[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071801
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 07 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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
1745 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 29W S OF 15N MOVING W NEAR 10 KT. THIS
WAVE REMAINS LOW AMPLITUDE ALTHOUGH SOME MID LEVEL TURNING IS
NOTED WITHIN 120NM EITHER SIDE OF THE AXIS FROM 7N-12N. DEEP
CONVECTION IS OVERALL MINIMAL...THOUGH SCATTERED MODERATE IS
FURTHER W WITHIN 150NM S OF THE ITCZ BETWEEN 33W-37W.

TROPICAL WAVE IS TILTED ALONG 21N42W TO 6N40W MOVING W 10-15 KT.
WAVE CONTINUES TO EXHIBIT A LARGE INVERTED V SHAPE IN THE
SURROUNDING STRATOCUMULUS CLOUDS. ISOLATED MODERATE CONVECTION
REMAINS CONFINED TO WHERE THE SRN PORTION OF THE AXIS INTERSECTS
WITH THE ITCZ FROM 7N-15N BETWEEN 38W-44W.

TROPICAL WAVE IS ALONG 51/52W S OF 15N MOVING W NEAR 10 KT.
SATELLITE DERIVED 850 MB VORTICITY CONTINUES TO DEPICT A SMALL
POSITIVE MAXIMUM IN THE VICINITY OF THE WAVE FROM 9N-14N. DEEP
CONVECTION REMAINS MINIMAL AND DISORGANIZED THOUGH...WITH ONLY
ISOLATED SHOWERS AND TSTMS NOTED WITHIN 90 NM EITHER SIDE OF THE
AXIS S OF 12N.

TROPICAL WAVE IS ALONG 72/73W S OF 21N MOVING W 10-15 KT. EXACT
WAVE POSITION REMAINS CHALLENGING ON THIS FEATURE DUE TO THE
WEAK TROUGHING AND HIGH MOISTURE CONTENT FURTHER E OVER THE ERN
CARIBBEAN. HOWEVER...BASED ON SATELLITE HOVMOLLER DIAGRAMS AND
THE UW-CIMMS TPW PRODUCT IT APPEARS AS IF A WAVE IS NEAR THE
CURRENT PLACEMENT. HOWEVER...A NEW WAVE OR SFC TROUGH WILL
LIKELY BE ADDED TO THE 1800 UTC MAP TO ACCOUNT FOR THE LOW LEVEL
TURNING NOTED IN THE ERN CARIBBEAN.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N17W 10N27W 13N38W 12N50W 10N63W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
INLAND OVER AFRICA FROM 11N-17N BETWEEN 7W-16W...POSSIBLY
ASSOCIATED WITH THE NEXT TROPICAL WAVE. SCATTERED MODERATE IS
WITHIN 150NM S OF THE ITCZ BETWEEN 33W-37W.

DISCUSSION...
GULF OF MEXICO...
A 1018 MB SFC HIGH IS S OF NEW ORLEANS NEAR 27N89W. THIS IS
KEEPING WINDS LIGHT TO MODERATE AND SEAS LOW...WHICH IS
GENERALLY EXPECTED TO PERSIST OVER THE NEXT COUPLE OF DAYS. AS
OF 7/1500 UTC A WEAK SFC TROUGH EXTENDS SW THROUGH THE
SOUTHEASTERN U.S. AND EXITS INTO THE GULF NEAR CAPE SAN BLAS
WHERE IT CONTINUES WSW IN THE NRN GULF TO NEAR 29N89W. THIS MAY
BE ENHANCING THE CLUSTER OF MODERATE CONVECTION NEAR THE NRN
GULF COAST FROM 28N-30N BETWEEN 87W-89W. IN ADDITION...SUBTLE
UPPER DIFFLUENCE MAY BE ADDING TO THE SUPPORT AROUND THE SW
PERIPHERY OF A LARGE UPPER ANTICYCLONE OVER TENNESSEE. THIS HAS
UPPER ELY FLOW OVER MOST OF THE GULF EXCEPT FOR NLY FLOW IN THE
SW PORTION AROUND ANOTHER UPPER HIGH OVER CENTRAL MEXICO.

CARIBBEAN SEA...
THERE ARE A COUPLE AREAS OF UNSETTLED WEATHER IN THE CARIBBEAN
THIS AFTERNOON...MAINLY OVER THE SW AND ERN PORTIONS. THE
SCATTERED MODERATE CONVECTION IN THE SW PORTION S OF 12N BETWEEN
76W-84W IS LIKELY ASSOCIATED WITH THE ITCZ IN ADDITION TO UPPER
DIFFLUENCE. SCATTERED SHOWERS/ISOLATED TSTMS ARE OVER THE ERN
CARIBBEAN E OF 66W IN ASSOCIATION WITH WEAK SFC TROUGHING. THE
MOST CONCENTRATED AREA OF MODERATE CONVECTION IS OVER THE SRN
WINDWARD ISLANDS...TRINIDAD...AND ADJACENT WATERS. IN
ADDITION...A WELL DEFINED UPPER HIGH IS SUPPORTING THIS ACTIVITY
CENTERED ABOVE BARBADOS NEAR 13N60W. ANOTHER CLUSTER OF MODERATE
CONVECTION IS AFFECTING THE COASTAL WATERS NEAR ERN JAMAICA FROM
17N-19N BETWEEN 75W-78W. ELSEWHERE ACROSS THE CARIBBEAN
CONDITIONS ARE FAIRLY TRANQUIL WITH MODERATELY DRY/STABLE MID TO
UPPER AIR IN PLACE. ELSEWHERE AT THE SFC TRADES ARE LIGHT TO
MODERATE WHICH IS EXPECTED TO PERSIST THROUGH MIDWEEK.

ATLANTIC OCEAN...
WEAK SFC TROUGHING IS EXTENDING THROUGH THE WRN ATLC FROM A 1014
MB SFC LOW NEAR 31N70W TO THE WRN BAHAMAS NEAR 25N78W. LIGHTNING
DATA SUPPORTS SCATTERED TSTMS NEAR THE NW BAHAMAS AND ATLC
WATERS FROM 26N-30N BETWEEN 76W-79W. UPPER NE FLOW CONTINUES TO
DOMINATE THE WRN ATLC AROUND THE WELL DEFINED UPPER HIGH OVER
TENNESSEE. AN UPPER LOW REMAINS NE OF THE LEEWARD ISLANDS NEAR
23N60W. THIS...ALONG WITH SOME WEAK LOW LEVEL CONFLUENCE IS
SUPPORTING THE CLOUDINESS WITH POSSIBLE SCATTERED
SHOWERS/ISOLATED TSTMS S OF 27N BETWEEN 54W-66W. MUCH OF THE
REMAINDER OF THE DISCUSSION AREA IS QUIET...WITH MODERATE TRADES
AND FAIR WEATHER/TYPICAL STRATOCUMULUS NOTED E OF 50W...ON THE
SRN PORTION OF THE 1031 MB HIGH NEAR 37N37W. STRONGER NE WINDS
REMAIN NEAR THE COAST OF NW AFRICA N OF 20N AND E OF 30W WHERE
THE TYPICALLY TIGHTER PRES GRADIENT EXISTS. AN ELONGATED UPPER
TROUGH REMAINS STRETCHED BETWEEN TWO UPPER RIDGES ALONG
45W...BUT IS NOT DOING MUCH MORE THAN GENERATING PATCHES OF
CIRRUS.

$$
WILLIS


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