000
AXPZ20 KNHC 110940
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN DEC 11 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
MONSOON TROUGH EXTENDS FROM 08N82W TO 06N91W...THEN TRANSITIONS 
TO ITCZ AXIS EXTENDING FROM 06N91W TO 05N111W TO 08N124W TO 
09N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...
ANTICYCLONE CENTERED NEAR 12N118W IS DOMINANT UPPER LEVEL FEATURE
IN THE DISCUSSION AREA THIS MORNING. UPPER LEVEL TROUGH W OF THE 
AREA HAS WEAKENED CONSIDERABLY AND DEEP CONVECTION HAS DISSIPATED
FROM STRONGER WESTERLY SHEAR W OF 130W. MOISTURE GENERATED FROM 
CONVECTION IN THE CENTRAL PACIFIC IS RIDING OVER THE CREST OF THE
RIDGE N OF 20N INTO WESTERN MEXICO. 

SURFACE RIDGE AXIS SPANS NW PORTION OF THE DISCUSSION AREA FROM
31N140W TO 20N112W. PRES GRADIENT ASSOCIATED WITH HIGH PRES N OF 
THE AREA AND LOWER PRES ALONG THE ITCZ W OF 125W IS PRODUCING 
FRESH E-NE TRADE WINDS FROM 10N TO 21N W OF 130W. A DEEP TROUGH 
WILL SWING ESE TOWARDS CALIFORNIA TONIGHT AND MON AND DEEPEN 
INTO A CLOSED LOW OFF THE SRN CALIFORNIA COAST THROUGH MON NIGHT 
AS IT CUTS OFF FROM NRN JET STREAM. A TRAILING WEAK COLD FRONT 
WILL EXTEND FROM THE LOW SW TO NEAR 22N120W BY EARLY TUE. PRES 
GRADIENT BETWEEN THIS LOW AND A STATIONARY HIGH NEAR 35N140W WILL
SUPPORT 20-25 KT W TO NW WINDS W OF FRONT WITH NW SWELLS LEADING 
TO 10 TO 14 FT BY MON AFTERNOON. SCATTERED SHOWERS ARE EXPECTED 
WITH THE LOW AND ALONG THE FRONT.

GALE WARNING PREVIOUSLY IN EFFECT FOR THE GULF OF TEHUANTEPEC HAS
BEEN DISCONTINUED FROM ABUNDANCE OF OBSERVATIONAL DATA THAT DOES 
NOT SUPPORT GALE-FORCE WINDS. HI-RESOLUTION ASCAT PASS DIRECTLY 
OVER THE GULF OF TEHUANTEPEC AT 0300 UTC INDICATED NO 35 KT WINDS
AND ONLY A SINGLE 30-KT WIND BARB NEAR 15N95W. IN ADDITION...OBS 
FROM SALINA CRUZ NEAR 16N95W ARE ONLY 17-18 KT WITH GUSTS TO 30 
KT. A JASON ALTIMETER PASS AT 0040 UTC SHOWED MAX SEAS OF 8-9 FT
ABOUT 2 FT BELOW WAVEWATCH GUIDANCE. PRIMARY REASON FOR DROPPING 
THE GALE WARNING WAS GFS FORECAST SHOWING 40 KT AT 0300 UTC WHILE
ASCAT SHOWED 30 KT AS SAME VALID-TIME VERIFICATION. INDICATIONS 
ARE GFS AND NAM WIND FORECAST IS 5-10 KT TOO HIGH. WILL CONTINUE 
GAP WINDS 20-30 KT THROUGH TUE BASED ON THIS ASSUMPTION.

$$
MUNDELL