000
AXNT20 KNHC 180532
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SAT NOV 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 52W/53W S OF 21N MOVING SLOWLY WWD. THE 
WAVE IS INTERACTING WITH A LARGE CUT OFF LOW CENTERED NEAR 
25N56W THAT IS SHEARING MOST OF THE CONVECTIVE ACTIVITY WELL TO 
THE E/NE OF THE WAVE. A CLUSTER OF MODERATE CONVECTION IS FROM 
17N-22N BETWEEN 48W-51W. ANOTHER AREA OF SIMILAR CONVECTION IS 
WITHIN 200 NM BEHIND THE WAVE AXIS FROM 12N-14N. 

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 71W S OF 20N 
MOVING W 10 TO 15 KT. THIS WAVE IS VERY WEAK WITH ONLY A HINT OF 
SOME CYCLONIC TURNING IN THE LOW-LEVEL CLOUDS. NO ORGANIZED 
CLOUDINESS OR SHOWER ACTIVITY IS ASSOCIATED WITH THIS WAVE.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 10N14W 6N30W 5N40W 10N52W. THE 
ITCZ IS PRETTY ACTIVE TONIGHT WITH SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION FROM 4N-8N BETWEEN 18W-37W. SIMILAR CONVECTION 
IS ALSO FOUND WITHIN 100-120 NM NORTH OF THE AXIS BETWEEN 
38W-45W.    

...DISCUSSION...
THE GULF OF MEXICO...
A BROAD DEEP LAYERED TROUGH EXTENDS ALONG THE EASTERN U.S. AND 
THE GULF NORTH OF 23N. SWLY FLOW AHEAD OF THIS TROUGH IS 
ADVECTING ABUNDANT UPPER LEVEL MOISTURE FROM WEAKENING T.S. 
SERGIO AND THE ITCZ IN THE EPAC ACROSS THE BAY OF CAMPECHE AND 
THE YUCATAN PENINSULA INTO CUBA AND THE BAHAMAS. THIS PLUME OF 
MOISTURE IS SLOWLY SEEPING SE AND WILL LIKELY CLEAR THE AREA BY 
EARLY TOMORROW.  DRY AND STABLE AIR ALOFT...RESULTING IN 
MODERATE TO STRONG SUBSIDENCE DOMINATES MOST OF THE GULF WHERE 
COOL/DRY CONDITIONS WITH LIGHT LOW-LEVEL WINDS PREVAIL. A 1019 
MB SURFACE HIGH CENTERED OVER LOUISIANA COVERS THE ENTIRE GULF. 
A REINFORCING FRONT WILL MOVE INTO THE NORTHERN GULF WATERS 
TODAY FOLLOWED BY INCREASED WINDS AND SEAS. STRONG NLY WINDS 
WILL BLOW ACROSS THE ENTIRE GULF LATER TODAY AS STRONG HIGH PRES 
BUILDS OVER THE TEXAS COAST. 
   
THE CARIBBEAN SEA...
A BROAD UPPER RIDGE DOMINATES THE MOST OF THE CARIBBEAN WATERS 
FROM AN UPPER HIGH LOCATED NEAR 14N81W. THE BASE OF AN UPPER 
TROUGH THAT LIES ACROSS THE CENTRAL ATLC DIGS INTO THE FAR E 
CARIBBEAN THROUGH THE LESSER ANTILLES. THE TAIL END OF AN ATLC 
FRONTAL BOUNDARY HAS BECOME STATIONARY FROM CENTRAL CUBA TO THE 
COAST OF HONDURAS. SCATTRED SHOWERS AND ISOLATED TSTMS ARE 
ASSOCIATED WITH THIS FRONT OVER THE NW CARIBBEAN WEST OF 80W. 
UPPER DIFFLUENCE BETWEEN THE UPPER HIGH NEAR 14N81W AND THE BASE 
OF THE TROUGH IN THE GULF IS PRODUCING A FAIR AMOUNT OF MOISTURE 
IN THIS REGION. THE REMAINDER OF THE BASIN IS QUIET WITH STABLE 
AIR ALOFT...PARTICULARLY OVER THE ERN CARIBBEAN THAT IS ON THE 
TYPICAL WEST SIDE OF THE UPPER LOW/TROUGH IN THE CENTRAL ATLC. 
TRADE WINDS ARE LIGHT ACROSS THE AREA...EXCEPT FOR MODERATE TO 
FRESH NE WINDS BEHIND THE FRONT. THE STATIONARY FRONT WILL 
GRADUALLY WEAKEN. A REINFORCING COLD FRONT MOVING THROUGH THE 
GULF OF MEXICO ON SUNDAY WILL CAUSE WINDS TO INCREASE OVER THE 
NW CORNER OF THE CARIBBEAN SEA MON THROUGH WED. 

THE ATLANTIC OCEAN...
A RIDGE/TROUGH/RIDGE PATTERN DOMINATES MOST THE ATLC. LARGE 
AMPLITUDE MID/UPPER LEVEL PATTERN IS ESTABLISHED ACROSS THE WRN 
AND PART OF THE CNTRL ATLC. THE BASE OF A BROAD UPPER TROUGH 
THAT LIES ACROSS THE EASTERN U.S. EXTENDS ACROSS THE ERN 
GULF...THE STATE OF FLORIDA AND THE FAR W ATLC. THE ASSOCIATED 
COLD FRONT STRETCHES FROM 32N71W ACROSS THE CENTRAL BAHAMAS AND 
CUBA. INSTABILITY ASSOCIATED WITH THE SFC BOUNDARY ALONG WITH A 
DIFFLUENT PATTERN ALOFT ARE GENERATING PATCHES OF SCATTERED 
MODERATE CONVECTION FROM 22N-26N BETWEEN 72W-80W. A NARROW UPPER 
RIDGE EXTENDS FROM THE CARIBBEAN ACROSS CUBA AND THE BAHAMAS 
INTO THE W ATLC TO 32N66W. EAST OF THE RIDGE...A LARGE CUT OFF 
UPPER LOW IS CENTERED NEAR 25N56W. VERY DRY AIR LIES TO THE W 
AND S OF THE UPPER LOW EXTENDING INTO THE ERN CARIBBEAN. A LARGE 
AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS EXISTS AHEAD OF 
THIS TROUGH FROM 20N-32N BETWEEN 45W-55W. A 1012 MB SURFACE LOW 
REMAINS NEAR 29N58W. ANOTHER RIDGE EXTENDS NORTH FROM THE TROPICS
ALONG 40W. THE FLOW THEN BECOMES FAIRLY ZONAL E OF 30W. SFC 
RIDGING IS WELL ESTABLISHED OVER THE EASTERN ATLC GIVING THE 
AREA FAIR WEATHER.

$$
GR