000
AXPZ20 KNHC 200325
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU JAN 20 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 CENTERED ALONG 06N77W 
TO 04N100W TO 09N128W TO 08N140W. SCATTERED MODERATE CONVECTION 
WITHIN 70 NM EITHER SIDE OF AXIS FROM 87W TO 90W. SIMILAR 
CONVECTION IS NOTED WITHIN 80 TO 90 NM N OF AXIS BETWEEN 85W AND 
87W. 

...DISCUSSION...

ALOFT...A DEEP LAYER TROUGH EXTENDS FROM THE SW CONUS WSW TO 
INTO THE AREA ALONG 29N125W 30N130W. A JET STREAM BRANCH ROUNDS 
THE BASE OF THE TROUGH AND TRACKS NEWD TO ACROSS CENTRAL BAJA 
CALIFORNIA INTO NORTHERN MEXICO. A MID/UPPER LEVEL RIDGE EXTENDS 
FROM ANTICYCLONE ANCHORED OVER NE VENEZUELA W THEN SW TO NEAR 
THE GALAPAGOS ISLANDS. A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH 
THIS FEATURE IS HELPING TO INDUCE CONVECTION ALONG THE ITCZ 
BETWEEN 85W AND 90W.

AT THE SURFACE...A 1032 MB HIGH PRES CENTERED NEAR 40N135W 
EXTENDS A RIDGE SE OVER THE FORECAST WATERS TO NEAR 19N110W. THE 
PRES GRADIENT BETWEEN THIS HIGH AND LOWER PRESSURE ASSOCIATED 
WITH THE ITCZ SUPPORTS FRESH TRADE WINDS TO 20 KT FROM 09N TO 
13N W OF 132W. AN EARLIER ASCAT PASS PROVIDED OBSERVATIONS OF 
THESE WINDS. 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 N OF 24N BETWEEN 
120W AND 135W. THESE WINDS ARE FORECAST TO REMAIN THROUGH 24 
HOURS...THEN DIMINISH TO BELOW 20 KT WITHIN 48 HOURS. 

A 1012 MB WEAK LOW PRES IS WITHIN THE ITCZ NEAR 05N104W. A SWIRL 
OF LOW CLOUDS IS ASSOCIATED WITH THIS FEATURE. A WEAK TROUGH IS 
ALSO WITHIN THE ITCZ AND EXTENDS FROM 13N129W TO 07N131W. A WELL 
DEFINED SWIRL OF LOW CLOUDS IS NOTED IN ASSOCIATION WITH THIS 
TROUGH. 

LONG PERIOD NW SWELLS WITH PERIODS OF 16-18 SEC ARE PRODUCING 
SEAS OF 8 TO 13 FT OVER THE N WATERS PARTICULARLY N OF 23N AND W 
OF 120W. A SECOND SET OF LONG PERIOD NW SWELLS WITH SIGNIFICANT 
WAVE HEIGHTS AS HIGH OF 15 FT WILL MOVE INTO THE FAR NW WATERS 
LATE THU SPREADING 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...
VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS FROM IXTEPEC 
MEXICO CAPTURED THE EXISTENCE OF A GAP WIND EVENT THROUGH THE 
GULF OF TEHUANTEPEC THIS WED. WINDS ARE FORECAST TO DIMINISH TO 
20 KT BY THU MORNING AS WINDS ACROSS THE GULF OF MEXICO VEER TO 
THE SOUTH. 

THE NEXT GULF OF TEHUANTEPEC EVENT IS THEN 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 WITH THE POSSIBILITY OF A BRIEF 
EPISODE OF WINDS REACHING MINIMAL GALE FORCE.

WINDS ARE EXPECTED TO INCREASE TO 20 KT OVER THE FAR NORTHERN 
PORTION OF THE GULF OF CALIFORNIA BEGINNING ON THU AFTERNOON AS 
STRONG HIGH PRES BUILDS OVER THE GREAT BASIN REGION. 

$$
GR