000
AXPZ20 KNHC 281611
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON FEB 28 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...
AXIS FROM 07N78W TO 01N96W THEN RESUMES FROM 00N109W TO 06N122W 
TO 03N136W TO 05N140W.  SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WITHIN 60 NM OF AXIS E OF 94W.

...DISCUSSION...
COLD FRONT ACROSS NE PORTIONS OVER THE WEEKEND HAS MOVED E AND 
SE ACROSS NORTHERN MEXICO AND INTO TEXAS...AND HAS BECOME ILL 
DEFINED FROM THE FAR SOUTHERN GULF OF CALIFORNIA AND WWD ALONG 
22N TO 120W AS DEPICTED IN STLT AND TPW IMAGERY. FEATURE HAS 
THUS BEEN DROPPED FROM SURFACE MAP. ASSOCIATED SHORTWAVE 
TROUGHING ALOFT WAS MOVING INTO LOWER MS VALLEY...AND OVER 
PERSISTENT W CARIB/GULF OF MEXICO UPPER RIDGE. RIDGE CURRENTLY 
EXTENDS W OF 110W. GLOBAL MODELS INDICATE THAT THE EXITING 
SHORTWAVE WILL ALLOW THE UPPER RIDGE TO SHIFT SLIGHTLY W AND 
EXPAND NORTHWESTWARD OVER MEXICO THROUGH WED MORNING. BROAD 
DIFFLUENT FLOW ALOFT BETWEEN THIS ANTICYCLONE AND AN UPPER LOW S 
OF THE EQUATOR NEAR 15S85W HAS ALLOWED FOR CONVECTION NEAR THE 
ITCZ BETWEEN 80W AND 95W TO INCREASE SIGNIFICANTLY IN THE PAST 
24-36 HOURS...AS A PLUME OF TROPICAL MOISTURE AND INCREASED LOW 
LEVEL CONVERGENCE HAS SHIFTED OFF OF COLOMBIA AND WWD ALONG THE 
ITCZ. CONVECTION THERE IS DESCRIBED IN THE ITCZ SECTION ABOVE. 
THE ITCZ JUST W OF THIS AREA CONTINUES TO BE DISRUPTED BY THE 
DEEP LAYER TROUGHING S OF THE EQUATOR BETWEEN 90W AND 105W 
ASSOCIATED WITH THIS UPPER LOW. 

ANOTHER DEEP LAYER TROUGH WAS SLOWLY APPROACHING THE NW WATERS 
AS THE GULF OF MEXICO UPPER RIDGE CONTINUES TO DIVERT UPPER 
LEVEL ENERGY NORTHEASTWARD ACROSS THE AREA. AN UPPER TROUGH 
AXIS LIES FROM 32N138W THROUGH 18N141W TO 08N159W WHILE A MUCH 
WEAKER NEGATIVELY TILTED UPPER SHORTWAVE LIES JUST AHEAD OF IT N 
OF 28N ALONG 127W. A BROAD AREA OF 50-70 KT SW WINDS LIES 
BETWEEN AND SE OF THESE TWO TROUGHS AND IS TRANSPORTING MID TO 
UPPER LEVEL MOSITURE FROM THE TROPICS NORTHEASTWARD AND N 
PORTIONS OF THE 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...WITH WINDS AHEAD OF THE FRONT 
EXPECTED TO INCREASE TO AROUND 30 KT LATER THIS AFTERNOON AND 
EVENING ACROSS THE FAR NW PORTIONS. THE FRONT WILL SLOWLY MOVE 
EAST AND 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 122W. 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. 20 KT NWLY WINDS ARE 
OCCURRING WITHIN 90 NM OF THE W COAST OF BAJA CALIFORNIA SUR 
THIS MORNING AND ALSO WITHIN THE SOUTHERN HALF OF THE GULF 
WATERS. WINDS ARE EXPECTED TO DIMINISH W OF BAJA THIS MORNING 
AND PERSIST NEAR 20 KT MAINLY IN THE GULF S OF 28N THROUGH TUE 
EVENING.

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.
 
$$
STRIPLING