[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 132357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI 13 AUG 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2330 UTC.

...SPECIAL FEATURES...

HURRICANE CHARLEY IS NOW CENTERED INLAND NEAR 28.0N 81.6W...OR
40 MILES SSW OF ORLANDO FLORIDA...AT 14/0000 UTC MOVING NNE 22
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 950 MB. MAXIMUM
SUSTAINED WIND SPEED HAS DECREASED TO 100 KT WITH HIGHER GUSTS.
SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
CHARLEY MADE LANDFALL AS A MAJOR CATEGORY 4 HURRICANE AT 3:45
PM...OR 1945 UTC...NEAR CAYO COSTA ISLAND AT THE MOUTH OF
CHARLOTTE HARBOR FLORIDA...OR JUST N OF SANIBEL ISLAND. THE
HURRICANE CONTINUES TO MOVE QUICKLY TO THE NNE APPROACHING
ORLANDO AND HAS MAINTAINED A WELL-DEVELOPED NEARLY CIRCULAR
SIGNATURE ON RADAR IMAGERY. A LARGE AREA OF VERY HEAVY RAINFALL
NOW EXTENDS ALONG MOST OF THE LENGTH OF THE FLORIDA PENINSULA
FROM NEAR NAPLES NWD TO THE GEORGIA BORDER...WITH THE HEAVIEST
CONVECTION WITHIN 40 NM OF THE CENTER AND WITHIN A STRONG SPIRAL
BAND WHICH EXTENDS FROM CAPE CANAVERAL TO DAYTONA BEACH TO OCALA
(WHICH ALSO HAPPENS TO CONTAIN A LARGE NUMBER OF LIGHTNING
STROKES). AN ADDITIONAL SPIRAL BAND EXTENDS FROM NEAR VERO BEACH
AND FT. PIERCE SWWD TO FT. MYERS AND NAPLES. NUMEROUS
MODERATE/STRONG CONVECTION FROM 26N-31N BETWEEN 80W-83W. IN
SATELLITE IMAGERY...CLOUD TOPS HAVE COOLED AND BECOME SLIGHTLY
MORE DISORGANIZED SINCE LANDFALL AND THE OUTFLOW IS JUST ABOUT
LIMITED TO THE NE QUADRANT AS THE STORM GETS SWEPT UP IN DEEP
SWLY FLOW.

TROPICAL DEPRESSION FIVE HAS DEVELOPED ABOUT 910 NM ESE OF THE
WINDWARD ISLANDS NEAR 8.9N 42.6W AT 18/2100 UTC MOVING W 17 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC
FOR MORE DETAILS. THE DEPRESSION HAS A SLIGHTLY ELONGATED
CIRCULATION EXTENDING JUST N OF THE ITCZ...BUT CONVECTION HAS
BECOME A LITTLE STRONGER AND CLOSER TO THE CENTER THROUGHOUT THE
DAY. CURRENTLY...THE TSTMS ARE FOCUSED IN AN AREA NEAR THE
CENTER WITH SCATTERED MODERATE FROM 7N-10N BETWEEN 45W-49W AND
ALSO ALONG A BAND RADIATING WWD FROM THE SYSTEM FROM 9N-12N
BETWEEN 43W-50W. THE SYSTEM IS FORECAST TO APPROACH THE WINDWARD
ISLANDS SUN EVENING...WITH HEAVY RAINFALL POSSIBLY MOVING IN
DURING THE DAY SUN.

TROPICAL DEPRESSION FOUR CENTERED NEAR 12.5N 24.0W...OR ABOUT
210 NM S OF THE CAPE VERDE ISLANDS...AT 18/2100 UTC MOVING W 13
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. MAXIMUM
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24
KNHC FOR MORE DETAILS. THE DEPRESSION HAS A PRONOUNCED AND
ALMOST CIRCULAR LOW/MID LEVEL PATTERN WITH A STRONG BAND OF
CONVECTION UP TO 160 NM S OF THE CENTER...WITH SCATTERED
MODERATE/STRONG FROM 10N-13N BETWEEN 22W-26W. ALSO...A WEAKER
BAND OF CONVECTION HAS DEVELOPED OVER THE NRN SEMICIRCLE OF THE
DEPRESSION WITH WIDELY SCATTERED MODERATE SWINGING THROUGH THE
ISLANDS OF MAIO...SANTIAGO...FOGO...AND BRAVA FROM 13N-16N
BETWEEN 23W-26W. THE DEPRESSION IS EMBEDDED WITHIN DEEP EASTERLY
FLOW...PRODUCING VERY LOW VERTICAL SHEAR VALUES...SO
INTENSIFICATION IS ANTICIPATED OVER THE NEXT 24-36 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED ABOUT 140 NM E OF BARBADOS ALONG 57W S OF
17N MOVING W 10-15 KT. THE WAVE IS APPROACHING THE WINDWARD
ISLANDS WITH ONLY ISOLATED SHOWERS/TSTMS FROM 11N-14N BETWEEN
56W-62W SPREADING FROM TRINIDAD NWD TO MARTINIQUE. THESE SHOWERS
WILL CONTINUE MOVING ACROSS THE ISLANDS INTO THE E CARIBBEAN
THROUGH SAT AFTERNOON.

...ITCZ...

ITCZ AXIS EMERGES OFF THE COAST OF SENEGAL ALONG 16N16W
16N20W...THEN FARTHER S ALONG 9N20W 6N33W 7N41W 5N48W 7N55W
5N62W 8N73W. SCATTERED MODERATE CONVECTION FROM 11N-17N BETWEEN
13W-17W OVER PARTS OF SENEGAL...GAMBIA...AND GUINEA-BISSAU.
WIDELY SCATTERED SHOWERS/TSTMS UP TO 140 NM N OF THE AXIS
BETWEEN 26W-31W. WIDELY SCATTERED MODERATE OVER PARTS OF GUYANA
AND VENEZUELA.

...DISCUSSION...

GULF OF MEXICO...
A STRONG UPPER LEVEL TROF CONTINUES TO SIT OVER THE N GULF
WATERS...GENERALLY N OF 27N...WITH AREAS OF DRY AIR INFILTRATING
SWD INTO THE W/CNTRL GULF. A FRONT...WHICH HAD BEEN MOVING EWD
ACROSS THE GULF AHEAD OF THE TROF...HAS RUN INTO HURRICANE
CHARLEY AND HAS ESSENTIALLY PULLED UP STATIONARY FROM NEAR
TALLAHASSEE FLORIDA SWWD TO 24N92W IN THE W GULF. THERE IS JUST
ENOUGH LOW-LEVEL CONVERGENCE TO SUPPORT ISOLATED SHOWERS/TSTMS
OVER THE W GULF FROM 21N-26N BETWEEN 88W-95W...BUT OF COURSE THE
MOST PRESSING ISSUE CURRENTLY IS THE HEAVY RAINFALL AND WINDS
NOW OVER CNTRL FLORIDA NEAR CHARLEY (SEE SPECIAL FEATURES ABOVE
FOR FURTHER DISCUSSION). EVEN AS CHARLEY MOVES NE OF FLORIDA TO
THE SOUTHEAST U.S. COAST...THE GFS SHOWS VERY LITTLE CHANGES IN
THE UPPER LEVEL FLOW PATTERN UNTIL THE TROF BEGINS TO LIFT OUT
ABOUT MON AND STRONGER RIDGING IS RE-ESTABLISHED ACROSS THE GULF.

CARIBBEAN...
DEEP EASTERLY FLOW EXTENDS ACROSS MUCH OF THE CARIBBEAN FROM THE
LESSER ANTILLES WWD TO ABOUT 83W...WITH THE REMNANT UPPER LOW
WHICH HAD BEEN AFFECTING HURRICANE CHARLEY NOW SITTING JUST
OFFSHORE COZUMEL MEXICO EXTENDING SWD TO THE GULF OF HONDURAS.
THE FLOW HAS USHERED IN A CONSIDERABLE SURGE OF DRY AIR ACROSS
THE BASIN BUT IT DOES APPEAR THAT THE AIR MASS IS MOISTENING UP
AGAIN OVER THE E CARIBBEAN. A LOW-LEVEL TROF HAS BEEN MOVING
ACROSS PUERTO RICO AND THE VIRGIN ISLANDS ALONG 15N68W
23N63W...AND THIS HAS SPURRED ISOLATED SHOWERS FROM THE NORTHERN
LEEWARD ISLANDS WWD TO HISPANIOLA. A FEW MORE SHOWERS WILL MOVE
ACROSS THE WINDWARD ISLANDS TONIGHT AND SAT ALONG AN APPROACHING
TROPICAL WAVE. THE NEXT SYSTEM TO WATCH FOR WILL BE TROPICAL
DEPRESSION FIVE WHICH IS FORECAST TO AFFECT THE WINDWARD ISLANDS
IN THE NEXT 48-72 HOURS.

SUBTROPICAL ATLANTIC...
A NARROWING UPPER LEVEL RIDGE EXTENDS FROM THE W BAHAMAS NEWD TO
32N73W WITH BROAD SWLY FLOW TO THE W PUSHING HURRICANE CHARLEY
ACROSS CNTRL FLORIDA TOWARDS THE SOUTHEAST U.S. COAST. WEAK SFC
RIDGING EXTENDS INTO THE AREA ALONG 28N BUT AN UPPER LOW NEAR
29N60W IS PRODUCING WIDELY SCATTERED MODERATE CONVECTION FROM
27N-32N BETWEEN 53W-62W. A SECOND UPPER LEVEL LOW/SHORTWAVE TROF
IS LOCATED NEAR 29N46W AND IS PRODUCING ITS OWN AREA OF WIDELY
SCATTERED MODERATE FROM 30N-33N BETWEEN 47W-50W...WHICH HAPPENS
TO BE JUST S OF A STATIONARY FRONT ALONG 33N. ELSEWHERE...A
STRONG UPPER HIGH IS CENTERED NEAR 23N41W WHILE A WEAK LEFTOVER
UPPER TROF APPROACHES THE CANARY AND MADEIRA ISLANDS FROM THE W.

TROPICAL ATLANTIC...
WITH THE STRONG UPPER LEVEL HIGH CENTERED NEAR 23N41W OVER THE
CENTRAL ATLC...THE MAJORITY OF THE TROPICAL ATLC IS UNDER THE
INFLUENCE OF STRONG EASTERLY FLOW AND LOW VALUES OF VERTICAL
SHEAR. THE UPPER PATTERN IS DIFFLUENT IN TWO AREAS...BOTH OF
WHICH ARE SUPPORTING CONVECTION NEAR T.D. FOUR AND FIVE. THE
RIDGE MAY SHIFT SLIGHTLY FARTHER S TO 18N/19N OVER THE NEXT
48-72 HOURS...WITH SOME INCREASING SHEAR POSSIBLE BETWEEN
40W-50W AS A CUT-OFF LOW DEVELOPS OVER THE SUBTROPICS.

$$
BERG




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