[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 182348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI JUL 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM BERTHA WAS UPGRADED TO HURRICANE AGAIN AT 18/2100
UTC. HURRICANE BERTHA IS CENTERED NEAR 37.6N 50.6W AT 18/2100
UTC MOVING NE AT 19 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
989 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80
KT. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. THE EYE HAS BECOME
BETTER-DEFINED WITH DEEP CONVECTION INCREASING AROUND A
CONSOLIDATING EYEWALL...HOWEVER IT IS NOT EXPECTED TO REMAIN A
HURRICANE FOR TOO LONG AS IT WILL BE MOVING OVER COOLER WATERS
BY THIS TIME ON SAT AND THEN WILL BECOME EXTRA-TROPICAL ON SUN.
SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OVER THE N
SEMICIRCLE AND WITHIN 90 NM OVER THE S SEMICIRCLE.

A BROAD AREA OF LOWER PRESSURE OFF THE GEORGIA/SOUTH CAROLINA
COAST CENTERED BY A 1013 MB LOW NEAR 31.5N80.5W WITH A SURFACE
TROUGH EXTENDING SW ACROSS THE FLORIDA PENINSULA INTO THE GULF
OF MEXICO. THIS SYSTEM IS BECOMING BETTER DEFINED AND A TROPICAL
DEPRESSION COULD FORM LATER TONIGHT/EARLY SAT. ALL INTERESTS
ALONG THE COASTS OF GEORGIA...SOUTH CAROLINA...AND NORTH
CAROLINA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. LOCALLY
HEAVY RAINFALL AND GUSTY WINDS ARE POSSIBLE IN THESE AREAS
DURING THE NEXT COUPLE OF DAYS AS THIS SYSTEM MOVES SLOWLY
NORTHEASTWARD NEAR THE COAST. SCATTERED SHOWERS/THUNDERSTORMS
ARE CURRENTLY OFFSHORE FROM 30N-32N BETWEEN 77W-80.5W. SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE N OF 28N W OF
76W TO INLAND OVER SE U.S.

TROPICAL WAVE IS ALONG 71W/72W S OF 18N WITH A 1008 MB LOW ALONG
THE WAVE AXIS NEAR 15N MOVING WNW 15-20 KT. A TROPICAL CYCLONE
COULD FORM AT ANY TIME AS THE SYSTEM MOVES TOWARD THE WNW. ALL
INTERESTS IN JAMAICA...THE CAYMAN ISLANDS...AND THE NORTHWESTERN
CARIBBEAN SEA SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS
SYSTEM. LOCALLY HEAVY RAINFALL IS MOVING ACROSS HISPANIOLA AND
WILL SPREAD ACROSS JAMAICA LATER THIS EVENING. SCATTERED
SHOWERS/THUNDERSTORMS ARE N OF 14N TO OVER HISPANIOLA BETWEEN W
PUERTO RICO AND E CUBA/WINDWARD PASSAGE. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS COVER THE REMAINDER OF BETWEEN
66W-78W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 50W S OF 17N MOVING W 10-15 20 KT. HIGH
AMPLITUDE INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY
WITH NO ASSOCIATED SHOWERS OR DEEP CONVECTION.

TROPICAL WAVE IS ALONG 86W/87W S OF 21N WITH A 1007 MB LOW ALONG
THE WAVE INLAND OVER HONDURAS. THIS SYSTEM IS NOT EXPECTED TO
BECOME A TROPICAL DEPRESSION. HOWEVER...THIS SYSTEM IS PRODUCING
GUSTY WINDS OVER PORTIONS OF THE NORTHWESTERN CARIBBEAN
SEA...AND LOCALLY HEAVY RAINS ARE EXPECTED TO CONTINUE OVER
PORTIONS OF HONDURAS...NICARAGUA...BELIZE AND GUATEMALA FOR THE
NEXT DAY OR TWO. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH
FLOODS AND MUDSLIDES. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE S OF 20N W OF 83W TO INLAND OVER CENTRAL AMERICA AND THE
YUCATAN PENINSULA.

THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N16W 6N28W 10N48W 10N62W.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 3N-7N BETWEEN
31W-33W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 4N-10N BETWEEN 20W-30W AND FROM THE EQUATOR
TO 2N BETWEEN 35W-40W.

DISCUSSION...

GULF OF MEXICO...
THE GULF HAS BECOME QUITE TRANQUIL COMPARED TO THE PAST FEW DAYS
AS THE 1013 MB LOW OFF THE GEORGIA/SOUTH CAROLINA CONTINUES TO
MOVE NE AND AWAY FROM FLORIDA. A SURFACE TROUGH DOES EXTEND
FROM THIS LOW ACROSS THE FLORIDA PENINSULA FROM ST. AUGUSTINE TO
TAMPA TO A WEAK 1016 MB LOW NEAR 27N87W. ISOLATED SHOWERS DOT
THE AREA N OF THE SURFACE TROUGH. AN UPPER LOW IS ALONG THE
COAST OF TEXAS NEAR CORPUS CHRISTI COVERS THE W GULF. AN UPPER
RIDGE EXTENDS FROM THE YUCATAN TO SE LOUISIANA COVERING THE
CENTRAL GULF AND PROVIDING ENOUGH DIFFLUENCE ALOFT TO GENERATE
SCATTERED CLUSTERS OF SHOWERS/ISOLATED THUNDERSTORMS N OF 27N
FROM 88W-95W. SCATTERED SHOWERS/THUNDERSTORMS ASSOCIATED WITH
THE TROPICAL WAVE OVER CENTRAL AMERICA /W CARIBBEAN ARE MOVING
OFF THE THE W COAST OF THE YUCATAN PENINSULA WITHIN 60 NM ALONG
THE COAST IN THE E BAY OF CAMPECHE. OTHERWISE THE REMAINDER OF
THE GULF REMAINS TRANQUIL THIS EVENING.

CARIBBEAN SEA...
THE MAIN FOCUS THIS EVENING IN THE CARIBBEAN IS THE E CARIBBEAN
TROPICAL WAVE ALONG 71W/72W. SEE SPECIAL FEATURES ABOVE.
INTERESTS IN THE W CARIBBEAN SEE THE TROPICAL WAVE SECTION ABOVE
FOR THE TROPICAL WAVE ALONG 86W/87W. AN UPPER LOW IS CENTERED
OVER CENTRAL CUBA NEAR CAMAGUEY COVERING THE N/CENTRAL CARIBBEAN
TO OVER THE BAHAMA ISLANDS. THIS IS ENHANCING THE SHOWERS/
ISOLATED THUNDERSTORMS THAT HAVE DEVELOPED OVER W CUBA MOVING S
INTO THE CARIBBEAN W OF THE ISLE OF YOUTH TO THE YUCATAN
CHANNEL. SCATTERED SHOWERS/THUNDERSTORMS ARE INLAND ALONG THE
IMMEDIATE COAST OF PANAMA AND COSTA RICA IN ASSOCIATION WITH THE
CLOSE PROXIMITY OF THE ITCZ AS IT ENTERS THE E PACIFIC REGION.
MOST NOTICEABLY IS THE LACK OF SHOWERS OR CLOUDS OVER E
CARIBBEAN E OF 65W TO ACROSS THE LESSER ANTILLES AND VIRGIN
ISLANDS.

ATLANTIC OCEAN...
THE MAIN FOCUS FOR THE W ATLC IS THE 1013 MB LOW OFF GEORGIA/
SOUTH CAROLINA COAST AND HURRICANE BERTHA N OF THE REGION...SEE
SPECIAL FEATURES ABOVE. A SHORTWAVE UPPER TROUGH IS OVER THE
N/CENTRAL ATLC N OF 28N FROM 52W-60W WITH A SURFACE TROUGH
EXTENDING FROM 31N56W TO 28N64W GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 125 NM S OF THE TROUGH AXIS. AN
UPPER LOW IS OVER CENTRAL CUBA TO OVER THE BAHAMA ISLANDS WITH A
SMALL UPPER HIGH TO THE NE CENTERED NEAR 30N62W. THIS PROVIDING
ENOUGH DIFFLUENCE ALOFT TO GENERATE SCATTERED CLUSTERS OF
SHOWERS/ISOLATED THUNDERSTORMS FROM 28N-30N BETWEEN 64W-68W.
ALSO AT THE SURFACE IS A WEAK 1020 MB HIGH NEAR 28N73W. ANOTHER
SMALL UPPER LOW IS IN THE CENTRAL ATLC NEAR 26N48W. A LARGE
UPPER HIGH COVERS THE REMAINDER OF THE ATLC ANCHORED NEAR
27N28W. STRONG SUBSIDENCE AND DRY STABLE AIR COVERS THE ATLC E
OF 50W WITH A SURFACE RIDGE ALSO COVERING THE E ATLC E OF 50W
ANCHORED BY 1030 MB HIGH N OF THE AZORES.

$$
WALLACE




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