[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 310542
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON JUL 30 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
0515 UTC.

...SPECIAL FEATURES...

NEWLY FORMED TROPICAL DEPRESSION THREE CENTERED NEAR 36.1N 66.0W
AT 31/0300 UTC OR 235 NM NORTH-NORTHWEST OF BERMUDA AND ABOUT
385 NM SOUTH-SOUTHEAST OF CHATHAM MASSACHUSETTS MOVING NNE 14
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM
SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR ADDITIONAL DETAILS. THE SYSTEM IS IN A SHEARED ENVIRONMENT
WITH THE THUNDERSTORM ACTIVITY WITHIN 120 NM NORTHEAST OF THE
EXPOSED LOW LEVEL CENTER. ALTHOUGH THE SYSTEM IS EXPECTED TO
REMAIN IN THIS ENVIRONMENT UNTIL IT TRANSITIONS TO AN
EXTRATROPICAL SYSTEM WITHIN 24 HOURS...THERE IS THE POTENTIAL
FOR THE DEPRESSION TO REACH STORM STRENGTH WITHIN THAT TIME.

1010 MB LOW NEAR 10N49W IN ASSOCIATION WITH THE TROPICAL WAVE
ALONG 49N WAS LOCATED ABOUT 750 NM ESE OF THE WINDWARD ISLANDS
IS FAIRLY WELL ORGANIZED WITH A CLUSTER OF SCATTERED STRONG
THUNDERSTORMS DEVELOPING WITHIN 120-150 NM OF THE LOW LEVEL
CENTER IN THE NE SEMICIRCLE. THIS SYSTEM IS IN A FAVORABLE
ENVIRONMENTAL FOR SOME DEVELOPMENT OVER THE NEXT COUPLE OF DAYS.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 29W S OF 18N WITH A 1009 MB LOW ALONG THE
WAVE NEAR 12N MOVING W NEAR 10 KT. BROAD CYCLONIC TURNING IN THE
STRATOCUMULUS FIELD WAS NOTED WITH THE SYSTEM WITH A FEW
EMBEDDED SHOWERS IN THE W SEMICIRCLE OF THE SYSTEM. SCATTERED
MODERATE THUNDERSTORMS WERE NOTED MAINLY WITHIN 90 NM OF THE
INTERSECTION OF THE WAVE AND ITCZ BETWEEN 26W AND 37W.

TROPICAL WAVE IN THE E-CENTRAL CARIBBEAN AND SW N ATLANTIC IS
TILTED FROM 23N67W THROUGH 15N69W TO INLAND OVER SOUTH AMERICA
NEAR 5N70W MOVING W NEAR 15 KT. BROAD LOW LEVEL INVERTED-V
SIGNATURE NOTED IN TRADE WIND CUMULUS FIELD GENERALLY IN THE ARE
BETWEEN 65W-75W. ISOLATED SHOWERS ARE MOVING FROM THE LESSER
ANTILLES ACROSS THE E CARIBBEAN BUT NO ASSOCIATED DEEP
CONVECTION IS NOTED.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N17W 10N28W 9N38W 11N46W 9N51W
6N57W. EXCEPT AS NOTED ABOVE...SCATTERED MODERATE/STRONG
CONVECTION IS MOVING OFF W AFRICA WITHIN 90 NM OF THE COAST FROM
9N-16N. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 90
NM OF THE ITCZ AXIS E OF 26W TO THE AREA OF CONVECTION ALONG THE
AFRICAN COAST.

...DISCUSSION...
GULF OF MEXICO...
LARGE MID TO UPPER LEVEL ANTICYCLONE WITH SEVERAL CENTERS OVER
THE RIO GRANDE VALLEY...E TEXAS AND SE LOUISIANA DOMINATED THE
FLOW OVER THE GULF OF MEXICO. ASSOCIATED RIDGE EXTENDED ESEWD
ACROSS THE NE GULF TO CENTRAL FLORIDA. A SMALL CYCLONIC
CIRCULATION NEAR 26N96W WAS UNDERCUTTING THE RIDGE. MODERATE
BUT SOMEWHAT DIFLUENT NELY UPPER LEVEL FLOW WAS ADVECTING
HIGH LEVEL CLOUD DEBRIS ACROSS THE ERN HALF OF THE GULF AND ALSO
MAINTAINING WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
IN THE AREA. AT THE SURFACE...WEAK RIDGE EXTENDS FROM THE W ATLC
ACROSS THE STRAITS OF FLORIDA TO A DISSIPATING 1015 MB HIGH OVER
N-CENTRAL CUBA NEAR 23N81W. THIS OVERALL PATTERN IS EXPECTED TO
REMAIN IN PLACE FOR THE NEXT SEVERAL DAYS OR SO. THE PRESENCE OF
DIFLUENT FLOW SE OF THE ANTICYCLONE AND AN APPROACHING UPPER
LEVEL TROUGH/ASSOCIATED FRONTAL SYSTEM OVER THE DEEP SOUTH HOLDS
THE POTENTIAL FOR ADDITIONAL SCATTERED THUNDERSTORMS OVER THE NE
GULF.

CARIBBEAN...
AN UPPER RIDGE EXTENDS FROM NW COLOMBIA NEAR 9N78W NW TO THE
YUCATAN PENINSULA NEAR BELIZE. WEAK UPPER LEVEL INVERTED TROUGH
COUPLED WITH DRY STABLE AIR DOMINATES THE REMAINDER OF THE
CARIBBEAN WITH WIDELY SCATTERED TRADE WIND SHOWERS AND A FEW
THUNDERSTORMS IN THE EASTERN CARIBBEAN PER SAN JUAN WSR-88D
DATA.

ATLANTIC...
SEE SPECIAL FEATURES FOR TROPICAL DEPRESSION THREE. VERY
AMPLIFIED PATTERN IN PLACE OVER THE N ATLANTIC WITH IMPLICATIONS
FOR THE NEWLY FORMED TROPICAL DEPRESSION. BROAD TROUGH COMPLEX
OVER THE NW ATLANTIC WITH FIRST NEGATIVELY TILTED SHORTWAVE
EXTENDING FROM NEW ENGLAND SEWD THROUGH 38N70W TO 34N65W. UPPER
LEVEL DIFFLUENCE E OF THE TROUGH AXIS IS ALLOWING DEEP
CONVECTION TO PERSIST NE OF THE EXPOSED LOW LEVEL CENTER AS THE
DEPRESSION MOVES NNE 14 KT. A SECOND POTENT SHORTWAVE TROUGH
SWINGING IN FROM THE W AND CUTTING ACROSS THE CAROLINAS TO
GEORGIA HAS ALLOWED SCATTERED STRONG THUNDERSTORMS TO PERSIST
AROUND ANOTHER AREA OF LOW PRESSURE NEAR 33N77W. THE FLOW IS
STRONGLY DIFLUENT AS WELL ON THIS AREA.

FURTHER S...AN ELONGATED RIDGE AXIS FROM 32N60W SWWD TO
THE WRN BAHAMAS WITH SOME MODERATE SUBSIDENCE NOTED S OF THE
RIDGE. CYCLONIC CIRCULATION NEAR 30N50W MOVING WWD 10 KT HAS
ASSOCIATED SHEAR AXIS EXTENDING SWWD TO A SMALL CYCLONIC
CIRCULATION NEAR 20N64W. ANTICYCLONES NEAR 16N47W AND 26N37W
AND ASSOCIATED FLOW PREVAIL OVER THE REMAINDER OF THE ATLANTIC
WITH DEEP EASTERLY FLOW IN PLACE OVER THE AREA. UW CIMSS SAL
ANALYSIS INDICATES SAHARAN DUST CONTINUES OVER THE ATLANTIC E OF
40W THROUGH THE COVERAGE IS NOT AS EXTENSIVE AS PREVIOUS DAYS.
AT THE SURFACE...DRY STABLE AIR E OF 60W AND A SURFACE RIDGE
ANCHORED BY A 1026 MB HIGH WELL N OF THE REGION NEAR 41N41W
DOMINATE THE ATLC GIVING THE AREA FAIR CONDITIONS TONIGHT.

$$
COBB





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