[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082333
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI 08 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.

...SPECIAL FEATURES...

TROPICAL STORM MATTHEW HAS DEVELOPED AND IS CENTERED NEAR 24.2N
93.8W...OR ABOUT 260 MILES ESE OF BROWNSVILLE TEXAS...AT 08/2100
UTC MOVING E 9 KT. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH
GUSTS TO 45 KT. MINIMUM CENTRAL PRESSURE REPORTED BY A
RECONNAISSANCE AIRCRAFT IS 1001 MB. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS. EARLIER THIS AFTERNOON...AN AIR FORCE RECONNAISSANCE
AIRCRAFT FOUND TROPICAL STORM FORCE WINDS NEAR THE CENTER OF THE
SYSTEM THAT WERE SEPARATE FROM THE TROPICAL STORM FORCE WINDS IN
THE STRONG GRADIENT FLOW OVER THE N GULF. MATTHEW HAS A
WELL-DEFINED CENTER WHICH IS SLIGHTLY EXPOSED TO THE W OF A
BROAD EXPANSE OF CLOUDINESS AND HEAVY RAINFALL OVER THE CNTRL/W
GULF. RECENTLY...THE STRONGEST CONVECTION HAS BECOME MORE
FOCUSED NEAR AND DIRECTLY TO THE E OF THE CENTER WITH NUMEROUS
MODERATE/STRONG FROM 23N-25.5N BETWEEN 91W-94W. SCATTERED
MODERATE CONVECTION IS ALSO ELSEWHERE FROM 20N-32N BETWEEN
89W-95.5W. WSR-88D IMAGERY SHOWS A BROAD SHIELD OF HEAVY RAIN
MOVING ONSHORE THE GULF COAST BETWEEN MOBILE ALABAMA AND LAKE
CHARLES LOUISIANA...TO THE E OF A SFC TROF WHICH EXTENDS N OF
MATTHEW TO THE TEXAS/LOUISIANA BORDER. MODEL GUIDANCE SUGGESTS
THE HEAVY RAINS WILL MOVE SLOWLY EWD TOWARDS FLORIDA THROUGH THE
WEEKEND AND SEVERAL LOCAL OFFICES HAVE ISSUED FLOOD WATCHES/
WARNINGS FROM LOUISIANA TO THE FLORIDA PANHANDLE IN ANTICIPATION
OF THIS.

A 1009 MB LOW HAS DEVELOPED ABOUT 425 NM SE OF BERMUDA NEAR
27N60W ALONG A SFC TROF WHICH EXTENDS ALONG FROM 23N68W TO THE
LOW THEN NEWD BEYOND 32N54W. SATELLITE IMAGERY ACTUALLY
INDICATES AT LEAST 2 SWIRLS ROTATING AROUND A COMMON
CENTER...AND THIS FEATURE IS SEMI-CONNECTED TO A SECOND TROF/LOW
FARTHER S OVER THE WINDWARD/LEEWARD ISLANDS. THE NORTHERN BRANCH
OF THIS LARGE AREA OF TROUGHINESS LIES BENEATH THE DIVERGENT
FLOW OF AN UPPER TROF ALONG 69W/70W...AND SCATTERED MODERATE
CONVECTION HAS DEVELOPED OVER THE NW SEMICIRCLE FROM 25N-30N
BETWEEN 59W-63W. WITH THESE UPPER LEVEL CONDITIONS...THERE IS
THE POSSIBILITY OF SOME KIND OF SUBTROPICAL OR HYBRID TROPICAL
DEVELOPMENT DURING THE NEXT 36 HRS.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED JUST W OF THE CAPE VERDE ISLANDS ALONG 26W
S OF 19N MOVING W NEAR 10 KT. THE SAL VERTICAL SOUNDING
INDICATES THE WAVE AXIS PASSED THE STATION PRIMARILY BETWEEN
3000 AND 10000 FT AROUND 00 UTC TODAY. A DEEP UPPER TROF LOCATED
TO THE N OF THE WAVE IS PRODUCING FAVORABLE DIVERGENCE OVER THE
AREA...AND WIDELY SCATTERED MODERATE/ISOLATED STRONG CONVECTION
HAS SPREAD TO THE E OF THE AXIS FROM 10N-17N BETWEEN 18W-29W.

TROPICAL WAVE LOCATED ABOUT 875 NM SE OF BARBADOS ALONG 45W S OF
14N MOVING W 15-20 KT. THE WAVE IS STILL EMBEDDED AMONG STRONG
CONVERGENCE IN THE ITCZ...WHICH HAS KEPT THE CONVECTION ALIGNED
IN A LINEAR E/W PATTERN. SEE ITCZ FOR RELATED CONVECTION. THE
WAVE MAY BECOME EVEN MORE DIFFICULT TO LOCATE OVER THE NEXT
SEVERAL DAYS AS IT APPROACHES THE EASTERN CARIBBEAN AND
INTERACTS WITH THE PERSISTENT TROF OVER THE AREA.

...ITCZ...

ITCZ AXIS EXTENDS OFF THE COAST OF GUINEA-BISSAU ALONG 12N16W
10N24W...THEN ALONG 9N27W 9N44W...THEN ALONG 9N46W 10N55W...THEN
ALONG 9N66W 9N83W. SCATTERED MODERATE/STRONG CONVECTION WITHIN
140 NM OF THE AXIS BETWEEN 8W-16W. ISOLATED MODERATE FROM 7N-10N
BETWEEN 21W-29W WITH SCATTERED MODERATE N OF 10N ASSOCIATED WITH
A TROPICAL WAVE. WIDELY SCATTERED MODERATE WITHIN 175 NM OF THE
AXIS BETWEEN 43W-52W. SCATTERED MODERATE OVER MOST OF N
VENEZUELA.

...DISCUSSION...

GULF OF MEXICO...
WITH T.S. MATTHEW AFFECTING MOST OF THE GULF...THERE IS LITTLE
ELSE TO TALK ABOUT. AN AMPLIFIED UPPER RIDGE IS CENTERED OVER
MATTHEW AT THE MOMENT...EXTENDING NWD INTO THE TENNESSEE VALLEY
WITH A LARGE SHIELD OF MID/UPPER LEVEL CLOUDS STREAMING ALL THE
WAY INTO NEW ENGLAND. A DEEP-LAYERED TROF IS LOCATED FARTHER W
OVER N MEXICO AND THE SOUTHERN ROCKIES AND IS TRIGGERING
ISOLATED TSTMS OVER THE MOUNTAINOUS TERRAIN OF MEXICO. THIS
FEATURE WILL CONTINUE MOVING EWD AND WILL PUSH MATTHEW IN A
GENERAL E/NE DIRECTION OVER THE GULF OVER THE WEEKEND.

CARIBBEAN/NEAR LESSER ANTILLES...
THE LARGE MID/UPPER TROF OVER THE W ATLC CONTINUES TO GO NOWHERE
FAST WITH ITS SRN EXTENSION PROTRUDING INTO THE E CARIBBEAN
BETWEEN 63W-73W. COUPLED WITH AN UPPER LEVEL RIDGE EXTENDING E
OF BELIZE...THE TROF IS PRODUCING BROAD N/NW FLOW OVER THE W
CARIBBEAN WITH DRY AIR STILL BEING PUMPED DOWN TO THE COLOMBIA
AND PANAMA COASTS. SCATTERED MODERATE CONVECTION DEVELOPED OVER
THE ISLANDS OF HISPANIOLA AND JAMAICA DURING THE DAY...BUT THE
WETTEST WEATHER IS LOCATED OVER THE LESSER ANTILLES WHERE
ABUNDANT MOISTURE IS STREAMING NWD FROM S AMERICA. A 1008 MB LOW
IS CENTERED NEAR GUADELOUPE AND DOMINICA WITH A TROF EXTENDING
ALONG 10N64W 21N59W. THE LOW ITSELF IS WEAK...BUT ALL THE
SHOWER/TSTM ACTIVITY IS E OF THE ISLANDS WHERE LOW-LEVEL
CONVERGENCE IS STRONGEST. SCATTERED MODERATE CONVECTION IS FROM
11.5N-18N BETWEEN 57W-61W.

SUBTROPICAL ATLANTIC...
A DEVELOPING MID/UPPER LEVEL LOW IS CENTERED ABOUT 315 NM SW OF
BERMUDA AND IS DRAGGING A LARGE AREA OF DRY AIR SWD OVER THE W
ATLC WATERS. THIS FEATURE IS PROVIDING THE IMPETUS FOR THE
POSSIBILITY OF (SUB)TROPICAL DEVELOPMENT WITH THE LOW NEAR
27N60W. A BROAD UPPER RIDGE LIES ALONG 20N49W 27N52W
33N64W...AND STRONG LOW-LEVEL SPEED CONVERGENCE BENEATH THIS
AXIS HAS LED TO THE FLARE-UP OF NUMEROUS MODERATE CONVECTION
FROM 17N-26N BETWEEN 51W-56W. ELSEWHERE...A POSITIVELY TILTED
UPPER TROF EXTENDS INTO THE AREA ALONG 32N23W 22N32W AND IS
PUSHING A WEAK COLD FRONT ACROSS THE CANARY ISLANDS ALONG 32N11W
28N16W 25N25W. A FEW ISOLATED SHOWERS ARE POSSIBLE ALONG THE
FRONT ESPECIALLY JUST SW OF THE CANARY ISLANDS.

TROPICAL ATLANTIC...
A LARGE UPPER LEVEL HIGH HAS DEVELOPED E OF THE LESSER ANTILLES
NEAR 14N47W AND IS ANCHORING THE LARGE RIDGE THAT EXTENDS NWD
INTO THE SUBTROPICS. A MID/UPPER TROF IS DIGGING SWD TO THE E OF
THE HIGH...WITH DRY AIR BEING PULLED S TO 10N BETWEEN 28W-40W
AND MOISTURE BEING PULLED N ACROSS THE CAPE VERDE ISLANDS TO THE
W COAST OF AFRICA. THIS HAS ALSO LED TO INCREASED COVERAGE OF
CONVECTION S/SE OF THE CAPE VERDES NEAR A TROPICAL WAVE AND THE
ITCZ.

$$
BERG





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