000
AXPZ20 KNHC 160236
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT APR 16 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...

INTERTROPICAL CONVERGENCE ZONE AXIS FROM 04N77W TO LOW PRES 1007 
MB NEAR 06N91W TO 02N110W TO 00N129W. SCATTERED TO NUMEROUS 
MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 120 NM S 
QUADRANT AND 60 NM NE QUADRANT OF LOW CENTER. SCATTERED MODERATE 
CONVECTION IS WITHIN 80 NM N OF AXIS FROM 92W TO 95W. 

...DISCUSSION...
A RIDGE/TROUGH/RIDGE PATTERN IS STILL NOTED OVER THE N WATERS. A 
CUT-OFF LOW IS DEVELOPING NEAR 21N122W. A 30 TO 45 KT SWLY FLOW 
AHEAD OF THIS LOW/TROUGH IS TRANSPORTING ABUNDANT MID/UPPER 
LEVEL MOISTURE FROM ACROSS THE SOUTHERN TIP OF BAJA CALIFORNIA 
INTO N-CENTRAL MEXICO. A GOOD AMOUNT OF MID/UPPER LEVEL MOISTURE 
IS ALSO REACHING THE FAR W PORTION OF THE FORECAST REGION AHEAD 
OF AN UPPER-LEVEL TROUGH LOCATED JUST EAST OF THE HAWAIIAN 
ISLANDS. MODERATE TO STRONG SUBSIDENCE COVER THE REMAINDER OF 
THE AREA N OF 20N W OF 120W...AND N OF 24N E OF 120W. AN 
UPPER-LEVEL RIDGE DOMINATES THE REGION E OF 100W...INCLUDING SE 
MEXICO AND CENTRAL AMERICA. UPPER DIFFLUENCE ASSOCIATED WITH 
THIS FEATURE IS HELPING TO INDUCE CONVECTION NEAR THE LOW PRES 
LOCATE AT 06N91W. 

IN THE DEEP TROPICS AN ANTICYCLONIC CIRCULATION IS LOCATED NEAR 
7N124W. A DIFFLUENT PATTERN ALOFT ON THE EAST SIDE OF THIS 
ANTICYCLONE WILL PROMOTE THE DEVELOPING OF SHOWER AND TSTM 
ACTIVITY ALONG THE ITCZ AND NEAR A SURFACE TROUGH THAT EXTENDS 
FROM 10N118W TO 05N115W. IN FACT...A CLUSTER OF MODERATE TO 
ISOLATED STRONG CONVECTION HAS DEVELOPED NEAR THE NORTHERN END 
OF THE TROUGH AXIS. 

SHOWERS AND TSTMS IN ASSOCIATION WITH THE WEAK AREA OF LOW PRES 
LOCATED NEAR 06N91W HAS BECOME A LITTLE BETTER ORGANIZED 
TONIGHT. LATEST SATELLITE PICTURES SHOW A 70-90 NM WIDE BAND OF 
MODERATE TO ISOLATED STRONG CONVECTION ON THE SE SEMICIRCLE OF 
LOW CENTER. AN EARLIER ASCAT PASS INDICATED A BROAD CYCLONIC 
CIRCULATION WITH MAINLY GENTLE TO MODERATE WINDS AROUND THE LOW. 
ACCORDING TO THE COMPUTER MODELS...THIS SYSTEM IS FORECAST TO 
PERSIST FOR THE NEXT SEVERAL DAYS. EXPECT THE LOW TO DRIFT WNW 
WITH LITTLE CHANGE IN INTENSITY. THIS MONSOON LOW MAY BE THE 
FIRST SIGN OF THE TRANSITION INTO THE UPCOMING EPAC TROPICAL 
SEASON. 

A 1027 MB SFC HIGH PRES JUST N OF THE AREA NEAR 32N132W EXTENDS 
A RIDGE SE TO AROUND 17N110W. THE COMBINATION OF THE HIGH AND A 
TROUGH OVER NW MEXICO IS RESULTING IN FRESH TO STRONG WINDS 
ACROSS THE GULF OF CALIFORNIA AND W OF THE BAJA CALIFORNIA 
PENINSULA. THE 0115 UTC EXPERIMENTAL ASCAT 25 KM COASTAL WINDS 
PROVIDED OBSERVATIONS OF 20 TO 25 KT ACROSS THE GULF OF 
CALIFORNIA WHILE SOME SHIP OBSERVATIONS ALONG WITH THE MOST 
RECENT ASCAT PASS VERIFIED THE WIND SPEEDS W OF THE BAJA 
PENINSULA. MODEL GUIDANCE INDICATES THE PRES GRADIENT WILL RELAX 
OVER THE NEXT 24 HOURS...ALLOWING WINDS TO DROP BELOW 20 KT SAT.

MODERATE TO FRESH TRADE WINDS S OF THE HIGH WILL CONTINUE AS WELL
THROUGH SAT. AS THE HIGH SHIFTS FURTHER W AND WEAKENS...EXPECT 
TRADES TO STEADILY DIMINISH THROUGH SUN. THIS WILL ALLOW SEAS TO 
SUBSIDE BELOW 10 FT SAT MORNING...AND NEAR 8 FT BY SUN MORNING. 
LARGE AREA OF LONG PERIOD 19-20 SEC SW SWELL WILL PROPAGATE 
THROUGH MUCH OF THE FORECAST AREA OVER THE NEXT SEVERAL DAYS.

$$
GR