000
AXPZ20 KNHC 072205
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE APR 07 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG FROM 4N77W 
6N91W 5N110W TO EQUATOR AT 113W...THEN RESUMES AT 128W TO 
5N140W. NO SIGNIFICANT CONVECTION  IS NOTED.

...DISCUSSION...

A CLOSED UPPER LEVEL LOW N OF THE AREA NEAR 36N128W MOVING 
ENE TOWARDS THE CALIFORNIA COAST HAS A TROUGH TRAILING S TO
28N. ITS SURFACE REELECTION IS SEEN AS A TROUGH EXTENDING INTO
THE AREA THROUGH 32N127W TO NEAR 28N133W. BROKEN LOW CLOUDS
WITH ISOLATED SHOWERS ARE WITHIN 60 NM OF THE TROUGH. MODERATE
SUBSIDENCE IN CONFLUENT FLOW ENTERS THE AREA TO THE W AND SW OF 
THE LOW...AND INTO THE BASE OF TROUGH THEN NUDGES NE TOWARDS SRN 
CALIFORNIA. THE UPPER LOW IS FORECAST TO TRACK INLAND THE U.S. 
WEST COAST LATE TONIGHT INTO WED MORNING WHILE THE SURFACE 
TROUGH GRADUALLY BECOMES DIFFUSE AS IT MOVES NEAR THE NRN BAJA 
CALIFORNIA COAST. QUIKSCAT DATA FROM NEAR 1500 UTC THIS MORNING 
SHOWED NW WINDS OF 20-25 KT N OF 28N BETWEEN 121W AND 135W. THIS 
WINDS ARE FORECAST TO DIMINISH IN ABOUT 24-30 HOURS AS THE 
TROUGH PULLS FURTHER E AND HIGH PRES OF 1023 MB CENTERED N OF 
THE AREA NEAR 25N123W WEAKENS. NW SWELLS OF 8-12 FT WITHIN THIS 
AREA WILL SLOWLY SUBSIDE TO 8-10 FT BY 24 HRS...AND TO 9 FT BY 
48 HRS. A COLD FRONT IS FORECAST TO SWEEP THROUGH THE NE WATERS 
THU BRINGING A SURGE OF NW-N WINDS OF 20-25 KT WITH SEAS 
BUILDING ONCE AGAIN TO 8-10 FT.

A HIGHLY AMPLIFIED RIDGE E OF THE TROUGH EXTENDS FROM NRN MEXICO 
TO ACROSS THE WRN U.S. THIS RIDGE WILL SHIFT FURTHER E IN ADVANCE
OF THE TROUGH. A JET STREAM BRANCH WITH MAXIMUM WINDS OF 60-70 KT
ENTERS THE REGION THROUGH 25N140W...AND EXTENDS ALONG 26N130W 
ROUNDING THE BASE OF THE UPPER TROUGH NE TO ACROSS NRN BAJA 
CALIFORNIA AND THE WRN PERIPHERY OF THE UPPER RIDGE. THE JET IS
TRANSPORTING AMPLE HIGH LEVEL BROKEN CLOUDS ENE TO ACROSS NRN AND
CENTRAL BAJA CALIFORNIA. LATEST NWP MODEL GUIDANCE INDICATES THAT
A LARGE UPPER LEVEL RIDGE WILL BUILD E TO THE N OF THE AREA IN 
THE WAKE OF THE NEXT UPPER LEVEL TROUGH ASSOCIATED WITH THE COLD 
FRONT EXPECTED THU ACROSS THE NE WATERS. TO THE S OF THE JET 
STREAM BRANCH...THE FLOW IS BROADLY ANTICYCLONIC WITH AN 
ANTICYLONE LOCATED NEAR 8N102W. THE FLOW IS INTERRUPTED BY A 
MID/UPPER LEVEL TROUGH THAT EXTENDS FROM 15N124W TO 9N123W. 
ANOTHER MID/UPPER LEVEL TROUGH IS OVER THE FAR WRN PORTION OF 
THE AREA THROUGH 22N139W TO 16N135W. NEITHER OF THE TROUGHS IS 
TRIGGERING OFF ANY SIGNIFICANT CONVECTION...WITH ONLY PATCHES OF 
BROKEN LOW CLOUDS WITH ISOLATED SHOWERS NOTED WITHIN 60-90 NM OF 
THE TROUGHS. ABUNDANT MODERATE TO STRONG SUBSIDENCE ASSOCIATED 
WITH UPPER LEVEL RIDGING IS RESULTING IN RATHER DRY AND STABLE 
CONDITIONS THROUGHOUT ALL LEVELS OF THE ATMOSPHERE S OF 17N AND 
E OF 111W. ONLY ISOLATED WEAK CONVECTION IS SEEN WITHIN 120 NM 
OF THE ITCZ BETWEEN 101W-105W AND 110-112W. SMALL PATCHES OF 
SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING W WITH POSSIBLE 
ISOLATED SHOWERS ARE N OF 20N W OF 134W...AND ARE BASICALLY 
BEING STEERED BY THE NE-E FLOW AROUND THE SRN PERIPHERY OF 
SURFACE RIDGING THAT EXTENDS FROM THE 1023 MB
HIGH NEAR 25N123W SE TO 19N107W. WITH RESPECT TO TRADE WINDS...
NE WINDS OF 20 KT ARE OCCURRING FROM 12N-18N W OF 124W WITH SEAS
IN THE 8 TO 10 FT RANGE IN MAINLY NW SWELL. THIS AREA OF NE WINDS
EXTEND E TO NEAR 119W IN ABOUT 24 HRS...AND DIMINISH TO W OF 130W
BY 48 HRS. SEAS WILL CONTINUE ABOUT 8-10 FT IN A MIXED NE AND 
NW SWELL...WITH SEAS TO 9 FT IN SUBSIDING NW SWELL OVER AN AREA
BOUNDED BY 30N126W 18N116W 8N120W 2N140W IN 48 HRS.

GAP WINDS...
THE HURRICANE FORCE WIND WARNING FOR THE GULF OF TEHUANTEPEC HAS 
BEEN ALLOWED TO EXPIRE THIS AFTERNOON...AND IS NOW A STORM 
WARNMING. THE STORM CONDITIONS SHOULD TILL THIS EVENING BEFORE
BECOMING A GALE EVENT. GALE FORCE CONDITIONS ARE THEN FORECAS
TO PERSIST THROUGH EARLY WED MORNING. A RECENT SHIP OBSERVATION
NEAR 15N95W REPORTED NE 50 KT WINDS WITH SEAS OF 13-18 FT.
SEAS WILL BE SLOW IN SUBSIDING ACROSS THE GULF AND VICINTY OVER
THE NEXT 48 HRS WITH SEAS UP TO 9 FT IN NE SWELL PROPAGATING AS 
FAR DOWNSTREAM BETWEEN 4N-14N BETWEEN 91W-107W.

INCREASING TRADE WINDS OVER THE CARIBBEAN REGION ARE FORECAST TO 
EXTEND INTO THE GULF OF PAPAGAYO AND PANAMA DURING THE NEXT FEW 
DAYS...WHEN SURFACE WINDS ARE EXPECTED TO REACH 20 KT. 
ALSO...ACROSS THE GULF OF CALIFORNIA...SW TO W WINDS WILL LIKELY 
DOWNSLOPE OFF THE BAJA CALIFORNIA MOUNTAINS IN RESPONSE TO 
INCREASING PRESSURE FALLS OVER WESTERN MEXICO BY MIDWEEK. 

$$
AGUIRRE