000
AXPZ20 KNHC 280843
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON FEB 28 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 
0800 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 05N77W 
TO 06N83W TO 03N95W THEN CONTINUES FROM 03N106W TO 07N119W TO 
05N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION LIES 
WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 82W AND 94W.


...DISCUSSION...

THE COLD FRONT THAT WAS OVER THE GULF OF CALIFORNIA AND NE 
WATERS AT 00Z DIMINISHED AS ITS ASSOCIATED TROUGHING ALOFT MOVED 
INLAND. THIS UPPER TROUGH WILL PASS N OF THE ANTICYCLONE 
CENTERED OVER THE NW CARIBBEAN TODAY AND ALLOW THE UPPER RIDGING 
TO EXPAND NORTHWESTWARD OVER MEXICO THROUGH THE END OF THE 
FORECAST PERIOD WED MORNING. BROAD DIFFLUENT FLOW ALOFT BETWEEN 
THIS ANTICYCLONE AND AN UPPER LOW S OF THE EQUATOR NEAR 15S85W 
IS ENHANCING VERTICAL MOTION NEAR THE ITCZ BETWEEN 80W AND 95W. 
CONVECTION THERE IS DESCRIBED IN THE ITCZ SECTION ABOVE. THE 
ITCZ CONTINUES TO BE DISRUPTED BY THE DEEP LAYER TROUGHING S OF 
THE EQUATOR ASSOCIATED WITH THIS UPPER LOW. 

ANOTHER DEEP LAYER TROUGH IS APPROACHING NW WATERS. ITS UPPER 
TROUGH AXIS LIES FROM 32N133W THROUGH 23N140W TO 10N150W WHILE A 
MUCH WEAKER NEGATIVELY TILTED UPPER TROUGH LIES FROM 13N118W TO 
00N102W. A BROAD AREA OF 50-70 KT SW WINDS LIES BETWEEN THESE 
TWO TROUGHS AND IS TRANSPORTING MID TO UPPER LEVEL MOSITURE FROM 
THE TROPICS INTO N WATERS WITH MULTIPLE CLOUD LAYERS NOTED OVER 
MUCH OF THE AREA W OF 120W. AN ATTENDANT COLD FRONT WILL MOVE 
INTO NW WATERS BY TUE MORNING...BUT WINDS AHEAD OF THE FRONT ARE 
EXPECTED TO INCREASE TO ABOVE ADVISORY CRITERIA BY THIS 
AFTERNOON. THE FRONT WILL SLOWLY MOVE SOUTHEASTWARD THROUGH WED 
MORNING WITH FRESH TO STRONG WINDS REMAINING AHEAD OF THE FRONT 
BETWEEN IT AND HIGH PRES TO ITS E.

BROAD SURFACE RIDGING CURRENTLY DOMINATES THE AREA N OF 15N. THE 
PRES GRADIENT BETWEEN THIS RIDGING AND LOWER PRES ASSOCIATED 
WITH THE ITCZ IS PRODUCING AN AREA OF FRESH TRADE WINDS FROM 06N 
TO 12N W OF 120W. THESE TRADES WILL MIGRATE E AND EXPAND 
NORTHWARD THROUGH TUE MORNING BEFORE DIMINISHING OVERNIGHT TUE 
NIGHT AS THE HIGH PRES CENTER IS FORCED NORTHEASTWARD BY THE 
APPROACHING COLD FRONT AND THEN WEAKENS. 

GULF OF CALIFORNIA...THE COLD FRONT THAT DISSIPATED OVER NE 
WATERS LAST NIGHT IS CONTINUING TO MOVE THROUGH MEXICO AND HIGH 
PRES IS BUILDING BOTH ON THE E SIDE OF THE GULF OF CALIFORNIA 
BEHIND THIS FRONT AS WELL ON THE W SIDE WITH THE AFOREMENTIONED 
NORTHEASTWARD MIGRATING PACIFIC HIGH. THE 0518Z ASCAT PASS AND 
SHIP 3FSB4 CONFIRM 20 KT WINDS WITHIN 90 NM OF THE W COAST OF 
BAJA CALIFORNIA SUR THIS MORNING. WINDS ARE EXPECTED TO DIMINISH 
HERE THIS MORNING AND LIE MAINLY IN THE GULF S OF 28N THIS 
MORNING THROUGH TUE AFTERNOON.

GULF OF TEHUANTEPEC...THE COLD FRONT OVER NE MEXICO WILL SWEEP 
SE ACROSS THE GULF OF MEXICO LATER TODAY. NORTHERLY WINDS WILL 
INCREASE TO 15 TO 20 KT IN THE GULF OF TEHUANTEPEC EARLY TUE 
MORNING...FURTHER INCREASING TO GALE FORCE JUST AROUND SUNRISE 
AND CONTINUING THROUGH JUST AFTER SUNRISE WED MORNING BEFORE 
DIMINISHING WED AFTERNOON.      

GULF OF PAPAGAYO...NE TO E WINDS WILL CONTINUE TO PULSE AT 15 TO 
20 KT THROUGH TUE MORNING...WITH ENHANCED DRAINAGE FLOW OFF 
THE CENTRAL AMERICA LANDMASS LATE AT NIGHT THROUGH EARLY 
MORNING. BUILDING HIGH PRES BEHIND THE COLD FRONT PASSING 
THROUGH MEXICO WILL HELP INCREASE THE PRES GRADIENT ACROSS THE 
GULF OF PAPAGAYO AND BRING WINDS TO 25 KT BY WED MORNING.
 
$$
SCHAUER