[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181037
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED OCT 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVE...
A TROPICAL WAVE IS ALONG 39W/40W SOUTH OF 18N MOVING WEST
NEAR 10 KT. THE WAVE SHOWS A INVERTED-V SIGNATURE. CONVECTION IS
BEING DISPLACED TO THE NE BY UPPER SW LEVEL FLOW. SCATTERED
MODERATE CONVECTION FROM 11N-15N BETWEEN 35W-40W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 7N25W 10N37W 9N41W 6N55W.
CLUSTERS OF MODERATE TO STRONG CONVECTION ARE FROM 6N-12N EAST
OF 20W PROBABLY ASSOCIATED WITH A NEW TROPICAL WAVE MOVING OUT
OF AFRICA. SIMILAR CONVECTION IS OBSERVED FROM 8N-15N BETWEEN
27W-36W.

...DISCUSSION...
GULF OF MEXICO...
THE SQUALL LINE OVER THE NE GULF AND THE FLORIDA PANHANDLE HAS
DISSIPATED BUT A BAND OF MODERATE SHOWERS WITH EMBEDDED TSTMS
REMAINS OVER THE AREA AND EXTENDS NE ACROSS SOUTHERN GEORGIA AND
THE COASTAL WATERS OF THE CAROLINAS. AT LOW LEVELS...A MOIST SLY
FLOW IS ENHANCING THIS SHOWER ACTIVITY. THE REMAINDER OF THE
GULF REMAINS DOMINATED BY 10-15 KT SLY FLOW AT THE SURFACE
BETWEEN HIGH PRESSURE WELL NE OF THE AREA AND LOWER PRESSURE
OVER MEXICO. A LARGE UPPER HIGH CENTERED NEAR 24N90W COVERS THE
ENTIRE AREA AND SOUTHERN MEXICO. UPPER LEVEL MOISTURE COVERS THE
GULF E OF 92W AND THE FLORIDA PENINSULA WHILE DRY AIR IS FOUND
ACROSS THE REMAINDER OF THE GULF. A NEW COLD FRONT WILL ENTER
THE NW GULF WATERS ON THU AND EXTEND FROM BIG BEND FLORIDA TO
NEAR TAMPICO ON FRIDAY. NLY WINDS OF 15-20 KT WILL FOLLOW THE
COLD FRONT.

CARIBBEAN SEA...
THE LARGE UPPER UPPER HIGH ANCHORED IN THE GULF OF MEXICO
EXTENDS A RIDGE EWD ACROSS MOST OF THE CARIBBEAN SEA AND CENTRAL
AMERICA GIVING THE REGION UPPER NE FLOW AND MOSTLY DRY AIR. A
VERY ELONGATED UPPER TROUGH FROM THE ATLC DIPS S OVER THE FAR
E CARIBBEAN. A 1007 MB AREA OF LOW PRESSURE REMAINS JUST NORTH
OF PUERTO RICO. THIS FEATURE IS PRODUCING DISORGANIZED SHOWERS
AND TSTMS AND UPPER-LEVEL WINDS REMAIN UNFAVORABLE FOR TROPICAL
CYCLONE DEVELOPMENT. A SURFACE TROUGH EXTENDS S FROM THIS LOW TO
THE ABC ISLANDS. THIS AREA OF LOW PRESSURE IS FORECAST TO MOVE
SLOWLY NE AND AWAY FROM PUERTO RICO DURING THE NEXT FEW DAYS.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION HAS FORMED AND
IS PROBABLY ASSOCIATED WITH THE NORTHWARD MIGRATION OF THE ITCZ
AXIS. UPPER DIFFLUENCE IS SUPPORTING THE DEVELOPMENT OF SHOWERS
AND TSTMS OVER NORTHERN SOUTH AMERICA...PARTICULARLY OVER THE
EASTERN PORTION OF VENEZUELA. TRADE WINDS ARE LIGHT ACROSS THE
BASIN DUE TO A WEAK PRESSURE PATTERN.

ATLANTIC OCEAN...
THE LARGE UPPER RIDGE SITUATED IN THE GULF OF MEXICO ALSO
EXTENDS ACROSS THE W ATLC TO 65W DRYING OUT THE AREA. A SURFACE
HIGH OVER THE W ATLC NORTH OF THE AREA EXTENDS A RIDGE ACROSS
THE BAHAMAS AND CUBA. DEEP LAYERED TROUGH EXTENDS INTO THE
W-CENTRAL ATLC ALONG 60W/61W TO THE FAR E CARIBBEAN. THE
ATTENDANT FRONTAL BOUNDARY ENTERS THE REGION NEAR 31N49W THEN
CONTINUES SW TO A 1010 MB LOW LOCATED NEAR 25N7W. THIS LOW HAS
DEVELOPED ALONG THE SURFACE TROUGH THAT RUNS FROM THIS POINT TO
THE LOW PRESSURE THAT REMAINS NORTH OF PUERTO RICO. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS AFFECTING ST. CROIX IN
THE U.S. VIRGIN ISLANDS AND THE NORTHERN LEEWARD ISLANDS.
SIMILAR CONVECTION IS SEEN FROM 18N-25N BETWEEN 50W-60W.
ANOTHER DEEP LAYERED TROUGH EXTENDS FROM THE E ATLC THROUGH
32N20W SW TO A WEAKENING UPPER LOW CENTERED NEAR 21N45W.
ISOLATED SHOWERS ARE RELATED TO THIS LOW. A 1018 MB SURFACE HIGH
IS NEAR 30N39W AND DOMINATES THE ATLC BETWEEN 20W-45W. THIS
FEATURE IS FORECAST TO MOVE SOUTH.

$$
GR



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