000
AXPZ20 KNHC 190339
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN APR 19 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 04N77W 
TO 06N86W TO 08N108W TO 07N125W TO 04N140W. SCATTERED MODERATE 
CONVECTION CAN BE FOUND WITHIN 60 NM N OF THE ITCZ AXIS BETWEEN 
86W AND 90W...WITHIN 120 NM N OF THE ITCZ AXIS BETWEEN 118W AND 
123W...AND WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS W OF 128W.

...DISCUSSION...

1028 MB HIGH PRES N OF THE AREA NEAR 39N130W WILL CONTINUE TO 
WEAKEN AND SHIFT NORTHWARD OVER THE NEXT FEW DAYS. THIS IS THE 
RESULT OF THE MIGRATION OF THE ASSOCIATED MID LEVEL HIGH CENTER 
WHICH WILL BE NUDGED NORTHWARD BY THE MID LEVEL LOW TO ITS 
SOUTH...CURRENTLY OVER NW WATERS...AS IT IS FORCED NORTHWARD ON 
THE LEADING EDGE OF THE DEEP LAYER TROUGH AMPLIFYING TO ITS W IN 
THE VICINITY OF HAWAII. WITH THE SURFACE RIDGE WEAKENED...TRADE 
WINDS ARE EXPECTED TO DIMINISH. IN THE MEAN TIME...THE PRES 
GRADIENT BETWEEN THE SURFACE HIGH N OF THE AREA AND BROAD LOW 
PRESSURE OVER THE CENTRAL U.S. AND EASTERN MEXICO CONTINUES TO 
BRING WINDY CONDITIONS IN THE GULF OF CALIFORNIA...WITH THE 1736 
UTC ASCAT PASS SHOWING 20 KT NW FLOW IN MUCH OF THE WESTERN GULF 
OF CALIFORNIA S OF 29N. WINDS ARE EXPECTED TO DIMINISH HERE SUN.

GAP WINDS...
GULF OF PAPAGAYO...NE WINDS TO 25 KT ARE FUNNELING THROUGH 
THE GULF OF PAPAGAYO ACCORDING TO SHIP 9HJD9 AND THE 1558 UTC 
ASCAT PASS. THIS FLOW WILL CONTINUE TO PULSE OVER THE NEXT 
DAY OR TWO...ESPECIALLY IN THE EARLY MORNING HOURS WHEN DRAINAGE 
FLOW IS AT A MAXIMUM. HOWEVER...LOOK FOR WIND SPEEDS TO COME 
DOWN STARTING MON AS THE HIGH PRES SYSTEM CURRENTLY ALONG 
THE SE U.S. COAST SHIFTS EASTWARD.

GULF OF PANAMA...ACCORDING TO OBSERVATIONS FROM SHIP ZCDF4 AND 
THE 1144 UTC QUIKSCAT PASS...NORTHERLY FLOW TO 20 KT IS REPORTED 
FROM THE GULF OF PANAMA S TO 06N AS A RESULT OF THE FUNNELING 
NORTH-NORTHEAST TRADE WIND FLOW IN THE SW CARIBBEAN THROUGH 
PANAMA. LIKE PAPAGAYO...EXPECT WINDS TO DIMINISH AND SHIFT MORE 
EASTERLY AS THE IMPETUS HIGH PRESSURE IN THE ATLC IS FORCED 
EASTWARD OVER THE NEXT FEW DAYS.

GULF OF TEHUANTEPEC...MODEL GUIDANCE SUGGESTS WINDS IN THE GULF 
OF TEHUANTEPEC MAY REACH GALE FORCE TUE AS THE DEEP LAYER TROUGH 
OVER THE CENTRAL U.S. RECEIVES A REINFORCING SHOT OF NORTHERN 
STREAM ENERGY AND SENDS STRONG NORTHERLY FLOW AT THE SURFACE 
THROUGH THE ISTHMUS OF TEHUANTEPEC.

CONVECTION...
SCATTERED MODERATE CONVECTION WITHIN 60 NM N OF THE ITCZ AXIS 
BETWEEN 86W AND 90W...IS ASSISTED BY THE LOW LEVEL CONVERGENCE 
EVIDENT IN THE 1144 UTC QUIKSCAT PASS AND 2.0 TO 2.25 INCH 
PRECIPITABLE WATER VALUES IN THE REGION. THE BROAD UPPER LEVEL 
DIFFLUENCE E OF THE UPPER RIDGE AXIS CURRENTLY ALONG 90W 
SHOULD SHIFT EASTWARD OVER THE NEXT FEW HOURS AWAY FROM THE MOST 
FAVORABLE LOW LEVEL MOISTURE CONVERGENCE...LIKELY LIMITING 
LIMITING CONVECTION.

FARTHER W...CONVECTION NOTED IN THE VICINITY OF THE ITCZ W OF 
118W ACCOMPANIES A SWATH OF 2.0 TO 2.5 INCH PRECIPITABLE WATER 
VALUES AND MODERATE LOW LEVEL CONVERGENCE AS NOTED IN THE 1742 
AND 1922 UTC ASCAT PASSES. IN ADDITION...A WEAK MID LEVEL 
INVERTED TROUGH LIES NEAR 125W. THIS TROUGH...AND THE ASSOCIATED 
CONVECTION...IS EXPECTED TO TRACK W OVER THE NEXT FEW DAYS.

$$
SCHAUER CLARK