000
AXPZ20 KNHC 210327
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI JAN 21 2011

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 
0300 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 06N77W TO 
05N100W TO 06N115W TO 06N130W TO 07N140W. ISOLATED MODERATE 
CONVECTION IS WITHIN 80 NM S OF AXIS FROM 85W TO 90W. 

...DISCUSSION...
ALOFT...AN UPPER LEVEL TROUGH EXTENDS FROM THE SOUTHWESTERN U.S. 
THROUGH CENTRAL BAJA CALIFORNIA TO 24N133W THEN NW TO 30N140W.  
MODERATE TO STRONG MID TO UPPER LEVEL SUBSIDENCE AND IMPLIED DRY 
AIR MASS IS NOTED N OF THE TROUGH AND S OF THE TROUGH TO 22N. AN 
70-110 KT JET STREAM BRANCH EXTENDS FROM THE SOUTHERN BAJA 
PENINSULA ACROSS NORTHERN MEXICO. A MID/UPPER LEVEL RIDGE 
DOMINATES THE EASTERN PART OF THE FORECAST WATERS PARTICULARLY E 
OF 100W. A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH THIS FEATURE 
IS HELPING TO INDUCE CONVECTION ALONG THE ITCZ BETWEEN 85W AND 
90W. 

AT THE SURFACE...A 1031 MB HIGH PRES CENTERED NEAR 38N138W 
EXTENDS A RIDGE SE OVER THE FORECAST WATERS TO NEAR 20N110W. THE 
PRES GRADIENT BETWEEN THIS HIGH AND LOWER PRESSURE ASSOCIATED 
WITH THE ITCZ SUPPORTS FRESH TRADE WINDS TO 20 KT FROM 10N TO 
20N W OF 130W. AN EARLIER WINDSAT AND ASCAT PASSES AND SOME SHIP 
OBSERVATIONS CORROBORATE THESE WIND SPEEDS. THE SURFACE HIGH 
PRESSURE IS FORECAST TO REMAIN NEARLY STATIONARY OVER THE NEXT 
24 HOURS WHICH WILL MAINTAIN THIS AREA OF FRESH TRADES. THE 
PRESSURE GRADIENT BETWEEN THE SURFACE HIGH MENTIONED ABOVE AND 
THE CALIFORNIA COASTAL TROUGH IS SUPPORTING FRESH TO STRONG N TO 
NE WINDS OF 20 TO 25 KT N OF 20N W OF 125W. THESE WINDS ARE 
FORECAST TO DIMINISH TO 20 KT THROUGH 24 HOURS...THEN TO BELOW 
20 KT WITHIN 48 HOURS AS THE GRADIENT SLACKENS. 

A PAIR OF WEAK TROUGHS ARE WITHIN THE ITCZ. THE EASTERNMOST IS 
ALONG 88W FROM 03N TO 10N DRIFTING WWD. ISOLATED MODERATE 
CONVECTION IS SEEN S OF THE ITCZ AND WITHIN 90 NM EITHER SIDE OF 
TROUGH AXIS. THE SECOND TROUGH EXTENDS FROM 12N136W TO 06N137W 
MOVING WWD AT 5 TO 10 KT. ISOLATED SHOWERS ARE MAINLY E OF THE 
TROUGH AXIS. 

LONG PERIOD NW SWELLS WITH PERIODS OF 16-18 SEC ARE REACHING 
100W. A SECOND SET OF LONG PERIOD NW SWELLS WITH SIGNIFICANT 
WAVE HEIGHTS AS HIGH OF 16 FT HAS MOVED INTO THE NW WATERS AND 
WILL CONTINUE TO SPREAD SE ACROSS THE REGIONAL WATERS BY FRI. 
THESE SWELLS...GENERATED FROM A SERIES OF INTENSE LOW PRES 
SYSTEMS WELL NW OF THE REGION...WILL CONTINUE THROUGH 48 HOURS. 

GAP WINDS...
THE NEXT GULF OF TEHUANTEPEC EVENT IS FORECAST TO BEGIN ON FRI 
AS HIGH PRES BUILDS S ACROSS MEXICO AND THE WESTERN GULF OF 
MEXICO IN THE WAKE OF A COLD FRONT THAT MOVES THROUGH THE BAY OF 
CAMPECHE AND SOUTHEASTERN MEXICO. THIS WILL BE A BRIEF EVENT. 

BASED ON SURFACE DATA....WINDS HAVE INCREASED TO 25 KT OVER THE 
FAR NORTHERN PORTION OF THE GULF OF CALIFORNIA. THIS WEATHER 
PATTERN WILL PERSIST OVER THE NEXT 24 HOUR EXTENDING FURTHER S 
TO 27N AS STRONG HIGH PRES BUILDS OVER THE GREAT BASIN REGION.  

$$
GR