000
AXPZ20 KNHC 091555
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN APR 09 2006

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 ALONG 7N78W 4N90W 6N120W 4N140W. SCATTERED MODERATE TO 
STRONG WITHIN 90 NM OF 7N78W AND 120 NM OF 7N137W. SCATTERED 
MODERATE ISOLATED STRONG FROM 3N TO 8N BETWEEN 89W AND 97W AND 
WITHIN 120 NM EITHER SIDE OF LINE 10N116W 4N124W.

...DISCUSSION...
THE NE PAC AND W COAST OF CONUS IS DOMINATED BY A LONGWAVE 
TROUGH. ONE UPPER CYCLONE IS NEAR 42N127W TRAILING A SHORTWAVE 
SW ALONG 32N133W 20N140W. A BAND OF DRY AIR IS NOTED WITHIN
60 NM EITHER SIDE OF LINE 32N119W 19N138W AND ANOTHER BAND NOTED 
WITHIN 120 NM EITHER SIDE OF LINE 32N130W 26N140W. 

AN UPPER ANTICYCLONE IS ESTIMATED NEAR 6N125W AND ANOTHER NEAR 
12N110W. AN UPPER RIDGE EXTENDS N ALONG 24N111W TO AN AMPLIFYING 
CREST NEAR 38N110W EVENTUALLY MERGING WITH A LONGWAVE RIDGE THAT 
DOMINATES N AMERICA ALONG 105W. UPPER DIFFLUENCE UNDER THE RIDGE 
IS ENHANCING CONVECTION ALONG AN INVERTED LOW LEVEL TROUGH THAT 
EXTENDS FROM 10N117W TO 3N123W. THE UPPER DEBRIS MOISTURE FROM 
THIS CONVECTION SPREADS NE THROUGH THE RIDGE AXIS BUT SEEMS TO 
EVAPORATE IN THE TROPICS. UPPER DIFFLUENCE UNDER THE RIDGE IS 
ALSO ENHANCING CONVECTION ALONG THE ITCZ BETWEEN 115W AND 145W. 
RESULTANT UPPER DEBRIS MOISTURE FROM THIS CONVECTION IS ADVECTED 
NE...MERGING WITH A 660 NM WIDE MOISTURE PLUME AXIS THAT ENTERS 
THE DISCUSSION AREA NEAR 12N140W...AND CONTINUES NE THROUGH 
25N120W...THEN TURNS ANTICYCLONICALLY E CROSSING THE UPPER RIDGE 
OVER THE BAJA PENINSULA AND SPILLING SE OVER OLD MEXICO TO THE N 
OF 20N.  

A POSITIVE TILT UPPER TROUGH DOMINATES THE ENTIRE EASTERN 
SEABOARD OF N AMERICA WITH A VIGOROUS SHORTWAVE TROUGH EXTENDING 
SW INTO THE DISCUSSION AREA FROM 32N82W TO 17N90W THEN THROUGH A 
SMALL UPPER CYCLONE NEAR 4N100W AND CONTINUING S ACROSS THE 
EQUATOR TO ANOTHER UPPER CYCLONE ESTIMATED NEAR 5S105W. DRY 
UPPER AIR IS INDICATED ON MOISTURE CHANNEL ROUGHLY WITHIN 240 NM 
EITHER SIDE OF LINE 25N85W 12N101W 2S105W.    

AN ILL-DEFINED UPPER ANTICYCLONE IS NOTED NEAR 6N90W AND ANOTHER 
IS OVER COLOMBIA NEAR 8N71W. TOGETHER THEY CREST ALONG POINTS 
15N90W 31N70W 23N52W. UPPER DIFFLUENCE IS ENHANCING CONVECTION 
ALONG THE ITCZ E OF 95W...WITH A THIN BAND OF DEBRIS MOISTURE 
ADVECTED NE ACROSS CENTRAL BECOMING ALMOST ZONAL ACROSS THE W 
AND CENTRAL CARIBBEAN. OTHERWISE DRY UPPER AIR DOMINATES THE 
CARIBBEAN AND EXTENDS ACROSS CENTRAL AMERICA N OF 10N.   

AT THE SURFACE...HIGH PRES 1020 MB IS NEAR 26N124W AND IS 
RETARDING THE E PROGRESS OF A WEAKENING FRONTAL TROUGH THAT LIES 
ALONG 32N127W 21N133W. THE TROUGH IS EXPECTED TO MOVE E ALONG 
30N AND E OF AREA LATE MON. AS MENTIONED ABOVE...AN INVERTED LOW 
LEVEL TROUGH EXTENDS FROM 10N117W TO 3N123W...AND IS SHIFTING W 
WITH TIME.

GAP WINDS...GULF OF TEHUANTEPEC...A COLD FRONT HAS MOVED 
THROUGH THE BAY OF CAMPECHE AND IS STALLING E TO W ACROSS THE 
ISTHMUS OF TEHUANTEPEC. NLY WINDS TO 20 KT SHOULD BE BRIDGING 
THROUGH THE GAP VERY SOON. THESE WINDS ARE EXPECTED TO INCREASE 
TO 25 KT...PERHAPS A BRIEF 30 KT SURGE...AND CONTINUE THROUGH 48 
HOURS. LATEST QSCAT WINDS SHOW ONLY NE 15 KT WINDS IN GULF OF 
PAPAGAYO. 

$$
NELSON