[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 080537
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...SPECIAL FEATURE...

A 1007 MB LOW IS CENTERED ABOUT 90 NM ENE OF TAMPICO MEXICO NEAR
23N96.5W. THE LOW IS LOCATED ALONG A SURFACE TROUGH WHICH
EXTENDS N TO INLAND OVER THE TEXAS COAST TO 30N96W AND S OF THE
LOW INTO THE BAY OF CAMPECHE TO NEAR COATZACOALCOS MEXICO ALONG
THE MEXICAN COAST. TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE OVER
THE NEXT COUPLE OF DAYS. EVEN IF IT DOES NOT DEVELOP INTO A
TROPICAL SYSTEM IT WILL CONTINUE TO BRING HEAVY RAIN AND
THUNDERSTORMS TO TEXAS AND LOUISIANA. SCATTERED MODERATE TO
STRONG CONVECTION IS N OF 23N TO INLAND OVER E TEXAS AND ALL OF
LOUISIANA FROM 90W-96.5W AND A SMALL AREA IN THE BAY OF CAMPECHE
WITHIN 75 NM ALONG THE COAST OF MEXICO FROM 92W-94W.

...TROPICAL WAVES...

TROPICAL WAVE IS LOCATED JUST NEAR THE CAPE VERDE ISLANDS ALONG
23W S OF 16N MOVING W NEAR 10 KT. SATELLITE IMAGERY SUGGESTS
THAT THE MAIN PART OF THE CIRCULATION REMAINS JUST S OF THE
CAPE VERDE ISLANDS. WIDELY SCATTERED MODERATE CONVECTION IS FROM
10N-16N BETWEEN 20W-27W.

TROPICAL WAVE BETWEEN THE CAPE VERDE ISLANDS AND THE LESSER
ANTILLES IS ALONG 37W/38W S OF 14N MOVING W 15-20 KT. STRONG
NORTHEASTERLY AND SOUTHEASTERLY LOW LEVEL FLOW IS CONVERGING
ALONG THE ITCZ OVER THE CENTRAL ATLC WHICH HAS GIVEN THIS WAVE A
VERY FLAT APPEARANCE. THE WAVE MAY BECOME MORE APPARENT OVER THE
NEXT 2-3 DAYS AS IT HEADS INTO THE WEAKER FLOW REGIME NEAR THE
LESSER ANTILLES. RIGHT NOW...CONVECTION IS ALIGNED LINEARLY
ALONG THE ITCZ AXIS.

TROPICAL WAVE THAT WAS LOCATED ABOUT 440 NM E OF BARBADOS IS NO
LONGER DISCERNIBLE ON THE SURFACE.

TROPICAL WAVE IS SITUATED OVER THE LEEWARD/WINDWARD ISLANDS
REMAINS ALONG 61W/62W S OF 20N DRIFTING W. SURFACE OBSERVATIONS
FROM THE LEEWARD ISLANDS INDICATE THAT A WEAK 1010 MB LOW
REMAINS ALONG THE WAVE JUST S OF GUADELOUPE NEAR 15N61W. SURFACE
TROUGH EXTENDS N OF THE WAVE INTO THE CENTRAL ATLC FROM 23N59W
TO A 1017 MB LOW JUST N OF THE REGION NEAR 35N54W. SW SHEAR IS
OVER THE WAVE KEEPING THE HEAVIEST SHOWERS/THUNDERSTORMS E OF
THE ISLANDS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N15W 8N43W 10N52W BECOMING
DISTORTED TO WEST OF 65W. CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION ARE FROM 7N-10N BETWEEN 20W-29W...10N-12N BETWEEN
35W-38W...AND FROM 5N-11N BETWEEN 38W-48W.

...DISCUSSION...

GULF OF MEXICO AND W ATLANTIC...
SEE SPECIAL FEATURES FOR DISCUSSION ON LOW NE OF TAMPICO.
ELSEWHERE...STRONG HIGH CONTINUES OVER THE NE U.S. INTO THE NW
ATLC WITH A TIGHTENING GRADIENT NOW EXTENDING OVER FLORIDA AND
THE W GULF OF MEXICO. A WEAKENING STATIONARY FRONT...MARKED MORE
OR LESS BY A MOISTURE GRADIENT ALONG THE LEADING EDGE OF THE
HIGH PRESSURE SYSTEM...EXTENDS FROM SE OF BERMUDA SW THROUGH THE
N BAHAMAS AND S FLORIDA. ISOLATED SHOWERS ARE ALONG THIS
BOUNDARY AND ARE NOW OVER EXTREME S FLORIDA...THE FLORIDA KEYS
INTO THE STRAITS OF FLORIDA. BROAD ANTICYCLONIC FLOW DOMINATES
THE UPPER LEVELS OVER THE GULF WITH BROAD DIFFLUENT FLOW
FOSTERING CONVECTION OVER THE W GULF WATERS. A STRONG SHORTWAVE
IS MOVING E AWAY FROM NEW MEXICO OVER CENTRAL TEXAS...AND MAY
INDUCE SOME SORT OF TROPICAL/NON-TROPICAL DEVELOPMENT AS THE LOW
NEAR THE MEXICAN COAST TRACKS N. FARTHER E...A MID/UPPER LEVEL
TROF HAS DROPPED DOWN OVER THE W ATLC WITH MUCH DRIER AIR E OF
FLORIDA TO 70W...AND TRIGGERING SCATTERED MODERATE CONVECTION
AHEAD OF THE STATIONARY FRONT OVER THE WATERS OF THE W ATLC FROM
24N-31N BETWEEN 60W-67W.

CARIBBEAN...
A LARGE AREA OF DRY MID/UPPER LEVEL AIR CONTINUES TO BE PUMPED S
OVER THE CENTRAL CARIBBEAN...SANDWICHED BETWEEN AN UPPER LEVEL
HIGH NEAR GUATEMALA AND A DEEP-LAYERED TROUGH EXTENDING FROM
PUERTO RICO TO COLOMBIA/PANAMA. ISOLATED THUNDERSTORMS CONTINUE
OVER HISPANIOLA...E CUBA...AND JAMAICA BUT OTHERWISE THE AREA IS
GENERALLY UNDER THE INFLUENCE OF EASTERLY TRADES WITH LIGHT LOW
LEVEL SHOWERS. HOWEVER...THE TRADES HAVE BEEN INTERRUPTED A BIT
OVER THE E CARIBBEAN DUE TO A SLOW-MOVING TROPICAL WAVE/TROF
OVER THE LESSER ANTILLES. THE UPPER TROUGH CONTINUES TO DRAG A
LOT OF MOISTURE NE FROM S AMERICA INTO THE CENTRAL ATLC BUT
FORTUNATELY THE HEAVIEST RAINFALL HAS STAYED TO THE E OVER OPEN
WATERS.

REMAINDER OF SUBTROPICS...
A BROAD UPPER LEVEL RIDGE EXTENDS N ACROSS THE CENTRAL ATLC FROM
15N52W TO 32N47W...WITH UPPER DIFFLUENCE PRODUCING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 20N FROM 50W-58W. FARTHER
E...A SURFACE RIDGE EXTENDS FROM ACROSS THE NE ATLC THROUGH
32N40W 24N44W WITH A BROAD UPPER LEVEL TROUGH COVERING THE
REMAINDER OF THE E ATLC E OF 35W. A MID-LEVEL SHORTWAVE IS
EMBEDDED WITHIN THE TROUGH NEAR 24N29 BUT THE ATMOSPHERE IS TOO
DRY FOR SIGNIFICANT WEATHER.

TROPICAL ATLANTIC...
THE TROPICS ARE REALLY JUST AN EXTENSION OF THE SUBTROPICAL
FEATURES WITH STRONG UPPER LEVEL RIDGING ALONG 8N47W 15N52W AND
BROAD UPPER LEVEL TROUGHING EXTENDING AS FAR S AS 10N E OF 35W.
CONVECTION NEAR THE ITCZ HAS BEEN FAIRLY LINEAR AND COMPACT OVER
THE PAST FEW DAYS...BUT DIFFLUENCE AHEAD OF THE TROF IS
BEGINNING TO MAKE THE ACTIVITY A LITTLE MORE WIDESPREAD IN
COVERAGE ESPECIALLY S OF THE CAPE VERDE ISLANDS.

$$
WALLACE


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