[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 21 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
1645 UTC.

...SPECIAL FEATURES...

TROPICAL STORM DOLLY AT 21/1800 IS CENTERED NEAR 22.8N 90.4W OR
ABOUT415 NM EAST-SOUTHEAST OF THE COAST OF THE LOWER RIO GRANDE
VALLEY OF SOUTH TEXAS AND NORTHEASTERN MEXICO MOVING WNW AT 16
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM
SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 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. VISIBLE SATELLITE IMAGERY CLEARLY
SHOWS THE CLOSED CENTER OF CIRCULATION WITH THE DEEP CONVECTION
MOSTLY OFFSHORE FROM THE YUCATAN CHANNEL OVER THE S/CENTRAL
GULF. SCATTERED STRONG CONVECTION IS WITHIN 250 NM OF THE CENTER
IN THE NW QUADRANT WITH SCATTERED MODERATE/STRONG CONVECTION
WITHIN 150 NM OF THE CENTER IN THE NW QUADRANT.

TROPICAL STORM CRISTOBAL AT 21/1500 UTC IS CENTERED NEAR 36.6N
72.6W OR ABOUT ABOUT 165 NM EAST-NORTHEAST OF CAPE HATTERAS
NORTH CAROLINA AND ABOUT 630 NM SOUTHWEST OF HALIFAX NOVA SCOTIA
MOVING NE AT 11 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. SOME FURTHER
INTENSIFICATION IS POSSIBLE WHILE THE CENTER MOVES ACROSS THE
GULF STREAM AND THE SHEAR REMAINS LOW DURING THE NEXT 24 HR OR
SO. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150
NM OF THE CENTER IN SE SEMICIRCLE.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 45W/46W S OF 13N MOVING W NEAR 20 KT. LOW
AMPLITUDE WAVE A WEAK MID LEVEL ROTATION EMBEDDED WITHIN THE
ITCZ NEAR 8N. THIS WAVE IS EMBEDDED WITHIN AN AREA OF DRY STABLE
AIR THUS NO ASSOCIATED SHOWERS/CONVECTION.

TROPICAL WAVE IN THE E CARIBBEAN IS ALONG 70W S OF 19N MOVING W
15-20 KT. WEAK WAVE IS EMBEDDED WITHIN DRY STABLE AIR. THUS
SATELLITE SIGNATURE IS NOT DISCERNIBLE. ISOLATED SHOWERS ARE
FROM OVER THE ABC ISLANDS TO THE N COAST OF VENEZUELA BETWEEN
66W-71W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N14W 8N26W 9N40W 6N55W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE
OF THE ITCZ E OF 18W TO THE COAST OF SW AFRICA. CLUSTERS OF
SIMILAR CONVECTION ARE FROM 11N-14N E OF 20W TO INLAND OVER W
AFRICA. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 150
NM N OF THE ITCZ FROM 22W-29W AND WITHIN 200 NM S OF THE ITCZ
FROM 19W-35W.

...DISCUSSION...

GULF OF MEXICO...
THE MAIN CONCERN FOR THE GULF IS T.S. DOLLY AS IT MOVES AWAY
FROM THE N YUCATAN COAST...SEE SPECIAL FEATURES ABOVE. BROAD
UPPER LEVEL OUTFLOW COVERS MOST OF THE GULF S OF 28N. WEAK UPPER
TROUGH EXTENDS FROM THE GEORGIA COAST TO ALONG THE E COAST OF
FLORIDA BRINGING DRIER AIR TO THE FLORIDA PENINSULA. AT THE
SURFACE A WEAK RIDGE OF HIGH PRESSURE COVERS THE SE U.S. WITH A
PAIR OF 1018 MB HIGHS IN THE NE AND NW GULF CENTERED NEAR 21N84W
AND 29N92W. A SMALL UPPER LOW IS IN THE W BAY OF CAMPECHE ALONG
THE MEXICAN COAST GENERATING ISOLATED SHOWERS/THUNDERSTORMS OF
21N W OF 94W. AN AREA OF ISOLATED SHOWERS/THUNDERSTORMS ARE
FEEDING INTO T.S. DOLLY FROM OFF THE N GULF COAST WITHIN 90 NM
OF LINE FROM 29N92W TO 25N94W. OTHERWISE THE MEXICAN COAST N OF
TUXPAN ALONG THE N GULF AND OVER THE FLORIDA PENINSULA REMAIN
CLEAR THIS AFTERNOON.

CARIBBEAN SEA...
T.S. DOLLY IS STILL PRODUCING AN AREA OF HEAVY SHOWERS/SCATTERED
THUNDERSTORMS OVER THE FAR NW CARIBBEAN N OF 20N W OF 83W ACROSS
THE FAR W TIP OF CUBA AND OVER THE NE TIP OF THE YUCATAN
PENINSULA. SEE SPECIAL FEATURES ABOVE. CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE REMAINDER OF THE NW
CARIBBEAN N OF 14N W OF 80W. BROAD UPPER LEVEL OUTFLOW COVERS
THE W CARIBBEAN W OF 78W. AN UPPER TROUGH COVERS THE REMAINDER
OF THE CARIBBEAN EXTENDING FROM AN UPPER LOW OVER PUERTO RICO SW
TO COLOMBIA. THIS IS DRAWING DRIER UPPER AIR FROM THE W ATLC
OVER THE E CARIBBEAN AND WITH LITTLE MOISTURE AT THE SURFACE IS
KEEPING THE CARIBBEAN E OF 78W CLEAR THIS AFTERNOON. UPPER LEVEL
N TO NE FLOW CONVERGING WITH LOW LEVEL EASTERLY TRADE WINDS ARE
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS IN THE SW
CARIBBEAN WITHIN 120 NM ALONG THE COAST OF PANAMA...COSTA
RICA...AND NICARAGUA.

ATLANTIC OCEAN...
T.S. CRISTOBAL IS MOVING NE AWAY FROM NORTH CAROLINA WITH SKIES
CLEARING ALONG THE COAST. SEE SPECIAL FEATURES ABOVE. WEAK UPPER
TROUGH EXTENDS FROM THE GEORGIA COAST TO ALONG THE E COAST OF
FLORIDA BRINGING DRIER AIR TO THE FLORIDA PENINSULA AND THE FAR
W ATLC. A SECOND WEAK UPPER LOW IS JUST TO E NEAR 28N72W AND IS
DRAWING UPPER LEVEL MOISTURE FROM T.S. CRISTOBAL S TO OVER THE
BAHAMAS BETWEEN 73W-77W BUT IS NOT PRODUCING ANY SHOWER
ACTIVITY. A COMPLEX UPPER LOW/TROUGH COVERS THE REMAINDER AND
INTO THE CENTRAL ATLC BETWEEN 52W-67W WITH A SURFACE TROUGH
EXTENDING FROM 33N57W THROUGH A PAIR OF 1012 MB LOWS CENTERED
NEAR 30N64W AND 27N67W CONTINUING TO 24N71W GENERATING SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM EITHER
SIDE OF THE SURFACE TROUGH. AN UPPER RIDGE IS OVER THE REMAINDER
OF THE CENTRAL ATLC INTO THE E ATLC ANCHORED NEAR 25N37W AND
PROVIDING UPPER LEVEL DIFFLUENCE TO THE E OF THE SURFACE TROUGH
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 23N-28N
BETWEEN 55W-60W. LARGE SURFACE RIDGE DOMINATES THE ATLC E OF 60W
ANCHORED BY A 1027 MB HIGH JUST N OF THE REGION NEAR 25N40W.

$$
WALLACE


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