000
AXPZ20 KNHC 121628
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU APR 12 2007

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 
1545 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N86W 8N96W 8N112W 5N123W 3N140W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF
THE AXIS BETWEEN 84W-108W...AND ALSO WITHIN 180 NM S OF THE AXIS
BETWEEN 110W-118W AND BETWEEN 118W-121W. SIMILAR CONVECTION IS
PRESENT WITHIN 120 NM N OF THE AXIS BETWEEN 118W-120W.

...DISCUSSION...

VERY PROGRESSIVE PATTERN CONTINUES TO BE OBSERVED OVER THE 
DISCUSSION AREA WITH A FAST MOVING SHORTWAVE TROUGH EXPANDING
SW INTO THE NE PART OF THE AREA THROUGH NRN BAJA CALIFORNIA
SW TO 25N120W TO 22N127W TO 18N132W WHERE A WEAK MID/UPPER
CYCLONIC CIRCULATION IS MOVING E AT 20 KT IS NOTED. THE TROUGH 
HAS MARKEDLY SHARPENED OVER THE PAST 24 HRS. TO THE W OF TROUGH 
N OF 20N MID/UPPER LEVEL RIDGING HAS AMPLIFIED OVER THE PAST 24 
HRS WITH AN AXIS EXTENDING FROM W OF THE AREA ALONG 144W NEWD 
INTO THE AREA THROUGH 24N140W AND CONTINUING TO WELL N OF THE 
AREA TO A CREST NEAR NEAR BRITISH COLOMBIA. TO ITS SE...BROAD 
DIFFUSE MID/UPPER LEVEL RIDGING IS NOTED FROM 11N-24N BETWEEN 
111W-129W WITH A RIDGE AXIS ALONG 115W. CONFLUENT FLOW EARLIER 
NOTED BEHIND THE TROUGH IS BEING REPLACED BY EXTENSIVE UPPER 
LEVEL MOISTURE. A SUBTROPICAL JET STREAM BRANCH IS EVIDENT ON 
SATELLITE WATER VAPOR IMAGERY EXTENDING FROM 11N121W NEWD TO 
16N117W TO ACROSS MEXICO NEAR ACAPULCO. SATELLITE DERIVED WINDS 
SHOW MAXIMUM WINDS IN THE RANGE OF 60-80 KT NEAR THE JET CORE.

THE UPPER LEVEL FLOW OVER THE TROPICAL E PACIFIC N OF 6N 
IS BROADLY ANTICYCLONIC AS WELL AS N TO ACROSS CENTRAL AMERICA
AND INTO THE NW CARIBBEAN SEA. ITCZ CONVECTION UNDERNEATH THIS
FLOW HAS BECOME ENHANCED AS WELL AS CONVECTION ALONG THE COAST
OF COSTA RICA. UPPER LEVEL DEBRIS CLOUDINESS IS BEING ADVECTED 
N FROM ITCZ CONVECTION TOWARDS SE MEXICO AND MUCH OF CENTRAL 
AMERICA. NWP MODELS INDICATE THAT THE UPPER LEVEL FLOW IS 
FORECAST TO BE GENERALLY SW TO W BY FRI...WITH VERY STRONG NW 
FLOW OVER THE FAR SW PORTION DUE TO THE NRN PERIPHERY OF AN 
UPPER LEVEL ANTICYCLONIC CENTER WELL SW OF THE AREA.

AT THE SURFACE...HIGH PRESSURE RIDGE EXTENDS INTO THE DISCUSSION 
AREA THROUGH 32N131W 25N125W AND SE TO NEAR 19N120.5W. THE 
ASSOCIATED HIGH CENTER WAS ANALYZED AT 12 UTC JUST N OF THE AREA 
NEAR 34N145W AS 1026 MB. HIGH PRES COVERS THE AREA N OF 13N W OF 
117W. TIGHT PRES GRADIENT OVER THE FAR NE PART OF THE AREA NOTED
BEHIND A DECAYING COLD FRONT IS USHERING STRONG NW FLOW AND 
LARGE NW SWELLS MAXING UP TO 15 FT JUST N OF THE AREA. THESE 
SWELLS ARE FORECAST BY NWW3 GUIDANCE TO SPREAD SE WHILE SLOWLY 
SUBSIDING OVER THE NEXT 48 HRS. LATEST NWP MODELS SUGGEST THAT A 
WEAKENING COLD FRONT WILL MOVE INTO THE EXTREME NW CORNER OF THE 
AREA IN ABOUT 48 HRS FOLLOWED BY A SURGE OF NW SWELL POSSIBLY 
MAXING OUT TO 8 TO 9 FT.

FOR SW AND W FACING COASTAL AREAS...SEAS IN THE 6-8 FT RANGE 
WITH LONG PERIOD SWELLS ON THE ORDER OF MOSTLY 14 SECONDS ARE 
NOTED OVER THE TROPICAL PACIFIC AND THE COASTS OF CENTRAL 
AMERICA AND SE MEXICO. HIGH RESOLUTION WAVE WATCH MODEL GUIDANCE 
SUGGESTS THAT THESE SWELLS SHOULD CONTINUE TO SLOWLY SUBSIDE 
THROUGH THE NEXT COUPLE OF DAYS.

$$
AGUIRRE