[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 12 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...
TROPICAL WAVE IS IN THE W TROPICAL ATLANTIC ALONG 50W/51W S OF
21N OR ABOUT 620 NM E OF THE LESSER ANTILLES WITH A 1009 MB LOW
ALONG THE WAVE NEAR 15N MOVING W 10-15 KT. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE N OF THE LOW WITHIN 120 NM OF LINE
FROM 18N48W TO 23N57W. A TROPICAL DEPRESSION COULD FORM DURING
THE NEXT DAY OR SO WITH THE SHOWER ACTIVITY MOVING OVER BARBADOS
LATE TODAY/TONIGHT. AN AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS SYSTEM LATER
TODAY...IF NECESSARY.

A 1009 MB LOW IS IN THE E TROPICAL ATLC NEAR 12N33W. ISOLATED
SHOWERS ARE WITHIN 120 NM OF THE LOW. THIS SYSTEM HAS CHANGED
LITTLE IN ORGANIZATION SINCE YESTERDAY...A TROPICAL DEPRESSION
COULD STILL FORM WITHIN THIS BROAD AREA OF WEATHER DURING THE
NEXT DAY OR TWO AS IT MOVES W 10-15 MPH.

...TROPICAL WAVES...
TROPICAL WAVE IS JUST W OF THE CAPE VERDE ISLANDS ALONG 26W/27W
S OF 18N MOVING W NEAR 15 KT. AN ELONGATED AREA OF LOWER
PRESSURE AS WELL AS THE MIMIC-TPW SHOWS A BROAD AREA OF DEEP
LAYERED MOISTURE SURROUNDING THIS WAVE AND THE 1009 MB LOW IN
THE SPECIAL FEATURES ...SEE ABOVE. SCATTERED MODERATE CONVECTION
IS MOSTLY W OF THE WAVE AXIS WITHIN 60/75 NM OF LINE FROM 17N27W
TO 14N31W.

TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 76W S OF 19N
MOVING W NEAR 15 KT. WAVE POSITION IS BASED ON CONTINUITY AS
HIGH CLOUDS COVER THE AREA OF THE CARIBBEAN MASKING SATELLITE
SIGNATURE. THE MIMIC-TPW SHOWS A LOW AMPLITUDE AREA OF
DEEP LAYERED MOISTURE COVERING THE SW CARIBBEAN MAINLY S OF 15N.
NO ASSOCIATED SHOWERS/DEEP CONVECTION.

TROPICAL WAVE IS IN THE W CARIBBEAN ALONG 86W/87W S OF 21N
MOVING W 15-20 KT. WELL-DEFINED MID LEVEL ROTATION IS OBSERVED
IN THE E PACIFIC REGION WITH NO ASSOCIATED SHOWERS/DEEP
CONVECTION IN THE CARIBBEAN OR OVER CENTRAL AMERICA.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 17N15W 14N23W 10N34W 9N40W 14N51W
10N62W ACROSS THE N PORTION OF SOUTH AMERICA INTO THE SW
CARIBBEAN ACROSS COSTA RICA INTO THE E PACIFIC REGION. SCATTERED
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 7N-11N BETWEEN 33W-50W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE MOVING OFF W AFRICA FROM 7N-10N E OF 18W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE EXTENDS ACROSS THE N GULF COAST ANCHORED
OVER CENTRAL TEXAS AND COVERS THE ENTIRE GULF PRODUCING A BAND
OF SCATTERED/NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS NE OF A
LINE FROM JUST S OF TAMPA FLORIDA TO OVER THE SE U.S. NEAR THE
FLORIDA/ALABAMA LINE. THE SURFACE RIDGE FROM THE W ATLC EXTENDS
THROUGH A 1016 MB HIGH IN THE FLORIDA STRAITS NEAR 24N81W OVER
THE E HALF OF THE GULF OF MEXICO. THIS IS PRODUCING RETURN FLOW
CONSISTING OF MODERATE/STRONG S TO SW WINDS ACROSS THE W GULF
AND MODERATE W WINDS OVER THE E GULF. BROKEN/OVERCAST LOW/MID
CLOUDS WITH ISOLATED SHOWERS ARE WITHIN 60 NM ALONG THE COAST OF
LOUISIANA AND TEXAS E OF HOUSTON. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE DEVELOPING OVER S FLORIDA AND THE FLORIDA KEYS
PUSHING EASTWARD INTO THE W ATLC. OTHERWISE...THE REMAINDER OF
THE GULF IS RELATIVELY CLEAR THIS AFTERNOON.

CARIBBEAN SEA...
THE BROAD UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE NW GULF
WITH UPPER NE FLOW. A BROAD UPPER RIDGE IS ANCHORED OVER N
COLOMBIA COVERING THE THE CENTRAL CARIBBEAN S OF JAMAICA BETWEEN
THE ABC ISLANDS AND CENTRAL AMERICA. AN UPPER LOW IS N OF PUERTO
RICO EXTENDING AN UPPER TROUGH INTO THE NE CARIBBEAN NEAR
16N68W. A MID LEVEL LOW IS BETWEEN THE TROPICAL WAVES NEAR
14N81W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
12N-16N BETWEEN 78W-82W. UPPER LEVEL DIFFLUENCE IS GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 45 NM ALONG THE
COAST OF NICARAGUA FROM 11N-14N. OTHERWISE THIN HIGH CLOUDS
COVER MOST OF THE REMAINDER OF THE CARIBBEAN THIS AFTERNOON WITH
CLEAR SKIES N OF 18N AND MODERATE/STRONG EASTERLY TRADE WINDS
ACROSS THE AREA.

ATLANTIC OCEAN...
THE UPPER RIDGE OVER THE GULF OF MEXICO EXTENDS OVER THE FAR W
ATLC W OF 75W WITH A WEAK UPPER LEVEL TROUGH EXTENDING S THROUGH
32N70W TO JUST E OF THE BAHAMAS NEAR 27N75W. AN UPPER HIGH IS
JUST TO THE E NEAR 29N64W WITH AN UPPER LOW JUST N OF PUERTO
RICO NEAR 20N66W. THIS SCENARIO IS GENERATING SCATTERED
SHOWERS/THUNDERSTORMS OVER THE W ATLC WITHIN 90/120 NM OF LINE
FROM THE FLORIDA STRAITS NEAR 24N80W ACROSS THE N BAHAMA ISLANDS
TO 28N72W AND FROM 28N-30N BETWEEN 75W-79W...AS WELL AS A
BROADER AREA OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF
25N BETWEEN 60W-72W. A SERIES OF BENIGN UPPER LOWS IS ACROSS THE
REMAINDER OF THE ATLC WITH THE FIRST INLAND OVER WESTERN SAHARA
NEAR 26N12W TO A SECOND NEAR 31N29W TO A THIRD NEAR 27N52W.
THESE UPPER LOWS ARE EMBEDDED WITHIN MODERATE/STRONG SUBSIDENCE
AND DRY STABLE AIR...THUS FAIR WEATHER THIS AFTERNOON ACROSS THE
ATLC E OF 60W. A SURFACE RIDGE COVERS THE ATLC ANCHORED BY A
1024 MB HIGH N OF THE REGION NEAR 36N39W AND EXTENDS OVER THE E
GULF OF MEXICO.

$$
WALLACE





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