[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 051037
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED ABOUT 300 NM E OF BARBADOS ALONG 54W S OF
20N MOVING W 10 KT. CONFIDENCE IN THE WAVE POSITION REMAINS LOW
AT THE MOMENT...NAMELY BECAUSE SEVERAL LOW-LEVEL CIRCULATIONS
HAVE BEEN OBSERVED IN DIFFERENT LOCATIONS OVER THE PAST 12 HOURS
OR SO. ISOLATED SHOWERS AND A WEAK V-SHAPE TO THE LOW-LEVEL FLOW
OVER AND TO THE NE OF THE LESSER ANTILLES WOULD ALMOST SUGGEST
THE WAVE BEING FARTHER W BETWEEN 58W-66W...BUT A NEW CIRCULATION
HAS NOW EMERGED FARTHER E NEAR 14N52W. THE WAVE IS MOVED BASED
ON CONTINUITY UNTIL VISIBLE IMAGERY GIVES A BETTER INDICATION OF
THE POSITION. SCATTERED MODERATE CONVECTION FROM 14N-18N BETWEEN
45W-53W.

W CARIBBEAN TROPICAL WAVE ALONG 82W/83W S OF 20N MOVING W 15-20
KT. A LINE OF TSTMS HAS DEVELOPED OFF THE NICARAGUA COAST IN
GOOD ALIGNMENT WITH THE WAVE AXIS. ALSO...THE CURACAO UPPER
LEVEL SOUNDING INDICATES A WAVE PASSAGE BETWEEN THE SURFACE AND
700 MB ABOUT 24 HOURS AGO...SO THE CURRENT POSITION SEEMS
REASONABLE PLUS OR MINUS A DEGREE OR TWO. CONVECTION HAS
BLOSSOMED OVER THE PAST COUPLE OF HOURS WITH SCATTERED
MODERATE/STRONG NOW FROM 10N-13N BETWEEN 79W-83W. WIDELY
SCATTERED MODERATE FROM 13N-17N BETWEEN 80W-84W.

TROPICAL WAVE MOVING W OVER THE MOUNTAINOUS TERRAIN OF MEXICO
ALONG 99W/100W IS NOW WEST OF THE AREA. A LEFTOVER PIECE OF THE
WAVE HAS HUNG 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
INCREASINGLY SCATTERED MODERATE CONVECTION OVER THE W GULF OF
MEXICO FROM 17N-26N BETWEEN 91W-97.5W.

...ITCZ...

ITCZ AXIS EMERGES OFF THE COAST OF SIERRA LEONE ALONG 10N11W
7N14W 6N21W...THEN ALONG 10N22W 9N30W 9N50W...THEN ALONG 6N56W
10N81W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 120
NM N AND 200 NM S OF THE AXIS BETWEEN 9W-17W. SCATTERED MODERATE
FROM 6N-10N BETWEEN 29W-34W. NUMEROUS MODERATE/WIDELY SCATTERED
STRONG FROM 6N-11N BETWEEN 34W-42W. ISOLATED SHOWERS/TSTMS 220
NM S OF THE AXIS BETWEEN 42W-51W. WIDELY SCATTERED MODERATE E OF
BONAIRE OVER THE VENEZUELAN ISLANDS FROM 10N-13N BETWEEN
64W-69W. SCATTERED MODERATE/STRONG NEAR LAKE MARACAIBO.

...DISCUSSION...

GULF OF MEXICO...
WEAK HIGH PRES HAS BUILT IN OVER MUCH OF THE GULF BEHIND A
DISSIPATING STATIONARY FRONT EXTENDING FROM 32N66W 28N76W THEN
WWD ACROSS CNTRL FLORIDA TO 28N84W. WATER VAPOR INDICATES THAT
THE MID/UPPER LEVEL FLOW OVER THE AREA IS PREDOMINANTLY WLY WITH
SLIGHT ANTICYCLONIC CURVATURE. THE STRONGEST TROF ENERGETICS ARE
SWEEPING ACROSS SRN ONTARIO AND QUEBEC...AND THIS HAS NOT BEEN
FAR ENOUGH S TO SUSTAIN THE FRONT OVER FLORIDA AND THE GULF.
HOWEVER...MODEL GUIDANCE SUGGESTS THAT A SECOND FRONT NOW ALONG
THE CAROLINA COAST 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 MESOSCALE CONVECTIVE COMPLEX THAT DEVELOPED ALONG
THE RIO GRANDE VALLEY IS NOW PRODUCING VERY HEAVY RAINFALL AND
POSSIBLY FLASH FLOODING OVER NRN MEXICO TO THE SE OF DEL RIO
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 ALONG THE W TIP 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 AND ITCZ CONVECTION
RACING N FROM VENEZUELA. NEAR CENTRAL AMERICA...AN UPPER RIDGE
EXTENDS FROM PANAMA NWWD TO THE YUCATAN COAST WITH SHOWER/TSTM
ACTIVITY FOCUSED AROUND THE TROPICAL WAVE NEAR 82W/83W.

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
32N53W 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 22N59W TO 30N54W AND THE OTHER FROM 21N50W
TO 25N40W...AND EACH IS PRODUCING SHOWERS/TSTMS OVER THE AREA.
WIDELY SCATTERED MODERATE CONVECTION IS FROM 21N-30N BETWEEN
52W-58W WITH OTHER ISOLATED SHOWERS IN THE IMMEDIATE VICINITY OF
THE TROFS. FARTHER E...A TUMBLING MID/UPPER LEVEL ANTICYCLONE IS
CENTERED NEAR 29N40W AND IS MOVING TO THE SE 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 20N30W.
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 12N40W TO 20N54W. 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
30W-42W. 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 14N22W 16710W WITH A SURGE OF E/SE
FLOW AND DRIER AIR COMING IN FROM THE SOUTHERN HEMISPHERE.

$$
BERG



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