000
AXPZ20 KNHC 261543
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

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

MONSOON TROUGH AXIS EXTENDS FROM 05N77W TO 09N85W TO 06N100W TO 
09N110W WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 07N130W 
TO 06N140W. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION 
IS NOTED FROM 03N TO 06N E OF 80W TO THE COAST OF COLOMBIA. 
SIMILAR CONVECTION IS SEEN FROM 06N TO 08N BETWEEN 83W AND 85W. 
SCATTERED MODERATE CONVECTION IS FROM 05N TO 12N BETWEEN 101W 
AND 115W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION CAN 
BE FOUND FROM 06N TO 10N BETWEEN 130W AND 135W.
       
...DISCUSSION... 

GULF OF TEHUANTEPEC...THE 1406 UTC OSCAT PASS SHOWS NORTHERLY 
WINDS OF 20-30 KT BLOWING THROUGH THE GULF...REACHING TO 13N. IN 
ADDITION...VISIBLE SATELLITE IMAGERY REVEALS NARROW LINES OF LOW 
CLOUD MOVING DOWNSTREAM OF THE GULF WHICH LIKELY DELINEATES THE 
LEADING EDGE OF THE CURRENT LATE SEASON GULF OF TEHUANTEPEC GAP 
WIND EVENT. THESE WINDS WILL GRADUALLY DIMINISH THROUGH EARLY 
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 
TONIGHT. 

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...A 
COUPLE OF SHIP OBSERVATIONS OVER THE GULF OF PANAMA INDICATED 
WINDS OF 20-25 KT...LIKELY DUE TO STRONGER NORTHERLY WINDS ON 
THE CARIBBEAN SIDE PUSHING THROUGH THE ISTHMUS. THESE WINDS WILL 
DIMINISH LATER TODAY. 

A 1024 MB HIGH PRES LOCATED NEAR 38N138W EXTENDS A RIDGE ACROSS 
THE N WATERS MAINLY N OF 18N AND W OF 110W. MODERATE TO FRESH 
TRADE WINDS ARE NOTED ON THE SOUTHERN PERIPHERY OF THE RIDGE AND 
N OF THE ITCZ AXIS. ON SAT...THE SUBTROPICAL RIDGE WILL BUILD S 
AND SE ACROSS THE FORECAST REGION...WITH AN INCREASE IN THE 
TRADE WIND FLOW. MARINE GUIDANCE ALREADY SHOWS A BELT OF FRESH 
TO STRONG TRADE WINDS WITH BUILDING SEAS TO AROUND 9 FT 
AFFECTING THE WEST-CENTRAL WATERS N OF THE ITCZ SAT EVENING 
THROUGH SUN EVENING. OTHERWISE...WINDS ARE EXPECTED TO REMAIN 
BELOW 25 KT OVER THE REMAINDER OF THE FORECAST WATERS THROUGH 
THE WEEKEND.

LATEST ASCAT DATA INDICATE A WEAK TROUGH IN THE DEEP TROPICS 
EXTENDING FROM 15N112W TO 10N112W. SCATTERED MODERATE CONVECTION 
IS NOTED WHERE THE TROUGH AXIS MEETS THE ITCZ...PARTICULARLY 
FROM 06N TO 10N BETWEEN 110W AND 114W. THIS TROUGH WILL MOVE 
WESTWARD THROUGH THE WEEKEND...IT WILL BECOME CENTERED DUE SOUTH 
OF THE SUBTROPICAL RIDGE...ALLOWING TRADE WINDS TO INCREASE.
 
ALOFT...BROAD AND COMPLEX TROUGHING DOMINATES MOST OF THE AREA W 
OF 115W TODAY. AN UPPER RIDGE EXTENDS FROM AN ANTICYCLONE NEAR 
09N100W NORTHWARD TO THE GULF OF TEHUANTEPEC AND THEN ACROSS SE 
MEXICO AND CENTRAL AMERICA INTO THE GULF OF MEXICO. ANOTHER 
RIDGE STRETCHES FROM THE SAME ANTICYCLONE WESTWARD TO ABOUT 
115W. THIS RIDGE WILL MAINTAIN FAVORABLE CONDITIONS FOR ACTIVE 
CONVECTION TO CONTINUE ACROSS THE TROPICS NEAR THE MONSOON 
TROUGH AND ITCZ AXES.  

$$
GR