[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 290536
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI 29 OCT 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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
0515 UTC.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED ABOUT 375 NM E OF THE LESSER ANTILLES
ALONG 54W S OF 18N MOVING W NEAR 15 KT. A DISTINCT LOW-LEVEL
FEATURE IS OBSERVED IN SHORTWAVE IR IMAGERY BUT MODERATE/STRONG
SUBSIDENCE IN THE AREA IS MOSTLY LIMITING DEEP CONVECTION.
WIDELY SCATTERED SHOWERS/TSTMS ARE FROM 11N-17N BETWEEN 51W-56W
CONCENTRATED AT THE LATITUDE OF GUADELOUPE.

TROPICAL WAVE LOCATED BETWEEN HAITI AND JAMAICA ALONG 76W S OF
18N MOVING W NEAR 10 KT. A 2324 UTC QSCAT PASS INDICATED A SHARP
WIND SHIFT TO THE N OF BARRANQUILLA COLOMBIA AND AN EASTERLY
WIND SURGE OVER THE E/CNTRL CARIBBEAN. LOW-LEVEL SPEED
CONVERGENCE AND THE WAVE AXIS ITSELF IS PRODUCING SCATTERED
MODERATE/STRONG CONVECTION FROM 13N-17N BETWEEN 73W-77W.

...ITCZ...

ITCZ AXIS IS ALONG 14N10W 7N30W 10N50W 10N85W. ISOLATED MODERATE
CONVECTION UP TO 350 NM S OF THE AXIS BETWEEN 12W-26W ESPECIALLY
OFF THE COAST OF SIERRA LEONE. SCATTERED MODERATE WITHIN 120 NM
OF THE AXIS BETWEEN 29W-33W. SCATTERED MODERATE 150 NM N OF THE
AXIS BETWEEN 35W-39W. ISOLATED SHOWERS/TSTMS NEAR TRINIDAD...
TOBAGO...AND GRENADA FROM 10N-12N BETWEEN 59W-62W. SCATTERED
MODERATE OVER MUCH OF W VENEZUELA. WIDELY SCATTERED MODERATE
OVER N COLOMBIA...PANAMA...AND THE SW CARIBBEAN SEA.

...DISCUSSION...

GULF OF MEXICO...
DEEP-LAYERED RIDGING REMAINS ENTRENCHED OVER FLORIDA AND THE
GULF OF MEXICO WITH VERY LITTLE CLOUD COVER OVER THE AREA. THE
SFC RIDGE EXTENDS FROM NEW ENGLAND TO THE CAROLINAS...WHERE A
MINOR COLD AIR DAMMING EPISODE IS ADDING REINFORCEMENT...THEN
BROADENS OVER THE GULF OF MEXICO. A MID/UPPER LEVEL HIGH IS
CENTERED OVER THE W GULF NEAR 24N93W WITH A RIDGE BUILDING NWD
INTO THE MISSISSIPPI VALLEY AND SOUTHERN PLAINS. MODERATE/STRONG
SUBSIDENCE IS IN CONTROL AND LIMITING MID/UPPER LEVEL CLOUDS BUT
HIGHER LEVELS OF LOW-LEVEL MOISTURE OVER THE W ATLC IS ADVECTING
PATCHES OF STRATOCUMULUS TOWARDS THE FLORIDA COAST FROM THE NE.
CONDITIONS WILL REMAIN PRETTY MUCH THE SAME UNTIL LATE MON OR
TUES WHEN A COLD FRONT MOVES OFF THE TEXAS COAST.

CARIBBEAN...
THE MID/UPPER LEVEL TROF WHICH HAS BEEN SITTING OVER THE
CARIBBEAN SEA FOR THE PAST SEVERAL DAYS HAS FLATTENED OUT A BIT
AND NOW EXTENDS FROM THE DOMINICAN REPUBLIC SWWD TO 14N80W
INLAND OVER N NICARAGUA. A WEAK LOW IS LOCATED ALONG THIS AXIS
NEAR 14N77W AND IS ENHANCING CONVECTION NEAR THE TROPICAL WAVE
ALONG 76W. OTHERWISE...A LARGE AREA OF DRY AIR HAS SPREAD ACROSS
MOST OF THE NW CARIBBEAN EWD TO PUERTO RICO WITH ONLY A FEW
PATCHES OF STRATOCUMULUS STRAGGLING ACROSS CUBA TOWARDS THE GULF
OF HONDURAS. UPPER LEVEL RIDGING HAS SET UP ALONG THE COAST OF
VENEZUELA AND COLOMBIA WHICH HAS ALLOWED MID/UPPER LEVEL
MOISTURE TO SPREAD NWD OVER THE S AND E CARIBBEAN. A DISSIPATING
TROF OVER THE E CARIBBEAN WATERS CONTINUES TO INITIATE SCATTERED
SHOWERS/TSTMS FROM 12N-16N BETWEEN 63W-67W.

ATLANTIC WEST OF 50W...
A WEAKENING MID/UPPER LEVEL TROF CONTINUES TO EXTEND NE OF THE
DOMINICAN REPUBLIC TO 21N62W 30N54W BUT IS NOW BEING OVERTAKEN
BY A STRONGER MID-LATITUDE TROF WHICH IS SWEEPING ACROSS THE W
ATLC WATERS ALONG 64W. A COLD FRONT STRETCHES FROM A GALE CENTER
N OF THE AREA ALONG 32N50W 25N55W TO ABOUT 80 NM N OF THE VIRGIN
ISLANDS WHICH MUCH DRIER AIR AND PATCHY STRATOCUMULUS STRETCHING
W TO THE U.S. COAST. SCATTERED SHOWERS/TSTMS WITH EMBEDDED
ISOLATED MODERATE CONVECTION EXTENDS UP TO 150 NM E OF THE FRONT
N OF 20N. THESE STORMS ARE EMBEDDED WITHIN A NARROW SWATH OF
MID/UPPER LEVEL MOISTURE WHICH EXTENDS FROM THE NRN LEEWARD
ISLANDS TO 30N45W...ALIGNED ALONG A 70-80 KT SWLY JET ON THE E
SIDE OF THE TROF.

ATLANTIC EAST OF 50W...
BROAD MID/UPPER LEVEL RIDGING SPANS ACROSS MUCH OF THE E/CNTRL
ATLC CENTERED ALONG 36W. A 1020 MB HIGH IS CENTERED JUST TO THE
E OF THE UPPER LEVEL RIDGE NEAR 24N33W WITH A SFC RIDGE ALONG
22N55W 26N20W. DESPITE THE BROAD-SCALE RIDGE...HOWEVER...TWO
DISTINCT CUT-OFF LOWS ARE TRAPPED IN THE WEAK FLOW AND ARE
CENTERED NEAR 17N43W AND 23N32W. THE WESTERNMOST LOW IS
PRODUCING ISOLATED SHOWERS/TSTMS WITHIN 125 NM W AND S OF THE
CENTER AS WELL AS WIDELY SCATTERED SHOWERS UP TO 350 NM TO THE E
AND SE. THE EASTERN LOW IS DRY AND CAUSING NO SIGNIFICANT
WEATHER. A RAGGED MID/UPPER HIGH IS CENTERED ABOUT 375 NM SW OF
THE CAPE VERDE ISLANDS WITH THE DEEPEST EASTERLY FLOW LIMITED TO
S OF 10N. NLY CROSS EQUATORIAL FLOW E OF 40W IS PRODUCING SOME
UPPER LEVEL DIFFLUENCE NEAR THE ITCZ...BUT ONLY WIDELY SCATTERED
TSTM CLUSTERS HAVE BEEN DEVELOPING NEAR THE AXIS. ELSEWHERE...A
LARGE UPPER LEVEL VORTEX IS CENTERED NEAR FRANCE AND THE BRITISH
ISLES WITH TROUGHING EXTENDING SWD PAST THE CANARY ISLANDS TO
THE CAPE VERDE ISLANDS AND MAURITANIA.

$$
BERG


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