000
AXPZ20 KNHC 201001
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI APR 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

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

WEAK MONSOON TROUGH FROM 11N88W TO 04N94W TO 05N107W. ITCZ AXIS 
EXTENDS FROM 04N112W TO 05N122W TO BEYOND 02N140W. SCATTERED 
MODERATE TO STRONG CONVECTION NOTED WITHIN 210 NM N OF ITCZ E OF 
134W. SCATTERED MODERATE CONVECTION NOTED FROM 02N TO 11N 
BETWEEN 99W AND 112W. 

...DISCUSSION...

AT UPPER LEVELS...A BROAD BLOCKING UPPER RIDGE WAS CENTERED ON 
AN ANTICYCLONE NEAR 31N122W...WITH RIDGING N OF 26N. NEARLY 
ZONAL FLOW ALOFT PREVAILED S OF THIS RIDGE TO 09N-10N. ACTIVE 
CONVECTION ALONG AND N OF THE ITCZ WAS MAINTAINING AN ELONGATED 
AND NARROW UPPER RIDGE FROM 05N133W TO 08N88W. 

AT LOWER LEVELS...A 1025 MB HIGH IS CENTERED NEAR 32N135W WITH 
ASSOCIATED RIDGE EXTENDING SE TO NEAR 15N106W. A COLD FRONT 
FURTHER W IS ADVANCING TOWARDS THE DISCUSSION AREA AND IS 
EXPECTED TO REACH NEAR 30N140W SAT NIGHT...AND WILL EXTEND FROM 
30N130W TO BEYOND 24N140W ON MONDAY EVENING. S OF THE RIDGE 
AXIS...SUFFICIENT PRES GRADIENT EXISTS TO INDUCE FRESH 
TRADEWINDS FROM 06N TO 20N W OF 130W AND FROM 07N TO 12N BETWEEN 
122W AND 130W...WHERE SEAS ARE RUNNING 8-9 FT IN NW SWELL. E OF 
THE HIGH...AND AREA OF 20 KT NLY WINDS WAS DEPICTED BY AN 0452 
ASCAT PASS N OF 28N BETWEEN 120W AND 125W. LIGHT WINDS PREVAILED 
E OF 110W...WHERE THE MONSOON TROUGH HAS BEGUN TO SLOWLY DEVELOP 
AS DESCRIBED ABOVE. THE SURFACE HIGH WILL SHIFT SLOWLY NE AND 
WEAKEN DURING THE NEXT TWO DAYS AS THE COLD FRONT REACHES THE 
LOCAL AREA. THIS WILL WEAKEN THE AREA OF TRADEWINDS AND LIMIT IT 
TO A VERY SMALL AREA ACROSS SW PORTIONS BY SAT.
 
A STRONG COLD FRONT IS FORECAST TO MOVE ACROSS THE GULF OF 
MEXICO FRI NIGHT AND SAT AND WILL ALLOW NLY FLOW TO SPILL 
THROUGH THE GULF OF TEHUANTEPEC SAT NIGHT...INCREASING TO GALE 
FORCE EARLY SUN. LATEST GLOBAL MODEL GUIDANCE SHOWS GALE FORCE 
WINDS POSSIBLY CONTINUING THROUGH TUE MORNING. A SUSTAINED 
PERIOD OF HIGH WINDS WILL ALLOW SEAS TO BUILD TO 12-13 FT 
DOWNSTREAM OF TEHUANTEPEC MON AND TUE.

$$
STRIPLING