000
AXPZ20 KNHC 262203
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC FRI APR 26 2013

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

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

MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 07N75W TO 03N79W 
TO 08N86W TO 07N95W WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON 
TO 11N114W TO 08.5N135W TO BEYOND 08N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION NOTED FROM 02N TO 08N E OF 86W TO NW 
PORTIONS OF COLOMBIA. SCATTERED TO NUMEROUS MODERATE TO STRONG 
CONVECTION NOTED FROM 05.5N TO 13N BETWEEN 105W AND 113W. 
SCATTERED MODERATE CONVECTION NOTED WITHIN 210 NM N OF ITCZ 
BETWEEN 124W AND 134W.
       
...DISCUSSION... 

GULF OF TEHUANTEPEC...VISIBLE SATELLITE IMAGERY THIS AFTERNOON 
REVEALS FINE NARROW LINES OF LOW CLOUD MOVING DOWNSTREAM OF THE 
GULF OF TEHUANTEPEC TO 10N98W...WHICH DELINEATES THE PLUME OF 
NORTHERLY WINDS ASSOCIATED WITH THIS LATE SEASON GULF OF 
TEHUANTEPEC GAP WIND EVENT. NORTHERLY FLOW FROM THE GULF OF 
MEXICO THROUGH THE CHIVELA PASS HAS ENDED...AND THE GAP WINDS 
WILL GRADUALLY DIMINISH TONIGHT AND END BY SATURDAY MORNING. 
DESPITE THE LIMITED DURATION AND FETCH...THE WINDS WILL MAINTAIN 
SEAS AS HIGH AS 9 FT DOWNSTREAM OF THE GULF OF TEHUANTEPEC 
LINGERING INTO TONIGHT. 

FARTHER SOUTH...GAP WINDS ARE ALSO FUNNELING ACROSS CENTRAL 
AMERICA AND THROUGH THE GULF OF PAPAGAYO...WITH E-NE WINDS 
AROUND 20 KT EXTENDING DOWNSTREAM TO NEAR 10N90W PER A 1604 UTC 
ASCAT-A PASS. THESE GAP WINDS ARE EXPECTED TO INCREASE TO AROUND 
25 KT LATE TONIGHT THROUGH THE EARLY MORNING HOURS DUE TO 
DRAINAGE FLOW ENHANCEMENT...THEN DECREASE TO 15-20 KT DURING THE 
DAY SATURDAY BEFORE DIMINISHING TO LESS THAN 20 KT BY SUNDAY 
MORNING. 

ELSEWHERE AT THE SURFACE...WEAK LOW PRES OFFSHORE OF THE 
SOUTHERN CALIFORNIA COAST CONTINUES TO WEAKEN AND IS DRIFTING NW 
THIS AFTERNOON...ALLOWING A WEAK HIGH PRES RIDGE TO BUILD FROM A 
1026 MB HIGH NEAR 34N126W S AND SE INTO THE DISCUSSION AREA...TO 
14N99W. MODERATE NE TRADE WINDS 15-20 KT NOW PREVAIL S OF 15N TO 
THE ITCZ...FROM 115W WESTWARD. ON SAT...THIS SUBTROPICAL RIDGE 
WILL BUILD S AND SE ACROSS THE FORECAST REGION...AND BEGIN TO 
INDUCE AN INCREASE IN THE TRADE WIND FLOW. MODEL GUIDANCE 
INDICATES THAT NE TRADE WINDS 20-25 KT WILL DEVELOP BY SAT 
AFTERNOON FROM 09N TO 15N W OF 125W AND PERSIST THROUGH 
SUNDAY...WITH SEAS BUILDING 8 TO 9 FT. OTHERWISE...WINDS ACROSS 
THE DISCUSSION AREA ARE EXPECTED TO REMAIN BELOW 25 KT OVER THE 
REMAINDER OF THE FORECAST WATERS THROUGH THE WEEKEND.

DEEP CONVECTION CONTINUES ALONG AND N OF THE ITCZ FROM 05.5N TO 
13N BETWEEN 105W AND 113W...ON THE E SIDE OF A LOW LEVEL TROUGH 
ALONG THE ITCZ AT 115W. ACTIVE CONVECTION THROUGH THIS REGION 
THE PAST FEW DAYS HAS HELPED THE UPPER LEVEL RIDGE PREVAILING S 
OF 20N AND E OF 120W THE PAST FEW DAYS...TO EXPAND W AND NW TO 
130W. OTHERWISE...A BROAD AND COMPLEX TROUGH DOMINATES MOST OF 
THE AREA W OF 120W...PRODUCING W TO SW FLOW ALOFT. MODEL 
GUIDANCE SUGGESTS THAT THE LOW LEVEL TROUGH WILL CONTINUE TO 
SHIFT W THROUGH THE WEEKEND...WITH ACTIVE CONVECTION CONTINUING 
ON ITS E SIDE...WITH THE UPPER RIDGE EXPANDING WWD IN TANDEM 
WITH THE LOW LEVEL TROUGH. 

$$
STRIPLING