000
AXPZ20 KNHC 070915
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI DEC 07 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...

THE MONSOON TROUGH EXTENDS FROM 08N78W TO 08N83W TO 07N95W. THE 
ITCZ EXTENDS FROM 07N95W TO 08N105W TO 08N120W...THEN CONTINUES 
FROM 08N125W TO 07N140W. SCATTERED MODERATE CONVECTION IS NOTED 
FROM 09N TO 11N BETWEEN 120W AND 125W.

...DISCUSSION...

W OF 110W...A COLD FRONT SAGGING SOUTH OF 30N BETWEEN 120W AND 
130W IS STARTING TO STALL AND DISSIPATE AS THE SUPPORTING MID TO 
UPPER LEVEL SHORT WAVE TROUGH PUSHES INTO SOUTHERN CALIFORNIA. 
1028 MB SURFACE HIGH PRES IS BUILDING N OF THE AREA NEAR 35N125W 
MERGING WITH A RIDGE FROM 30N140W THROUGH HAWAII. SCATTEROMETER 
DATA AND SHIP OBSERVATIONS INDICATE FRESH TO STRONG NORTHERLY 
FLOW BETWEEN THE HIGH PRES AND THE CALIFORNIA COAST N OF 30N E 
OF 130W. ASSOCIATED FRESH SWELL 8 TO 9 FT WILL PUSH AS FAR S AS 
27N BETWEEN 115W AND 125W THROUGH LATE TODAY BEFORE DECAYING 
BELOW 8 FT. FARTHER SOUTH FRESH TO STRONG TRADE WINDS ARE NOTED 
S OF THE RIDGE FROM 08N TO 18N W OF 135W. WHILE TRADE WINDS ARE 
ONLY 10 TO 15 KT FARTHER EAST BETWEEN 120W AND 125W...LOW LEVEL 
CONVERGENCE AIDED BY DIVERGENCE ASSOCIATED WITH A SHARP UPPER 
TROUGH EXTENDING FROM 25N123W TO 10N125W ARE SUPPORTING THE 
SCATTERED MODERATE CONVECTION FROM 09N TO 11N BETWEEN 120W AND 
125W. DRY AIR W OF THE TROUGH AXIS IS PRECLUDING CONVECTIVE 
GROWTH DESPITE DECENT LOWER LEVEL CONVERGENCE OF THE FRESH TO 
STRONG TRADES W OF 135W. THE TRADES WILL DIMINISH INTO SAT AS 
ANOTHER MID/UPPER LEVEL SHORT WAVE TROUGH NW OF THE AREA MOVES 
TO 27N139W...WEAKENING THE SURFACE RIDGING AND ALLOW THE PRES 
GRADIENT TO LOOSEN. THE SCATTERED CONVECTION WILL LIKELY 
DIMINISH AS WELL AS THE SHARP UPPER TROUGH BECOMES LESS 
AMPLIFIED AND SHIFTS EAST. 

E OF 110W...SUCCESSIVE PULSES OF 20 KT WINDS THROUGH THE GULF OF 
PAPAGAYO ARE AIDING THE DEVELOPMENT OF A BROAD AND WEAK 
CIRCULATION ALONG THE MONSOON TROUGH AXIS DOWNSTREAM AND TO THE 
WEST OF THE GULF OF PAPAGAYO NEAR 07N89W. GLOBAL MODEL CONSENSUS 
INDICATES A WEAK TROUGH WILL FORM OUT OF THIS FEATURE THROUGH 24 
HOURS...WITH A WEAK AND SHORT-LIVED LOW PRES AREA FORMING BY 48 
HOURS. WINDS MAY REACHING 20 KT WITHIN 120 NM ON THE N 
SEMICIRCLE OF THIS LOW ON SAT. 

LOOKING AHEAD...NW TO N WINDS OVER THE NORTHERN GULF OF 
CALIFORNIA WILL INCREASE TO 20 TO 25 KT BY LATE SUN AS HIGH PRES 
BUILDS OVER THE GREAT BASIN AFTER THE PASSAGE A DEEP LAYER 
TROUGH THROUGH THE ROCKIES. THE SAME FRONT WILL START TO WEAKEN 
EARLY NEXT WEEK AS THE UPPER SUPPORT BECOMES MORE BROAD AND 
LIFTS OUT. GLOBAL MODELS DO NOT SHOW THE NEXT STRONG PUSH OF GAP 
WINDS INTO THE GULF OF TEHUANTEPEC UNTIL AFTER MID WEEK 
FOLLOWING A REINFORCING TROUGH DIGGING INTO THE CENTRAL PLAINS.

$$
CHRISTENSEN