000
AXPZ20 KNHC 080346
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED APR 08 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 
0345 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG 4N77W 6N86W
3N100W TO 1N101W WHERE IT BECOMES DIFFUSE...THEN RESUMES AT 
1N127W 4N140W. NO SIGNIFICANT CONVECTION IS NOTED.

...DISCUSSION...

A CLOSED UPPER LEVEL LOW N OF THE AREA NEAR 37N127W 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. SCATTEROMETER DATA FROM EARLIER TODAY SHOWED
NW WINDS OF 20-25 KT N OF 28N BETWEEN 121W AND 135W. THESE 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-104W AND 110W-114W. 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 SE INTO THE AREA THROUGH 28N137W TO 
25N123W TO NEAR 21N113W. WITH RESPECT TO TRADE WINDS...NE WINDS 
OF 20 KT ARE OCCURRING FROM 12N-18N W OF 120W 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...
A STORM WARNING IS IN EFFECT FOR THE GULF OF TEHUANTEPEC...BUT
WILL SHORTLY DIMINISH TO GALE FORCE. THE GALE CONDITIONS ARE 
THEN FORECAST TO PERSIST THROUGH ABOUT 15 UTC WED MORNING BEFORE
DROPPING OFF TO 20-30 KT. A RECENT SHIP OBSERVATION NEAR 14N95W 
REPORTED NE WINDS OF 36 KT WITH SEAS OF 10-14 FT. SEAS WILL BE 
SLOW IN SUBSIDING ACROSS THE GULF AND VICINITY OVER THE NEXT 48 
HRS WITH SEAS UP TO 9 FT IN NE SWELL PROPAGATING FAR DOWNSTREAM 
FROM THE GULF TO THE AREA FROM 4N-14N BETWEEN 91W-107W.

A TIGHT PRES GRADIENT OVER THE WRN CARIBBEAN IS FUNNELING NE 
20-25 KT THROUGH THE GULF OF PAPAGAYO...AND N WINDS TO 20 KT 
THROUGH GULF OF PANAMA. EXPECT THE PAPAGAYO WINDS TO LAST 
ANOTHER 24 HRS AT 20 KT...THEN DIMINISH TO LESS THAN 20 KT IN 48 
HRS. GULF OF PANAMA WINDS SHOULD DIMINISH TO LESS THAN 20 KT IN 
48 HRS. SEAS OF 8-10 FT IN THE GULF OF PAPAGAYO WILL SUBSIDE TO 
8 FT IN 36 HRS.

ACROSS THE GULF OF CALIFORNIA...SW TO W WINDS TO 20 KT ARE 
EXPECTED TO BEGIN IN ABOUT 12 HRS AS THEY DOWNSLOPE OFF THE BAJA 
CALIFORNIA MOUNTAINS IN RESPONSE TO INCREASING DEEPENING LOW 
PRES OVER THE  SRN PLAINS S TO NRN MEXICO. THESE WINDS SHOULD 
DIMINISH TO LESS THAN 20 KT IN 36 HRS AS THE LOW PRES AREA 
ADVANCES EASTWARD.

$$
AGUIRRE