000
AXPZ20 KNHC 280919
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE FEB 28 2012
 
TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0800 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THERE IS NEITHER AN ITCZ NOR A MONSOON TROUGH OF NOTE OVER THE 
FORECAST AREA AT THIS TIME.

...DISCUSSION...

THE 1032 MB SUBTROPICAL HIGH LIES NW OF THE AREA NEAR 35N148W 
AND EXTENDS A RIDGE SOUTHEASTWARD TO 20N115W. A COLD FRONT CUTS 
THROUGH THE GULF OF CALIFORNIA FROM 31N113W TO 29N114W AND 
EXTENDS INTO PACIFIC WATERS N OF THE RIDGE AXIS TO 25N120W. 
FRESH TO STRONG NW FLOW LIES OFF THE W COAST OF BAJA CALIFORNIA 
BEHIND THE FRONT ACCORDING TO THE 0428 UTC ASCAT PASS. THIS 
FRONT WILL MOVE EASTWARD THROUGH NORTHERN MEXICO TODAY AND THE 
TIGHTEST PRES GRADIENT BETWEEN THE TROUGHING OVER MEXICO AND THE 
SUBTROPICAL RIDGE WILL EXPAND SOUTHWARD OFF THE BAJA CALIFORNIA 
COAST WHERE IT WILL PERSIST THROUGH THE END OF THE FORECAST 
PERIOD EARLY THU MORNING. 

S OF THE RIDGE AXIS...FRESH NE TRADE WINDS DOMINATE MUCH OF THE 
AREA W OF 120W. LITTLE CHANGE IS EXPECTED IN THE STRENGTH OR 
POSITION OF THESE WINDS OVER THE NEXT TWO DAYS AS THE 
SUBTROPICAL RIDGE REMAINS NEARLY STATIONARY.

THE MEAN TROUGH ALOFT EXTENDS FROM 32N125W TO 20N140W. A 60-80 
KT SOUTHWESTERLY JET LIES ON THE LEADING EDGE OF THIS TROUGH. 
THIS JET IS TRANSPORTING TROPICAL MOISTURE NORTHEASTWARD FROM 
NEAR 05N125W THROUGH THE MOUTH OF THE GULF OF CALIFORNIA AND 
INTO THE RIO GRANDE VALLEY. THIS MOISTURE IS MANIFESTED AS BAND 
OF MID TO UPPER LEVEL CLOUDINESS. 

A WEAK UPPER RIDGE LIES FROM 11N91W TO 00N100W. AN AREA OF SPEED 
CONVERGENCE AT THE SURFACE LIES UNDER THE RIDGE ACCORDING TO THE 
0420 UTC ASCAT PASS. MOISTURE CONVERGED IN THIS AREA IS BEING 
LIFTED BY THE DIFFLUENCE ALOFT...ENHANCING AN AREA OF SCATTERED 
MODERATE CONVECTION FROM 02N TO 05N BETWEEN 92W AND 98W.

GAP WINDS...

GULF OF CALIFORNIA...THE WINDSAT PASS AT 0106 UTC CAPTURED NEAR 
GALE FORCE S-SW WINDS IN THE NORTHERN GULF OF CALIFORNIA AHEAD 
OF THE COLD FRONT. THE FRONT NOW LIES FROM 31N113W TO 29N114W 
ACROSS THE NORTHERN GULF...WITH THE STRONGEST WINDS FOUND N OF 
27N. AS THE COLD FRONT PASSES INTO MAINLAND MEXICO...THE 
TIGHTEST PRES GRADIENT WILL SHIFT INTO THE SOUTHERN GULF. N TO 
NW WINDS ARE EXPECTED TO REACH S OF 28N IN THE GULF AND TO AS 
FAR S AS 19N ALONG THE COAST OF MAINLAND MEXICO BY EARLY WED 
MORNING CONTINUING THROUGH EARLY THU.

GULF OF TEHUANTEPEC...N WINDS WILL CONTINUE TO PULSE TO NEAR 
GALE FORCE IN THE EARLY MORNING HOURS WHEN MOUNTAIN DRAINAGE 
FLOW IS AT A MAXIMUM THROUGH WED MORNING. BY WED EVENING...WINDS 
IN THE WESTERN GULF OF MEXICO WILL TURN MORE SOUTHERLY AHEAD OF 
THE AFOREMENTIONED COLD FRONT MAKING ITS WAY THROUGH NORTHERN 
MEXICO. THIS WILL TURN OFF THE NORTHERLY FLOW THROUGH THE 
CHIVELA PASS. 

GULF OF PAPAGAYO...A STRONG PRES GRADIENT ACROSS THE WESTERN 
CARIBBEAN AND CENTRAL AMERICA IS FORCING STRONG NE FLOW INTO THE 
GULF OF PAPAGAYO THAT IS EXPECTED TO CONTINUE THROUGH THE END OF 
THE PERIOD THU MORNING. IN ADDITION...MID LEVEL ENERGY EXTENDING 
DOWNWIND FROM PAPAGAYO IS ENHANCING NE WINDS AT THE SURFACE AS 
FAR W AS 105W BASED ON OBSERVATIONS FROM SHIP BATFR53 AND THE 
0422 UTC ASCAT PASS. THESE WINDS WILL ALSO CONTINUE WITH LITTLE 
CHANGE THROUGH THE PERIOD.

GULF OF PANAMA...FRESH TO STRONG NORTHERLY WINDS ARE CROSSING 
THE ISTHMUS INTO THE GULF OF PANAMA. THESE STRONG WINDS ARE 
EXPECTED TO CONTINUE THROUGH THU MORNING.

$$
SCHAUER