000
AXPZ20 KNHC 061517
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED APR 06 2011

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 1515 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 08N83W 
TO 06N90W TO 03N103W THEN RESUMES FROM 05N114W TO 03N125W TO 
05N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 240 
NM S OF THE AXIS E OF 86W AND WITHIN 90 NM N OF THE AXIS E OF 
86W.

...DISCUSSION...

THE UPPER LEVEL LOW CENTERED NEAR 31N120W THAT HAS BEEN THE 
DOMINANT FEATURE OVER THE FORECAST AREA THE PAST FEW DAYS IS 
BEING PICKED UP BY NORTHERN STREAM TROUGHING AND IS QUICKLY 
MOVING NE TOWARD THE SOUTHERN CALIFORNIA AND NW MEXICO COASTAL 
AREAS. SCATTERED SHOWERS PRIMARILY NE OF THE LOW CENTER ARE 
APPROACHING THOSE COASTAL AREAS AS INDICATED BY KNKX WSR-88D 
RADAR LOCATED NEAR SAN DIEGO CALIFORNIA. THIS UPPER LEVEL SYSTEM 
HAS DISRUPTED THE SUBTROPICAL HIGH PRES AND THE CORRESPONDING 
TRADE WINDS USUALLY FOUND OVER THE N AND W WATERS. 

A SURFACE TROUGH ASSOCIATED WITH THE VERTICALLY TILTED SYSTEM 
LIES FROM 18N127W TO 12N129W. AN EARLIER ASCAT PASS SHOWED 20 KT 
WINDS OVER THE NW WATERS NW OF THE TROUGH WHERE THE PRES 
GRADIENT IS THE TIGHTEST BETWEEN THE TROUGH AND THE 1041 MB 
SUBTROPICAL HIGH NEAR 41N152W. THE UPPER LEVEL LOW WILL CONTINUE 
TO WEAKEN TODAY AS IT MOVES NE. THIS WILL CAUSE ITS ASSOCIATED 
SURFACE TROUGH TO DISSIPATE. NE TRADE WINDS ARE EXPECTED TO 
RETURN TO WESTERN WATERS N OF 14N BY THE END OF THE PERIOD FRI 
MORNING. ANOTHER SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ FROM 
09N112W TO 02N114W. SCATTERED MODERATE CONVECTION WAS WITHIN 90 
NM OF THE TROUGH.

AN UPPER RIDGE AXIS LIES FROM CENTRAL PANAMA TO NEAR 05N99W. 
UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS ENHANCING 
CONVECTION ALONG THE EASTERN PORTION OF THE ITCZ NEAR THE COASTS 
OF PANAMA AND COSTA RICA IN A REGION WHERE PRECIPITABLE WATER 
VALES ARE AROUND 50 MILLIMETERS. THIS CONVECTION IS AS DESCRIBED 
IN THE ITCZ SECTION ABOVE.

CROSS-EQUATORIAL SW SWELLS HAVE RAISED SIGNIFICANT WAVE HEIGHTS 
TO THE 8-10 FT RANGE OVER THE S CENTRAL WATERS. THIS SWELL WILL 
GRADUALLY DIMINISH TO 8 FT BY THE END OF THE PERIOD.

GAP WINDS...
GULF OF CALIFORNIA...SW WINDS WILL PICK UP TO 20 KT OVER THE FAR 
NORTHERN GULF OVERNIGHT TONIGHT AHEAD OF THE NEXT STRONG COLD 
FRONT WHICH WILL MOVE THROUGH THE WESTERN CONUS.

GULF OF TEHUANTEPEC...WINDS HAVE DIMINISHED BELOW GALE FORCE 
WITH EARLY MORNING DRAINAGE FLOW HAVING ENDED AND WITH A COLD 
FRONT IN THE GULF OF MEXICO HAVING WEAKENED. WINDS ARE FORECAST
TO DIMINISH BELOW ADVISORY CRITERIA THIS EVENING AS THE PRES 
GRADIENT OVER THE REGION RELAXES WITH LINGERING NE SWELLS TO 9 
FT OVER THE AREA GRADUALLY SUBSIDING TO LESS THAN 8 FT BY THU 
MORNING.

GULF OF PAPAGAYO...THE PRES GRADIENT BETWEEN RIDGING OVER THE 
GULF OF MEXICO THROUGH SOUTHERN MEXICO AND TROUGHING OVER NW 
SOUTH AMERICA IS GENERATING 20 KT E WINDS. WINDS WILL INCREASE 
TO 20 TO 25 KT BY THU MORNING WHEN A COLD FRONT THAT BROUGHT THE 
GALE CONDITIONS TO THE GULF OF TEHUANTEPEC MOVES INTO THE AREA 
ALONG WITH ENHANCED EARLY MORNING DRAINAGE FLOW. WINDS WILL 
DIMINISH BACK TO 20 KT BY FRI MORNING AS THE FRONT DISSIPATES.

$$
LEWITSKY