[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 231803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 23 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...

DOLLY...A CATEGORY TWO HURRICANE ON THE SAFFIR/SIMPSON HURRICANE
SCALE MADE LANDFALL ON SOUTH PADRE ISLAND AT 23/1800 UTC. ITS
POSITION WAS ESTIMATED NEAR LATITUDE 26.3 NORTH...LONGITUDE 97.2
WEST...ABOUT 35 MILES...60 KM...NORTHEAST OF BROWNSVILLE TEXAS
OR 40 MILES...65 KM...EAST-SOUTHEAST OF RAYMONDVILLE. BEFORE THE
LANDFALL...THE MINIMUM PRESSURE DROPPED TO 964 MB. MAXIMUM
SUSTAINED WIND SPEED IS 85 KT WITH GUSTS TO 105 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. THE SATELLITE
PRESENTATION HAS IMPROVED SIGNIFICANTLY SINCE YESTERDAY. DOLLY
HAS NOW A RAGGED EYE ON BOTH VIS AND IR IMAGES...AND SOME
ADDITIONAL STRENGTHENING IS POSSIBLE DURING THE NEXT SEVERAL
HOURS BEFORE LANDFALL. THE BROWNSVILLE DOPPLER RADAR SHOWS THE
SPIRAL RAINBANDS WRAPPING AROUND THE CENTER. ONE OF THEM IS
CURRENTLY AFFECTING BROWNSVILLE THAT HAS REPORTED HEAVY RAIN AND
GUSTY WIND UP TO 58 KT. MATAMOROS IN MEXICO ALSO REPORTED GUSTY
WINDS OF 55 KT. A FEEDER BAND IS WITHIN 300 NM E OF CENTER WITH
MODERATE TO STRONG CONVECTION. DOLLY IS EXPECTED TO PRODUCE
TOTAL RAINFALL ACCUMULATIONS OF 6 TO 10 INCHES...WITH ISOLATED
AMOUNTS OF 15 INCHES...OVER PORTIONS OF SOUTH TEXAS AND
NORTHEASTERN MEXICO OVER THE NEXT FEW DAYS.  THESE RAINS WILL
LIKELY CAUSE WIDESPREAD FLOODING ACROSS PORTIONS OF SOUTH TEXAS
AND NORTHEAST MEXICO. ISOLATED TORNADOES ARE ALSO POSSIBLE OVER
PORTIONS OF SOUTH TEXAS TODAY AND TONIGHT. PERSONS ARE ADVISED
NOT TO VENTURE OUTDOORS DURING THE RELATIVE CALM OF THE EYE
BECAUSE WINDS WILL SOON INCREASE QUITE RAPIDLY.

...TROPICAL WAVES...

A TROPICAL WAVE IS LOCATED OVER THE FAR EASTERN ATLANTIC...A
COUPLE HUNDRED MILES WEST OF THE CAPE VERDE ISLANDS. IT AXIS IS
TILTED FROM 22N26W TO 9N27W. A WEAK 1012 MB SFC LOW REMAINS
ASSOCIATED WITH THIS WAVE AND IS NEAR 16.5N26.5W. DEVELOPMENT OF
THIS SYSTEM IS NOT EXPECTED DURING THE NEXT COUPLE OF DAYS AS
THE WAVE CONTINUES TO MOVE WWD NEAR 15 KT. SATELLITE IMAGERY
INDICATES AN ELONGATED CENTER WITH A COUPLE OF LOW LEVEL SWIRLS.
THE WAVE SHOWS UP VERY WELL ON THE MIMIC-TPW PRODUCT FROM CIMSS
WHERE A LARGE AMPLITUDE MOISTURE SURGE IS OBSERVED. SCATTERED
SHOWERS AND ISOLATED TSTMS ARE WITHIN 150 NM AHEAD OF THE WAVE
AXIS FROM FROM 14N-18N.

A TROPICAL WAVE IS ALONG 56W/57W S OF 15N MOVING W 10-15 KT.
WEAK INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY. THE
WAVE IS GENERATING SOME SHOWER ACTIVITY OVER GUYANA.

A TROPICAL WAVE IN THE WESTERN CARIBBEAN AND EXTENDS FROM NEAR
THE CAYMAN ISLANDS TO WESTERN PANAMA. IT IS MOVING W NEAR 15 KT.
A CLUSTER OF MODERATE TO STRONG CONVECTION HAS DEVELOPED ON THE
SOUTHERN END OF WAVE OVER THE SW CARIBBEAN. A DIFFLUENT PATTERN
ALOFT IS ALSO ENHANCING THIS CONVECTIVE ACTIVITY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 9N25W 7N35W 6N45W 8N54W. F
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-8N E
OF 21W TO THE AFRICAN COAST. SCATTERED MODERATE CONVECTION IS
WITHIN 120 NM S OF AXIS BETWEEN 30W-35W.

...DISCUSSION...

GULF OF MEXICO...
ATTENTION REMAINS FOCUSED ON HURRICANE DOLLY THAT IS FORECAST TO
MAKE LANDFALL ACROSS THE LOWER TEXAS COAST THIS AFTERNOON. SEE
SPECIAL FEATURE ABOVE FOR DETAILS. BROAD UPPER LEVEL ANTICYCLONE
ASSOCIATED WITH DOLLY IS HELPING TO INDUCE SOME SHOWER ACTIVITY
OVER THE EASTERN GULF DUE TO UPPER DIFFLUENCE. THE ATLANTIC
RIDGE EXTENDS WWD AND ENVELOPS THE E GULF GIVING THE AREA LIGHT
TO MODERATE SE WINDS.

CARIBBEAN SEA...
UPPER-LEVEL NORTHERLY OUTFLOW FROM HURRICANE DOLLY COVERS THE NW
CARIBBEAN W OF 80W. BROAD COMPLEX UPPER TROUGH SYSTEM IN THE W
ATLC EXTENDS S OVER THE CENTRAL CARIBBEAN THROUGH E CUBA AND
JAMAICA PRODUCING MODERATE SUBSIDENCE/DRY AIR. THE REMAINDER OF
THE BASIN IN UNDER THE INFLUENCE OF RIDGE ANCHORED ON AN UPPER
LEVEL HIGH LOCATED JUST E OF THE LEEWARD ISLANDS NEAR 17N60W.
SWLY FLOW BETWEEN THE ABOVE MENTIONED UPPER LEVEL FEATURES IS
DRAWING ABUNDANT UPPER LEVEL MOISTURE FROM N SOUTH AMERICA INTO
THE CARIBBEAN SEA SOUTH OF HISPANIOLA. A TROPICAL WAVE IS MOVING
WWD ACROSS THE WESTERN CARIBBEAN. MOISTURE FROM THIS SYSTEM IS
FORECAST TO SPREAD OVER CENTRAL AMERICA TONIGHT AND THU.
MODERATE TO STRONG TRADE WINDS ARE BLOWING ACROSS THE AREA WITH
THE STRONGEST WINDS JUST OFF THE COLOMBIAN COAST. THIS WEATHER
PATTERN WILL PERSIST DURING THE NEXT FEW DAYS.

ATLANTIC OCEAN...
A 1029 MB SURFACE HIGH PRESSURE LOCATED NEAR 35N43W EXTENDS A
RIDGE FROM THE EAST CENTRAL ATLANTIC TO THE FLORIDA PENINSULA
AND THE EASTERN GULF. THIS SYSTEM WILL SLIGHTLY STRENGTHEN OVER
THE NEXT 24-36 HOURS PRODUCING MODERATE TO STRONG TRADE WINDS
ACROSS THE TROPICS. BROAD AREA OF UPPER TROUGHING COVERS THE WRN
ATLC WITH AN UPPER LOW SITUATED NEAR 24N68W. THE TROUGH EXTENDS
S INTO THE CENTRAL CARIBBEAN. A BAND OF SHOWERS WITH EMBEDDED
TSTMS IS WITHIN 200 NM NE OF LINE FROM 30N70W TO 23N63W LIKELY
ASSOCIATED WITH LOW LEVEL WIND SPEED CONVERGENCE. A SFC TROUGH
IS ANALYZED OVER THE CENTRAL ATLC AND RUNS FROM 30N50W TO
23N53W. VIS SAT IMAGERY SHOWS A BROAD SWIRL OF LOW LEVEL CLOUDS
SPINNING ACROSS THE AREA. THE REMAINDER OF THE ATLC IS DOMINATED
BY BENIGN UPPER LEVEL FEATURES...STRONG SUBSIDENCE AND IMPLIED
DRY STABLE ATMOSPHERE. A LARGE AREA OF STRATOCUMULUS CLOUDS IS
WRAPPING AROUND THE WEAK LOW ASSOCIATED WITH THE TROPICAL WAVE
OVER THE FAR E ATLC.

$$
GR


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