[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 010550
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED AUG 01 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC.

...SPECIAL FEATURES...

TROPICAL STORM CHANTAL IS CENTERED NEAR 43.6N 58.5W AT 01/0300
UTC OR ABOUT 225 NM EAST-SOUTHEAST OF HALIFAX NOVA SCOTIA AND
ABOUT 295 NM SOUTHWEST OF CAPE RACE NEWFOUNDLAND MOVING RAPIDLY
NE AT 28 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB.
MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT.
CHANTAL IS RAPIDLY TRANSITIONING TO AN EXTRATROPICAL CYCLONE AS
IT SWEEPS OVER COOLER WATERS AND ENTRAINS COOLER AIR FROM THE
CANADIAN MARITIMES. NONETHELESS THE SYSTEM STILL EXHIBITS A
CURVED BAND STRUCTURE CONSISTING OF SCATTERED MODERATE
CONVECTION WITHIN 60-90 NM IN THE S SEMICIRCLE OF A LOW LEVEL
CIRCULATION. AN ADDITIONAL BAND OF CONVECTION IS BECOMING
INCREASINGLY DISPLACED NEWD FROM THE LOW LEVEL CENTER AND IS
APPROACHING THE S COAST OF NEWFOUNDLAND. THIS IS THE LAST
FORECAST/ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON
CHANTAL. ADDITIONAL INFORMATION CAN BE FOUND IN HIGH SEAS
FORECASTS ISSUED BY THE OCEAN PREDICTION CENTER UNDER AWIPS/WMO
HEADER NFDHSFAT1/FZNT01 KWBC.

A 1010 MB LOW NEAR 12N53W IS ABOUT 375 NM E OF THE S WINDWARD
ISLANDS. ALTHOUGH DEEP CONVECTION HAS DIMINISHED IN THE
VICINITY OF THE LOW OVER THE PAST SEVERAL HOURS THE OVERALL
ORGANIZATION OF THE SYSTEM REMAINS INTACT AND THUS THE SYSTEM
STILL HAS THE POTENTIAL FOR FURTHER DEVELOPMENT AND COULD BECOME
A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM
IN THE W SEMICIRCLE OF THE LOW LEVEL CENTER WITH A MUCH LARGER
AREA OF MULTILAYERED CLOUD DEBRIS EXTENDING FROM 9N TO 16N
BETWEEN 49W AND 57W.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 20W FROM 8N TO 20N HAS EMERGED OFF THE
AFRICAN COAST. THE 1200 UTC 31 JULY SOUNDING FROM DAKAR
INDICATED THE WAVE WAS VERY NEAR THE SITE AT THAT TIME AND
FORWARD EXTRAPOLATION COMBINED WITH WELL DEFINED LOW AND MID
LEVEL TURNING IN SATELLITE IMAGERY INDICATED THE WAVE IS NOW
ALONG 20W. A FEW THUNDERSTORMS ARE NOTED NEAR THE LOW LEVEL
CENTER IN THE E SEMICIRCLE THOUGH THE BULK OF THE DEEP
CONVECTION IS ALONG THE INTERSECTION OF THE WAVE AND THE ITCZ
FROM 8N TO 11N BETWEEN 18W AND 24W.

TROPICAL WAVE IS ALONG 37W S OF 20N MOVING W 10 KT. WAVE NOTED
BY CYCLONIC TURNING IN STRATOCUMULUS FIELD. SCATTERED MODERATE
CONVECTION NOTED AT THE INTERSECTION OF THE WAVE AXIS AND ITCZ
BETWEEN 37W AND 41W.

TROPICAL WAVE IS OVER THE E CARIBBEAN ALONG 63W MOVING W 15-20
KT. 0000 UTC SOUNDING FROM GUADELOUPE INDICATED THE WAVE HAD
PASSED TO THE W OF THE SITE. WIDELY SCATTERED SHOWERS AND TSTMS
WERE NOTED WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS PASSING
OVER THE CARIBBEAN S OF PUERTO RICO AND SPREADING EWD TO THE
WINDWARD ISLANDS.

TROPICAL WAVE IN THE CENTRAL CARIBBEAN AND SW ATLC IS TILTED
FROM 24N71W THROUGH 15N73W TO INLAND OVER THE N COAST OF
COLOMBIA/SOUTH AMERICA. THE N PORTION OF THE WAVE OVER THE SW
ATLC MAY BECOME SEPARATED FROM THE MAIN WAVE OVER THE NEXT 12 TO
24 HOURS. THIS WAVE IS EMBEDDED WITHIN SOME RATHER DRY STABLE
AIR ESPECIALLY OVER THE CARIBBEAN...THUS ONLY ISOLATED
THUNDERSTORMS ARE BEING GENERATED OVER THE HIGH TERRAIN OF THE
SOUTH COAST OF HAITI.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N16W 12N28W 9N32W 8N41W 13N51W
11N61W. EXCEPT AS NOTED IN ASSOCIATION WITH THE TROPICAL WAVES
ABOVE...ISOLATED MODERATE TO STRONG CONVECTION IS NOTED WITHIN
120 NM OF THE AXIS W OF 58W TO TRINIDAD AND TOBAGO.

...DISCUSSION...
GULF OF MEXICO...
ANOMALOUSLY DEEP LAYERED TROUGH FOR EARLY AUGUST ALONG THE US
EASTERN SEABOARD IS BEGINNING TO EXERT MORE INFLUENCE ON THE
NE GULF AS THE MID TO UPPER LEVEL ANTICYCLONE OVER S-CENTRAL
TEXAS CONTINUES TO RETROGRADE AND THE ASSOCIATED RIDGE AXIS
ALONG 28N90W TO S-CENTRAL FLORIDA SAGS SLOWLY SWD WITH TIME.
DESPITE THE PATTERN CHANGES ANTICYCLONIC FLOW STILL COVERS THE
ENTIRE GULF WITH THE FLOW BECOMING DIFLUENT OVER THE NE THIRD
OF THE GULF WITH WIDELY SCATTERED SHOWERS AND TSTMS OVER THE
E HALF OF THE GULF. THIS PATTERN IS EXPECTED TO REMAIN IN PLACE
FOR THE SEVERAL DAYS GENERATING ADDITIONAL TSTMS OVER THE E GULF
STATES AND FLORIDA AS A COLD FRONT CURRENTLY OVER THE FLORIDA
PANHANDLE SAGS SLOWLY SWD AND THE WEAK SURFACE RIDGE EXTENDING
ACROSS THE CENTRAL BAHAMAS...THE FLORIDA STRAITS TO THE CENTRAL
GULF REMAINS IN PLACE.

CARIBBEAN...
CONDITIONS ACROSS THE MAJORITY OF THE CARIBBEAN SEA ARE TRANQUIL
TONIGHT AS A RESULT OF A VAST AREA OF DRY STABLE AIR
ALOFT. WEAK UPPER LEVEL INVERTED TROUGH EXTENDS ACROSS THE
CENTRAL CARIBBEAN FROM COLOMBIA TO JUST S OF HISPANIOLA ALLOWING
FOR SE FLOW ALOFT OVER THE E CARIBBEAN AND E TO NE FLOW OVER THE
W CARIBBEAN. WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE
CONFINED TO THE E-CENTRAL CARIBBEAN E OF 68W IN ASSOCIATION WITH
THE TROPICAL WAVE NOW ENTERING THE REGION. THIS COULD BE THE
BEGINNING OF SEVERAL DAYS OF UNSETTLED WEATHER OVER THE WINDWARD
ISLANDS AND E CARIBBEAN AS THE AREA OF LOW PRESSURE E OF THE
ISLANDS APPROACHES AND THE ASSOCIATED SHOWER AND THUNDERSTORM
ACTIVITY SPREADS OVER THOSE AREAS.

ATLANTIC...
SEE SPECIAL FEATURES FOR INFORMATION ON TROPICAL STORM CHANTAL
AND THE 1010 MB LOW IN THE W TROPICAL ATLC. ANOMALOUSLY DEEP
LAYERED TROUGH ALONG THE US EASTERN SEABOARD EXTENDS INTO THE W
ATLC N OF 28N W OF 72W TO OVER NE FLORIDA WITH AN ASSOCIATED
WEAK COLD FRONT ENTERING THE REGION NEAR 32N73W TO ACROSS NE
FLORIDA NEAR ST AUGUSTINE TO INLAND OVER THE N GULF COAST
STATES. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 28N
AND WITHIN 360 NM E OF THE COLD FRONT. ADDITIONAL THUNDERSTORM
ACTIVITY IS OVER THE SW PORTION OF THE FLORIDA PENINSULA.
A NARROW EXTENSION OF THE GULF RIDGE EXTENDS OVER S-CENTRAL
FLORIDA INTO THE W ATLC ALONG 27N70W TO BEYOND 32N63W. A SHARP
NARROW SHEAR AXIS/TROUGH OVER THE CENTRAL ATLANTIC EXTENDS FROM
A CYCLONIC CIRCULATION NEAR 31N51W SWD TO 22N52W. THE REMAINDER
OF THE ATLC IS DOMINATED BY ANTICYCLONES NEAR 17N50W AND
26N30W WITH DEEP LAYERED EASTERLY FLOW NOTED. UW CIMSS SAL
ANALYSIS INDICATES A VAST AREA OF AFRICAN DUST MAINLY N OF 15N
AND E OF 45W WITH SOME OF DUST AND STABLE AIR BEING ENTRAINED
INTO THE TROPICAL WAVES ALONG 37W AND THE ONE EMERGING OFF THE W
COAST OF AFRICA THEREBY LIMITING CONVECTION TO THE ITCZ. AT THE
SURFACE...HIGH PRESSURE RIDGE CONTINUES TO DOMINATE THE ATLC
ANCHORED BY A 1027 MB W OF THE AZORES NEAR 35N39W.

$$
COBB








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