87W.

CARIBBEAN SEA...
THE ACTIVITY IN THE CARIBBEAN IS MAINLY DUE TO THE TROPICAL WAVE
ALONG 86W/87W ENHANCED BY AN UPPER LOW CENTERED OVER N BELIZE.
ACROSS THE CENTRAL AND E CARIBBEAN...DEEP LAYER DRY AIR AND
GENERALLY FAIR WEATHER IS OBSERVED. FRESH TRADE WINDS ARE
USHERING IN LOW LEVEL FAST MOVING ISOLATED SHOWERS WESTWARD
ACROSS THE LESSER ANTILLES TO 72W. SMALL AREA OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN A 60/75 NM RADIUS OF
17.5N74.5W INCLUDING THE FAR SW COAST OF HAITI.

ATLANTIC OCEAN...
AN UPPER LOW COVERS THE W ATLC CENTERED NEAR 25N69W WITH A
SECOND UPPER LOW TO THE E NEAR 27N53W...ALL SUPPORTING A SURFACE
TROUGH THAT EXTENDS FROM 31N62W TO 22N68W AND ISOLATED SHOWERS
WITH POSSIBLE ISOLATED THUNDERSTORMS FROM 21N-29N BETWEEN
63W-75W. ISOLATED SHOWERS ARE ALSO WITHIN 75 NM OF LINE FROM
25N54W TO 29N50W. ATMOSPHERIC LIFT IN THE SOUTHERN FLOW ALOFT TO
THE E OF AN SE TO NW ELONGATED UPPER TROUGH IN THE W TROPICAL
ATLC TO THE NE OF ANA IS SUPPORTING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 120 NM OF LINE FROM 16N57W TO 23N60W. A
BROAD SURFACE RIDGE DOMINATES THE REMAINDER OF THE ATLC ANCHORED
BY A PAIR OF 1023 MB HIGHS N OF THE REGION CENTERED NEAR 33N55W
AND 33N27W GIVING THE E ATLC FAIR WEATHER THIS MORNING.

$$
PAW





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