[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 241149
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU JUL 24 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...
DOLLY IS PRODUCING HEAVY RAINS OVER THE DEEP SOUTH TEXAS.
AT 24/1200 UTC IT IS NEAR 27.2N 98.9W...OR ABOUT 45 NM/80 KM
EAST-SOUTHEAST OF LAREDO TEXAS. DOLLY IS MOVING WEST-NORTHWEST 6
KT. A CONTINUED MOTION TOWARD THE WEST-NORTHWEST IS EXPECTED
DURING THE NEXT DAY OR SO...WITH A SLIGHT INCREASE IN FORWARD
SPEED UNTIL THE SYSTEM DISSIPATES ON FRIDAY. TROPICAL STORM
FORCE WINDS EXTEND OUTWARD UP TO 75 NM/140 KM FROM THE CENTER.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 45 KT WITH HIGHER GUSTS. PLEASE READ
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/
WTNT34 KNHC FOR MORE DETAILS. STRONG SHOWERS AND THUNDERSTORMS
ARE WITHIN 30 NM OF THE CENTER IN THE SOUTHERN SEMICIRCLE...AND
MOVING ONSHORE FROM 27N TO 28N BETWEEN 97W AND 98W. SCATTERED
MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE FROM 28N
TO 30N BETWEEN 92W AND 97W. DOLLY IS EXPECTED TO PRODUCE TOTAL
RAINFALL ACCUMULATIONS OF 8 TO 12 INCHES...WITH ISOLATED AMOUNTS
OF 20 INCHES...ACROSS SECTIONS OF SOUTH TEXAS AND NORTHEASTERN
MEXICO. IT IS LIKELY THAT THESE RAINS WILL CAUSE WIDESPREAD
FLOODING. DOLLY IS EXPECTED TO WEAKEN AS IT MOVES FARTHER
INLAND...AND IT IS EXPECTED TO BECOME A TROPICAL DEPRESSION LATER
TODAY.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 33W/34W SOUTH OF 22N
MOVING WEST ABOUT 15 KT. AN UPPER LEVEL TROUGH IS ALONG 22N34W
12N40W. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS
ARE FROM 14N TO 18N BETWEEN 32W AND 36W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 57W/58W SOUTH OF 18N
MOVING WEST 10 KT. THE LAST VISIBLE IMAGES IN THIS PART OF THE
ATLANTIC OCEAN ENDING AROUND 23/1945 UTC SHOWED SLIGHT CYCLONIC
FLOW IN THE LOW CLOUD FIELD AROUND 55W. THE LATEST SHORTWAVE
INFRARED IMAGERY SHOWED THE SAME AMOUNT OF SLIGHT CYCLONIC FLOW
IN THE LOW CLOUD FIELD NOW AROUND 57W/58W. WE WILL RELATE THE
POSITION OF THIS WAVE TO WHAT WE SEE IN THE IMAGERY. SHOWERS ARE
POSSIBLE FROM 15N TO 20N BETWEEN 53W AND 60W.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 83W/84W SOUTH OF
17N MOVING WEST 10 TO 15 KT. THIS WAVE IS MOVING THROUGH AN AREA
OF A MIDDLE TO UPPER LEVEL TROUGH. IT IS NOT EASY TO SEPARATE
ANY CONVECTIVE PRECIPITATION WITH THE TROUGH AND SOMETHING
THAT MAY BE OCCURRING WITH THE TROPICAL WAVE.

...THE ITCZ...
11N15W 12N23W 6N41W 6N53W. SCATTERED STRONG SHOWERS AND
THUNDERSTORMS FROM 7N TO 11N BETWEEN 16W AND 20W. ISOLATED
MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE ELSEWHERE
FROM 5N TO 12N BETWEEN 10W AND 23W.

...DISCUSSION...

THE GULF OF MEXICO...
TROPICAL STORM DOLLY IS ON TOP OF THE LOWER RIO GRANDE VALLEY.
EXPECT RAIN AND WIND AND POSSIBLE FLOODING IN THE DEEP SOUTH
TEXAS AND NORTHERN MEXICO FOR THE NEXT 24 TO 48 HOURS AS THE
PRESSURE AROUND DOLLY FILLS IN AND IT WEAKENS STEADILY.
UPPER LEVEL ANTICYCLONIC FLOW CURVES AWAY FROM DOLLY FOR
A DISTANCE OF 600 NM TO THE EAST OF DOLLY INTO GULF OF MEXICO.
THE BASE OF A MIDDLE TO UPPER LEVEL TROUGH MOVES SOUTHWARD FROM
THE EASTERN U.S.A. REACHING 29N87W IN THE NORTHEASTERN GULF OF
MEXICO. ISOLATED MODERATE SHOWERS ARE NORTH OF 28N BETWEEN 77W
AND 87W FROM THE ATLANTIC OCEAN INTO THE EASTERN GULF OF MEXICO.
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS ON TOP OF
THE BAHAMAS AND THE WATERS IN BETWEEN THE BAHAMAS AND CUBA NEAR
23N79W.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC OUTFLOW FROM TROPICAL STORM DOLLY
CURVES FROM THE CENTRAL AND EASTERN GULF OF MEXICO INTO THE
NORTHWESTERN CARIBBEAN SEA. SOME OF IT CROSSES HONDURAS AND
EVENTUALLY REACHES THE EASTERN PACIFIC OCEAN. A MIDDLE TO UPPER
LEVEL TROUGH EXTENDS FROM THE EASTERN CUBA TO NORTHERN HONDURAS
TO A CYCLONIC CIRCULATION CENTER IN EL SALVADOR. HIGH CLOUDS ARE
MOVING NORTHWARD BETWEEN 70W AND 80W. DRY AIR IN SUBSIDENCE
MOVES INTO THE CARIBBEAN SEA EAST OF 70W UNDER A SLIGHT AMOUNT
OF UPPER LEVEL ANTICYCLONIC FLOW.

THE ATLANTIC OCEAN...
ONE MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC
CIRCULATION CENTER NEAR 31N73W TO A CYCLONIC CENTER NEAR 23N79W
BETWEEN THE BAHAMAS AND CUBA. ISOLATED MODERATE SHOWERS ARE
BETWEEN 70W AND 71W FROM 26N TO 32N. A MIDDLE TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER IS NEAR 26N63W. CYCLONIC FLOW IS
WITHIN 180 NM OF THE CENTER IN THE NORTHERN SEMICIRCLE...AND
WITHIN 240 NM OF THE CENTER IN THE SOUTHERN SEMICIRCLE. A MIDDLE
TO UPPER LEVEL TROUGH EXTENDS FROM A 28N56W CYCLONIC CIRCULATION
CENTER TO 20N53W. THIS TROUGH IS SURROUNDED BY DRY AIR. A
SURFACE TROUGH IS ALONG 31N57W 23N60W. SHOWERS ARE POSSIBLE FROM
24N TO 32N BETWEEN 68W AND 71W. UPPER LEVEL ANTICYCLONIC FLOW IS
NORTH OF 25N BETWEEN 33W AND 43W. AN EASTERN ATLANTIC OCEAN
TROUGH EXTENDS FROM A 31N17W CYCLONIC CIRCULATION CENTER TO A
SECOND CYCLONIC CENTER NEAR 27N31W.

$$
MT


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