[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 221749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 22 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM DOLLY IS CENTERED NEAR 24.3N 94.9W AT 22/1800 UTC
OR ABOUT 170 NM SE OF BROWNSVILLE TEXAS MOVING NW AT 9 KT.
THE MINIMUM CENTRAL PRESSURE RECENTLY REPORTED BY A NOAA
HURRICANE HUNTER PLANE WAS 990 MB.MAXIMUM SUSTAINED WIND SPEED
IS 60 KT WITH GUSTS TO 75 KT. PLEASE SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE
DETAILS. DOLLY IS EXPECTED TO BECOME A HURRICANE LATER TODAY OR
WEDNESDAY BEFORE MAKING LANDFALL. BROAD OUTFLOW COVERS MOST OF
THE GULF EXTENDING S ON THE E SIDE INTO THE NW CARIBBEAN.
SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 150 NM E OF THE
CENTER WITH SIMILAR CONVECTION WITHIN 120 NM BOTH N AND S OF THE
CENTER. CLUSTERS OF SIMILAR CONVECTION ARE TO THE W OF THE
CENTER BETWEEN 22N-27N MOVING TO THE COAST OF MEXICO AND 30 NM
OF THE TEXAS COAST. HEAVY SHOWERS/WITH EMBEDDED THUNDERSTORMS
ARE TO THE N WITHIN 102 NM OF LINE FROM 26N89W 29N92W TO 29N95W
INCLUDING THE COAST OF LOUISIANA AND TEXAS. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE POSSIBLE OVER THE REMAINDER OF THE
GULF N OF 20N W OF 86W. DOLLY IS EXPECTED TO PRODUCE TOTAL RAIN
ACCUMULATIONS OF 4 TO 8 INCHES...WITH ISOLATED AMOUNTS OF 15
INCHES...OVER MUCH OF S TEXAS AND NE MEXICO OVER THE NEXT FEW
DAYS. COASTAL STORM SURGE FLOODING OF 4 TO 6 FEET ABOVE NORMAL
TIDE LEVELS...ALONG WITH LARGE AND DANGEROUS BATTERING
WAVES...CAN BE EXPECTED NEAR AND TO THE NORTH OF WHERE THE
CENTER MAKES LANDFALL.

TROPICAL STORM CRISTOBAL IS CENTERED NEAR 40.9N 65.9W AT 22/1500
UTC OR ABOUT ABOUT 245 MB SSW OF HALIFAX NOVA SCOTIA MOVING NE
AT 22 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM
SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. PLEASE SEE
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT3/
WTNT33 KNHC FOR MORE DETAILS. SURFACE CIRCULATION SUGGESTS IT IS
BECOMING ELONGATED FROM SE TO NW AND NOW THAT CRISTOBAL HAS
PASSED N OF THE GULF STREAM AND MOVING OVER COOLER WATERS...
RAPID EXTRATROPICAL TRANSITION IS FORECAST.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 21W/22W S OF 23N WITH A 1009 MB LOW ALONG
THE WAVE NEAR 17N MOVING W NEAR 15 KT. WELL DEFINED CIRCULATION
IN THE LOW/MID LEVELS WITH AN UPPER INVERTED TROUGH WELL DEFINED
IN THE UPPER LEVELS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE FROM 15N-19N BETWEEN 21W-26W INCLUDING THE CAPE VERDE
ISLANDS.

TROPICAL WAVE IS ALONG 51W/52W S OF 13N MOVING W 15 KT. WEAK
INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY. HOWEVER
THE WAVE HAS BEEN BROADENING OVER THE PAST 24 HOURS WHICH LEADS
THE WAVE AXIS TO APPEAR TO BE MOVING SLOWER. NO ASSOCIATED
SHOWER ACTIVITY/CONVECTION.

TROPICAL WAVE IN THE A CENTRAL CARIBBEAN IS ALONG 75W S OF 19N
MOVING W NEAR 15 KT. WAVE CONTINUES TO MOVE BENEATH AN UPPER
TROUGH AND THROUGH AN AREA OF DRIER AIR. THUS...NO REAL
SATELLITE SIGNATURE OF SHOWERS ACTIVITY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 11N22W 7N31W 5N45W 7N58W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 6N-13N BETWEEN 20W TO INLAND OVER W AFRICA. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 2N-10N BETWEEN 37W-50W
WITH SCATTERED CLUSTERS OF SIMILAR CONVECTION FROM 5N-11N
BETWEEN 25W-35W.

...DISCUSSION...

GULF OF MEXICO...
THE MAIN CONCERN FOR THE GULF THIS AFTERNOON IS T.S. DOLLY
MOVING ACROSS THE W GULF...SEE SPECIAL FEATURES ABOVE. WEAK
UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM SW GEORGIA TO OVER THE
FLORIDA PENINSULA. THIS COUPLED WITH THE BROAD UPPER HIGH
ASSOCIATED WITH DOLLY IS GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS INLAND AND ALONG THE IMMEDIATE COAST WATERS OF THE
NE GULF COAST FROM TAMPA FLORIDA ALONG THE FLORIDA PANHANDLE TO
S MISSISSIPPI. AFTERNOON SEA BREEZED INDUCED THUNDERSTORMS ARE
DEVELOPING ALONG THE E COAST OF FLORIDA.

CARIBBEAN SEA...
UPPER LEVEL OUTFLOW FROM T.S. DOLLY COVERS THE NW CARIBBEAN W OF
81W. POSSIBLE ISOLATED SHOWERS/THUNDERSTORMS COULD DEVELOP OVER
THIS AREA. BROAD COMPLEX UPPER TROUGH SYSTEM IN THE W ATLC
EXTENDS S OVER THE CENTRAL CARIBBEAN BETWEEN 63W-81W. THIS IS
DRYING OUT THE CENTRAL CARIBBEAN WITH THE EXCEPTION OF THE FAR
SW CARIBBEAN WHERE UPPER DIFFLUENCE COUPLED WITH LOW LEVEL
CONVERGENCE ARE GENERATING CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 11N BETWEEN COLOMBIA AND CENTRAL
AMERICA. OTHERWISE THE REMAINDER OF THE CARIBBEAN REMAINS
REMARKABLY CLEAR THIS AFTERNOON.

ATLANTIC OCEAN...
T.S. CRISTOBAL IS MOVING NE AWAY FROM THE E SEABOARD OF NEW
ENGLAND...SEE SPECIAL FEATURES ABOVE. AFTERNOON SEA BREEZE
INDUCED SHOWERS/THUNDERSTORMS ARE DEVELOPING ALONG THE E COAST
OF FLORIDA S OF DAYTONA BEACH TO MIAMI. BROAD AREA UPPER TROUGH
COVERS THE W ATLC W OF 60W EXTENDING S INTO THE CENTRAL
CARIBBEAN WITH SEVERAL EMBEDDED UPPER LOWS. SCATTERED SHOWERS/
THUNDERSTORMS ARE BEING GENERATED WITHIN 75 NM OF LINE FROM
31N75W TO OFF THE FLORIDA COAST NEAR PALM BEACH AND A SECOND
AREA WITHIN 90 NM OF LINE FROM 25N61W TO 28N69W. ISOLATED
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVERS THE
BAHAMAS AND COULD DEVELOP OVER THE AREA W OF 65W. THE REMAINDER
OF THE ATLC IS DOMINATED BY BENIGN UPPER LEVEL FEATURES...STRONG
SUBSIDENCE...DRY STABLE AIR...AND A SURFACE RIDGE ANCHORED BY A
1032 MB HIGH N OF THE REGION GIVING THE ATLC E OF 60W FAIR
WEATHER CLOUDS AND DRY CONDITIONS WITH THE EXCEPTION OF THE AREA
NEAR THE TROPICAL WAVE ALONG 21W/22W...SEE TROPICAL WAVES ABOVE.

$$
WALLACE




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