000
AXPZ20 KNHC 111549
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
MONSOON TROUGH EXTENDS FROM 09N83W TO 06N92W...THEN TRANSITIONS 
TO ITCZ AXIS EXTENDING FROM 06N92W TO 06N111W TO 09N126W TO 
07N140W. ISOLATED MODERATE CONVECTION N OF 05N E OF 83W.

...DISCUSSION...
ANTICYCLONE CENTERED NEAR 12N117W IS THE DOMINANT UPPER LEVEL 
FEATURE IN THE DISCUSSION AREA THIS MORNING. SUBSIDENT 
CONDITIONS ARE THUS PREVALENT AND NO DEEP CONVECTION IS PRESENT 
ANYWHERE EXCEPT THAT MENTIONED ABOVE JUST SOUTH OF PANAMA.  THIS 
LIMITED AREA OF CONVECTION IS LIKELY BEING ENHANCED BY AN UPPER 
LEVEL TROUGH CENTERED SOUTH OF GUATEMALA NEAR 10N95W.  UPPER 
LEVEL MOISTURE AND CLOUDINESS GENERATED FROM CONVECTION IN THE 
CENTRAL PACIFIC IS RIDING OVER THE CREST OF THE RIDGE N OF 20N 
INTO NW MEXICO. 

SURFACE RIDGE AXIS SPANS NW PORTION OF THE DISCUSSION AREA FROM 
31N140W TO 20N115W. PRESSURE GRADIENT ASSOCIATED WITH 1032 MB 
HIGH PRESSURE N OF THE AREA AND LOWER PRES ALONG THE ITCZ IS 
PRODUCING FRESH E-NE TRADE WINDS FROM 08N TO 20N W OF 128W.  
LITTLE CHANGE WITH THESE TRADES ARE EXPECTED DURING THE NEXT TWO 
DAYS.

A VIGOROUS DEEP TROUGH IS SWINGING ESE TOWARDS CALIFORNIA TODAY 
MONDAY AND SHOULD DEEPEN INTO A CLOSED LOW OFF THE SRN 
CALIFORNIA COAST THROUGH TUESDAY MORNING AS IT CUTS OFF FROM NRN 
JET STREAM.  EITHER A WEAK TRAILING COLD FRONT OR TROUGH WILL 
EXTEND FROM THE LOW SW TO NEAR 21N120W BY EARLY TUESDAY. 
PRESSURE GRADIENT BETWEEN THIS LOW AND A STATIONARY HIGH NEAR 
33N140W WILL SUPPORT 20-25 KT W TO NW WINDS W OF FRONT/TROUGH 
WITH NW SWELLS LEADING TO 10 TO 14 FT BY MONDAY AFTERNOON. 
SCATTERED SHOWERS ARE EXPECTED WITH THE LOW AND ALONG THE 
FRONT/TROUGH.

ADDITIONALLY ASSOCIATED WITH THIS SURFACE LOW WILL BE SOME 
FRESH SOUTHERLY WINDS IN THE NORTHERN GULF OF CALIFORNIA.  THESE 
SHOULD COMMENCE MONDAY MORNING AND DIMINISH BY TUESDAY EVENING.  
THEY ARE UNLIKELY TO REACH GALE FORCE NOR PRODUCE SIGNIFICANT 
WAVE HEIGHTS OF 8 FT.

THE GULF OF TEHUANTEPEC GAP WIND EVENT CONTINUES THIS MORNING 
WITH PEAK WINDS ANALYZED TO BE JUST UNDER GALE FORCE.  AS IS 
TYPICAL...LITTLE IN THE WAY OF OBSERVATIONS ARE AVAILABLE THIS 
MORNING TO KNOW WHETHER THE PEAK WINDS ARE 30 OR 35 KT.  
REGARDLESS...A MODERATE PRESSURE GRADIENT ACROSS THE SW GULF OF 
MEXICO TO THE GULF OF TEHUANTEPEC SHOULD CONTINUE THROUGH 
WEDNESDAY WITH STRONGEST WINDS 30-35 KT...PEAKING AROUND SUNRISE 
MONDAY...TUESDAY...AND WEDNESDAY MORNINGS.

$$
LANDSEA