000
AXPZ20 KNHC 050940
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN APR 05 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0745 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 6N77W 
TO 07N85W TO 03N109W TO 03N132W TO 04N140W. ISOLATED MODERATE 
CONVECTION CAN BE FOUND WITHIN 60 NM OF AXIS BETWEEN 99W AND 
103W.

...DISCUSSION...
A LATE SEASON GULF OF TEHAUNTEPEC STORM FORCE WIND EVENT WILL BE 
INDUCED BY A COLD FRONT PASSING THROUGH THE BAY OF CAMPECHE 
MONDAY...SENDING STRONG NORTHERLY FLOW THROUGH THE ISTHMUS OF 
TEHUANTEPEC BEGINNING MON AFTERNOON/EVENING. THE FRONT IS 
EXPECTED TO BE PARTICULARLY POTENT FOR THIS TIME OF THE 
YEAR...ALLOWING MID LEVEL ENERGY TO PASS SOUTHWARD FROM THE 
SUPPORTING DEEP LAYER TROUGH OVER THE GULF OF MEXICO THROUGH 
SOUTHERN MEXICO INTO THE PACIFIC ON THE EASTERN EDGE OF A STRONG 
MID TO UPPER LEVEL ANTICYCLONE. WINDS IN THE GULF OF TEHUANTEPEC 
WILL QUICKLY INCREASE TO STORM FORCE TUE MORNING. IN 
ADDITION...THE PRESSURE GRADIENT BETWEEN THE TROUGH SUPPORTING 
THIS COLD FRONT AND A WEAKENING SURFACE RIDGE OFF THE COAST OF 
BAJA CALIFORNIA WILL INDUCE WINDS TO 20 KT OVER THE GULF OF 
CALIFORNIA LATER TODAY ENDING MON EVENING.

A NEW COLD FRONT HAS ENTERED FAR NW WATERS. THE QUIKSCAT PASS 
FROM 0256 UTC SHOWS 20 KT WINDS W OF THE FRONT OVER THE FORECAST 
AREA. NW SWELL ASSOCIATED WITH THE SYSTEM IS LAGGING 
BEHIND...BUT SEAS SHOULD BUILD TO THE 10 TO 15 FT RANGE BY THIS 
AFTERNOON. THE DEEP LAYER TROUGH SUPPORTING THIS COLD FRONT WILL 
CUT OFF FROM THE NORTHERN STREAM FLOW LATER TODAY AND THEN 
SLOWLY CRAWL EASTWARD TOWARD CALIFORNIA. THE ASSOCIATED COLD 
FRONT WILL BE SLOW TO MOVE EASTWARD AS A RESULT...ALLOWING THE 
NW SWELL TO MOVE AHEAD OF THE SURFACE BOUNDARY BEGINNING MONDAY. 
NO SIGNIFICANT CONVECTION IS ASSOCIATED WITH THIS COLD FRONT AS 
IT LIES WITHIN A RELATIVELY DRY AIR MASS N OF 25N W OF 120W. 
CURRENTLY...THE COLD FRONT IS MOVING EASTWARD...WEAKENING THE 
RIDGE AXIS TO ITS EAST WHERE STRONG NORTHERLY FLOW THE PAST FEW 
DAYS ON THE EAST SIDE OF THE RIDGE AXIS HAS LEFT SOME RESIDUAL 
NORTHERLY SWELL PRIMARILY N OF 25N E OF 130W THAT WILL SUBSIDE 
MON MORNING. 

THE SUBTROPICAL JET ORIGINATES SW OF HAWAII AND STRETCHES ALONG 
A LINE FROM 15N140W TO 25N110W. THIS 70 TO 90 KT JET IS PUMPING 
MID TO UPPER LEVEL MOISTURE EASTWARD ACROSS THE FORECAST 
AREA...WITH MULTILAYERED CLOUDINESS FOUND WITHIN 270 NM OF THE 
JET AXIS. 

A WEAK UPPER TROUGH LIES S OF 10N ALONG 112W. VERTICAL LIFT 
ASSOCIATED WITH THE REAR RIGHT QUADRANT OF THE WEAK SOUTHERLY 
UPPER JET ON THE EASTERN EDGE OF THIS TROUGH IS ACTING ON 
PLENTIFUL LOW LEVEL MOISTURE...WITH PRECIPITABLE WATER VALUES IN 
EXCESS OF 2 INCHES. WHILE MUCH OF THIS REGION IS DOMINATED BY 
STRONG SUBSIDENCE ALOFT ASSOCIATED WITH THE ANTICYCLONE CENTERED 
NEAR 10N100W ...ISOLATED MODERATE CONVECTION WAS ABLE TO FORM IN 
THIS REGION WITHIN 60 NM OF THE ITCZ AXIS BETWEEN 99W AND 103W. 
ELSEWHERE EAST OF THIS UPPER TROUGH...THE STRONG ANTICYCLONE AND 
AN ASSOCIATED DRY AIR MASS ALLOWS SUBSIDENCE TO DOMINATE THE 
AREA S OF 20N. THIS RIDGE ENVELOPS SE MEXICO AND MOST OF CENTRAL 
AMERICA WHERE MOSTLY FAIR WEATHER PREVAILS.

$$
SCHAUER CLARK