000
AXPZ20 KNHC 212135
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT APR 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH FROM 07N81W TO 05N85W TO 07N105W. ITCZ IS FROM 07N105W TO 
08N120W...THEN FROM 05N128W TO 04N135W. SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION WITHIN 60 NM S OF AXIS FROM 82W TO 
90W. SCATTERED MODERATE CONVECTION FROM 08N TO 10N BETWEEN 105W 
AND 115W.

...DISCUSSION...
THE MAIN ISSUE FOR THE NEXT 48 HOURS CONTINUES TO BE THE ONSET 
OF GALE FORCE WINDS THROUGH THE GULF OF TEHUANTEPEC STARTING 
TONIGHT...DUE TO A UNSEASONABLY STRONG COLD FRONT PUSHING 
THROUGH THE GULF OF MEXICO. HIGH PRES WILL BUILD OVER THE 
SOUTHERN PLAINS AND NW GULF AS DEEPENING LOW PRES PUSHES THROUGH 
THE NE GULF. STRONG GAP WIND FLOW BEHIND THE FRONT IS PUSHING 
SOUTH OVER THE FAR WESTERN GULF OF MEXICO THIS AFTERNOON...AND 
WILL FUNNEL THROUGH THE CHIVELA PASS BY LATE EVENING...AND BRING 
GALE FORCE WINDS TO THE GULF OF TEHUANTEPEC OVERNIGHT. THESE 
WINDS MAY DIMINISH SLIGHTLY BELOW GALE FORCE LATER ON SUN...BUT 
INCREASE AGAIN IN EXCESS OF GALE FORCE SUN NIGHT DUE TO STRONG 
HIGH PRES BUILDING BEHIND THE FRONT OVER THE WESTERN GULF OF 
MEXICO AS WELL AS NOCTURNAL DRAINAGE INFLUENCES. THE STRONG GAP 
FLOW WILL PERSIST THROUGH MON...CREATING A LONG PLUME OF NE TO E 
WINDS WITH FRESH NE SWELL WITH HEIGHTS OF 8 TO 11 FT REACHING AS 
FAR AS 800 NM SW OF THE GULF OF TEHUANTEPEC. 

ELSEWHERE S OF 20N...WEAK HIGH PRES N OF 20N WILL MAINTAIN 
GENERALLY LIGHT TO MODERATE TRADE WIND FLOW FROM ROUGHLY 06N TO 
20N W OF 110W THROUGH EARLY NEXT WEEK. LIGHT SW FLOW ASSOCIATED 
WITH A POORLY DEFINED MONSOON TROUGH E OF 105W IS STILL 
PROVIDING ENOUGH LOW LEVEL CONVERGENCE TO SUPPORT SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION BETWEEN 82W AND 90W ALONG 
04N. FURTHER WEST...LIGHT TO MODERATE TRADE WIND CONVERGENCE S 
OF A 1015 MB SURFACE HIGH NEAR 23N120W IS AIDING SCATTERED 
MODERATE CONVECTION FROM 08N TO 10N BETWEEN 105W AND 115W.

N OF 20N...A SHARP UPPER TROUGH N OF 23N ALONG 145W CONTINUES TO 
MAKE SLOW MODEST PROGRESS EASTWARD DUE TO A BLOCKING UPPER 
RIDGE CENTERED OVER SOUTHERN CALIFORNIA. AN ASSOCIATED COLD 
FRONT IS APPROACHING THE AREA FROM THE N CENTRAL PACIFIC...BUT 
WILL MOVE VERY SLOWLY EASTWARD AS IT PUSHES INTO A 1015 MB 
SURFACE HIGH NEAR 23N120W ASSOCIATED WITH THE MID/UPPER RIDGE 
OVER SOUTHERN CALIFORNIA. SURFACE RIDGING EXTENDS TO THE SE 
ALONG THE COAST OF MEXICO NEAR 15N105W. THE FRONT WILL REACH 
FROM 30N134W TO 24N140W BY 18Z SUN ...AND FROM 30N128W TO 
24N135W BY 18Z MON BEFORE STARTING TO STALL AND WEAKEN FROM 
35N127W TO 23N130W BY 18Z TUE. THE HIGH PRES WILL ALSO ALLOW 
WINDS TO REMAIN FAIRLY LIGHT N OF 20N INTO EARLY NEXT WEEK. 
GLOBAL MODEL CONSENSUS SHOWS FRESH TO STRONG NW FLOW WILL FOLLOW 
THE COLD FRONT OVER THE FAR NW PORTION OF THE DISCUSSION AREA BY 
LATE MON...ACCOMPANIED BY NW SWELL WITH HEIGHTS OF 8 TO 12 FT.

$$
CHRISTENSEN