[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 062341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED 06 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE INTRODUCED ABOUT 500 NM SW OF THE CAPE VERDE
ISLANDS ALONG 30W S OF 12N MOVING W 10-15 KT. THE DAKAR UPPER
LEVEL TIMESECTION INDICATES THAT A WAVE PASSED NEAR 00Z
10/3...BELOW THE 750 MB LEVEL. A SEVERAL-DAY HOVMOELLER DIAGRAM
ALSO SHOWS A CLUSTER OF TSTMS MOVING OFF THE AFRICAN COAST ON
THE 3RD...THEN DISSIPATING...AND RE-FORMING NEAR 25W-30W TODAY.
THE CLUSTER IS NOW DISSIPATING AGAIN WITH ONLY ISOLATED
SHOWERS/TSTMS ALONG THE ITCZ.

TROPICAL WAVE LOCATED ABOUT 725 NM E OF BARBADOS ALONG 47W S OF
17N MOVING W 15 KT. A LOW-LATITUDE DISTURBANCE IS OBSERVED ALONG
THE WAVE AXIS WITH A CONVERGENCE LINE EXTENDING SW INTO THE
ITCZ. THIS LINE MARKS THE LEADING EDGE OF DRIER AIR WHICH HAS
BEEN PROPAGATING ACROSS THE ATLC. WIDELY SCATTERED MODERATE
CONVECTION FROM 10N-15N BETWEEN 42W-48W.

TROPICAL WAVE REPOSITIONED TO 58W/59W S OF 20N MOVING W 10 KT.
SATELLITE IMAGERY INDICATES A SHARP WAVE AXIS AND ASSOCIATED
LOW-LEVEL CIRCULATION APPROACHING BARBADOS AND THE LESSER
ANTILLES. THE WAVE HAD BEEN LOCATED FARTHER W OVER THE
CARIBBEAN...BUT THIS FEATURE HAS BEEN MADE A SFC TROF OVER THE
MONA PASSAGE AS A REFLECTION OF THE MID/UPPER LOW NEAR PUERTO
RICO. SCATTERED MODERATE/STRONG CONVECTION IS DEVELOPING
PRIMARILY E OF THE WAVE AXIS FROM 12N-20N BETWEEN 51W-58W IN
RESPONSE TO BROAD WLY SHEAR OVER THE REGION.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N12W 7N18W 8N28W 5N31W 12N44W...
THEN ALONG 9N48W 13N58W...THEN ALONG 9N70W 9N83W. NUMEROUS
MODERATE CONVECTION OVER S SENEGAL...GUINEA-BISSAU...AND W
GUINEA FROM 10N-16N BETWEEN 11W-16W. WIDELY SCATTERED MODERATE
FROM 5N-11N BETWEEN 17W-24W. ISOLATED MODERATE WITHIN 90 NM OF
THE AXIS BETWEEN 33W-43W AND 51W-56W. WIDELY SCATTERED MODERATE
OVER PARTS OF N GUYANA...W VENEZUELA...N COLOMBIA...AND PANAMA.

...DISCUSSION...

GULF OF MEXICO...
A 1010 MB LOW HAS DEVELOPED JUST E OF TUXPAN MEXICO NEAR 21N96W
ALONG A STATIONARY SFC TROF WHICH HAS BEEN JUST OFFSHORE THE
MEXICAN COAST FOR THE PAST 2 DAYS. SATELLITE IMAGERY HAS
SUGGESTED THAT A LOW-LEVEL CIRCULATION HAS BECOME BETTER DEFINED
DURING THE DAY...AND WIDESPREAD TSTM ACTIVITY HAS FLARED UP OVER
MUCH OF THE W GULF. CURRENTLY...SCATTERED MODERATE CONVECTION
EXTENDS FROM 20N-26N BETWEEN 89W-97W WITH OTHER WIDELY SCATTERED
MODERATE ALONG THE MEXICAN COAST BETWEEN CAMPECHE AND
VILLAHERMOSA. FARTHER N...A STATIONARY FRONT EXTENDS FROM CNTRL
FLORIDA TO COASTAL LOUISIANA AS STRONG HIGH PRES BUILDS IN FROM
THE N OVER THE EASTERN UNITED STATES. THE WESTERN PART OF THE
FRONT NEAR THE TEXAS COAST APPEARS TO HAVE DISSIPATED WITH
STRONG SLY RETURN FLOW DEVELOPING FROM THE GULF INTO THE
SOUTHERN PLAINS. THIS MOIST FLOW HAS SUPPORTED WIDELY SCATTERED
SHOWERS AND TSTMS OFF THE TEXAS COAST...WELL N OF THE DEVELOPING
SFC LOW...N OF 26N BETWEEN 90W-97W. A BROAD UPPER LEVEL HIGH IS
CENTERED OVER THE SW YUCATAN PENINSULA AND IS BRINGING ABUNDANT
MOISTURE FROM THE W GULF TSTMS EWD TOWARDS FLORIDA AND THE W
ATLC. IT SHOULD BE FAIRLY WET ALONG THE GULF COAST NOW THROUGH
THE WEEKEND AS THE SFC LOW MOVES N AND INTERACTS WITH THE
STATIONARY FRONTAL BOUNDARY...MAYBE PRODUCING A HYBRID-TYPE
SUBTROPICAL SYSTEM.

CARIBBEAN...
THE DOMINANT FEATURE OVER THE AREA CONTINUES TO BE THE LARGE
MID/UPPER LEVEL TROF WHICH EXTENDS N OF THE S AMERICAN COAST
BETWEEN THE NORTHERN LEEWARD ISLANDS AND THE W CARIBBEAN. THE
MAIN TROF AXIS STRETCHES ACROSS PUERTO RICO SWWD TO THE GUAJIRA
PENINSULA OF COLOMBIA...AND STRONG SUBSIDENCE BEHIND THIS AXIS
IS PRODUCING MOSTLY DRY CONDITIONS FOR THE CNTRL CARIBBEAN. ONLY
A FEW TSTMS WHICH DEVELOPED OVER E CUBA...JAMAICA...AND
HISPANIOLA ARE NOW MOVING S OVER COASTAL WATERS.
ELSEWHERE...UPPER LEVEL RIDGING AND MORE ABUNDANT MOISTURE OVER
CNTRL AMERICA HAS FOSTERED SCATTERED MODERATE/STRONG CONVECTION
EXTENDING FROM THE YUCATAN PENINSULA TO NICARAGUA...THEN TO
PANAMA...BUT MOST OF THIS ACTIVITY IS NOW PUSHING TO THE PACIFIC
SIDE OF THESE COUNTRIES. ALSO...SWLY FLOW ON THE E SIDE OF THE
TROF IS BRINGING HIGH LEVEL CLOUDINESS ACROSS THE
LEEWARD/WINDWARD ISLANDS BUT THE STRONGEST CONVECTION REMAINS
WELL TO THE E OVER THE TROPICAL ATLC...OR E OF AN APPROACHING
TROPICAL WAVE.

SUBTROPICAL ATLANTIC...
A MID/UPPER LEVEL TROF IS PUSHING OFF THE MID-ATLC COAST OF THE
UNITED STATES WITH A COLD FRONT PUSHING ACROSS THE W ATLC BACK
TO CNTRL FLORIDA ALONG 32N64W 27N75W 27.5N81W. THE FRONT IS
RUNNING INTO A GENERALLY DRY AIR MASS EXTENDING N OF HISPANIOLA
AND PUERTO RICO SO THERE IS LITTLE IN THE WAY OF ASSOCIATED
SHOWERS/TSTMS. HOWEVER...STRONG UPPER LEVEL RIDGING IS BUILDING
OVER THE CNTRL ATLC TO THE E OF THE DEEP TROF OVER THE
CARIBBEAN...AND THIS IS PUMPING A GOOD AMOUNT OF MOISTURE NWD
INTO THE SUBTROPICS. A WEAK SFC TROF IS EMBEDDED BENEATH THIS
FLOW FROM 20N60W 28N54W...AND SCATTERED MODERATE CONVECTION IS
LOCATED FROM 20N-27N BETWEEN THE TROF AND 50W. FARTHER E...A
BROAD MID/UPPER TROF COVERS MUCH OF THE AREA E OF 40W. A
DISSIPATING COLD FRONT IS ENTERING THE AREA FROM THE N BUT THE
UPPER TROF NOW APPEARS TO BE LIFTING TO THE NE AND THE SFC
BOUNDARY WILL PROBABLY WASH OUT BEFORE MAKING MUCH HEADWAY INTO
THE REGION. STRONG SFC RIDGING ALONG 30N40W 28N20W AND MODERATE
SUBSIDENCE IN THE MID/UPPER LEVELS IS KEEPING THE AREA MOSTLY
DRY.

TROPICAL ATLANTIC...
STRONG UPPER LEVEL RIDGING IS DEVELOPING E OF THE LESSER
ANTILLES FROM 16N NWD INTO THE SUBTROPICS...WITH FAIRLY SOLID
WLY FLOW STREAMING E/SEWD S OF 16N. UPPER LEVEL DIVERGENCE HAS
FORMED WHERE THESE TWO FLOWS HAVE SPLIT...FOCUSING TSTM ACTIVITY
TO THE E OF THE TROPICAL WAVE APPROACHING THE ISLANDS. E OF
40W...BROAD CYCLONIC/WLY FLOW HAS PLUNGED SWD TO THE LATITUDE OF
THE CAPE VERDE ISLANDS...AND THIS HAS CREATED A NARROW RIDGE
AXIS ALONG 10N. ITCZ CONVECTION IS PRIMARILY S OF THE RIDGE AXIS
WHERE THE WITH SUCCESSIVE CLUSTERS OF TSTMS BEING PUSHED TO THE
W BETWEEN AFRICA AND 35W.

$$
BERG


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