000
AXPZ20 KNHC 181612
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU NOV 18 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...
AXIS ALONG 09N78W TO 06N93W TO 12N113W TO 09N131W TO 08N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 180 
NM N OF AXIS BETWEEN 123W AND 131W.

...DISCUSSION...
THE BROAD OMEGA BLOCK DOMINATING THE PACIFIC E OF 150W HAS 
COMPLETED ITS BREAKDOWN DURING THE PAST 24 HOURS...AS FORECAST 
BY GLOBAL MODELS. HOWEVER...A BLOCKING UPPER PATTERN STILL SPANS 
THE DISCUSSION AREA...RESEMBLING A SMALLER VERSION OF A REX 
BLOCK...WITH RIDGING EXTENDING FROM AN UPPER ANTICYCLONE NEAR 
13N123W...N-NW TO 33N128W. AN UPPER RIDGE PERSISTS ACROSS THE 
CARIBBEAN AND EXTENDS W ALONG ABOUT 15N TO 95W. 

A WEAKENING 1022 MB SURFACE HIGH NEAR 32N127W WILL CONTINUE TO 
SHIFT SE AND COLLAPSE DURING THE NEXT 24 HOURS AS A COLD FRONT 
APPROACHES THE AREA FROM THE NW. THE WEAKENING PRESSURE GRADIENT 
S OF THIS HIGH HAS LIMITED TRADES WINDS N OF THE  ITCZ TO 
GENERALLY LESS THAN 20 KT...EXCEPT FOR A NARROW STRETCH BETWEEN 
11N AND 13N W OF 122W. SUFFICIENT LLVL CONVERGENCE HAS CONTINUED 
THOUGH ACROSS THE N PERIPHERY OF THE ELONGATED 1011 MB SURFACE 
LOW NEAR 12N112W...RESULTING IN BANDS OF SCATTERED MODERATE TO 
STRONG CONVECTION. OTHERWISE...LIGHT TO MODERATE ANTICYCLONIC 
FLOW PREVAILS AT THE SURFACE W OF 115W...WITH SEAS 7 TO 8 FT IN 
LONG PERIOD NW SWELL. MONSOONAL LLVL FLOW GENERALLY PREVAILS E 
OF 115W...WITH LIGHT NW TO W WINDS N OF THE ITCZ AND MODERATE SW 
TO W WINDS TO THE S OF THE ITCZ. HOWEVER THIS PATTERN IS ABOUT 
TO CHANGE QUICKLY TODAY...AS NLY FLOW IS BLOWING THROUGH THE 
GULF OF TEHUANTEPEC IN ADVANCE OF A COLD FRONT MOVING INTO THE 
GULF OF MEXICO. THIS TEHUANTEPEC EVENT WILL STRENGTHEN TO GALE 
FORCE THIS AFTERNOON...AND LIKELY AT OR NEAR STORM FORCE WITHIN 
12 TO 18 HOURS. HIGH PRESSURE BUILDING BEHIND THE GULF OF MEXICO 
COLD FRONT WILL PRODUCE FRESH TO STRONG TRADE WINDS ACROSS 
PORTIONS OF THE CARIBBEAN THIS WEEKEND THAT WILL  BLOW ACROSS 
CENTRAL AMERICA AND ESTABLISH ELY TRADE WINDS ACROSS THE FAR E 
TROPICAL EPAC N OF THE ITCZ BY SAT AFTERNOON.  
 
A COLD FRONT WILL MOVE INTO NW PORTIONS OF THE AREA BY SAT 
MORNING AND WEAKEN AS IT DRIFTS SE THROUGH SUN...WITH HIGH PRES 
BEHIND IT STRENGTHENING THE PRESSURE GRADIENT ACROSS W 
PORTIONS...AND BRINGING A RETURN OF  MODERATE TO FRESH NELY 
TRADE WINDS W OF 115W.
 
$$
STRIPLING