[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 200526
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0500 UTC.

...SPECIAL FEATURE...

TROPICAL STORM DANIELLE CENTERED NEAR 29.7N 36.7W...OR ABOUT 800
MILES SW OF THE AZORES...AT 20/0300 UTC MOVING E 3 KT. MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1008 MB. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS. DANIELLE HAS BEEN MEANDERING OVER THE PAST 24 HOURS AND
REMAINS IN THE GRIPS OF A LARGE MID/UPPER LOW ABOUT 200 NM TO
ITS NORTH. THE SWLY SHEAR HAS BEEN UNRELENTING...AND THE
LOW-LEVEL CENTER IS STILL COMPLETELY EXPOSED 60 NM TO THE S OF
FREQUENT BURSTS OF CONVECTION. WIDELY SCATTERED MODERATE
CONVECTION FROM 31N-33N BETWEEN 34W-38W.

...TROPICAL WAVES...

TROPICAL WAVE CROSSING THE CAPE VERDE ISLANDS ALONG 23W/24W S OF
19N MOVING W 10-15 KT...WITH A 1013 MB LOW ALONG THE AXIS NEAR
16N. A SHIP JUST SE OF THE CAPE VERDES REPORTED A SW WIND AT 5
KT AT 0000 UTC AND SAL REPORTED A SE WIND AT 5 KT...WHICH SEEMS
TO SUPPORT THE LOCATION OF THE LOW. SW IR IMAGERY ALSO SHOWS A
WELL-DEVELOPED LOW-LEVEL CIRCULATION CROSSING THE ISLANDS BUT
ALL CONVECTION IS WELL TO THE SW ALONG THE ITCZ.

TROPICAL WAVE LOCATED 600 NM E OF THE WINDWARD ISLANDS ALONG 51W
S OF 17N MOVING W A LITTLE SLOWER NOW AT 15-20 KT. THE WAVE HAS
A VERY LOW AMPLITUDE AND ALL ASSOCIATED CONVECTION IS LIMITED TO
THE ITCZ.

E CARIBBEAN TROPICAL WAVE ALONG 65W S OF 16N MOVING W 15-20 KT.
THE WAVE IS VIRTUALLY INVISIBLE COMPARED TO 24 HOURS AGO...AND
CAN ONLY BE TRACED ALONG A CLUSTER OF TSTMS OVER CENTRAL
VENEZUELA. WIDELY SCATTERED MODERATE CONVECTION FROM 4N-9N
BETWEEN 63W-69W.

...ITCZ...

ITCZ AXIS EMERGES OFF THE COAST OF SENEGAL ALONG 16N16W
16N21W...THEN ALONG 11N26W 10N32W 9N60W 7N80W. SCATTERED
MODERATE CONVECTION WITHIN 120 NM OF THE AXIS BETWEEN 25W-35W.
ISOLATED TSTMS UP TO 180 NM S OF THE AXIS BETWEEN 35W-39W.
SCATTERED MODERATE WITHIN 125 NM OF THE AXIS BETWEEN 52W-60W.
SCATTERED MODERATE/STRONG 225 NM S OF THE AXIS OVER NW COLOMBIA.

...DISCUSSION...

GULF OF MEXICO...
STRONG SFC RIDGING OVER THE SUBTROPICAL ATLC CONTINUES TO REACH
WWD ALONG 30W TO THE FLORIDA PANHANDLE WITH BROAD SE/S FLOW
BRINGING LOTS OF TROPICAL MOISTURE FROM THE GULF INLAND BETWEEN
ALABAMA AND SE TEXAS. A MID/UPPER LEVEL SHORTWAVE TROF IS MOVING
ACROSS THE E GULF TOWARDS FLORIDA...WHICH WILL ONCE AGAIN
ENHANCE TSTM COVERAGE OVER THE PENINSULA LATER TODAY...BUT THE
VERTICAL LIFT AHEAD OF THIS FEATURE IS NOT ENOUGH TO CAUSE
WIDESPREAD CONVECTION. A WEAK LOW-LEVEL CONVERGENCE LINE HAS
BEEN DRAPED ACROSS THE GULF WATERS FOR MUCH OF THE
DAY...TRIGGERING ISOLATED SHOWERS/TSTMS WHICH NOW EXTEND FROM
26N-30N BETWEEN 88W-90W. TSTM COVERAGE MAY INCREASE ALONG THE
GULF COAST ON SAT AS A FRONTAL BOUNDARY BECOMES STATIONARY OVER
THE SOUTHEAST U.S.

CARIBBEAN...
THE AIR MASS IS BEGINNING TO MOISTEN UP AGAIN...ESPECIALLY OVER
THE SOUTHERN HALF OF THE CARIBBEAN...AFTER A SURGE OF DRIER AIR
TRAVERSED THE BASIN OVER THE PAST COUPLE OF DAYS. EVEN
STILL...THE GREATEST UPPER AIR SUPPORT IS FROM PANAMA SWD INTO
THE EPAC...WHICH HAS BEEN KEEPING MOST OF THE CONVECTION ALONG
THE ITCZ FROM COLOMBIA TO COSTA RICA. THE AREA IS STILL
DOMINATED BY AN UPPER TROF WHICH EXTENDS FROM PUERTO RICO SWWD
TO 12N78W IN THE SW CARIBBEAN WITH MODERATE/STRONG SUBSIDENCE
EXTENDING N TO THE GREATER ANTILLES.

SUBTROPICAL ATLANTIC...
THERE IS LITTLE SIGNIFICANT WEATHER ACROSS THE SUBTROPICS THIS
LATE NIGHT...AND EVEN THE HIGH LEVEL CLOUDINESS SEEMS TO BE
DIMINISHING. STRONG SUBTROPICAL RIDGING ALONG 30N EXTENDS W OF
45W WITH THE ELY TRADES LIMITED TO THE LOWEST LEVELS. A COLD
FRONT OVER THE NW ATLC IS SKIRTING THE AREA PAST BERMUDA BUT IS
ONLY INITIATING ISOLATED SHOWERS N OF 30N BETWEEN 63W-66W. A
GOOD AMOUNT OF UPPER LEVEL MOISTURE IS CROSSING FLORIDA INTO THE
W ATLC...BUT A NEARLY STATIONARY MID/UPPER LOW N OF PUERTO RICO
NEAR 23N65W CONTINUES TO SUSTAIN MOSTLY DRY AIR E OF 70W.
FARTHER E...MID/UPPER RIDGING LIES ALONG 20N50W 29N20W WITH A
SECOND MID/UPPER LOW RIDING ALONG THE NRN PERIPHERY OF THE RIDGE
N OF 30N BETWEEN 35W-50W. THIS LOW CONTINUES TO SHEAR APART T.S.
DANIELLE BUT SINCE THE UPPER AND LOW LEVEL CIRCULATIONS ARE
DECOUPLED...THE SWLY FLOW IS NOT SHOOTING THE STORM TO THE NE AS
PREVIOUSLY THOUGHT. THE RIDGE CONTINUES TO BUILD E BUT A
LEFTOVER MID/UPPER TROF IS LOITERING NEAR THE CANARY ISLANDS AND
APPROACHING THE COAST OF MOROCCO.

TROPICAL ATLANTIC...
A NEARLY CLOSED UPPER LEVEL ANTICYCLONE HAS DEVELOPED NE OF THE
LESSER ANTILLES NEAR 19N52W AND HAS INCREASED THE DEEP ELY FLOW
OVER THE TROPICS BETWEEN 45W-60W. TSTMS ASSOCIATED WITH THE 51W
TROPICAL WAVE AND THE ITCZ HAVE BEEN SPEEDING TO THE W AND
SHOULD BE AFFECTING THE SOUTHERN WINDWARD ISLANDS DURING THE
DAY. A COUPLE OF INVERTED TROFS ARE APPROACHING THE AREA FROM
THE E...ALONG ABOUT 30W AND 43W...WITH THE EASTERNMOST TROF
SUPPORTING A FLARE UP OF CONVECTION ALONG THE ITCZ BETWEEN
30W-38W. UPPER DIVERGENCE CONTINUES TO INCREASE OFF THE COAST OF
GUINEA AND SIERRA LEONE...WHICH SHOULD BE ABLE TO SUSTAIN
CONVECTION AS IT MOVES OFF THE COAST LATER TODAY.

$$
BERG


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