000
AXPZ20 KNHC 282125
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED MAR 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

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

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N113W TO 
05N121W TO 07N140W. SCATTERED MODERATE CONVECTION IS FROM 07N TO 
09N BETWEEN 137W AND 140W.

...DISCUSSION...
A BROAD AND ENERGETIC UPPER LEVEL TROUGH IS ACROSS THE WESTERN 
COAST OF THE U.S. WITH AXIS EXTENDING OVER NORTHERN CALIFORNIA 
TO A BASE NEAR 29N127W. THIS TROUGHING STRETCHES AND EXTENDS TO 
THE WEST-SOUTHWEST TO A MIDDLE TO UPPER LEVEL CUT-OFF LOW 
CENTERED NEAR 17N144W. THIS CUT-OFF LOW REMAINS SLOW TO MOVE AND 
CONTINUES TO DRIFT SE DUE TO A VERY BROAD RIDGE ALOFT BUILDING 
INTO THE CENTRAL PACIFIC BEHIND THE WEST COAST TROUGH. MIDDLE TO 
UPPER LEVEL DIFFLUENT FLOW IS MAXIMIZED EAST OF THE CUT-OFF 
UPPER LEVEL LOW AND ALONG WITH LOW-LEVEL MOISTURE CONVERGENCE IN 
A ZONE NORTH OF THE ITCZ CONTINUES TO PRODUCE SCATTERED MODERATE 
CONVECTION 09N TO 16N BETWEEN 130W AND 139W THIS AFTERNOON INTO 
THE EVENING HOURS.OTHERWISE...ZONAL FLOW ALOFT PREVAILS OVER THE 
AREA S OF 23N TO 100W. E OF 105W...A BROAD UPPER LEVEL TROUGHING 
IS NOTED WITH AXIS EXTENDING FROM 14N98W TO 02N91W. 

AT THE LOW LEVELS...A DISSIPATING COLD FRONT IS ANALYZED FROM 
32N124W TO 26N137W AND CONTINUES TO BECOME MORE DIFFUSE. WINDS 
SURROUNDING THE FRONT REMAIN BELOW 20 KT...HOWEVER LARGE NW 
SWELLS ASSOCIATED WITH THE FRONT CONTINUE TO PROPAGATE 
SOUTHEASTWARD...WITH SEAS 8 TO 13 FT ACROSS MUCH OF THE NW 
PORTION OF THE AREA. 

WEAK HIGH PRESSURE IS LOCATED SE OF THE FRONT AS A 1021 MB HIGH 
CENTERED NEAR 27N126W. A SUFFICIENT PRESSURE GRADIENT EXISTS 
ALONG THE W COAST OF THE BAJA CALIFORNIA PENINSULA TO PRODUCE 
NORTHERLY WINDS OF 20 KT N OF 26N WITHIN 120 NM OF THE W COAST. 
A RECENT 28/1654 UTC PARTIAL ASCAT PASS DEPICTED THE SOUTHERN 
EXTENT OF THESE 20 KT WINDS. TO THE S OF THE HIGH...FRESH NE TO 
E TRADEWINDS WERE SHOWN BY EARLY AFTERNOON SCATTEROMETER PASSES 
GENERALLY FROM 05N TO 18N W OF 115W...WHERE SEAS WERE IN THE 
RANGE OF 8 TO 12 FT IN MIXED NE AND NW SWELL. THESE FRESH TRADES 
WILL PERSIST THROUGH THURSDAY AND CONTINUE TO INITIATE STRONG 
CONVECTION W OF 130W AS THE ASSOCIATED MOISTURE CONTINUES TO 
INTERACT WITH THE CUT-OFF UPPER LEVEL LOW. NW SWELL IS EXPECTED 
TO MERGE WITH SW SWELL FROM THE SOUTHERN HEMISPHERE OVERNIGHT 
INTO THURSDAY PRODUCING A CONFUSED SEA STATE.

EAST OF 110W...SURFACE WINDS REMAIN LIGHT TO MODERATE...WITH GAP 
WIND FLOW THROUGH THE GULF OF PAPAGAYO INCREASING TO NEAR 20 KT 
ONLY DURING THE LATE NIGHT AND EARLY MORNING HOURS. A NEW PULSE 
OF STRONG SW SWELL WILL REACH THE CENTRAL AMERICAN COASTLINES ON 
THURSDAY TO PRODUCE MODERATE SIZED...BUT POWERFUL AND DANGEROUS 
SURF ALONG THE LOCAL REEFS AND BEACHES.

$$
HUFFMAN