[Tropical] Tropical Weather Discussion

Tue Oct 5 00:31:57 CDT 2004

AXNT20 KNHC 050531
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE 05 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
0500 UTC.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED ABOUT 375 NM E OF BARBADOS ALONG 53W S OF
18N MOVING W 10 KT. AN ELONGATED E/W LOW-LEVEL CIRCULATION IS
LOCATED ALONG THE WAVE AXIS NEAR 13.5N53W BUT QSCAT IMAGERY FROM
A 2202Z PASS INDICATED PRIMARILY ELY TRADE WIND FLOW RUNNING
THROUGH THE AXIS. THE FLOW AROUND THE WAVE IS NO MORE THAN ABOUT
5-10 KT AT THE MOMENT...WHICH IS GIVING THE AXIS SUCH A SLOW WWD
TRANSLATION. A LARGE BATCH OF TSTMS WHICH WAS CENTERED JUST E OF
THE WAVE HAS DISSIPATED...BUT ADDITIONAL WIDELY SCATTERED
MODERATE CONVECTION IS DEVELOPING FROM 13.5N-16N BETWEEN 53W-56W.

W CARIBBEAN TROPICAL WAVE ALONG 80W S OF 21N MOVING W 15-20 KT.
THE WAVE HAS BECOME VERY DIFFUSE AND IS ESSENTIALLY BEING
TRACKED BY A PATCH OF LOW/MID LEVEL CLOUDS CROSSING 80W AND
NEARING THE HONDURAS/NICARAGUA COAST. HOWEVER...THE CURACAO
UPPER LEVEL SOUNDING INDICATES A WAVE PASSAGE BETWEEN THE
SURFACE AND 700 MB ALMOST 24 HOURS AGO...SO THE CURRENT POSITION
SEEMS REASONABLE PLUS OR MINUS A DEGREE OR TWO. THERE IS VERY
LITTLE CONVECTIVE ACTIVITY ASSOCIATED WITH THE WAVE
ITSELF...EXCEPT FOR ISOLATED TSTMS OVER THE FAR SW CARIBBEAN AND
WIDELY SCATTERED MODERATE ALONG THE HONDURAS/NICARAGUA COAST.

TROPICAL WAVE MOVING W OVER THE MOUNTAINOUS TERRAIN OF MEXICO
ALONG 98W S OF 22N MOVING W 15 KT. AS THE MAIN WAVE AXIS MOVES W
OVER THE PACIFIC WATERS WITH STRONG CONVECTION NEAR ACAPULCO...A
LEFTOVER PIECE OF THE WAVE IS HANGING UP ALONG THE EASTERN
SLOPES OF THE SIERRA MADRE ORIENTAL MOUNTAINS FROM NEAR TAMPICO
TO COATZACOALCOS. THIS FEATURE IS ENHANCING LOW-LEVEL
CONVERGENCE AND PRODUCING WIDELY SCATTERED MODERATE CONVECTION
OVER THE W GULF OF MEXICO FROM 18N-25N BETWEEN 90W-97W.

...ITCZ...

ITCZ AXIS EMERGES OFF THE COAST OF GUINEA ALONG 10N13W 10N25W
6N42W 10N50W...THEN ALONG 9N55W 7N65W 8N79W. WIDELY SCATTERED
MODERATE OFF THE COASTS OF SIERRA LEONE AND LIBERIA FROM 5N-8N
BETWEEN 9W-16W. ISOLATED MODERATE WITHIN 120 NM OF THE AXIS
BETWEEN 26W-32W. NUMEROUS MODERATE/SCATTERED STRONG WITHIN 250
NM N AND 160 NM S OF THE AXIS BETWEEN 33W-48W. SCATTERED
MODERATE/STRONG OVER MUCH OF NW VENEZUELA INCLUDING ALONG AND UP
TO 90 NM OFF THE COAST BETWEEN CARACAS AND MARACAIBO.

...DISCUSSION...

GULF OF MEXICO...
WEAK HIGH PRES HAS BUILT IN OVER MUCH OF THE GULF BEHIND A
DISSIPATING COLD FRONT...WHICH IS NOW BECOMING STATIONARY...
EXTENDING FROM 32N67W 28.5N76W THEN WWD ACROSS CNTRL FLORIDA TO
28N85W. A FEW ISOLATED SHOWERS/TSTMS HAD DEVELOPED ALONG THIS
BOUNDARY OVER CNTRL FLORIDA EARLIER THIS EVENING BUT ARE NOW
DISSIPATING. WATER VAPOR INDICATES THAT THE MID/UPPER LEVEL FLOW
OVER THE AREA IS PREDOMINANTLY WLY WITH THE STRONGEST TROF
ENERGETICS SWEEPING ACROSS THE GREAT LAKES...AND THIS HAS NOT
BEEN ENOUGH TO SUSTAIN THE FRONT OVER FLORIDA AND THE GULF.
HOWEVER...MODEL GUIDANCE SUGGESTS THAT A SECOND FRONT NOW OVER
THE APPALACHIANS AND DEEP SOUTH WILL MOVE OFF THE EAST COAST
DURING THE DAY WITH STRONGER HIGH PRES BUILDING SWD INTO
FLORIDA. THIS WILL CREATE WINDY CONDITIONS ACROSS FLORIDA AND
THE WATERS OF THE E GULF AND W ATLC BEGINNING WEDNESDAY.
ELSEWHERE...A FEW MESOSCALE CONVECTIVE COMPLEXES THAT DEVELOPED
ACROSS TEXAS AND LOUISIANA ARE NOW NEAR THE GULF COASTAL WATERS
WITH WIDELY SCATTERED SHOWERS/TSTMS EXTENDING FROM THE
MISSISSIPPI/ALABAMA BORDER WWD INTO E TEXAS. OTHER SHOWERS/TSTMS
ARE OVER THE W GULF NEAR A SFC TROF ALONG THE MEXICAN COAST AS
DESCRIBED IN THE TROPICAL WAVES SECTION ABOVE.

CARIBBEAN...
A DEEP MID/UPPER LEVEL CUT-OFF TROF HAS DUG DOWN WELL INTO THE
CARIBBEAN BASIN...EXTENDING BETWEEN THE NORTHERN LEEWARD ISLANDS
AND THE CAYMAN ISLANDS SWD TO THE N COAST OF VENEZUELA. AN
ELONGATED BUT WELL-DEFINED CIRCULATION IS OBSERVED IN THIS TROF
JUST SW OF PUERTO RICO AND WATER VAPOR IMAGERY SHOWS A LARGE
AREA OF MODERATE/STRONG SUBSIDENCE SWEEPING ACROSS A GOOD CHUNK
OF THE CNTRL CARIBBEAN. AS SUCH...MOST OF THE AREA E OF 80W IS
UNDER FAIR SKIES EXCEPT FOR THE OCCASIONAL TRADE WIND SHOWER
OVER THE E CARIBBEAN WATERS. NEAR CENTRAL AMERICA...AN UPPER
RIDGE EXTENDS FROM PANAMA NWWD TO THE YUCATAN COAST AND THIS IS
WHERE MOST OF THE SHOWER/TSTM ACTIVITY IS FOCUSED WITH WIDELY
SCATTERED MODERATE CONVECTION SPECKLING THE AREA FROM BELIZE
DOWN TO COSTA RICA. SUFFICIENT UPPER LEVEL DIVERGENCE S OF THE
UPPER LEVEL TROF IS ALSO ENHANCING CONVECTIVE ACTIVITY OVER MUCH
OF NW VENEZUELA.

SUBTROPICAL ATLANTIC...
WESTERLY UPPER LEVEL FLOW EXTENDS FROM FLORIDA EWD OVER OPEN
WATERS TO ABOUT 60W WITH MOSTLY DRY AIR COVERING THE SAME AREA
SWD INTO THE CARIBBEAN. A LEFTOVER TROF/SHEAR AXIS WITH MULTIPLE
EMBEDDED CIRCULATIONS EXTENDS INTO THE AREA THEN SWWD ALONG
32N54W 25N60W 18N67W AND ABUNDANT MOISTURE IS BEING PULLED NWD
ON THE E SIDE OF THIS AXIS FROM THE CARIBBEAN ACROSS MUCH OF THE
CNTRL ATLC. TWO SEPARATE SFC TROFS ARE EMBEDDED BENEATH THIS
MOISTURE...ONE FROM 18N59W TO 29N53W AND THE OTHER FROM 19N48W
TO 26N42W...AND EACH IS PRODUCING SHOWERS/TSTMS OVER THE AREA.
SCATTERED MODERATE CONVECTION IS FROM 26N-30N BETWEEN 51W-58W.
WIDELY SCATTERED SHOWERS/TSTMS ARE FROM 20N-25N BETWEEN 40W-61W.
FARTHER E...A TUMBLING MID/UPPER LEVEL ANTICYCLONE IS CENTERED
NEAR 29N39W AND IS MOVING TO THE E INTO THE E ATLC. A STRONG
MID/UPPER LOW IS CENTERED BETWEEN THE CANARY ISLANDS AND MADEIRA
ISLAND NEAR 31N16W WITH A TROF EXTENDING SWWD TO 23N30W. A FEW
SHOWERS MAY EXTEND NEAR THE EASTERNMOST CANARY ISLANDS AND COAST
OF MOROCCO BUT OVERALL IT IS MOSTLY MID/UPPER LEVEL MOISTURE
SPREADING E OF THE LOW.

TROPICAL ATLANTIC...
WITH DEEP UPPER LEVEL TROUGHING CENTERED OVER THE CARIBBEAN...A
BROAD SWATH OF UPPER MOISTURE IS BEING PULLED NEWD ACROSS THE
LESSER ANTILLES INTO THE TROPICAL CNTRL ATLC WHERE A RIDGE AXIS
EXTENDS FROM 10N40W TO 19N53W. BROAD UPPER LEVEL DIVERGENCE IS
OCCURRING MOSTLY TO THE S OF THE RIDGE/CNTRL HIGH WHICH HAS
ULTIMATELY LED TO A LARGE OUTBREAK OF ITCZ CONVECTION BETWEEN
33W-45W. WESTERLY FLOW EXTENDS E OF 38W INTO THE E ATLC...THEN
NEWD ACROSS THE CAPE VERDE ISLANDS INTO W AFRICA. ANOTHER RIDGE
PROTRUDES W OF AFRICA ALONG 13N24W 16N10W WITH A SURGE OF E/SE
FLOW AND DRIER AIR COMING IN FROM THE SOUTHERN HEMISPHERE.

$$
BERG

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