[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 021159
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU 02 SEP 2004

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 0945 UTC.

...SPECIAL FEATURES...

CATEGORY FOUR HURRICANE FRANCES CENTER NEAR 23.2N 73.5W OR ABOUT
80 MILES/135 KM...SOUTHEAST OF SAN SALVADOR ISLAND IN THE
BAHAMAS. THIS POSITION IS ALSO ABOUT 470 MILES/755 KM
EAST-SOUTHEAST OF PALM BEACH FLORIDA...AT 02/1500 UTC...MOVING
WEST-NORTHWEST 11 KT. MAXIMUM SUSTAINED WIND SPEED 125 KT/145
MPH WITH HIGHER GUSTS. ESTIMATED MINIMUM CENTRAL PRESSURE
REPORTED BY A RECONNAISSANCE AIRCRAFT IS 939 MB. SEE LATEST NHC
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC
AND THE FORECAST/ ADVISORY UNDER HEADERS MIATCMAT1/WTNT21 KNHC
FOR ADDITIONAL INFORMATION. FRANCES CONTINUES TO RADIATE
IMPRESSIVE UPPER LEVEL CIRRUS OVER THE NORTHERN...EASTERN...AND
SOUTHERN QUADRANTS EXTENDING OUTWARD UP TO 500 NM AWAY FROM THE
CENTER. THE OUTFLOW IS SLIGHTLY MORE RESTRICTED TO THE W OF THE
HURRICANE...ABOUT 225 NM AWAY...AS IT RUNS INTO THE DRIER AIR
NEAR AN UPPER TROF BETWEEN THE BAHAMAS AND FLORIDA. NUMEROUS
STRONG SHOWERS AND THUNDERSTORMS FROM 21N TO 24N BETWEEN 71W AND
75W. VERY HEAVY RAINFALL AND STRONG WINDS ARE NOW AFFECTING
PARTS OF THE SOUTHEASTERN BAHAMAS NOW...AND WILL CONTINUE TO
SPREAD ACROSS THE REST OF THE BAHAMAS DURING THE COURSE OF
TODAY. THE COLDEST CLOUD TOPS...COLDER THAN -70C...ARE ONCE
AGAIN WRAPPING ENTIRELY AROUND THE EYE. FLUCTUATIONS IN
INTENSITY ARE EXPECTED DURING THE NEXT 24 HOURS. RESIDENTS AND
VISITORS TO THE BAHAMAS AND FLORIDA ARE URGED TO FOLLOW THE
DIRECTIONS OF LOCAL EMERGENCY MANAGERS AND BE PREPARED TO
EXPERIENCE TROPICAL STORM OR HURRICANE CONDITIONS THROUGH THE
NEXT SEVERAL DAYS.

A 1012 MB LOW PRESSURE CENTER IS NEAR 19N40W...ALONG A TROUGH/
THE NORTHERN PART OF A TROPICAL WAVE...WHICH IS ALONG 25N39W
19N40W 15N40W. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND
THUNDERSTORMS FROM 18N TO 26N BETWEEN 34W AND 41W. STRONG UPPER
LEVEL SOUTHWESTERLY WINDS ARE AFFECTING THE SYSTEM (CIMSS
ESTIMATES SHOW 50 TO 60 KT OF SHEAR NORTHWEST OF THE LOW
CENTER). TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE WITHIN THE
NEXT 36 HOURS IF THE LOW CENTER IS ABLE TO WITHSTAND THE SHEAR.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 17N24W 10N25W 7N25W...NOW PASSING OVER THE
OF THE CAPE VERDE ISLANDS...MOVING WEST ABOUT 15 KT. AN 1010 MB
LOW PRESSURE CENTER IS ALONG THE WAVE NEAR 10N25W. SCATTERED
MODERATE TO STRONG SHOWERS AND THUNDERSTORMS FROM 7N TO 12N
BETWEEN 25W AND 30W. SEVERAL NUMERICAL MODELS STRENGTHEN THIS
SYSTEM OVER THE ATLANTIC OCEAN WATERS. IT WILL BE WATCHED FOR
FURTHER DEVELOPMENT.

TROPICAL WAVE ALONG 24N56W 16N58W 8N58W...MOVING WEST 15 KT.
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR
26N47W. CYCLONIC FLOW FROM 18N TO 32N BETWEEN 40W AND 55W.
ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS
FROM 16N TO 23N BETWEEN 45W AND 56W. BROAD MIDDLE LEVEL CYCLONIC
TURNING IS PRESENT FROM 12N TO 20N BETWEEN 54W AND 63W. UPPER
LEVEL ANTICYCLONIC OUTFLOW FROM HURRICANE FRANCES REACHES THE
EASTERN CARIBBEAN SEA ISLANDS NORTH OF 15N. OTHER UPPER LEVEL
CYCLONIC FLOW...IN DRY AIR...IS CUTTING ACROSS THIS WAVE FROM
WEST TO EAST...FROM BROAD UPPER LEVEL CYCLONIC FLOW. ITCZ-
RELATED SHOWERS AND THUNDERSTORMS ARE UP AGAINST THE COAST OF
SOUTH AMERICA FROM 7N TO 11N BETWEEN 57W AND 63W.

...ITCZ...

ITCZ 10N14W 8N23W 13N33W 9N50W 8N58W...AND IN THE CARIBBEAN SEA
10N76W 9N82W. ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND
THUNDERSTORMS IN THE WATERS FROM 4N TO 10N BETWEEN 10W AND 18W...
AND FROM 7N TO 10N BETWEEN 36W AND 48W. NO DISCERNIBLE DEEP
CONVECTIVE ACTIVITY IS APPARENT IN THE SOUTHWESTERN CORNER OF
THE CARIBBEAN SEA.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER LEVEL RIDGE STRETCHES FROM THE MEXICO PACIFIC COAST
NEAR 22N105W TOWARD SOUTH TEXAS AND SOUTHEASTERN LOUISIANA. IT
HELPS TO HAVE EASTERN PACIFIC HURRICANE HOWARD NEAR 17.0N 112.4W
AND ITS ASSOCIATED UPPER LEVEL OUTFLOW. THE UPPER LEVEL MOISTURE
WITH THIS ANTICYCLONIC FLOW IS WEST OF 30N88W 19N91W. ISOLATED
TO WIDELY SCATTERED MODERATE/LOCALLY STRONG SHOWERS ARE WEST OF
THIS LINE. ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND
THUNDERSTORMS ARE ALSO EAST OF 90W...IN AN AREA OF UPPER
LEVEL DIFFLUENT FLOW...WITH REGARD TO THE ATLANTIC-TO-STRAITS
OF FLORIDA TROUGH AND BROAD UPPER LEVEL ANTICYCLONIC WIND FLOW
ELSEWHERE IN THE EASTERN AND NORTHEASTERN GULF. MIDDLE TO UPPER
LEVEL CYCLONIC FLOW FROM 15N TO 23N BETWEEN 85W AND 93W...
ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS
FROM THE YUCATAN PENINSULA TO THE ISTHMUS OF TEHUANTEPEC OF
MEXICO. THE SURFACE TROUGH WHICH WAS A PART OF THE 02/0600 UTC
ANALYSIS WAS NOT A PART OF THE 02/0900 UTC ANALYSIS AS IT JUST
HAS BECOME TOO DIFFICULT TO LOCATE. THE ISOBARIC PATTERN DOES
INDICATE A CYCLONIC SENSE TO IT IN THE CENTRAL GULF.

...THE CARIBBEAN SEA...
MOST OF THE AREA ACTUALLY IS EXPERIENCING FAIRLY GOOD WEATHER...
WITH THE CIRCULATION OF HURRICANE FRANCES NOW NORTH OF
HISPANIOLA. THE DEEP-LAYERED FLOW IS MOSTLY FROM THE EAST BUT
EXTENSIVE CIRRUS OUTFLOW FROM THE HURRICANE HAS EXPANDED ACROSS
THE EXTREME WESTERN PART OF PUERTO RICO AND ALL OF HISPANIOLA...
EVEN APPEARING TO FAN OUT AS FAR SOUTH AS THE SOUTH CENTRAL
CARIBBEAN SEA WATERS...AND EVEN POSSIBLY TOUCHING NORTHERN
COLOMBIA. THERE IS A BIT OF A MIDDLE LEVEL TROUGH FROM THE
VENEZUELAN ISLANDS NORTHEASTWARD TO THE VIRGIN ISLANDS. MIDDLE
LEVEL DRY AIR IS IN PLACE WEST OF 65W...WITH THE UPPER LEVEL
HURRICANE OUTFLOW BLOWING RIGHT ON TOP OF IT.

...THE SUBTROPICAL ATLANTIC/THE TROPICAL ATLANTIC...
HURRICANE FRANCES IS MOVING TOWARD THE WEST-NORTHWEST AT THIS
MOMENT...ITS EYE IS NORTH OF THE SOUTHEASTERN BAHAMAS...MOVING
ROUGHLY TOWARD PARTS OF THE CENTRAL BAHAMAS. A MIDDLE TO UPPER
LEVEL TROUGH...AN OLD CLOSED CYCLONIC CENTER...RUNS FROM 31N74W
TO THE WATERS BETWEEN THE NORTHERN BAHAMAS AND FLORIDA...TOWARD
SOUTH FLORIDA AND THE STRAITS OF FLORIDA. THIS IS ADDING TO THE
WEAKNESS IN THE MIDDLE LEVEL RIDGE...WHICH IS ALLOWING HURRICANE
FRANCES TO TAKE A MORE WEST-NORTHWEST OR NORTHWEST TRACK NOW.
MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR
26N47W. CYCLONIC FLOW FROM 18N TO 32N BETWEEN 40W AND 55W.
ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS
FROM 16N TO 23N BETWEEN 45W AND 56W. BROAD UPPER LEVEL
ANTICYCLONIC FLOW FROM THE EQUATOR TO 30N BETWEEN AFRICA AND
40W...EXCEPT FOR A SMALL PART OF THE AREA ABOUT 350 NM WEST OF
THE CANARY ISLANDS...WHICH IS BEING OVERRUN BY THE BASE OF
MIDDLE TO UPPER LEVEL TROUGH WHICH IS DROPPING SOUTHWARD...AND
COVERING THE AREA NORTH OF 26N BETWEEN AFRICA AND 30W.

$$
MT


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