000
AXPZ20 KNHC 090945
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN DEC 09 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 
0915 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH FROM 07N78W TO 08N85W. ITCZ FROM 08N85W TO LOW 
PRES NEAR 08N95W 1008 MB TO 09N108W...THEN CONTINUES FROM 
09N113W 07N140W. SCATTERED MODERATE CONVECTION WITHIN 30 NM N OF 
ITCZ AXIS W OF 135W.

...DISCUSSION...

A SHARP UPPER TROUGH IS DIGGING SOUTHWARD ACROSS THE WESTERN 
STATES. THIS IS AHEAD OF DEEP LAYER RIDGING CENTERED N OF THE 
AREA SUPPORTING A 1030 MB SURFACE HIGH NEAR 38N135W. A 06 UTC 
ASCAT PASS INDICATED A BROAD SWATH OF FRESH TO STRONG N WINDS 
PERSISTING E OF 130W TO THE COAST OF CENTRAL AND SOUTHERN 
CALIFORNIA. THE ASCAT PASS ALSO INDICATED FRESH TO STRONG TRADE 
WINDS S OF THE HIGH PRES GENERALLY N OF 15N AND W OF 135W. 
GLOBAL MODELS SHOW THE DEEP LAYER RIDGE N OF THE AREA FLATTENING 
OUT THROUGH MON AS A VIGOROUS SHORT WAVE TROUGH DIGS ACROSS THE 
FAR NE PACIFIC. THE WEAKENING THESE WINDS PERSISTING THROUGH 36 
HOURS THEN STARTING TO DIMINISH BY 48 HOURS...LEAVING A SWATH OF 
SEAS TO 8 FT IN NE SWELL. VERY MODEST CONVECTION IS NOTED S OF 
THE TRADE WIND BELT ALONG THE ITCZ W OF 135W. 

AN UPPER TROUGH THAT HAD BEEN SITUATED ALONG 120W FROM 10N TO 
25N IS DEAMPLIFYING AND LIFTING NE. THIS HAD BEEN SUPPORTING 
PERSISTENT CONVECTION N OF THE ITCZ TO THE SE OF THE 
TROUGH...BUT THIS APPEARS TO HAVE DISSIPATED. A 0426 UTC ASCAT 
PASS DETECTED A WEAK SURFACE TROUGH NEAR 110W ALONG THE ITCZ 
THAT IS LIKELY RELATED TO THE WEAKENING UPPER FEATURE. THE GFS 
SHOWS THE SURFACE TROUGH PERSISTING ANOTHER 24 HOURS THEN 
DISSIPATING. 

FARTHER EAST...A WEAK 1009 MB LOW PRES CONTINUES TO DRIFT W 
ALONG THE ITCZ...NEAR 08N96W AT 06 UTC. THIS FEATURE IS EXPECTED 
TO PERSIST THROUGH 72 HOURS ALONG THE ITCZ DRIFTING W...BUT WILL 
LIKELY GENERATE NO MORE THAN 15 TO 20 KT WINDS ON ITS NORTHERN 
PERIPHERY. 

GULF OF CALIFORNIA...HIGH PRES BUILDING N OF THE AREA OVER THE 
GREAT BASIN WILL SUPPORT FRESH TO STRONG NE WINDS OVER THE 
NORTHERN GULF OF CALIFORNIA STARTING TONIGHT...AND SPREADING 
DOWN THE LENGTH OF THE GULF THROUGH TUE.  
     
GAP WINDS...
GULF OF TEHUANTEPEC...A COLD FRONT WILL ENTER THE NW GULF OF 
MEXICO SUN NIGHT. THE ASSOCIATED NLY WINDS WILL SURGE AT 
15-20 KT THROUGH THE CHIVELA PASS TUE AFTERNOON...WITH WINDS 
GRADUALLY INCREASING TUE NIGHT AND EARLY WED...REACHING NEAR 
GALE FORCE BY LATE WED...AND CONTINUING INTO MIDDAY THU. GIVEN 
THAT THE SEA SURFACE TEMPERATURES IN THE GULF OF TEHUANTEPEC 
HAVE NOT FULLY RECOVERED FROM EARLIER TEHUANTEPEC 
EVENTS...MIXING OF HIGHER MOMENTUM WINDS TO THE SURFACE WILL NOT 
BE AS EFFICIENT AS IN THE LAST COUPLE OF WEEKS. 

GULF OF PAPAGAYO...
BOTH ASCAT AND OSCAT DATA FROM SAT MORNING AND AFTERNOON 
RESPECTIVELY HIGHLIGHTED NE WINDS OF 15-20 KT WITHIN 90 NM NW OF 
THE GULF OF PAPAGAYO. EXPECT THESE WINDS TO CONTINUE INTO 
SUN...THEN DIMINISH TO 10-15 KT SUN AFTERNOON WITH LITTLE CHANGE 
INTO WED. ON WED NIGHT...MODEL GUIDANCE (GFS BEING THE MOST 
PRONOUNCED) SUGGESTS THAT NE WINDS WILL BEGIN TO PULSE 
DOWNSTREAM OF THE GULF AT THE INCREASED SPEEDS OF 20-25 KT WHILE 
SPREADING WSW INTO THE FORECAST WATERS.

$$
CHRISTENSEN/AGUIRRE