000
AXPZ20 KNHC 302156
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON NOV 30 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...ITCZ...
AXIS ANALYZED ALONG 06N78W TO 08N96W TO 07N110W TO 11N128W TO 
10N140W. SCATTERED MODERATE CONVECTION WITHIN 75 NM EITHER SIDE
OF THE AXIS BETWEEN 79W AND 81W AND WITHIN 90 NM N OF THE AXIS 
BETWEEN 92W AND 98W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION WITHIN 120 NM N OF THE AXIS BETWEEN 105W AND 112W. 
SCATTERED MODERATE CONVECTION WITHIN 75 NM EITHER SIDE OF THE 
AXIS W OF 132W.

...DISCUSSION...
AN AMPLIFIED OMEGA BLOCK PATTERN REMAINS IN PLACE OVER THE 
DISCUSSION AREA. A LARGE MID TO UPPER LEVEL RIDGE REMAINS THE 
DOMINANT FEATURE OVER THE DISCUSSION AREA W OF 125W. 1028 MB 
HIGH PRES IS CENTERED NEAR 42N131W WITH A RIDGE AXIS EXTENDING 
SE INTO BASIN TO 25N120W. THE TIGHT RIDGE IS RESULTING IN NE 
TRADE WINDS W OF 112W IN THE 20 TO 25 KT RANGE. THE RIDGE WILL 
WEAKEN DURING THE NEXT 48 HOURS AS THE HIGH PRES CENTER SHIFTS 
OFF TO THE NE...AS A COLD FRONT APPROACHES THE NW CORNER OF THE 
BASIN. THE STRONGEST WINDS ASSOCIATED WITH THIS FRONT WILL 
REMAIN N AND W OF THE DISCUSSION AREA. ALSO...AS THE RIDGE 
WEAKENS OVER OUR AREA...THE AREA OF STRONG TRADES WILL DIMINISH 
IN STRENGTH AND COVERAGE DURING THE NEXT 48 HOURS. ALSO... 
ANOTHER EPISODE OF LARGE LONG PERIOD NW SWELLS WILL SPREAD SE 
FOLLOWING THE COLD FRONTAL PASSAGE TO THE N LATE IN THE FORECAST 
PERIOD. 

A LONGWAVE UPPER TROUGH AND ATTENDANT COLD FRONT IS APPROACHING 
THE AREA W OF 140W...BUT WILL WEAKEN AS IT ENCOUNTERS THE RIDGE 
WITH THE MAJORITY OF ANY ASSOCIATED ENERGY AND MOISTURE 
REMAINING N OF 32N. ANOTHER UPPER TROUGH EXTENDS OVER THE NE 
PORTION OF THE AREA ON THE FRONT/E SIDE OF THE RIDGE EXTENDING 
FROM S CENTRAL TEXAS TO NEAR THE SOUTHERN TIP OF THE BAJA 
PENINSULA TO 19N117W...WITH VERY DRY AND STABLE AIR IN PLACE N 
OF THE TROUGH. A JET CORE WITH SATELLITE DERIVED WINDS OF 
120-130 KT ALONG THIS TROUGH AXIS EXTENDS FROM S OF THE BAJA 
ACROSS CENTRAL MEXICO...AND WAS ADVECTING A LARGE PLUME OF 
TROPICAL MOISTURE ACROSS NORTH CENTRAL MEXICO WHICH IS FEEDING 
INTO A FRONTAL BOUNDARY NOW OVER THE NW GULF OF MEXICO. 

A LARGE UPPER LEVEL LOW CENTERED NEAR 32N110W HAS CUT OFF FROM 
THE MAIN FLOW PATTERN AND CONTINUES TO DRIFT TO THE SE TOWARD 
EXTREME NORTHERN MEXICO. SURFACE LOW PRES OF 1010 MB IS 
PRESENTLY FUNNELING NW TO N WINDS OF 20 TO 25 KT INTO THE N GULF 
OF CALIFORNIA. THIS FEATURE WILL MOVE QUICKLY NE EFFECTIVELY 
DIMINISHING WINDS BELOW 20 KT BY LATE TUE. 

MODEL GUIDANCE IS 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 ECMWF...NAM 
AND NOGAPS SOLUTIONS DIFFER SIGNIFICANTLY FROM THE GFS SOLUTION 
AND ARE MORE REASONABLE. AS IN THE PREVIOUS DISCUSSION THE HIGH 
SEAS FORECAST FOLLOWS THE ECMWF WHICH HAS A MUCH WEAKER SYSTEM 
AND HENCE LIGHTER WINDS. 

ELSEWHERE AT THE SURFACE...A WEAK SURFACE TROUGH...WHICH IS THE 
REMNANTS OF PREVIOUS LOW PRES...ALONG 110W CONTINUES TO WEAKEN 
AS IT ENCOUNTERS HOSTILE SW SHEAR AND VERY DRY AIR ALOFT. THIS 
FEATURE IS EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS WHILE 
SEAS TO 10 FT CONTINUE IN LARGE LONG PERIOD NW SWELLS. 

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

$$
LEWITSKY