[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI OCT 07 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...

A 1012 MB LOW IS CENTERED ABOUT 425 NM NE OF THE NORTHERN
LEEWARD ISLANDS NEAR 23N57W MOVING W 5-10 KT. THE LOW IS
COLLOCATED WITH AN UPPER LEVEL LOW CENTERED NEAR 22N54W AND IS
HELPING TO PRODUCE SCATTERED MODERATE CONVECTION MAINLY E OF THE
SURFACE CENTER FROM 22N-30N BETWEEN 50W-58W. DEEP MOIST
SOUTHERLY FLOW AHEAD OF THE UPPER TROUGH IS ALSO PRODUCING
ADDITIONAL SCATTERED MODERATE CONVECTION FROM 19N-24N BETWEEN
47W-52W...AND FROM 26N-30N BETWEEN 41W-50W. DEEP CONVECTION HAS
INCREASED NEAR THE SURFACE LOW OVER THE PAST 24 HRS AND IF THIS
TREND CONTINUES IT IS POSSIBLE THAT IT COULD DEVELOP INTO A
TROPICAL CYCLONE WITHIN THE NEXT 36 HRS. THE LOW IS EXPECTED TO
CONTINUE MOVING GENERALLY W/NW OVER THE NEXT FEW DAYS REMAINING
FAR FROM ANY LAND AREAS EXCEPT FOR BERMUDA.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE INTRODUCED ALONG 29W S OF 15N MOVING
W 10-15 KT. UPPER LEVEL DATA FROM SAL IN THE CAPE VERDE ISLANDS
SHOWS A WELL-DEFINED WIND SHIFT BETWEEN 900 AND 650 MB BETWEEN
00 AND 12 UTC YESTERDAY. THE WAVE IS POSITIONED NEAR 29W BASED
ON EXTRAPOLATION FROM THIS DATA...A WEAK CIRCULATION NOTED IN
METEOSAT-8 IMAGERY...AND A MODEST-SIZED CLUSTER OF
SHOWERS/TSTMS. WIDELY SCATTERED SHOWERS/TSTMS FROM 6N-11N
BETWEEN 27W-34W.

SHARP CENTRAL ATLANTIC TROPICAL WAVE ALONG 47W S OF 20N MOVING W
10-15 KT. ALTHOUGH DEEP CONVECTION IS QUITE AGGRESSIVE...
ESPECIALLY ALONG THE NRN PART OF THE WAVE...THE ATTACHED SURFACE
LOW HAS BECOME INCREASINGLY DIFFUSE AND IT IS UNCERTAIN IF IT
EVEN HAS A CLOSED WIND FIELD. THE LOW HAS BEEN DROPPED FROM THE
ANALYSIS AND TROPICAL DEVELOPMENT APPEARS UNLIKELY AT THIS TIME.
NUMEROUS MODERATE CONVECTION FROM 10N-13N BETWEEN 46W-49W...AND
FROM 14N-21N BETWEEN 44W-49W.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 70W S OF 19N MOVING W 10
KT. THE WAVE IS EMBEDDED WITHIN MODERATE SOUTHERLY FLOW AND IS
MOVING INTO AN AREA OF BROAD LOW PRES...MAKING ITS EXACT
POSITION SOMEWHAT HARD TO FIND. HOWEVER...A CLUSTER OF SCATTERED
MODERATE CONVECTION IS LOCATED FROM THE DOMINICAN REPUBLIC SWD
AND THIS SEEMS LIKE A REASONABLE POSITION FOR THE WAVE.
SCATTERED MODERATE CONVECTION FROM 14N-19N BETWEEN 68W-72W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 12N26W...THEN ALONG 6N30W
15N45W...THEN ACROSS NRN COLOMBIA AND SE PANAMA. ISOLATED
SHOWERS/TSTMS FROM 3N-7N BETWEEN 10W-26W. WIDELY SCATTERED TSTMS
FROM 9N-12N BETWEEN 21W-26W. SCATTERED MODERATE CONVECTION FROM
8N-12.5N BETWEEN 74W-80W.

...DISCUSSION...

NORTHERN MEXICO...
A COLD FRONT WHICH HAS MOVED OFF THE TEXAS COAST IS SURGING SWD
ACROSS THE MEXICAN COASTAL PLAINS E OF THE SIERRA MADRES AND HAS
RECENTLY PASSED CIUDAD VICTORIA AND TAMPICO. THE FRONT HAS
BECOME STATIONARY FROM NEAR MONTERREY TO S OF CHIHUAHUA TO NEAR
TUCSON ARIZONA...GENERALLY HUGGING THE NE SLOPES OF THE HIGHER
TERRAIN. OVERCAST LOW CLOUDS AND FOGGY CONDITIONS EXTEND N OF
THE FRONT INTO TEXAS AND NEW MEXICO WITH A FEW SHOWERS NEAR THE
RIO GRANDE VALLEY. ALSO...TEMPERATURES N OF THE FRONT ARE BELOW
60F IN PLACES AND EVEN DRIER DEWPOINTS HAVE BEEN SLIDING S ALONG
THE COAST. THE FRONT IS EXPECTED TO DISSIPATE WITHIN THE NEXT
24-48 HRS.

GULF OF MEXICO...
A COLD FRONT CONTINUES TO SLIDE ACROSS THE N/CENTRAL AND NW GULF
WATERS FROM THE FLORIDA PANHANDLE SW TO 24N96W TO S OF TAMPICO
MEXICO. COOLER AND DRIER AIR HAS SPREAD ACROSS TEXAS AND NE
MEXICO BUT THE WATERS OF THE NW GULF ARE MODIFYING THE AIR
MASS...SO THE FRONT IS MOSTLY MARKED BY INCREASED WINDS TO 20
KT. THE FRONT IS RUNNING INTO A 1003 MB LOW...PARTLY THE
REMNANTS OF T.S. TAMMY...LOCATED ABOUT 140 NM S OF PENSACOLA
FLORIDA NEAR 28N87W. THIS LOW WILL CONTINUE MERGING WITH THE
FRONT AND IS EXPECTED TO SLIDE E ACROSS FLORIDA SAT AND SUN. A
WEAK 1004 MB LOW IS LOCATED AHEAD OF THE FRONT NEAR NAPLES
FLORIDA WITH A TROUGH EXTENDING ACROSS W CUBA TO COZUMEL...AND
THIS AXIS IS THE DIVIDING LINE BETWEEN A MOIST AIR MASS OVER
FLORIDA AND THE W ATLC AND DRIER AIR SLOWLY FILTERING IN ACROSS
THE GULF. SCATTERED SHOWERS EXTEND FROM THE STRAITS OF FLORIDA
NWD INTO THE SOUTHEAST U.S. AND A FEW TSTMS ARE LOCATED NEAR THE
INTERSECTION OF THE LOW/FRONT. ISOLATED SHOWERS/TSTMS ALSO
EXTEND WITHIN 75 NM OF THE MEXICAN COAST S OF 22N.

CARIBBEAN...
THE TAIL END OF A SURFACE TROUGH IS MOVING ACROSS THE FAR NW
PART OF THE CARIBBEAN AT THE MOMENT AND IS SPARKING ANOTHER
ROUND OF HEAVY CONVECTION BETWEEN W CUBA AND THE GULF OF
HONDURAS. THIS AREA ALSO APPEARS TO BE PARTLY FORCED BY AN AREA
OF UPPER LEVEL SPEED DIVERGENCE AT THE ENTRANCE REGION OF A JET
THAT EXTENDS NWD INTO FLORIDA. SCATTERED STRONG CONVECTION FROM
15N-22N BETWEEN 80W-84W. FARTHER E...A TROPICAL WAVE IS MOVING
ACROSS THE CNTRL CARIBBEAN AND IS HELPING TO PRODUCE SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 15N-20N BETWEEN 68W-76W
EXTENDING FROM HISPANIOLA AND THE WINDWARD PASSAGE SWD. A
SURFACE TROUGH ALSO EXTENDS FROM 17N67W EWD ACROSS THE
MONTSERRAT/ANTIGUA AREA AND IS PRODUCING ISOLATED MODERATE
CONVECTION FROM 13N-17N BETWEEN 62W-67W...SOME OF WHICH MAY
AFFECT PARTS OF THE WINDWARD ISLANDS LATER TODAY. SCATTERED
MODERATE/STRONG CONVECTION ALSO EXTENDS OFF THE COLOMBIAN COAST
IN ASSOCIATION WITH THE ITCZ AND AN INVERTED UPPER TROUGH ALONG
79W.

ATLANTIC...
DEEP MOISTURE FLOW AHEAD OF THE BROAD AREA OF LOW PRES OVER THE
GULF OF MEXICO IS SUPPORTING ROUNDS OF SHOWERS/TSTMS OVER MOST
OF FLORIDA...THE BAHAMAS...AND THE W ATLC WATERS. SCATTERED
MODERATE CONVECTION EXTENDS N OF 21N AND SW OF A LINE FROM
21N72W 32N76W. A LARGE UPPER LEVEL RIDGE AXIS LIES JUST TO THE E
OF THIS CONVECTIVE AREA ALONG 74W AND IS ADVECTING THE CIRRUS
OUTFLOW SEWD TOWARDS THE NRN LEEWARD ISLANDS. THIS FLOW THEN
FEEDS INTO THE BASE OF AN UPPER TROUGH/LOW ALONG 55W WHICH IS
SUPPORTING A 1012 MB LOW NEAR 23N57W. SEE SPECIAL FEATURES FOR
FURTHER DISCUSSION ON THIS FEATURE. FARTHER E...A GALE CENTER IS
LOCATED SE OF THE AZORES AND HAS BEEN SHEDDING SEVERAL SURFACE
TROUGHS TO THE S...ONE WHICH EXTENDS FROM MADEIRA ISLAND TO THE
WESTERNMOST CANARY ISLANDS TO 23N26W...THE OTHER FARTHER W ALONG
32N20W 28N27W 30N35W. SCATTERED SHOWERS/TSTMS LIE N OF 30N
BETWEEN 15W-25W AND CONTINUED SHOWERS WILL BE POSSIBLE OVER THE
CANARY ISLANDS OVER THE NEXT FEW DAYS AS THE LOW MEANDERS TO THE
N. A DIFFUSE PLUME OF SAHARAN DUST EXTENDS ACROSS THE TROPICAL
ATLC FROM 10N-20N E OF 45W BUT THE CONCENTRATION IS NOT AS THICK
AS PLUMES HAVE BEEN EARLIER IN THE SEASON.

$$
BERG


This weather bulletin was brought to you by:
www.nashvilleweather.net