000
AXPZ20 KNHC 090358
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED FEB 09 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 
0230 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE IS ANALYZED ALONG AN AXIS 
FROM 05N77W TO 03N95W TO 09N115W TO 06N133W TO 07N140W. 
SCATTERED MODERATE WITHIN 60 NM OF THE AXIS BETWEEN 125W AND 
131W. 

...DISCUSSION...
W OF 110W...A REX BLOCK PATTERN REMAINS ENTRENCHED AT THE MID 
AND UPPER LEVELS ACROSS THE AREA WITH AN UPPER RIDGE ANCHORED N 
OF THE AREA NEAR 37N132W AND TO THE N OF A BROAD COMPLEX UPPER 
LOW CENTERED NEAR 24N133W. THIS OVERALL PATTERN IS BLOCKING THE 
EASTWARD PROGRESS OF A STATIONARY FRONTAL BOUNDARY WELL TO THE 
NW OF THE AREA OVER THE N CENTRAL PACIFIC. THE RIDGE APPEARS TO 
BE BUILDING TO THE NW WITH TIME AND AS SUCH THERE ARE 
INDICATIONS THAT THE OVERALL PATTERN MAY BE IN THE PROCESS OF 
BREAKING DOWN. THIS ALLOWS THE UPPER LOW COMPLEX TO OPEN UP INTO 
A TROUGH FROM CENTRAL CALIFORNIA TO 18N140W. AT THE SURFACE...A 
1038 MB HIGH PRES ASSOCIATED WITH THE UPPER RIDGE IS CENTERED 
WELL N OF THE AREA NEAR 44N134W. A TIGHT PRESSURE GRADIENT 
BETWEEN THIS HIGH AND A TROUGH ALONG THE CALIFORNIA COAST IS 
RESULTING IN A PERSISTENT LONG FETCH OF 20 TO 25 KT NE WINDS 
FROM CENTRAL CALIFORNIA TO NEAR 25N140W...ACCOMPANIED BY FRESH 
NE SWELL. ASIDE FROM THESE WINDS...TRADES TO THE SOUTH REMAIN 
FAIRLY MODEST IN STRENGTH AND AREAL COVERAGE DUE TO THE 
DISPLACEMENT OF THE SURFACE HIGH PRES WELL TO THE NORTH.  
SCATTERED MODERATE CONVECTION WAS CONFINED TO WITHIN 60 NM OF 
THE ITCZ BETWEEN 125W AND 131W WITHIN A LARGE AREA OF 
SUBSIDENCE. WEAK TRADE WIND FLOW AT THE SURFACE AND DECENT 
DIVERGENT FLOW ALOFT CONTRIBUTED TO THE MAINTENANCE OF ANY 
CONVECTIVE ACTIVITY. OTHERWISE...LONG PERIOD NW SWELL CONTINUES 
TO SHIFT SE THROUGH THE AREA. 

E OF 110W...THE MAIN FORECAST ISSUES REMAIN GAP WINDS IN THE 
GULFS OF TEHUANTEPEC AND PAPAGAYO. RECENT SURFACE OBSERVATIONS 
NEAR THE ISTHMUS OF TEHUANTEPEC INDICATED WINDS HAVE DECREASED 
MARKEDLY AND ARE ESTIMATED AT 20-25 KT. NWP MODELS FORECAST THE 
AREA OF WINDS TO DISSIPATE ALTOGETHER EARLY WED...BUT ARE 
INDICATING A SURGE OF ARCTIC AIR IN THE GULF OF MEXICO WILL 
RESULT IN ANOTHER GAP WIND EVENT BY LATE THU WITH WINDS REACHING 
GALE FORCE LATE THU AND THU NIGHT IN THE GULF OF TEHUANTEPEC.  
FURTHER SOUTH...FRESH TO STRONG GAP FLOW THROUGH PAPAGAYO WILL
MAXIMIZE EARLY WED DURING DIURNALLY ENHANCED DRAINAGE FLOW. THE 
WINDS ARE FORECAST TO WEAKEN AS THE PRESSURE GRADIENT OVER THE 
SW CARIBBEAN SLACKENS. 

GULF OF CALIFORNIA...A COLD FRONT WILL APPROACH THE NORTHERN 
GULF OF CALIFORNIA LATE TONIGHT AND INCREASE WINDS TO 20 TO 25 
KT IN THE NORTHERN GULF WED MORNING. THESE WINDS ARE FORECAST TO 
SPREAD SOUTHWARD TO ALONG 25N/26N BY LATE THU. 

$$
COBB