000
AXPZ20 KNHC 190943
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN APR 19 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 
0930 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 04N77W 
TO 06N95W TO 03N140W. SCATTERED MODERATE CONVECTION 150 NM N OF 
AXIS BETWEEN 120W AND 125W.

...DISCUSSION...
W OF 105W...LARGE SCALE UPPER PATTERN CONTINUES TO BECOME MORE 
AMPLIFIED AS A SHARP LONG WAVE TROUGH EXTENDING FROM THE GULF OF 
ALASKA TO ALMOST HAWAII PUSHES EAST. UPPER RIDGING CONTINUES TO 
BUILD AHEAD OF THIS TROUGH OVER ALONG 130W N OF 35W. 
MEANWHILE...A SHORT WAVE TROUGH HAS CUTOFF SOUTH OF THE UPPER 
RIDGE NEAR 28N130WA. THE TREND FOR THE PAST COUPLE OF DAYS HAS 
BEEN THAT SURFACE HIGH PRES ASSOCIATED WITH THE UPPER RIDGE WAS  
SHIFTING NORTH AS THE RIDGE BUILDS. THIS SURFACE RIDGE HAS BEEN 
WEAKENING AS WELL WITH THE MID/UPPER SHORT WAVE CUTTING OFF. THE 
RESULT HAS BEEN DIMINISHING SURFACE WINDS ON THE PERIPHERY OF 
THE SURFACE HIGH. 02Z QUIKSCAT PASS INDICATED THAT NORTHERLY 
WINDS ALONG THE BAJA COAST AND IN THE GULF OF CALIFORNIA ARE 
LESS THAN 20 KT...AND THE AREA OF 20 KT TRADE WINDS S OF THE 
SURFACE HIGH HAS SHRUNK. A 50 TO 70 KT UPPER JET ON THE SOUTHERN 
SIDE OF THE CUT OFF SHORTWAVE IS EVIDENT BETWEEN 10N TO 20N W OF 
120W. UPPER DIVERGENCE RELATED TO THE JET WILL ENHANCE POCKETS 
OF ITCZ CONVECTION W OF 120W THROUGH TUESDAY. LOOKING AHEAD 
THROUGH MID WEEK...GFS AND ECMWF ARE IN GENERAL AGREEMENT 
SHOWING THE CUT OFF SHORT WAVE OPENING UP AND LIFTING NORTH 
AHEAD OF THE LONG WAVE TROUGH...ITSELF CUTTING OFF NE OF HAWAII. 
THIS WILL INDUCE A WEAK SURFACE HIGH PRES CENTER TO FORM NEAR 
25N135W BY TUESDAY...WHICH MAINTAINS A BAND OF TRADE WINDS 
FURTHER SOUTH. MEANWHILE...AS N TO NE SWELL DECAYS THROUGH 
MONDAY...A NEW ROUND OF LONG PERIOD SW SWELL PUSHES THROUGH THE 
AREA S OF 20N THROUGH WED.

E OF 105W...MAIN ISSUE THROUGH THE NEXT 48 HOURS WILL BE 20 KT 
GAP WIND FLOW THROUGH THE GULFS OF PAPAGAYO AND PANAMA. LATEST 
DATA SHOW LESS THAN 20 KT FLOW IN PAPAGAYO...BUT THIS IS LIKELY 
TO INCREASE DUE TO DRAINAGE LATER THIS MORNING. A 03Z ASCAT PASS 
SHOWED 20 KT NORTHERLY FLOW THROUGH THE GULF OF PANAMA. 
CARIBBEAN TRADE WIND FLOW IS TRENDING DOWNWARD...AND THESE WINDS 
WILL FOLLOW SUIT INTO MONDAY. MEANWHILE A COLD FRONT WILL PUSH 
INTO THE SOUTHERN GULF OF MEXICO...PROMOTING STRONG FUNNELING 
WINDS INTO THE GULF OF TEHUANTEPEC BY LATE MONDAY. THE MAIN 
ISSUE FROM MONDAY THROUGH LATE TUESDAY WILL BE THE POSSIBILITY 
OF GALE FORCE WIND IN THE GULF OF TEHUANTEPEC. THIS COINCIDES 
WITH THE ARRIVAL OF SW SWELL UP TO 6 FT WITH PERIODS TO 20 KT 
NEAR THE MEXICAN AND CENTRAL AMERICAN COASTS...PROVIDING THE 
POTENTIAL FOR CONFUSED SEAS NEAR THE GULF OF TEHUANTEPEC.  

$$
CHRISTENSEN