000
AXPZ20 KNHC 301525
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON NOV 30 2009

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 
1515 UTC.

...ITCZ...
AXIS ALONG 06N77W TO 09N93W TO 07N110W TO 12N130W TO 10N140W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 90 NM OF AXIS BETWEEN 
104W AND 110W...AND WITHIN 60 NM OF AXIS BETWEEN 131W AND 135W. 
SCATTERED MODERATE WITHIN 60 NM OF AXIS BETWEEN 90W AND 100W.

...DISCUSSION...
AMPLIFIED PATTERN IN PLACE OVER THE DISCUSSION AREA WITH A 
SERIES OF TROUGHS OVER THE SUBTROPICAL ZONE. THE MOST 
SIGNIFICANT AFFECTING THE AREA IS A SHARP DEEP LAYER TROUGH 
WHICH EXTENDS FROM A WELL DEFINED CYCLONE OVER NW MEXICO SW 
THROUGH 18N119W. JET CORE WITH SATELLITE DERIVED WINDS OF 
120-130 KT IS SLICING ACROSS EXTREME SRN BAJA CALIFORNIA 
ACROSS CENTRAL MEXICO AND WAS ADVECTING A LARGE PLUME OF 
TROPICAL MOISTURE ACROSS NORTHERN MEXICO TO FEED FRONTAL 
BOUNDARY NOW OVER SE TEXAS. SURFACE LOW PRES 1010 MB PRESENTLY 
FUNNELING NW TO N WINDS OF 20-25 KT INTO GULF OF CALIFORNIA WILL 
MOVE QUICKLY NE EFFECTIVELY DIMINISHING WINDS BELOW 20 KT BY 
LATE TUE. DOWNSTREAM MID TO UPPER LEVEL RIDGE MAINTAINS VERY DRY 
SUBSIDING AIR MASS SE OF TROUGH AXIS WITH A SMALL PATCH OF 
CONVECTION ALONG ITCZ AXIS BETWEEN 90W AND 100W. SOME UPLIFT 
CAUSED BY SURFACE TROUGH ALONG 110W WAS RESULTING IN ADDITIONAL 
AREA OF SCATTERED MODERATE CONVECTION ALONG ITCZ. OTHERWISE ONLY 
OTHER SIGNIFICANT CONVECTION NOTED ALONG ITCZ IS IN VICINITY OF 
BROAD COMPLEX LOW PRES AREA W OF 130W.  

MODEL GUIDANCE STILL SPLIT IN THEIR SOLUTIONS TO THE COMPLEX 
SURFACE LOW PRES AREA W OF 130W WITH GFS STILL SUPPORTING AN
APPARENTLY TROPICAL VORTICITY MAXIMUM FROM WELL W OF AREA AND 
SPINNING GALE FORCE WINDS W OF 130W ABSORBING AND INTENSIFYING 
COMPLEX LOW PRES AREA. THIS OUTLIER SOLUTION POSSIBLY DUE TO THE 
CONVECTIVE FEEDBACK INHERENT IN THE GFS MODEL. THE EUROPEAN .NAM 
AND NOGAPS SOLUTION DIFFER SIGNIFICANTLY FROM GFS SOLUTION AND
ARE MORE REASONABLE. AS IN THE PREVIOUS DISCUSSION THE HIGH SEAS 
FORECAST FOLLOWS ECMWF WHICH HAS A MUCH WEAKER SYSTEM AND HENCE 
LIGHTER WINDS. 

ELSEWHERE AT THE SURFACE...
TROUGH...REMNANTS OF PREVIOUS LOW PRES...ALONG 110W CONTINUES TO 
WEAKEN AS IT ENCOUNTERS HOSTILE SW SHEAR AND VERY DRY AIR ALOFT.
SYSTEM EXPECTED TO DISSIPATE WITHIN 24 HRS WHILE SEAS CONTINUE 
UNDER LARGE NW SWELLS. ELSEWHERE...1025 MB HIGH PRES CENTER NEAR 
40N131W WITH RIDGE EXTENDING SE INTO BASIN TO 25N120W.  RIDGE 
FORCES NE TRADE WINDS W OF 120W...BUT WEAKEN AS HIGH PRES CENTER 
SHIFT NE.  AREA OF STRONG TRADES DIMINISH STRENGTH AND COVERAGE 
NEXT 48 HOURS.

HIGH PRES CENTER FORCED OUT BY COLD FRONT APPROACHING NW CORNER 
OF BASIN TUE. SW WINDS AND HIGHER SEAS ASSOCIATED WITH FRONT 
EXPECTED TUE AND WED AS FRONT WEAKENS AND STAYS N OF 25N.  
ANOTHER EPISODE OF LARGE LONG PERIOD NW SWELLS SPREADING SE 
FOLLOW COLD FRONT LATE IN FORECAST PERIOD. 

...GAP WINDS...
EASTERLY TRADE WINDS ACROSS W CARIBBEAN CONTINUE TO FUNNEL WINDS 
THROUGH GULF OF PAPAGAYO AND DOWNSTREAM WATERS TO 90W. 

$$
COBB