[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251808 RRA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 29W SOUTH OF 13N MOVING WEST 15 KT. SOME
CYCLONIC TURNING IS EVIDENT AT LOW LEVELS. A CLUSTER OF
MODERATE/STRONG CONVECTION IS FROM 9N-12N BETWEEN 26W-30W.

A 1010 MB LOW PRESSURE CENTER IS NEAR 20N45W. CLOUDINESS AND
SHOWERS ASSOCIATED WITH THIS BROAD AREA OF LOW PRESSURE REMAIN
POORLY ORGANIZED. UPPER-LEVEL WINDS ARE NOT CONDUCIVE FOR
SIGNIFICANT DEVELOPMENT. SOME OF THE COMPUTER MODELS MOVE THIS
BROAD AREA OF LOW PRES NORTHWESTWARD AND DISSIPATE BEFORE IT
REACHES 30N.

TROPICAL WAVE IS ALONG 52W SOUTH OF 13N MOVING WEST 10 KT. THIS
IS A WEAK WAVE EMBEDDED WITHIN DRY AIR THAT HAS NO ASSOCIATED
CONVECTION.

TROPICAL WAVE LIES ALONG THE MONA PASSAGE TO THE ABC ISLANDS.
MOST OF THE SHOWER ACTIVITY IS ON THE NORTHERN END OF THE WAVE
AXIS AFFECTING THE VIRGINS ISLANDS...PUERTO RICO AND DOMINICAN
REPUBLIC. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED TO
NUMEROUS SHOWERS WITH EMBEDDED TSTMS OVER THESE ISLANDS AND THE
SURROUNDING COASTAL WATERS. PERIODS OF LOCALLY HEAVY RAIN AND
GUSTY WINDS ARE EXPECTED WITH THE HEAVIEST SHOWERS OVER PUERTO
RICO AND DOMINICAN REPUBLIC THIS AFTERNOON. THE WAVE IS
INTERACTING WITH AN UPPER LOW LOCATED JUST EAST OF THE SOUTHERN
BAHAMAS. MOISTURE BEHIND THE WAVE AXIS IS ALSO GENERATING
SCATTERED SHOWERS OVER THE LESSER ANTILLES.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N16W 8N27W 7N40W 8N50W 10N60W.
OUTSIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 7N-14N AND E OF 18W TO INLAND OVER WEST
AFRICA PROBABLY ASSOCIATED WITH A NEW TROPICAL WAVE COMING OUT
OF AFRICA. SCATTERED MODERATE CONVECTION IS FROM 3N-7N BETWEEN
34W-40W.

...DISCUSSION...
THE GULF OF MEXICO...
THE MAIN FEATURE ACROSS THE GULF TODAY IS STILL THE COLD FRONT.
AS OF 1500 UTC...THE COLD FRONT EXTENDS FROM NORTHERN FLORIDA
ACROSS THE CENTRAL GULF TO CENTRAL MEXICO. THE CITY OF MONTERREY
IN NE MEXICO REPORTED 4.16 INCHES OF RAIN THIS MORNING DUE TO
THE PASSAGE OF A SQUALL LINE AND THE FRONTAL BOUNDARY. THE FRONT
IS EXPECTED TO EXTEND FROM TAMPA BAY TO THE BAY OF CAMPECHE
TONIGHT AND WILL WEAKEN ON TUE. A BROAD UPPER TROUGH THAT
EXTENDS OVER THE EASTERN U.S. IS SUPPORTING THIS STRONG COLD
FRONT. AN UPPER HIGH IS CENTERED OVER NE MEXICO NEAR 24N98
COVERING MOST OF THE GULF AND MEXICO. ANOTHER UPPER HIGH IS
ANCHORED IN THE W ATLC EXTENDING A RIDGE OVER THE STATE OF
FLORIDA. AN UPPER LOW REMAINS BETWEEN THESE RIDGES AND IS
CENTERED OVER THE YUCATAN PENINSULA NEAR 19N90W. THIS FEATURE IS
GENERATING SCATTERED SHOWERS AND TSTMS OVER THE BAY OF
CAMPECHE...THE YUCATAN PENINSULA AND BELIZE. A SURFACE TROUGH IS
OVER THE BAY OF CAMPECHE ALONG 93/94W. MODERATE TO STRONG WINDS
OF 20-25 KT WILL FOLLOW THE COLD FRONT AS IT CONTINUES TO MOVE
SEWD ACROSS THE GULF.

THE CARIBBEAN SEA...
AN UPPER LOW IS BETWEEN JAMAICA AND THE CAYMAN ISLANDS WITH A
TROUGH EXTENDING WWD TO ANOTHER UPPER LOW OVER THE YUCATAN
PENINSULA. THIS FEATURE IS PRODUCING ISOLATED TO SCATTERED
SHOWERS OVER THE NW CARIBBEAN. A LARGE CLUSTER OF MODERATE TO
STRONG CONVECTION HAS DEVELOPED OVER THE SSW CARIBBEAN SOUTH OF
13N BETWEEN 75W-83W DUE TO THE CLOSE PROXIMITY OF THE ITCZ AND
THE PRESENCE OF THE COLOMBIAN LOW. LATEST SATELLITE PICTURES
SHOW THAT THE CLOUDS TOP ARE WARMING UP. A DIFFLUENT PATTERN
ALOFT...ASSOCIATED WITH AN UPPER HIGH LOCATED NEAR 9N76W IS
ENHANCING THIS CONVECTIVE ACTIVITY. AN UPPER HIGH IS NE OF THE
LEEWARD ISLANDS NEAR 19N59W. THE COMBINATION OF THE ATLC RIDGE
AND THE COLOMBIAN LOW IS PRODUCING MODERATE/STRONG TRADES OVER
THE S/CENTRAL CARIBBEAN. EARLIER QUIKSCAT PASS SHOWED 20 TO 25
KT WINDS IN THE AREA...WITH THE STRONGEST WINDS MAINLY JUST OFF
THE COAST OF COLOMBIA.

THE ATLANTIC OCEAN...
AN UPPER RIDGE COVERS THE W ATLC ANCHORED BY AN UPPER HIGH
LOCATED NEAR 30N75W. AN UPPER LOW IS JUST EAST OF THE SOUTHERN
BAHAMAS WHILE ANOTHER WEAK UPPER TROUGH EXTENDS FROM 23N52W SW
TO JUST E OF THE WINDWARD ISLANDS. BROAD UPPER HIGH SITUATED NW
OF THE CAPE VERDE ISLANDS NEAR 18N32W DOMINATES THE REMAINDER OF
THE E ATLC. AT THE SURFACE...A COLD FRONT ENTERS THE AREA NEAR
31N31W...THEN CONTINUES SOUTHWESTWARD TO 27N40W. A STATIONARY
FRONT GOES FROM THIS POINT ALONG 24N50W 25N60W 29N64W. A NARROW
BAND OF LOW/MID CLOUDS WITH ISOLATED SHOWERS IS RELATED TO THE
FRONT. THE W ATLC SURFACE RIDGE EXTENDS FROM A 1022 MB HIGH
LOCATED NEAR 32N53W TO THE BAHAMAS...FLORIDA AND WESTERN CUBA.
A 1019 MB HIGH IS NEAR 26N30W WITH A RIDGE COVERING THE REGION N
OF 20N EAST OF THE FRONTAL BOUNDARY.

$$
GR







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