000
AXPZ20 KNHC 020319
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED NOV 02 2011

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 0230 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG 09N79W TO LOW PRES NEAR 09N88W 1008 
MB TO 07N97W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS 
FROM 07N97W TO 09N120W TO 08N140W. SCATTERED MODERATE CONVECTION 
IS WITHIN 90-120 NM IN THE NE SEMICIRCLE OF THE LOW. SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION IS FROM 07N TO 11N W OF 
130W.

...DISCUSSION...

1031 MB SURFACE HIGH PRES IS CENTERED NW OF THE AREA NEAR 
36N140W EXTENDING INTO THE AREA NEAR 32N134W TO 17N110W. A TIGHT 
PRES GRADIENT EXISTS OVER THE NW PORTION OF THE AREA AND 1754 
AND 1934 UTC ASCAT SCATTEROMETER PASSES INDICATED FRESH NE-E 
WINDS ACROSS THE MAJORITY OF THE WATERS W OF 125W. A SHIP WITH 
CALL-SIGN PDAN NEAR 28N133W REPORTED NE 24 KT WINDS AND 12 FT 
SEAS AT 2100 UTC. MIXED NE AND NW SWELL OF 8-12 FT COVERS THE 
AREA NW OF A LINE FROM 30N120W TO 20N135W TO 20N140W. THE HIGH 
AND RIDGING WILL WEAKEN THROUGH WED AS A COLD FRONT MOVES FROM 
THE N CENTRAL PACIFIC INTO THE NE PACIFIC...ALLOWING THE WINDS 
TO DIMINISH IN INTENSITY AND AREAL EXTENT...WITH SWELL ALSO 
GRADUALLY SUBSIDING THROUGH 48 HOURS. ANOTHER ROUND OF FRESH 
NE-E WINDS AND A NEW SET OF NW SWELL WILL ARRIVE BEHIND THE 
FRONT JUST BEYOND 48 HOURS. MEANWHILE...THE CONVERGENCE OF THE 
FRESH TRADE WIND FLOW IS SUPPORTING MODEST CONVECTION ALONG THE 
ITCZ AS DESCRIBED ABOVE.

AN UPPER LEVEL TROUGH IS EVIDENT IN WATER VAPOR SATELLITE 
IMAGERY FROM 25N120W TO 00N100W WITH VERY DRY AIR ACROSS THE 
AREA BETWEEN 95W AND 110W. AN UPPER LEVEL ANTICYCLONE IS OVER 
18N90W WITH RIDGING EXTENDING S TO NEAR THE GALAPAGOS ISLANDS. 
1008 MB SURFACE LOW PRES IS EMBEDDED IN THE MONSOON TROUGH NEAR 
09N88W WITH ASSOCIATED CONVECTION AS DESCRIBED ABOVE BEING 
SUPPORTED ON THE E SIDE OF THE RIDGING. THE SURFACE LOW IS 
FORECAST TO MOVE TO NEAR 10N93W IN 24 HOURS WITH NO DEVELOPMENT 
ANTICIPATED.

CROSS-EQUATORIAL SW SWELL TO 8 FT WITH PEAK WAVE PERIODS OF 
17-19 SECONDS HAS BREACHED THE EQUATOR OVER THE FAR SE PORTION 
E-NE OF THE GALAPAGOS ISLANDS. THIS SWELL WILL SUBSIDE TO LESS 
THAN 8 FT WITHIN THE NEXT 24 HOURS...WITH A NEW SET OF SW SWELL 
ARRIVING OVER THE S CENTRAL WATERS IN 48 HOURS.

GULF OF CALIFORNIA...STRONG HIGH PRES WILL BUILD OVER THE UNITED 
STATES GREAT BASIN REGION BEHIND A COLD FRONT DURING THE NEXT 24 
HOURS. STRONG NORTHERLY WINDS ARE FORECAST TO COMMENCE IN THE 
FAR NORTHERN GULF OF CALIFORNIA PRIOR TO SUNRISE WED. FINDINGS 
FROM A LOCAL RESEARCH STUDY INDICATE A HIGH LIKELIHOOD (NEAR 100 
PERCENT CHANCE) FOR GALE CONDITIONS IN THE GULF N OF 29N WITH A 
VERY TIGHT PRES GRADIENT DEVELOPING OVER THE REGION BETWEEN THE 
HIGH AND TROUGHING E OF THE GULF OF CALIFORNIA. A GALE WARNING 
HAS BEEN RAISED FOR THIS AREA FROM 12 UTC WED THROUGH 00 UTC 
THU. ALSO...THE HI-RES WAVEWATCH MODEL GUIDANCE DOES BUILD SEAS 
TO 10 FT N OF 29N GIVEN A 12 HOUR DURATION OF GALE FORCE WINDS 
DESPITE THE LIMITED FETCH AREA. WINDS WILL THEN GRADUALLY 
DIMINISH TO LESS THAN 20 KT BY 48 HOURS AS THEY SPREAD SOUTHWARD 
THROUGH THE GULF.

GULF OF TEHUANTEPEC...AN EARLIER 1616 UTC ASCAT SCATTEROMETER
PASS COVERED THE GULF OF TEHUANTEPEC REGION AND INDICATED MAINLY 
20-25 KT WINDS WHILE LAND BASED STATION IXTEPEC IN THE MEXICAN 
STATE OF OAXACA REPORTED GUSTS TO 25 KT AT 00 UTC. A SHIP WITH 
CALL-SIGN A8MW6 NEAR 15N95W REPORTED 29 KT WINDS AT 28 METERS 
AND THE GALE WARNING HAS BEEN ALLOWED TO EXPIRE AT 00 UTC. THE 
NEXT STRONG COLD FRONT WILL MOVE BY TO THE N THROUGH THE SW GULF 
OF MEXICO LATE THU WITH ANOTHER SURGE OF COLD AND DENSE AIR 
EXPECTED TO FUNNEL THROUGH THE CHIVELA PASS AND DOWNWIND INTO 
THE GULF OF TEHUANTEPEC BEHIND THE FRONT. MODEL GUIDANCE TOPS 
WINDS OUT AT 30 KT AT THIS TIME...ALTHOUGH WILL NEED TO CONTINUE 
TO MONITOR CONDITIONS AS WE GET CLOSER TO THE EVENT IN CASE 
ANOTHER GALE WARNING IS NEEDED.

$$
LEWITSKY