000
AXPZ20 KNHC 110919
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON APR 11 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 10N86W 
TO 04N108W TO 06N125W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION WAS WITHIN 120 NM N AND 90 NM S OF THE ITCZ AXIS 
BETWEEN 106W AND 116W. SCATTERED MODERATE CONVECTION WAS FROM 90 
NM TO 300 NM N OF THE ITCZ AXIS BETWEEN 116W AND 120W AS WELL AS 
WITHIN 390 NM S OF THE ITCZ AXIS BETWEEN 86W AND 95W. 


...DISCUSSION...

A WEAK UPPER LOW THAT WAS OVER THE NW PORTION OF THE FORECAST 
AREA YESTERDAY IS BEING OVERTAKEN BY A BROAD NORTHERN STREAM 
UPPER TROUGH THAT HAS MOVED INTO NW WATERS. THIS UPPER TROUGH 
EXTENDS INTO THE FORECAST AREA FROM 32N133W TO 20N135W TO 
16N140W. A 60-90 KT SOUTHWESTERLY JET LIES ON THE E SIDE OF THIS 
TROUGH AND IS TRANSPORTING SOME MID TO UPPER LEVEL MOISTURE INTO 
THE N CENTRAL PORTION OF THE AREA WHICH IS MARKED BY 
MULTI-LAYERED CLOUDINESS PRIMARILY N OF 25N BETWEEN 120W AND 
135W AS A RESULT. A WEAKENING COLD FRONT HAS MOVED INTO THE FAR 
NW PORTION OF THE AREA AND SHOULD DISSIPATE BY THIS AFTERNOON. 
THE APPROACH OF THIS FRONT WILL WEAKEN THE 1030 MB HIGH NEAR 
32N130W TODAY. THE DOMINANT SUBTROPICAL HIGH PRES IS ALREADY 
SHIFTING TO THE 1037 MB HIGH BEHIND THE FRONT NEAR 39N150W.

FRESH TO STRONG TRADE WINDS LIE OVER MUCH OF THE W CENTRAL 
PORTION OF THE FORECAST AREA ACCORDING TO THE 0546 ASCAT PASS. 
AS THE HIGH PRES TO THE N REORGANIZES TO THE W...LOOK FOR THE 
AREA OF FRESH TO STRONG NORTHEAST TRADES TO SHIFT W TODAY IN 
RESPONSE.

THE PRES GRADIENT HAS TIGHTENED BETWEEN THE SUBTROPICAL RIDGE W 
OF THE BAJA CALIFORNIA PENINSULA AND LOW PRES CENTERED OVER 
CENTRAL MEXICO. FRESH TO STRONG NORTHERLY WINDS LIE OVER THE 
CENTRAL GULF OF CALIFORNIA IN RESPONSE TO THE PRES GRADIENT AND 
ARE CONFIRMED BY THE 0408 UTC ASCAT PASS. THE PRESSURE GRADIENT 
W OF THE BAJA CALIFORNIA COAST HAS ALSO TIGHTENED ENOUGH TO 
SUPPORT 20 KT NW TO N WINDS NEAR SHORE AS CONFIRMED BY SHIP DHER 
NEAR 23N112W AT 0600 UTC. THESE WINDS WILL GRADUALLY EXPAND W 
AND SHIFT N THROUGH TUE MORNING IN RESPONSE TO THE MIGRATING 
HIGH PRES. FARTHER S...THE PRES GRADIENT ON THE EASTERN EDGE OF 
THE SURFACE RIDGE NEAR CABO CORRIENTES MEXICO IS SUPPORTING 
FRESH TO STRONG NW TO N WINDS. THESE WINDS ARE EXPECTED TO 
DIMINISH THIS EVENING.

AN ANTICYCLONE ALOFT NEAR 16N97W EXTENDS A RIDGE SOUTHWESTWARD 
TO A COL NEAR 04N123W. BROAD DIFFLUENCE ALOFT ALONG THE RIDGE 
AXIS IS ENHANCING VERTICAL LIFT NEAR THE ITCZ. THIS AREA 
COINCIDES WITH PRECIPITABLE WATER VALUES AT OR ABOVE 50 MM 
ACCORDING TO SATELLITE IMAGERY. CONVECTION DESCRIBED IN THE ITCZ 
SECTION ABOVE HAS BEEN IDENTIFIED WITHIN THIS AREA. 

THE AFOREMENTIONED ANTICYCLONE EXTENDS A SECOND RIDGE AXIS
SOUTHEASTWARD TO 05N90W. THE HIGHEST PRECIPITABLE WATER VALUES 
OVER THE FORECAST AREA LIE UNDER THIS UPPER RIDGE NEAR THE 
EASTERN EDGE OF THE ITCZ AND CONVECTION LIES IN THIS AREA OF 
INCREASED LIFT OF THE MOIST AIRMASS. THIS CONVECTION IS ALSO
DESCRIBED ABOVE.

GAP WINDS...
GULF OF PAPAGAYO...NE TO E WINDS WILL CONTINUE TO PULSE TO 20 KT 
IN THE GULF OF PAPAGAYO DURING THE NEXT COUPLE OF DAYS 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.
 
GULF OF TEHUANTEPEC...A WEAK COLD FRONT IN THE GULF OF MEXICO 
WILL PASS THROUGH THE ISTHMUS OF TEHUANTEPEC OVERNIGHT TUE NIGHT 
AND BRIEFLY BRING 20 KT N WINDS TO THE GULF OF TEHUANTEPEC.

$$
SCHAUER