[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 260004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON SEP 25 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 30W SOUTH OF 14N MOVING WEST 10 TO 15 KT.
CYCLONIC TURNING IS EVIDENT IN THE LOW TO MID CLOUD MOTIONS. THE
SCATTERED MODERATE CONVECTION THAT WAS FROM 7N-13N BETWEEN
25W-34W UNTIL 1800 UTC HAS SINCE BECOME MORE ISOLATED IN NATURE
WITH CLOUD TOPS WARMING A BIT AS WELL.

A 1010 MB LOW PRESSURE CENTER IS NEAR 20N46W MOVING WNW NEAR 10
KT. CLOUDINESS AND SHOWERS ASSOCIATED WITH A TROPICAL WAVE AND A
BROAD AREA OF LOW PRESSURE LOCATED ABOUT 890 NM EAST OF THE
NORTHERN LEEWARD ISLANDS REMAIN POORLY ORGANIZED. ATMOSPHERIC
CONDITIONS COULD BECOME A LITTLE MORE FAVORABLE FOR DEVELOPMENT
DURING THE NEXT DAY OR TWO. A CLUSTER OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 20N-23N BETWEEN
41W-47W...DISPLACED MAINLY E AND NE OF THE CENTER DUE TO SW/W
SHEAR IN THE VICINITY.

TROPICAL WAVE IS ALONG 50W/51W SOUTH OF 14N MOVING WEST NEAR 10
KT. THIS WAVE HAS BEEN REPOSITIONED SLIGHTLY TO THE E DUE TO THE
SMALL AREA OF CYCLONIC TURNING SEEN FROM IN THE LAST FEW VISIBLE
PICTURES THIS EVENING FROM 9N=14N BETWEEN 45W-53W. GOES LOW
LEVEL HIGH DENSITY WINDS IN THIS REGION ALSO SUGGEST THIS MORE
EAST LOCATION. THIS WAVE REMAINS WEAK WITH MINIMAL DEEP
CONVECTION.

TROPICAL WAVE IS ALONG 69W S OF 21N MOVING W 10 TO 15
KT...EXTENDING THROUGH THE DOMINICAN REPUBLIC AND THE ABC
ISLANDS. MOST OF THE SHOWER ACTIVITY REMAINS NEAR THE NORTHERN
END OF THE WAVE AXIS AFFECTING PUERTO RICO...HISPANIOLA AND THE
ADJACENT WATERS. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED
TO NUMEROUS SHOWERS WITH EMBEDDED TSTMS OVER THESE ISLANDS AND
THE SURROUNDING COASTAL WATERS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N15W 9N28W 7N33W 9N44W 9N53W
9N61W. OUTSIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OVER
THE AFRICAN COAST AND ADJACENT ATLC WATERS FROM 9N-15N BETWEEN
13W-19W. CLUSTERS OF SCATTERED MODERATE CONVECTION SEEN FROM
7N-9N BETWEEN 20W-25W...AND FROM 4N-8N BETWEEN 37W-42W.

...DISCUSSION...
THE GULF OF MEXICO...
THE MAIN FEATURE ACROSS THE GULF THIS EVENING IS STILL THE COLD
FRONT.  THE FRONT EXTENDS THROUGH NE FLORIDA ACROSS THE CENTRAL
GULF AND INTO CENTRAL MEXICO. SATELLITE IMAGERY AND SURFACE
OBSERVATIONS SUGGEST THE WRN PORTION OF THIS FRONT IS BECOMING
STATIONARY WHILE THE PORTION OVER NE FLORIDA IS STILL A
PROGRESSIVE COLD FRONT. ISOLATED SHOWER AND TSTM ACTIVITY IS
SEEN WITHIN 150NM OF THE FRONTAL BOUNDARY. THE SHOWER ACTIVITY
AND CLOUDINESS ASSOCIATED WITH THE FRONT IS MOVING MOSTLY
ANTICYCLONICALLY AROUND THE UPPER HIGH OVER NE MEXICO.  DIURNAL
CONVECTION OVER THE YUCATAN PENINSULA AND WRN CUBA IS MOVING
INTO THE ADJACENT GULF WATERS WITH MID TO UPPER EASTERLY FLOW.
BEHIND THE FRONT...A 1024MB SURFACE HIGH IS BUILDING INTO THE NW
GULF FROM CENTRAL TEXAS. LOOK FOR THE FRONT AND ASSOCIATED
SHOWER ACTIVITY TO CONTINUE PUSHING SLOWLY INTO THE CENTRAL GULF
AND NORTH/CENTRAL FLORIDA OVER THE NEXT 24HRS.

THE CARIBBEAN SEA...
A MID TO UPPER TROUGH IS EXTENDING THROUGH THE NW
CARIBBEAN...WRN CUBA...AND THE SE BAHAMAS. THIS FEATURE IS
PRODUCING ISOLATED TO SCATTERED SHOWERS OVER THE NW CARIBBEAN.
CLOUDINESS WITH ISOLATED MODERATE CONVECTION IS OVER THE SW
CARIBBEAN BUT THIS ACTIVITY IS NOT AS SIGNIFICANT AS IT WAS A
FEW HOURS AGO. THE CLOUDINESS AND SHOWERS ARE MOVING MOSTLY TO
THE N AROUND A MID TO UPPER HIGH JUST W OF THE NW COLOMBIAN
COAST. THE TROPICAL WAVE ALONG 69W IS PRODUCING SHOWERS/TSTMS
NEAR HISPANIOLA AS DESCRIBED ABOVE. ISOLATED SHOWERS/TSTMS ARE
OVER THE FAR E CARIBBEAN AND LESSER ANTILLES...ROTATING AROUND
AN UPPER LOW JUST SOUTH OF BARBADOS. ELSEWHERE AT THE
SFC...10-20 KT TRADES DOMINATE WITH SLIGHTLY STRONGER WINDS OFF
THE COLOMBIAN COAST.

THE ATLANTIC OCEAN...
A MID TO UPPER RIDGE AND DRY AIR A COVERS MUCH OF THE W ATLC
ANCHORED BY UPPER HIGHS LOCATED NEAR 30N75W AND 30N55W. MID TO
UPPER LEVEL TROUGHING COVERS THE AREA FROM THE NW CARIBBEAN TO
THE SE BAHAMAS AND THE ADJACENT SW NORTH ATLC WATERS. ASSOCIATED
ISOLATED SHOWERS/TSTMS FROM 21N-27N BETWEEN 65W-80W. THERE IS A
MID TO UPPER LEVEL VORTICITY MAXIMUM SEEN ON WV IMAGERY E OF THE
BAHAMAS NEAR 24N69W...WHICH SEEMS TO BE INTERACTING WITH THE N
PORTION OF THE TROPICAL WAVE MOVING THROUGH HISPANIOLA. THERE IS
A SMALL UPPER LOW NEAR 23N52W THAT IS SURROUNDED BY DRY AIR.
JUST TO THE E OF THIS AREA LIES THE SURFACE LOW NEAR 20N46W AS
DESCRIBED ABOVE. A BROAD UPPER HIGH SITUATED WNW OF THE CAPE
VERDE ISLANDS NEAR 18N34W DOMINATES THE REMAINDER OF THE E ATLC.
AT THE SURFACE...A COLD FRONT ENTERS THE AREA NEAR 31N31W...THEN
CONTINUES SOUTHWESTWARD TO 28N36W. A DYING STATIONARY FRONT
EXTENDS W FROM THIS POINT ALONG 26N50W 27N63W. A NARROW BAND OF
LOW/MID CLOUDS WITH ISOLATED SHOWERS IS RELATED TO THE FRONT.
THE W ATLC SURFACE RIDGE EXTENDS FROM A 1021 MB HIGH LOCATED
NEAR 32N52W TO THE BAHAMAS. A COLD FRONT IS BEGINNING TO PUSH
OFF THE SE US COAST WITH ASSOCIATED ISOLATED SHOWER/TSTMS WITHIN
100NM OF THE BOUNDARY. THIS WILL CONTINUE PUSHING SLOWLY SE OVER
THE NEXT 24 HRS.

$$
WILLIS




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