000
AXPZ20 KNHC 020924
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN DEC 02 2012

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 08N78W TO 09N86W TO 07N109W WHERE IT 
TRANSITIONS TO THE ITCZ EXTENDING TO 07N125W TO BEYOND 07N140W. 
ISOLATED MODERATE IS WITHIN 90 NM EITHER SIDE OF TROUGH BETWEEN 
94W AND 107W. SCATTERED MODERATE ISOLATED STRONG IS WITHIN 135 
NM N OF ITCZ AXIS BETWEEN 120W AND 125W. A DIFFLUENT PATTERN 
ALOFT SUPPORTS THIS CONVECTIVE ACTIVITY.

...DISCUSSION...

ALOFT...A SHORTWAVE TROUGH EXTENDS FROM SOUTHERN CALIFORNIA TO 
30N123W TO 22N130W. A SECOND SHORTWAVE TROUGH STRETCHES FROM 
17N120W NEAR 02N130W. BROKEN HIGH CLOUDS STREAMING NE ARE 
OBSERVED AHEAD OF THESE TROUGHS WHILE MODERATE TO STRONG 
SUBSIDENCE IS NOTED ALONG AND BEHIND THE TROUGH AXES. BROAD 
MID/UPPER RIDGING PERSISTS ACROSS THE E WATERS WITH A MEAN RIDGE 
AXIS STRETCHING FROM NORTHERN SOUTH AMERICA TO NEAR 14N105W. 
UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS HELPING TO INDUCE 
ISOLATED MODERATE CONVECTION ALONG THE MONSOON TROUGH. 

AT THE SURFACE...NW SWELLS GENERATED BY A LARGE EXTRATROPICAL 
CYCLONE IN THE GULF OF ALASKA CONTINUES TO PUSH INTO THE 
FORECAST REGION WITH SEAS TO 12 FT IN THE NE PART OF THE AREA. 
THIS SWELL EVENT WILL CONTINUE TO PROPAGATE S AND E ACROSS THE 
REGIONAL WATERS WHILE SLOWLY SUBSIDING. BY TONIGHT...SWELLS FROM 
THIS EVENT WITH COMBINED SEAS OF AT LEAST 8 FT WILL COVER MOST 
OF THE REGION WEST OF 110W. 

A 1021 MB HIGH PRES IS CENTERED NEAR 27N125W WITH A RIDGE 
EXTENDING WWD TO PAST 140W. THE PRES GRADIENT BETWEEN THIS AREA 
OF HIGH PRESSURE AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ 
IS MAINTAINING MODERATE TO FRESH TRADEWINDS. THE 0514 UTC ASCAT 
PASS ALSO INDICATED THE PRESENCE OF 15-20 KT NW WINDS NEAR THE 
WEST COAST OF BAJA CALIFORNIA...PARTICULARLY N OF 25N. THE HIGH 
PRES WILL REMAIN NEARLY STATIONARY WHILE STRENGTHENING. AS A 
RESULT...EXPECT FRESH TO STRONG TRADE WINDS MON AND TUE COVERING 
ROUGHLY THE AREA FROM 08N TO 19N W OF 128W BY TUE WITH SEAS OF 
AROUND 9 FT IN MIXED NW SWELL AND NE WIND WAVES.

GAP WINDS...
N TO NE WINDS OF 20 TO 30 KT WILL CONTINUE TO FUNNEL THROUGH THE 
CHIVELA PASS INTO THE GULF OF TEHUANTEPEC WITH SEAS OF 8-9 FT. 
WINDS WILL PEAK...NEAR 30 KT...DURING THE OVERNIGHT AND EARLY 
MORNING HOURS WITH THE AID OF THE NOCTURNAL DRAINAGE FLOW. WINDS 
WILL THEN DIMINISH TO NEAR 25 KT DURING THE AFTERNOON HOURS. 
LOOKING AHEAD...MARINE GUIDANCE CONTINUE TO SUGGEST THE 
POSSIBILITY OF A NEW GULF OF TEHUANTEPEC GAP WIND EVENT 
OCCURRING WED AND THU...BUT LIKELY REMAINING BELOW GALE FORCE. 
ALL GLOBAL MODELS SHOW NLY WINDS OF 20-30 KT WITH BUILDING SEAS 
OF 8-10 FT.

WINDS WILL PULSE IN THE GULF OF PAPAGAYO TO 20 KT DURING THE 
OVERNIGHT HOURS THEN DIMINISHING BELOW 20 KT DURING THE 
AFTERNOON HOURS. 

$$
GR