000
AXPZ20 KNHC 130922
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED APR 13 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 
0630 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 
09N105W TO 03N111W TO 03N128W TO 05N138W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 210 NM N OF THE ITCZ AXIS BETWEEN 127W AND 
134W AS WELL AS WITHIN 75 NM EITHER SIDE OF THE ITCZ AXIS 
BETWEEN 121W AND 127W. A TROUGH WAS EMBEDDED IN THE ITCZ FROM 
07N137W TO 02N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS 
WITHIN 90 NM W AND 210 NM E OF TROUGH.

...DISCUSSION...

A PROGRESSIVE NORTHERN STREAM UPPER TROUGH EXTENDS SOUTHWARD 
INTO THE FORECAST AREA FROM 32N123W TO 22N140W. THIS TROUGH IS 
ASSOCIATED WITH A COLD FRONT CURRENTLY MOVING INTO THE U.S. 
PACIFIC NORTHWEST THAT WILL PASS THROUGH THE WESTERN U.S. AND 
INTO THE CENTRAL U.S. THU. 1029 MB HIGH PRES NEAR 31N132W AHEAD 
OF THE FRONT WILL BE FORCED EASTWARD AND WILL STRENGTHEN THROUGH 
THU BEFORE WEAKENING FRI. THE PRES GRADIENT BETWEEN THIS HIGH 
AND TROUGHING OVER THE GULF OF CALIFORNIA AND WESTERN U.S. 
ENHANCED BY THE DEEP LAYER TROUGHING PUSHING E THROUGH THE U.S. 
WILL INCREASE THE WINDS OFF THE COAST OF BAJA CALIFORNIA TO 25 
KT OVERNIGHT TONIGHT AND DECREASE TO 20 KT OVERNIGHT THU NIGHT 
AS HIGH PRES WEAKENS. CURRENTLY...FRESH NW TO N WINDS LIE OFF 
THE W COAST OF BAJA CALIFORNIA ACCORDING TO SHIP V7DS3 NEAR 
27N115W AND SHIP 9V8798 NEAR 25N113W AT 0600 UTC. AS THE DEEP 
LAYER TROUGH MOVES EASTWARD...LOOK FOR FRESH TO STRONG NW WINDS 
TO ALSO SWEEP SOUTHWARD THROUGH THE GULF OF CALIFORNIA THU INTO 
FRI MORNING.

FRESH TO STRONG TRADE WINDS LIE OVER MUCH OF THE CENTRAL PORTION 
OF THE FORECAST AREA W OF 120W ACCORDING TO THE 0206 UTC WINDSAT 
PASS. LITTLE CHANGE IS EXPECTED IN THE STRENGTH AND AREAL EXTENT 
OF THESE TRADE WINDS THROUGH FRI MORNING.

AN ANTICYCLONE ALOFT NEAR 20N100W EXTENDS A RIDGE AXIS SE TO 
08N87W AND SW TO 08N124W. ANOTHER RIDGE AXIS EXTENDS NORTHWARD 
FROM AN ANTICYCLONE S OF THE EQUATOR THROUGH 00N99W TO 
05N90W...CLOSE TO THE SE RIDGE AXIS. THERE IS NO SIGNIFICANT 
CONVECTION NEAR THESE DIFFLUENT UPPER RIDGE AXES LIKELY DUE TO A 
LACK OF AVAILABLE MOSITURE OVER THIS REGION. THE EDGE OF THE SW 
RIDGE AXIS LIES NEAR THE ITCZ UNDER A PRECIPITABLE WATER MAXIMA. 
VERTICAL LIFT OF THE TROPICAL MOISTURE CONVERGED NEAR THE ITCZ 
IS ENHANCING CONVECTION NEAR 125W AS DESCRIBED IN THE ITCZ 
SECTION ABOVE. 

AN INVERTED UPPER LEVEL TROUGH LIES ALONG 135W S OF 07N AND IT 
IS ASSOCIATED WITH A SURFACE TROUGH FROM 07N137W TO 02N140W. THE 
MODERATE TO STRONG CONVECTION NEAR THIS TROUGH IS DESCRIBED IN 
THE ITCZ SECTION.

GAP WINDS...
GULF OF TEHUANTEPEC...A COLD FRONT THAT PASSED THROUGH THE 
ISTHMUS OF TEHUANTEPEC LAST NIGHT BROUGHT STRONG N WINDS TO THE 
GULF OF TEHUANTEPEC ACCORDING TO THE 0322 UTC ASCAT PASS. WINDS 
ARE EXPECTED TO DIMINISH BELOW ADVISORY CRITERIA BY THIS 
AFTERNOON.

GULF OF PAPAGAYO...WINDS WILL CONTINUE TO PULSE TO 20 KT THE 
THROUGH THU MORNING WITH SEAS REMAINING JUST BELOW 8 FT. THE 
LARGEST AREAL EXTENT OF THE 20 KT WINDS WILL BE IN THE EARLY 
MORNING HOURS WITH THE AID OF NOCTURNAL DRAINAGE FLOW.

$$
SCHAUER