000
AXPZ20 KNHC 131516
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE DEC 13 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 FROM 9N85W 5N90W 6N100W. ITCZ AXIS FROM 6N100W 
10N110W 9N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
WITHIN 60 NM EITHER SIDE OF AXIS BETWEEN 110W-115W.

...DISCUSSION...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 8N132W 
WITH A RIDGE EXTENDING FROM THE ANTICYCLONE N TO 30N138W. UPPER 
LEVEL MOISTURE IS FLOWING THROUGH THE RIDGE N OF 17N. A DEEP 
LAYERED TROUGH EXTENDS FROM A LARGE CYCLONIC CIRCULATION OVER 
THE WESTERN U.S. S TO 32N117W TO 17N117W. A 95-100 KT NW 
JETSTREAM FROM 32N125W TO 27N117W THEN WINDS BECOME SW AND 
INCREASE TO 105-115 KT FROM 27N117W TO CENTRAL BAJA CALIFORNIA 
INTO NW MEXICO. AN UPPER LEVEL ANTICYCLONIC CIRCULATION SE TO 
THE UPPER TROUGH IS CENTERED NEAR 12N103W WITH RIDGE NE INTO 
SOUTHERN MEXICO. STRONG SUBSIDENCE WITH DRY STABLE AIR AT THE 
MIDDLE AND UPPER LEVELS COVERS THE AREA FROM 10-20N BETWEEN 
90W-120W. 

TIGHT PRES GRADIENT ACROSS SOUTHERN MEXICO IS PRODUCING STRONG 
NLY WINDS TO 30 KT THROUGH THE GULF OF TEHUANTEPEC. THESE WINDS 
ARE EXPECTED TO DECREASE TO BELOW 20 KT WED NIGHT.

SURFACE RIDGE EXTENDS FROM NEAR 32N138W SE TO 21N114W. 
COMBINATION OF RIDGE WITH ITCZ ASSOCIATED LOW PRES IS SUSTAINING 
E-NE WINDS 20 KT FROM 10-17N W OF 130W WITH 9-10 FT SEAS. STRONG 
NLY WINDS IN THE 20-30 KT RANGE WITH SEAS 9-14 FT N OF 25N 
BETWEEN 117W-131W. THESE WINDS ARE FORECAST TO DECREASE TO LESS 
THAN 20 KT WED...HOWEVER LARGE NLY SWELLS WILL CONTINUE.

$$
DGS