000
AXPZ20 KNHC 091539
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU APR 09 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 10N85W 
TO 04N95W TO 02N105W TO 04N123W TO 03N140W. NO SIGNIFICANT 
CONVECTION.

...DISCUSSION...

A BROAD AREA OF TRADE WINDS IS BEING ENHANCED ON THE SOUTHERN 
PERIPHERY OF A BROAD SURFACE RIDGE OVER THE NW QUARTER OF THE 
DISCUSSION AREA. NE WINDS TO 20 KT ARE PRESENT FROM 05N TO 21N W 
OF 120W BASED ON AN ASCAT PASS AROUND 09/0500 UTC. NWP MODELS 
GUIDANCE INDICATES THESE WINDS CONTINUING IN APPROXIMATELY THE 
SAME LOCATION DURING THE NEXT FEW DAYS AS THE SURFACE RIDGE 
TRANSLATES EASTWARD N OF THE DISCUSSION AREA. SATELLITE IMAGERY 
AND SCATTEROMETER DATA INDICATE THREE INVERTED TROUGHS LOCALLY 
ENHANCING THESE WINDS...THE WESTERN TROUGH EXTENDING FROM 
12N131W TO 07N133W...THE CENTRAL TROUGH EXTENDING FROM 10N121W 
TO 03N122W...AND THE EASTERN AND MOST PRONOUNCED TROUGH 
EXTENDING FROM 13N113W TO 07N113W. ENHANCED BOUNDARY LAYER 
MOISTURE CONVERGENCE NEAR THIS TROUGH IS SUPPORTING SCATTERED 
SHOWERS AND THUNDERSTORMS FROM 11N TO 13N BETWEEN 111W AND 115W. 
ALSO...SURFACE PRESSURE FALLS OVER MEXICO DURING THE NEXT FEW 
DAYS...COMBINED WITH LOCAL TOPOGRAPHICAL EFFECTS...WILL LOCALLY 
ENHANCE NORTHWESTERLY WINDS NEAR THE COAST OF BAJA CALIFORNIA S 
OF 27N AND NEAR THE COAST OF MEXICO FROM 17N TO 20N. WINDS WILL 
LOCALLY REACH 20 KT IN THESE AREAS...AS RECENT ASCAT AND 
QUIKSCAT PASSES INDICATE. AS FOR WAVE HEIGHTS...SEAS OF 8 TO 11 
FT IN GENERALLY MIXED SW AND NW SWELL WILL IMPACT MUCH OF THE 
DISCUSSION AREA DURING THE NEXT FEW DAYS...RESULTING FROM 
PREVIOUS STORM COMPLEXES OUTSIDE OF THE DISCUSSION AREA ALONG 
WITH THE RECENT GULF OF TEHUANTEPEC GAP WIND EVENT.

IN THE UPPER LEVELS...THE AXIS OF THE SUBTROPICAL JET STREAM 
STRETCHES ALONG A LINE FROM 23N140W TO 24N130W TO CENTRAL BAJA 
CALIFORNIA WITH CORE SPEEDS OF 100-120 KT. THIS JET IS ADVECTING 
ABUNDANT MID TO UPPER LEVEL MOISTURE EASTWARD ACROSS THE 
DISCUSSION AREA. SE OF THIS JET...ATMOSPHERIC STABILITY AND DEEP 
LAYERED DRY AIR IN THE VICINITY OF AN UPPER RIDGE OVER THE SE 
PORTION OF THE DISCUSSION AREA IS SUPPORTING FAIR WEATHER 
CONDITIONS THERE.

AS FOR THE FORECAST...A DIGGING SHORTWAVE TROUGH CURRENTLY OVER 
THE NE PACIFIC ALONG 133W WILL CONTINUE SE WHILE DEEPENING...THIS
MAINLY DUE TO A VIGOROUS MID/UPPER-LEVEL JET ON THE BACKSIDE OF 
THE TROUGH. NWP MODEL GUIDANCE IS IN GOOD AGREEMENT THAT AN 
ASSOCIATED DISSIPATING SURFACE COLD FRONT WILL APPROACH THE 
NORTHEASTERN WATERS EARLY FRI...WITH STRONG WINDS ON EITHER 
SIDE OF THE FRONT. GUIDANCE ALSO INDICATES THAT A SURFACE LOW 
WILL DEVELOP NEAR THE CALIFORNIA COAST BEFORE REDEVELOPING 
INLAND LATE FRIDAY. THIS WILL SERVE TO STRENGTHEN THE SURFACE 
PRESSURE GRADIENT NEAR THE FRONT...WITH THE W TO NW WINDS OF 
25-30 KT WITH HIGHER GUSTS W OF THE REMNANT SURFACE TROUGH. 
WAVEWATCH GUIDANCE INDICATES SEAS BUILDING TO 18 FT BY LATE FRI 
IN THE WAKE OF THE FRONT.

GAP WINDS...
INCREASED TRADE WINDS OVER THE CARIBBEAN REGION ARE NOW 
EXTENDING INTO THE GULF OF PAPAGAYO AND PANAMA. SURFACE WINDS 
ARE EXPECTED TO OCCASIONALLY REACH 20-25 KT...MAINLY IN THE GULF 
OF PAPAGAYO REGION. WINDS SUBSIDE IN THE GULF OF PANAMA WITHIN 
24 HOURS AND IN THE GULF OF PAPAGAYO BY SAT. 

$$
COBB