000
AXPZ20 KNHC 290239
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI APR 29 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 05N77W 
TO 04N100W TO 08N110W TO 05N125W TO 02N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS FROM 05N TO 09N BETWEEN 112W AND 
120W. ISOLATED MODERATE CONVECTION IS FROM 05N TO 11N BETWEEN 
102W AND 110W. 

...DISCUSSION...
AN UPPER-LEVEL LOW IS JUST MOVING INTO THE FORECAST AREA FROM 
THE WEST. THE LOW IS NOW LOCATED NEAR 23N140W. ABUNDANT MID TO 
UPPER LEVEL MOISTURE IS NOTED AHEAD OF THIS UPPER-LEVEL LOW 
AFFECTING THE FORECAST REGION W OF 130W. THIS SYSTEM WILL MOVE 
ACROSS THE FAR NW PORTION OF THE AREA AND WEAKEN BY FRI NIGHT. 
E OF 125W...A BROAD UPPER-LEVEL RIDGE DOMINATES MUCH OF THE 
FORECAST WATERS. UPPER DIFFLUENCE BETWEEN THE RIDGE AND AN 
UPPER-LEVEL LOW SITUATED NEAR 4N110W IS HELPING TO MAINTAIN THE 
MODERATE TO ISOLATED STRONG CONVECTION THAT COVER THE AREA FROM 
5N TO 9N BETWEEN 112W AND 120W. A SURFACE TROUGH IS LOCATED TO 
THE EAST OF THIS CONVECTIVE ACTIVITY ALONG 111W/112W FROM 6N TO 
11N. THE RIDGE IS ALSO HELPING TO INDUCE SOME CONVECTION OVER 
PANAMA AND COSTA RICA.

AN UPPER LEVEL RIDGE ALONG 140W AND N OF 30N OVER THE NE PACIFIC 
WILL STRENGTHEN AS IT SHIFTS EAST THROUGH 48 HOURS. THIS WILL 
ACT TO REINFORCE A 1034 MB SURFACE HIGH CURRENTLY NEAR 42N142W 
AS IT ALSO SHIFTS EASTWARD. AS A RESULT...EXPECT INCREASING 
WINDS AND BUILDING SEAS ROUGHLY N OF 20N AND W OF THE BAJA 
CALIFORNIA PENINSULA THROUGH SAT. FRESH NW TO N WINDS OFF THE 
NORTHERN BAJA COAST WILL PERSIST AND INCREASE TO 20 TO 25 KT BY 
FRI MORNING. SEAS ALONG THE OFFSHORE WATERS OF THE UPPER BAJA 
PENINSULA WILL BUILD TO 14 FT IN NW SWELL IN THE AREA N OF 24N E 
OF 122W TONIGHT. A SMALL AREA OF FRESH TRADE WINDS IS NOTED ON 
THE SOUTHERN PERIPHERY OF THE RIDGE MAINLY FROM 03N TO 20N W OF 
132W. THE MOST RECENT ASCAT PASS PROVIDE OBSERVATIONS OF THESE 
WIND SPEEDS. MODEL GUIDANCE ALSO SUGGESTS INCREASING WINDS UP TO 
25 KT ACROSS THE GULF OF CALIFORNIA IN ABOUT 36 HOURS AS HIGH 
PRES SETTLES OVER THE GREAT BASIN.

FURTHER EAST...LIGHT AND VARIABLE WINDS CONTINUES ACROSS THE 
TROPICAL EPAC E OF 110W...WITH WEAK MONSOONAL FLOW E OF 90W. 

GAP WINDS...
A SHORT-LIVED GAP WIND EVENT IS EXPECTED THROUGH THE GULF OF 
TEHUANTEPEC THIS FRI. WIND FLOW TO 20 KT WILL BEGIN LATE TONIGHT 
AS A WEAK COLD FRONT MOVES INTO THE SW GULF OF MEXICO...AND 
INCREASE TO NEAR 30 KT FRI MORNING BEFORE QUICKLY DIMINISHING 
BELOW 20 KT BY LATE FRI AS THE AIRMASS TO THE NORTH MODIFIES AND 
SHIFTS E. 

FRESH TRADES OVER THE SW CARIBBEAN WILL ALSO ENHANCE FLOW 
THROUGH THE GULF OF PAPAGAYO BY LATE FRI INTO SAT.   

$$
GR