[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021807
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI OCT 02 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 41W S OF 15N MOVING W NEAR 15 KT. WAVE
COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE AS INDICATED IN
TOTAL PRECIPITABLE WATER IMAGERY BUT REMAINS AT A LOW AMPLITUDE.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 9N-16N BETWEEN 38W-44W.

TROPICAL WAVE THAT WAS ALONG 55W IS NOW A SURFACE TROUGH
EXTENDING FROM 20N51W THROUGH A 1014 MB LOW NEAR 16N52W TO
13N53W MOVING W 5-10 KT. A DISTINCT LOW LEVEL SWIRL IS OBSERVED
ON VISIBLE SATELLITE IMAGERY AND IS TO THE E OF THE PREVIOUS
ANALYSIS...THUS THE CONVERSION TO A SURFACE TROUGH.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 14N15W 9N28W 10N43W 9N55W
10N62W. SCATTERED CLUSTERS OF SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION ARE FROM 4N-14N E OF 35W TO THE COAST OF W
AFRICA.

...DISCUSSION...

GULF OF MEXICO...
A STRONG COLD FRONT HAS MOVED INTO THE GULF ENTERING THE AREA
OVER CENTRAL LOUISIANA NEAR 30N92W SW TO ACROSS S TEXAS NEAR
CORPUS CHRISTI. THE FRONT IS SUPPORTED BY A LARGE UPPER LEVEL
TROUGH THAT DIPS ACROSS THE N GULF COAST. A BROAD UPPER RIDGE
ANCHORED OVER CENTRAL MEXICO EXTENDS ACROSS THE GULF FROM
TAMPICO TO S FLORIDA PROVIDING DIFFLUENCE ALOFT TO ENHANCE
SCATTERED/NUMEROUS SHOWERS/THUNDERSTORMS SE OF THE FRONT WITHIN
90 NM OF LINE FROM 28N89W 26N92W TO JUST OFF THE TEXAS COAST
NEAR 27N97W. ISOLATED/SCATTERED SHOWERS ARE WITHIN 90 NM OF LINE
FROM 28N89W TO INLAND OVER THE N GULF COAST BETWEEN PANAMA CITY
FLORIDA AND SE COAST OF LOUISIANA. THE REMNANTS OF A STATIONARY
FRONT EXTENDS ACROSS EXTREME S FLORIDA PENINSULA S OF MIAMI JUST
N OF THE FLORIDA KEYS TO 25N84W. DRY STABLE CONDITIONS DOMINATE
THE S AND E GULF GIVING THE REMAINDER OF THE GULF RELATIVELY
CLEAR SKIES THIS AFTERNOON. HOWEVER CONDITIONS WILL DETERIORATE
ACROSS THE N GULF AS THE FRONT PUSHES EASTWARD.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH EXTENDS FROM AN UPPER LOW OVER THE BAHAMAS
ACROSS CENTRAL CUBA INTO THE CARIBBEAN TO JUST S OF JAMAICA.
THIS COMBINED WITH THE UPPER RIDGE OVER THE GULF OF MEXICO IS
USHERING IN DRY STABLE AIR TO 14N W OF 79W INCLUDING PORTIONS OF
CENTRAL AMERICA AND THE YUCATAN PENINSULA. THE UPPER TROUGH IS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 17N
FROM 72W-76W. AN UPPER RIDGE IN THE SE PACIFIC EXTENDS FROM
COLOMBIA TO S OF CENTRAL AMERICA DRAWING UPPER LEVEL MOISTURE
ACROSS PANAMA AND COSTA RICA AND COUPLED WITH THE ITCZ THAT
EXTENDS ACROSS COLOMBIA N OF PANAMA INTO THE E PACIFIC OVER E
COSTA RICA ARE GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS S OF A LINE FROM THE TIP OF HONDURAS/NICARAGUA TO
COLOMBIA NEAR 11N74W. A WEAK SURFACE TROUGH IS OVER THE NE
CARIBBEAN EXTENDING FROM 20N65W ACROSS THE VIRGIN ISLANDS TO
16N64W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS WITHIN 90 N M EITHER SIDE OF THE TROUGH AXIS.
MOSTLY CLEAR SKIES PREVAIL ACROSS THE CENTRAL CARIBBEAN FROM E
TO W WITH THE EXCEPTION OF A FEW ISOLATED SHOWERS BEING USHERED
IN ON MODERATE TO FRESH EASTERLY TRADE WINDS.

ATLANTIC OCEAN...
A COLD FRONT ENTERS THE REGION NEAR 32N61W EXTENDING SW TO
28N67W WHERE IT BECOMES STATIONARY OVER THE N BAHAMA ISLANDS
NEAR 27N77W THEN DISSIPATING ACROSS EXTREME S FLORIDA INTO THE
SE GULF OF MEXICO S OF MIAMI SUPPORTED BY AN UPPER TROUGH WHICH
COVERS THE ATLC N OF 30N W OF 60W. ISOLATED/SCATTERED SHOWERS
ARE WITHIN 60 NM E OF THE COLD FRONT. AN UPPER TROUGH IS OVER
THE W ATLC EXTENDING FROM AN UPPER LOW OVER THE N BAHAMA ISLANDS
NEAR 26N77W S ACROSS CENTRAL CUBA INTO THE NW CARIBBEAN.
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF
30N TO OVER THE GREATER ANTILLES BETWEEN 70W-80W. A BROAD UPPER
RIDGE COVERS THE REMAINDER OF THE W ATLC INTO THE CENTRAL ATLC
ANCHORED NEAR 21N58W EXTENDING N TO BEYOND 32N52W. DIFFLUENCE
ALOFT IS ENHANCING SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS OVER AN AREA FROM 25N-30N BETWEEN 43W-56W. A
SURFACE TROUGH...PREVIOUSLY A TROPICAL WAVE...EXTENDS FROM
20N51W THROUGH A 1014 MB LOW NEAR 16N52W TO 13N53W GENERATING
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
14N-18N BETWEEN 50W-56W. AN UPPER TROUGH IS IN THE E/CENTRAL
ATLC EXTENDING FROM AN UPPER LOW WELL N OF THE REGION NARROWING
S OF 29N ALONG 29N38W INTO THE TROPICS TO 16N51W. A SURFACE
TROUGH EXTENDS FROM A DISSIPATING COLD FRONT ENTERING THE REGION
NEAR 32N21W SW ALONG 28N30W TO 27N40W. SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 90 NM EITHER SIDE OF
THE FRONT/TROUGH. THE TYPICAL E/W UPPER RIDGE DOMINATES MUCH OF
THE TROPICS WITH THE AXIS EXTENDING ALONG 10N/11N TO 42W
ENHANCING THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE AND
THE ITCZ. WEAK SURFACE RIDGE CUTS A SWATH ACROSS THE REGION
BETWEEN 20N-30N WITH A WEAK 1018 MB HIGH NEAR 26N59W.

$$
WALLACE





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