000
AXPZ20 KNHC 310926
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT MAR 31 2012

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0730 UTC.

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

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 03N110W TO 
04N118W TO 04N140W. ISOLATED MODERATE CONVECTION LIES WITHIN 
150 NM N OF THE AXIS BETWEEN 112W AND 125W. 

...DISCUSSION...

A POSITIVELY TILTED UPPER TROUGH LIES OVER THE FORECAST AREA 
FROM THE TEXAS BIG BEND THROUGH CENTRAL BAJA CALIFORNIA TO 
23N130W THEN SOUTHWESTWARD TO A STRONG UPPER LOW JUST W OF THE 
AREA NEAR 13N144W. THIS ANOMALOUSLY DEEP LOW IS FOUR STANDARD 
DEVIATIONS DEEPER THAN THE CLIMATOLOGICAL PATTERN AT BOTH 200 MB 
AND 500 MB. THIS LOW WILL BEGIN TO BE PULLED EASTWARD TODAY AS 
THE SUPPORTING TROUGH IS NUDGED EASTWARD BY THE PROGRESSIVE 
NORTHERN STREAM. WHILE STILL PROGRESSIVE...THE NORTHERN STREAM 
IS BECOMING INCREASINGLY MORE AMPLIFIED. RIDGING WILL BUILD OVER 
THE SOUTHWESTERN U.S. BEHIND THE TROUGH...SLOWING DOWN AND 
INTENSIFYING THE NEW TROUGH THAT IS CURRENTLY ENTERING THE 
FORECAST AREA FROM THE NW. THIS NEW TROUGH WILL ALSO HELP LURE 
THE DEEP UPPER LOW EASTWARD INTO THE FORECAST AREA.

SYNOPTIC SCALE LIFT AND MID-LEVEL CONVERGENCE ASSOCIATED WITH 
THE UPPER LOW IS PRODUCING MULTI-LAYERED CLOUDINESS AND WIDELY 
SCATTERED SHOWERS AND TSTMS PRIMARILY W OF THE FORECAST AREA. 
70-80 KT SW WINDS ALOFT ON THE SE SIDE OF THE UPPER LOW ARE 
TRANSPORTING MID TO UPPER LEVEL MOISTURE...MANIFESTED PRIMARILY 
AS CIRRUS CLOUDS...OVER THE REGION FROM 08N TO 16N W OF 125W. 
GRADUAL WEAKENING OF THIS CYCLONE WILL OCCUR OVER THE WEEKEND AS 
IT MOVES E-NE. THIS FEATURE SHOULD CONTINUE TO INITIATE 
CONVECTION EAST OF THE TROUGH AXIS THROUGH THE WEEKEND...WITH 
THE CONVECTIVELY ACTIVE AREA SHRINKING DURING THAT TIME AS THE 
ATMOSPHERE BECOMES MORE STABLE NEAR THE WEAKENING LOW.

AT THE LOWER LEVELS...A 1024 MB SUBTROPICAL HIGH IS CENTERED 
NEAR 26N130W AND EXTENDS A RIDGE AXIS TO 12N96W. SOUTH OF THE 
RIDGE AXIS...A SMALL AREA OF FRESH TRADES LIES W OF 137W. THESE 
TRADEWINDS WILL BUILD EASTWARD TODAY AS HIGH PRES BEHIND A COLD 
FRONT MOVING IN FROM THE NW WILL BECOME THE DOMINANT SUBTROPICAL 
HIGH. STRONG NW WINDS ARE ACCOMPANYING THE FRONT...BUT THE 
BIGGER STORY IS THE LARGE NW SWELL TO 20 FEET EXPECTED OVER N 
WATERS THROUGH THE WEEKEND. THE FRONT CURRENTLY LIES FROM 
30N134W TO 27N140W. IT WILL CONTINUE EASTWARD REACHING BAJA 
CALIFORNIA SUNDAY. THE FRONTAL PASSAGE WILL BRING FRESH NW TO N 
WINDS INTO THE NORTHERN GULF OF CALIFORNIA BY EARLY MON MORNING.

LIGHT TO MODERATE WINDS OTHERWISE PREVAIL E OF 110W...WITH GAP 
WIND FLOW CURRENTLY PULSING TO NEAR 20 KT IN THE GULF OF 
PAPAGAYO BUT EXPECTED TO DIMINISH LATER THIS MORNING. A SURFACE 
TROUGH LIES S OF THE GULF OF PAPAGAYO FROM 08N84W TO 05N85W TO 
04N100W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 150 
NM N AND 90 NM S OF THE TROUGH BETWEEN 86W AND 100W. CONVECTION 
HERE IS BEING ENHANCED BY SPEED DIFFLUENCE ALOFT BETWEEN 40-45 
KT SW FLOW TO THE N AND LIGHT AND VARIABLE WINDS TO THE S. 

$$
SCHAUER