000
AXPZ20 KNHC 060917
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED APR 06 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 0700 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 08N82W 
TO 05N90W TO 03N127W TO 05N140W. SCATTERED MODERATE CONVECTION 
WAS BETWEEN 120 NM AND 270 NM S OF THE ITCZ AXIS BETWEEN 91W AND 
95W. ISOLATED MODERATE CONVECTION WITHIN 120 NM N AND 210 NM S 
OF THE ITCZ AXIS BETWEEN 81W AND 85W.

...DISCUSSION...
THE UPPER LOW CENTERED NEAR 28N123W 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 
NORTH AMERICA. SCATTERED SHOWERS ARE PRIMARILY NE OF THE LOW 
CENTER AND ARE APPROACHING THE SOUTHERN CALIFORNIA/BAJA 
CALIFORNIA NORTE COAST. THIS SYSTEM HAS DISRUPTED THE 
SUBTROPICAL HIGH PRES AND THE TRADE WINDS USUALLY FOUND OVER N 
WATERS. A SURFACE TROUGH ASSOCIATED WITH THE VERTICALLY TILTED 
SYSTEM LIES FROM 24N127W TO 15N131W. THE 0554 UTC ASCAT PASS 
SHOWS 20 KT WINDS OVER NW WATERS N OF THE TROUGH WHERE THE PRES 
GRADIENT IS TIGHTEST BETWEEN THE TROUGH AND THE 1041 MB 
SUBTROPICAL HIGH NEAR 41N152W. THE UPPER 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 07N BY THE END OF THE PERIOD EARLY 
FRI MORNING.

AN UPPER RIDGE AXIS LIES FROM WESTERN PANAMA TO THE EQUATOR NEAR 
86W. UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS ENHANCING 
CONVECTION ALONG THE EASTERN PORTION OF THE ITCZ NEAR THE COAST 
OF PANAMA/COSTA RICA IN A REGION WHERE PRECIPITABLE WATER VALES 
ARE AROUND 50 MILLIMETERS. THIS CONVECTION IS DESCRIBED IN THE 
ITCZ SECTION ABOVE. 

CROSS-EQUATORIAL SW SWELLS HAVE RAISED SIGNIFICANT WAVE HEIGHTS 
TO THE 8-10 FT RANGE OVER 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 OVER NIGHT TONIGHT AHEAD OF THE NEXT STRONG COLD 
FRONT TO MOVE THROUGH THE WESTERN CONUS.

GULF OF TEHUANTEPEC...THE 0408 UTC ASCAT EXPERIMENTAL COASTAL 
WIND RETRIEVALS PROVIDED BY NESDIS SHOW WINDS JUST BELOW GALE 
FORCE IN THE GULF OF TEHUANTEPEC FOLLOWING THE PASSAGE OF A 
STRONG COLD FRONT THROUGH THE GULF OF MEXICO LAST NIGHT. 
HOWEVER...THE EARLY MORNING DRAINAGE FLOW SHOULD CURRENTLY BE 
KEEPING WINDS TO MINIMAL GALE FORCE. THESE WINDS ARE FORECAST TO 
DIMINISH BELOW GALE FORCE LATER THIS MORNING AND BELOW ADVISORY 
CRITERIA BY THU MORNING AS HIGH PRES BEHIND THE FRONT QUICKLY 
MOVES E AWAY FROM THE AREA.

GULF OF PAPAGAYO...THE PRES GRADIENT BETWEEN RIDGING FROM THE 
GULF OF MEXICO INTO SOUTHERN MEXICO AND TROUGHING OVER NW 
SOUTH AMERICA IS GENERATING E WINDS TO 20 KT WITH THE ASSISTANCE 
OF EARLY MORNING DRAINAGE FLOW INTO THE GULF OF PAPAGAYO. WINDS 
WILL BECOME STRONG BY THU MORNING WHEN THE COLD FRONT THAT 
BROUGHT THE GALE TO TEHUANTEPEC MOVES INTO THE AREA...BUT WILL 
DIMINISH TO 20 KT BY FRI MORNING.

$$
SCHAUER