000
AXPZ20 KNHC 160945
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN JAN 16 2011

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0930 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS CENTERED ALONG 7N79W
6N88W 5N100W 8N115W 6N123W 8N140W. SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN 
100W-107W SCATTERED MODERATE CONVECTION IS WITHIN 60 NM N OF THE 
AXIS BETWEEN 108W-112W...AND 120 NM N OF THE AXIS W OF 137W.

...DISCUSSION...

AN UPPER LEVEL TROUGH PUSHING RAPIDLY SWD EXTENDS FROM MIDWEST
PORTION OF THE U.S. SW TO NW MEXICO...TO CENTRAL BAJA CALIFORNIA
AND TO 27N120W. VERY LITTLE IN THE WAY OF ANY MOISTURE IS 
ASSOCIATED WITH THIS TROUGH AS MODERATE SUBSIDENCE AND RESULTANT 
DRY AIR PREVAILS OVER THE EASTERN PORTION OF THE AREA N OF 18N E 
OF 120W AS WELL AS SE OF THE TROUGH OUTSIDE THE ITCZ REGION. SW 
OF THE TROUGH THE AREA IS UNDER RATHER AMPLIFIED MID/UPPER LEVEL 
RIDGING RESPONDING TO A LARGE CYCLONIC VORTEX THAT HAS MOVED W 
OF THE AREA DURING THE PAST 24 HOURS NOW LOCATED NEAR 17N145W. 
DIVERGENT FLOW ALOFT TO THE E OF THE VORTEX IN THE AREA OF THE 
MID/UPPER RIDGING AIDED BY ADDITIONAL MOISTURE TIED TO
WEAK SURFACE TROUGHS ALONG 115W AND 137W CONTINUES TO ENHANCE 
ITCZ CONVECTION AS DESCRIBED ABOVE...WITH THE TROUGH ALONG 137W
PRODUCING THE MOST CONVECTIVE ACTIVITY AS IT IS CLOSER TO THE 
CYCLONIC VORTEX. A WEAK 1011 MB LOW ON THE TROUGH NEAR 115W 
EARLIER HAD ENHANCED TSTM ACTIVITY ALONG THE ITCZ. THE MOIST SSW 
UPPER FLOW WITHIN THE AREA OF MID/UPPER LEVEL RIDGING IS 
ADVECTING BROKEN HIGH CLOUDINESS FROM THE DEEP TROPICS N AND NE 
TO 22N...AND THEN EASTWARD TO NEAR 110W WHERE THEY EVAPORATE IN 
THE SUBSIDENCE REGION.

N OF THE SSW MOIST FLOW MODERATE SUBSIDENCE WITH VERY STABLE
ENVIRONMENTAL CONDITIONS ARE OBSERVED ON SATELLITE IMAGERY AS 
MODERATE TO STRONG SUBSIDENCE STAYS IN PLACE. AT THE SURFACE...
A NEARLY STATIONARY 1032 MB HIGH CENTERED N OF THE AREA NEAR 
36N130W HAS AN ATTENDANT RIDGE SE TO 23N125W. A TIGHT PRES 
GRADIENT ON THE SOUTHERN PERIPHERY OF THE RIDGE DUE TO THE PRES 
DIFFERENCE BETWEEN RIDGE AND LOWER PRES TO ITS S ALONG THE ITCZ 
CONTINUES TO MAINTAIN A LARGE AREA OF NE TO E 20 TO 25 KT NE 
TRADES FROM 8N TO 24N W OF 120W. LARGE NW SWELLS DERIVED FROM A 
SERIES OF LOW PRES SYSTEMS WELL TO THE NW OF THE REGION WILL 
KEEP THE SEA STATE UP TO A MAX OF 11 FT WITHIN WITHIN THE AREA 
OF TRADES. THE HIGH WILL ONLY WEAKEN SIGHTLY OVER THE NEXT 24-48 
HOURS ALLOWING FOR THE TRADES TO DIMINISH TO 20 KT WHILE THE 
ACTUAL AREA DECREASE IN AREAL COVERAGE. SEAS ARE FORECAST TO 
SUBSIDE TO 8 FT ON MON...HOWEVER A VERY IMPRESSIVE LARGE SET OF 
NW SWELLS IS FORECAST BY THE NWW3 GUIDANCE TO BE APPROACHING 
140W ALSO ON MON.

WITH BROAD DEEP SCALE RIDGING REMAINING IN PLACE OVER MUCH OF 
THE AREA W OF 115W...EXPECT UPPER LEVEL ATMOSPHERIC ENERGY TO 
CONTINUE TO STAY WELL N OF THE AREA THROUGH THE NEXT 48 HOURS
COLD FRONTS BLOCKED FROM ENTERING THE REGION AS THEY STAY WELL
TO THE N OF REGION.

NW 20-25 KT WINDS EARLIER EVIDENT THROUGH THE GULF OF CALIFORNIA 
N OF 26N HAVE SINCE DIMINISHED TO 20 KT FROM 24N TO 28N...BUT 
WILL DROP TO LESS THAN 20 KT BY EARLY THIS AFTERNOON AS THE 
CULPRIT STRONG PRES GRADIENT THAT RESULTED FROM COMBINATION OF 
STRONG HIGH PRES OVER THE WRN CONUS AND LOWER PRES OVER THE NW 
MEXICO WEAKENS.

GAP WINDS...
THE GULF OF TEHUANTEPEC GALE WARNING EXPIRED YESTERDAY AFTERNOON 
AS THE PRES GRADIENT OVER SE MEXICO WEAKENS AND SE FLOW CONTINUES
TO TAKE PLACE OVER THE WESTERN GULF OF MEXICO. AN ASCAT PASS 
FROM 0322 UTC LATE LAST NIGHT SUGGESTED THAT NLY FLOW CONSISTING
OF 20-25 KT WINDS WAS OCCURRING WITHIN ABOUT 90 NM FROM THE 
TEHUANTEPEC COAST...HOWEVER WITH CONTINUING WEAKENING OF THE 
GRADIENT THESE WINDS WILL DIMINISH TO LESS THAN 20 KT SUN 
MORNING. MIXED NE AND SE SWELLS LEADING TO SEAS OF 8 TO 10 FT 
DOWNSTREAM FROM THE GULF OF TEHUANTEPEC OVER THE AREA S OF 13N 
BETWEEN 93W-115W WILL DECREASE TO 8 FT IN 18 HOURS AND TO LESS 
THAN 8 FT IN 48 HOURS.

$$
AGUIRRE