[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 252335
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUL 25 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE WILL BE INTRODUCED ALONG 27W S OF 17N MOVING W
ABOUT 15 KT. THERE ARE SEVERAL INDICATIONS OF THIS WAVE. 1...A
WEAK SIGNAL IS NOTED IN THE DAKAR SOUNDING BETWEEN 00Z AND 12Z
ON THE 23RD. 2...A SIGNAL IS NOTED IN THE SAL SOUNDING BETWEEN
12Z ON THE 24TH AND 00Z ON THE 25TH MAINLY IN 850-900 MB LEVEL.
3...A 1946Z QUIKSCAT PASS SHOWS A WEAK CIRCULATION CENTERED W OF
THE CAPE VERDES NEAR 13N27W. SCATTERED MODERATE CONVECTION IS
FROM 12N-15N BETWEEN 25W-28W.

TROPICAL WAVE ROUGHLY ALONG 40W/41W S OF 15N MOVING W 10-15 KT.
SATELLITE IMAGERY INDICATES AN ELONGATED E/W ZONE OF LOW-LEVEL
CYCLONIC TURNING EXTENDING ABOUT 300-400 NM EITHER SIDE OF THE
WAVE AXIS ALONG 11N. THE WAVE IS ALSO EVIDENT IN THE SSM/I-
DERIVED TPW PRODUCT WITH SOME CYCLONIC TURNING AND A SURGE OF
MOISTURE S OF 15N.

TROPICAL WAVE LOCATED OVER THE FAR SE CARIBBEAN ALONG 64W S OF
15N MOVING W 20-25 KT. UPPER LEVEL SOUNDINGS FROM TRINIDAD AND
GUADELOUPE INDICATE THAT THE WAVE PASSED THOSE STATIONS JUST
BEFORE 12Z THIS MORNING AND THE TPW PRODUCT NOW INDICATES THAT
IT HAS PROBABLY REACHED ABOUT 65W. A FEW TSTMS DEVELOPED NEAR
THE APEX OF THE WAVE AXIS EARLIER IN THE DAY BUT MOST OF THIS
ACTIVITY HAS SINCE DISSIPATED.

TROPICAL WAVE MOVING INLAND ACROSS THE YUCATAN PENINSULA AND THE
SE GULF OF MEXICO ALONG 89W S OF 24N MOVING W 20 KT. SATELLITE
IMAGERY INDICATES THAT THE WAVE IS ASSOCIATED WITH THE LEADING
EDGE OF A MOISTURE SURGE WITH ENHANCED CLOUDINESS AND
CONVECTION. SCATTERED MODERATE CONVECTION IS CURRENTLY FOCUSED
FROM 20N-25N BETWEEN 84W-91W OVER THE S/CENTRAL GULF OF MEXICO.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N17W 12N32W 7N43W 8N55W 8N62W.
WIDELY SCATTERED MODERATE CONVECTION OFF THE COAST OF SENEGAL
FROM 12N-16N BETWEEN 16W-21W. SCATTERED MODERATE FROM 9N-14N
BETWEEN 29W-36W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK SURFACE RIDGE HAS BUILT IN ACROSS GULF REGION WITH THE
MAIN AXIS STRETCHING FROM N/CENTRAL FLORIDA TO THE TEXAS/MEXICO
BORDER. THE UPPER LEVEL TROUGH WHICH HAS BEEN SITUATED OVER THE
AREA THE PAST FEW DAYS HAS RETROGRADED NW OVER TEXAS AND HAS
BEEN REPLACED BY BROAD ANTICYCLONIC FLOW WITH THE UPPER HIGH
CENTERED JUST E OF CANCUN MEXICO. A SERIES OF TROPICAL WAVES
MOVING ACROSS THE SRN PART OF THE GULF HAS ALREADY BROUGHT IN
LOW-LEVEL MOISTURE AND NOW THE SOUTHWESTERLY UPPER FLOW IS
BRINGING IN MORE MID/UPPER LEVEL MOISTURE FROM THE PACIFIC. AS A
RESULT...PRECIPITABLE WATER VALUES ARE WELL OVER 2.0" OVER THE
WRN GULF. LOW-LEVEL SPEED CONVERGENCE OF EASTERLY WINDS OVER THE
SW GULF SERVED AS THE TRIGGERING MECHANISM FOR SCATTERED
MODERATE CONVECTION TO DEVELOP...NOW EXTENDING FROM 21N-25N
BETWEEN 88W-95W AND MERGING WITH TSTM ACTIVITY ASSOCIATED WITH
THE TROPICAL WAVE ALONG 88W. SCATTERED SHOWERS/TSTMS ARE ALSO
LOCATED N OF 25N TO THE N GULF COAST W OF 87W TO THE W GULF
COAST. THE AIR MASS OVER THE E GULF IS MUCH DRIER AND IS
DOMINATED BY CIRRUS EMANATING FROM THE CONVECTION OVER THE W
GULF.

CARIBBEAN...
AS MENTIONED ABOVE...A LARGE UPPER HIGH IS CENTERED JUST E OF
CANCUN MEXICO AND ITS CIRCULATION COVERS MUCH OF THE W CARIBBEAN
W OF 75W. THIS AREA ALSO HAS THE HIGHEST MOISTURE VALUES IN THE
WAKE OF THE TROPICAL WAVE ALONG 88W. LOW-LEVEL TRADE CONVERGENCE
AND MULTIPLE OUTFLOW BOUNDARY COLLISIONS ARE PRODUCING SCATTERED
MODERATE CONVECTION FROM 15N-20N BETWEEN 76W-83W. SOME OF THESE
TSTMS ARE ORIGINATING INLAND OVER CUBA AND JAMAICA AND ARE
MOVING WWD IN THE PREVAILING FLOW. FARTHER E...AN INVERTED UPPER
TROUGH EXTENDS FROM PUERTO RICO SW TO THE GUAJIRA PENINSULA
WHILE A RIDGE AXIS POKES W ACROSS THE WINDWARD ISLANDS INTO THE
SE CARIBBEAN. THE BULK OF THE AREA E OF 75W IS UNDER FAIRLY DRY
CONDITIONS EXCEPT FOR A FEW SHOWERS/TSTMS OCCASIONALLY
DEVELOPING NEAR THE SE CARIBBEAN TROPICAL WAVE.

ATLANTIC...
AN EXTENSIVE AREA OF HIGH PRES COVERS MUCH OF THE ATLC WITH A
1028 MB HIGH CENTERED NEAR 36N42W. HOWEVER...A WEAK SURFACE
TROUGH DOES LIE OVER THE W ATLC WATERS FROM 31N75W SW TO NEAR SE
FLORIDA. BROAD UPPER LEVEL TROUGHING OVER THE ERN U.S. AND AN
UPPER RIDGE OVER THE BAHAMAS ARE PRODUCING ENOUGH DIFFLUENCE FOR
SCATTERED MODERATE CONVECTION TO DEVELOP E OF THE SURFACE TROUGH
FROM 26N-31N BETWEEN 69W-76W. FARTHER E...A CLOSED MID/UPPER LOW
IS CENTERED NEAR 31N55W AND IS CAUSING ISOLATED SHOWERS/TSTMS N
OF 28N BETWEEN 50W-54W. THE E AND CENTRAL ATLC ARE DOMINATED BY
A LARGE UPPER RIDGE WHICH EXTENDS FROM WRN SAHARA SW TO THE
WINDWARD ISLANDS. WATER VAPOR IMAGERY AND TPW LOOPS SHOW THAT
THE DEEPEST MOISTURE IS LIMITED S OF 15N IN THE TROPICS WHILE
MODERATE SUBSIDENCE PREVAILS FARTHER N.

$$
BERG


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