000
AXPZ20 KNHC 220932
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED APR 22 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 
0915 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 04N77W TO 07N83W TO 03N125W TO 
04N140W. SCATTERED MODERATE ISOLATED STRONG WITHIN 180 NM S OF 
AXIS BETWEEN 80W AND 87W.

...DISCUSSION...

GAP WINDS...A 03Z QUIKSCAT PASS INDICATED SUB GALE WINDS TO 30 
KT THROUGH THE GULF OF TEHUANTEPEC. A SHIP OBSERVATION FROM 
AROUND 05Z INDICATED WINDS TO 35 KT STILL IN EFFECT...ALTHOUGH 
TAKING INTO ACCOUNT A KNOWN SLIGHT HIGH BIAS FOR THE SHIP THIS 
AGREES WITH THE SCATTEROMETER DATA. WINDS ARE EXPECTED TO 
GRADUALLY DIMINISH TO 20 TO 25 KT THROUGH EARLY AFTERNOON...THEN 
BELOW 20 KT MIDDAY THU AS HIGH PRES IN THE GULF OF MEXICO SHIFTS 
EAST. FURTHER SOUTH...FRESH TO STRONG CARIBBEAN TRADES CONTINUE 
TO SUPPORT 20 TO 25 KT GAP WIND FLOW THROUGH THE GULF OF 
PAPAGAYO. LITTLE CHANGE IS EXPECTED. FOR BOTH AREAS LONG PERIOD 
SW SWELL IS PUSHING INTO THE CENTRAL AMERICAN AND MEXICAN 
COASTS...CREATING THE POTENTIAL FOR ROUGH CONFUSED SEAS IN AREAS 
WITH OPPOSING N TO NE GAP WIND FLOW. IN THE GULF OF PANAMA...A 
SHIP REPORTED 20 KT NE FLOW ON THE CARIBBEAN SIDE OF THE ISTHMUS 
HINTING OF RESIDUAL FRESH NORTHERLY FLOW THROUGH THE GULF OF 
PANAMA. THIS FLOW SHOULD TAPER OFF THROUGH THE DAY AS TRADE WIND 
FLOW BECOMES MORE EASTERLY. 

ELSEWHERE E OF 100W...DIVERGENT FLOW ALOFT ASSOCIATED WITH AN 
UPPER LEVEL TROUGH EXTENDING THROUGH THE WESTERN CARIBBEAN IS 
INTERACTING WITH LOW LEVEL DRAINAGE FLOW CONVERGENCE OFF THE 
WESTERN PANAMA COAST...ALONG WITH ITCZ INTERACTION...TO PRODUCE 
A LARGE CLUSTER OF CONVECTION AS DESCRIBED ABOVE.

W OF 100W...DEEP LAYER CUT OFF LOW REMAINS CENTERED N OF HAWAII 
NEAR 33N150W. AN ASSOCIATED COLD FRONT ALONG 143W IS MOVING 
SLOWLY EASTWARD...BUT IS LIKELY TO STALL AND DISSIPATE THROUGH 
THURSDAY IN THE ABSENCE OF UPPER SUPPORT. THIS LEAVES 1022 MB 
SURFACE HIGH PRES IN PLACE NEAR 26N132W THROUGH THURSDAY...WHICH 
IN TURN WILL SUPPORT A SMALL AREA OF TRADE WINDS S OF THE HIGH 
PRES MAINLY S OF 15N W OF 120W. A QUASI-STATIONARY UPPER TROUGH 
OVER THE DEEP TROPICS S OF 15N ALONG 130W HAD BEEN AIDING MODEST 
CONVECTION N OF THE ITCZ S OF 120W...WHERE THE BEST TRADE WIND 
CONVERGENCE IS...BUT THIS HAS DIED DOWN. LOOKING AHEAD...EVEN AS 
THE WEAK COLD FRONT NE OF HAWAII DISSIPATES...AN UPPER TROUGH 
DIGGING IN THE PACIFIC NORTHWEST STATES CURRENTLY WILL PROMOTE A 
SURFACE COLD FRONT S ALONG THE NE PACIFIC OFF THE U.S. WEST 
COAST...POSSIBLY REACHING WATERS OFF NORTHERN BAJA BY SATURDAY. 
FOLLOWED BY BUILDING HIGH PRES AND INCREASED TRADES INTO THE 
WEEKEND.  

$$
CHRISTENSEN