[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 221206
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED AUG 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURE...
HURRICANE DEAN IS CENTERED NEAR 20.5N 95.5W...OR 85 NM NNE OF
VERACRUZ MEXICO AND ABOUT 105 NM ESE OF TUXPAN MEXICO...AT
22/1200 UTC MOVING WNW AT 17 KT. MAXIMUM SUSTAINED WIND SPEEDS
ARE NEAR 80 KT WITH HIGHER GUSTS. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 976 MB. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE LATEST
PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS
INCLUDING THE LATEST WATCH AND WARNING INFORMATION.
DEAN IS SLOWLY RE-ORGANIZING OVER THE BAY OF CAMPECHE...EXPECTED
TO MAKE LANDFALL LATER TODAY. SOME FURTHER STRENGTHENING IS
POSSIBLE BEFORE LANDFALL...FOLLOWED BY WEAKENING AFTER LANDFALL.
NUMEROUS MODERATE TO STRONG CONVECTION IS OVER THE WRN AND
CENTRAL BAY OF CAMPECHE S OF 23N W OF 92W. IN ADDITION
SATELLITE...BROWNSVILLE RADAR...AND LIGHTNING DATA DEPICT
SCATTERED SHOWERS AND TSTMS ELSEWHERE OFF THE S TEXAS AND MEXICO
COASTS S OF 28N W OF 93W.

...TROPICAL WAVES...
TROPICAL WAVE IS TILTED ALONG 21N58W 7N55W MOVING W 15-20 KT.
SHORTWAVE IR IMAGERY SHOWS AN ELONGATED AND NARROW ZONE OF LOW
LEVEL CYCLONIC TURNING IN ASSOCIATION WITH THIS WAVE. DEEP
CONVECTION IS  OVERALL MINIMAL AND DISORGANIZED WITH THIS
WAVE...THOUGH LIGHTNING DATA IS SUPPORTING SCATTERED TSTMS NEAR
THE NRN PORTION OF THE AXIS FROM 20N-23N BETWEEN 55W-57W.
SCATTERED MODERATE CONVECTION IS ALSO FURTHER S...MOVING TOWARDS
TRINIDAD...WITHIN 120 NM EITHER SIDE OF THE AXIS FROM 9N-12N.

TROPICAL WAVE IS ALONG 71W/72W S OF 30N MOVING W 15-20 KT. THIS
WAVE HAS SHOWED UP WELL IN RECENT QUIKSCAT AND ASCAT PASSES.
SATELLITE IMAGERY NOW SHOWS A LITTLE MORE CYCLONIC TURNING ALONG
THE WAVE JUST E OF THE CENTRAL BAHAMAS. HOWEVER...AM NOT SURE
THERE IS A CLOSED SFC LOW WITH THIS SPINNING...WITH BAHAMAS
METAR DATA TO THE S OF THE CIRCULATION REPORTING LIGHT NE WINDS.
WILL DIAGNOSE THIS AGAIN FOR THE 22/1200 UTC MAP AS MORE VISIBLE
IMAGERY BECOMES AVAILABLE. DISORGANIZED SCATTERED SHOWERS AND
TSTMS ARE BEGINNING TO MOVE THROUGH THE BAHAMAS FROM 21N-29N
BETWEEN 72W-78W...WHICH IS ALSO BEING SUPPORTED BY DIFFLUENT
FLOW ALOFT AROUND THE NRN PERIPHERY OF THE UPPER LOW JUST S OF
CUBA. UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT
DEVELOPMENT OF THIS SYSTEM. THERE IS ALSO NUMEROUS
MODERATE/ISOLATED STRONG CONVECTION FURTHER S WITH THE CARIBBEAN
PORTION OF THE WAVE...S OF 15N BETWEEN 73W-80W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N15W 9N30W 10N40W 10N54W 9N62W.
THERE IS A LITTLE MORE CONVECTION ALONG THE AXIS THIS MORNING
BUT THE ITCZ REMAINS HIGHLY ZONAL ACROSS THE TROPICAL ATLC.
NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM
EITHER SIDE OF THE AXIS BETWEEN 18W-33W. SCATTERED
MODERATE/ISOLATED STRONG IS WITHIN 120 NM EITHER SIDE OF THE
AXIS BETWEEN 34W-54W.

DISCUSSION...

GULF OF MEXICO...
THE MAIN FOCUS THIS EVENING REMAINS HURRICANE DEAN THAT IS IN
THE CENTRAL BAY OF CAMPECHE. SEE SPECIAL FEATURES ABOVE. DEAN IS
BEING STEERED WWD BY A DEEP LAYER RIDGE TO ITS N/NE. DRY/STABLE
AIR IS OVER THE ERN GULF EXCEPT FOR A SMALL PATCH OF MOISTURE
AND A COUPLE ISOLATED TSTMS FROM 24N-28N BETWEEN 84W-88W. SFC
RIDGING WILL REMAIN QUASI STATIONARY OVER THE N GULF OVER THE
NEXT FEW DAYS.

CARIBBEAN SEA...
WITH DEAN NOW WELL W OF THE AREA...THE MOST SIGNIFICANT AREA OF
WEATHER IN THE CARIBBEAN HAS SHIFTED TO THE SRN PORTION OFF THE
COAST OF COLOMBIA AND PANAMA. THE CONVECTION IN THIS VICINITY
MAY IN PART BE DUE TO THE TROPICAL WAVE ALONG 72W AS DESCRIBED
ABOVE...BUT IS ALSO BEING SUPPORTED BY DIFFLUENT FLOW ALOFT.
MOISTURE WITH THIS WAVE...AND THE WAVE NEARING THE WINDWARD
ISLANDS...WILL PUSH W THROUGH THE BASIN OVER THE NEXT COUPLE OF
DAYS. ELSEWHERE AT THE SFC LIGHT TO MODERATE TRADES ARE IN PLACE
AND GENERALLY EXPECTED TO PERSIST THROUGH THU. THE UPPER PATTERN
IS DOMINATED BY THE LARGE AND ELONGATED UPPER LOW JUST S OF
CUBA...AND THE SRN PERIPHERY OF AN UPPER RIDGE OVER THE ERN
PORTION.

ATLANTIC OCEAN...
THE AREA JUST OFF THE IMMEDIATE COAST OF FLORIDA AND GEORGIA IS
EXPERIENCING FAIR WEATHER WITH DRY/STABLE MID TO UPPER AIR IN
PLACE. HOWEVER...SHOWERS AND TSTMS ASSOCIATED WITH THE TROPICAL
WAVE NOW MOVING THROUGH THE CENTRAL BAHAMAS ARE APPROACHING AND
WILL AFFECT THE AREA OVER THE NEXT SEVERAL HOURS...SEE DETAILS
ABOVE. AN UPPER HIGH IS NEAR 31N63W THAT HAS RIDGING EXTENDING S
TO THE ERN CARIBBEAN. BENIGN UPPER LOWS ARE NOTED NEAR
24N49W AND 31N35W...WHILE THE REMAINDER OF THE FAR ERN ATLC AREA
IS DOMINATED BY TYPICAL UPPER RIDGING. ELSEWHERE AT THE SFC A
1024 MB HIGH IS NEAR 30N52W...EXPECTED TO SLIDE SLOWLY SW IN
ADVANCE OF THE FRONTAL SYSTEM N OF THE AREA. LIGHT TO MODERATE
TRADE WINDS AND FAIR WEATHER AROUND THIS RIDGING DOMINATE MUCH
OF THE AREA N OF 13N E OF 50W.

$$
WILLIS


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