000
AXPZ20 KNHC 260859
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0745 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
THE MONSOON TROUGH AXIS EXTENDS FROM 07N78W TO 07N86W TO 07N91W 
WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 07N104W TO 
08N110W...THEN CONTINUES FROM 08N113W TO 05N128W TO 06N140W.  
SCATTERED MODERATE CONVECTION IS FROM 02N TO 07N BETWEEN 94W AND 
106W. SIMILAR CONVECTION IS FROM 04N TO 15N BETWEEN 108W TO 
115W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 
06N TO 10N BETWEEN 127W AND 135W.
       
...DISCUSSION... 

GULF OF TEHUANTEPEC...LAND BASED SURFACE OBSERVATIONS FROM BOTH 
THE NORTHERN AND SOUTHERN ENDS OF THE ISTHMUS OF TEHUANTEPEC 
INDICATED NORTHERLY 15 TO 20 KT WINDS WITH GUSTS TO NEAR GALE 
FORCE LATE YESTERDAY. THE STRONG GALES ARE INDICATIVE OF THE 
BOUNDARY LAYER WINDS...AND MUCH OF THIS IS MIXING TO THE SURFACE 
OVER THE RELATIVELY WARMER WATERS OF THE ADJACENT GULF OF 
TEHUANTEPEC THIS MORNING. THESE WINDS WILL GRADUALLY DIMINISH 
THROUGH MIDDAY SAT AS HIGH PRES OVER THE GULF OF MEXICO WEAKENS 
AND SHIFTS E. DESPITE THE LIMITED DURATION AND FETCH...THE WINDS 
WILL GENERATE SEAS AS HIGH AS 9 FT IN THE GULF OF TEHUANTEPEC 
LINGERING INTO SAT AFTERNOON. 

FARTHER SOUTH...PULSE OF WIND TO MAINLY 20 KT WILL PERSIST OVER 
THE GULF OF PAPAGAYO DUE TO ENHANCED TRADE WIND FLOW OVER THE SW 
CARIBBEAN. THE BEST TIME FOR THESE PULSES WILL BE IN THE EARLY 
MORNING HOURS DUE TO DRAINAGE FLOW ENHANCEMENT. SIMILARLY...SHIP 
REPORTS OVER THE GULF OF PANAMA FROM A FEW HOURS AGO INDICATED 
WINDS TO 20 KT...LIKELY DUE TO STRONGER NORTHERLY WINDS ON THE 
CARIBBEAN SIDE PUSHING THROUGH THE ISTHMUS. THESE WINDS WILL 
DIMINISH THROUGH TODAY. 

DIVERGENT SW FLOW ALOFT ON THE WESTERN SIDE OF A MID/UPPER RIDGE 
CENTERED NEAR 08N100W IS AIDING SCATTERED MODERATE TO ISOLATED 
STRONG CONVECTION FROM 02N TO 08N BETWEEN 95W AND 105W. 

W OF 110W...THE MAIN WEATHER INFLUENCES INCLUDE A DEEP LAYER 
RIDGE CENTERED WELL N OF THE DISCUSSION AREA...WITH A 1025 MB  
SURFACE HIGH OFF THE OREGON COAST. A SHARP MID/UPPER LEVEL 
TROUGH EXTENDS FROM THE CENTRAL ROCKIES SOUTH OF THE RIDGE TO 
33N130W...AHEAD OF A WEAK UPPER LEVEL SHORT WAVE TROUGH PASSING 
THROUGH 135W N OF 25N. THE MAIN IMPACT OF THIS ON THE WEATHER 
INTO EARLY NEXT WEEK WILL BE TO KEEP THE RIDGE FAIRLY WEAK AND 
CENTERED WELL N OF THE AREA. ASCAT DATA FROM THE PREVIOUS 12 
HOURS SHOW ONLY 15 TO 20 KT TRADE WINDS FLOW S OF THE RIDGE. 
ASCAT DATA AS WELL GOES HIGH DENSITY WINDS ALSO INDICATE A WEAK 
TROUGH IN THE DEEP TROPICS EXTENDING FROM 09N TO 14N ALONG 112W. 
AS THIS TROUGH MOVES WESTWARD THROUGH THE WEEKEND...IT WILL 
BECOME CENTERED DUE SOUTH OF THE WEAK RIDGE N OF THE 
AREA...ALLOWING TRADE WINDS TO INCREASE FROM 09N TO 15N W OF 
120W. SEAS WILL BUILD TO 9 FT IN THE AREA OF ENHANCED TRADES 
THROUGH SUN. WEAK BOUNDARY LAYER CONVERGENCE INTO THE ITCZ ALONG 
WITH DIVERGENCE ALOFT ARE AIDING DEVELOPMENT OF CLUSTERS OF 
MODERATE TO ISOLATED STRONG CONVECTION FROM 06N TO 10N BETWEEN 
127W AND 135W. 

$$
EC/NR