000
AXPZ20 KNHC 250921
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT FEB 25 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 
0630 UTC.

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

THE ITCZ AXIS EXTENDS FROM 03N112W TO 04N125W TO 03N140W. 
SCATTERED MODERATE CONVECTION WAS ON THE EASTERN EDGE OF THE 
ITCZ FROM 00N TO 03N BETWEEN 106W AND 113W.

...DISCUSSION...

THE SUBTROPICAL HIGH HAS SHIFTED WELL N OF THE AREA TO 42N142W. 
THIS 1040 MB HIGH LIES N OF A COLD FRONT DISSIPATING OVER THE 
WATERS OFFSHORE OF CENTRAL CALIFORNIA. A RIDGE EXTENDS S OF THE 
HIGH TO 30N142W AND THEN SOUTHEASTWARD TO 23N120W. THE 
SOUTHEASTERN SIDE OF THE SUBTROPICAL RIDGE IS BEING ERODED BY 
THE SURFACE REFLECTION OF A MID LEVEL LOW NEAR 25N123W. THIS LOW 
IS EVIDENT ON WATER VAPOR IMAGERY AND IS REFLECTING A SURFACE 
TROUGH ALONG 123W N OF 25N. THE PRES GRADIENT BETWEEN THE 
SUBTROPICAL RIDGE AND THIS TROUGHING IS RESPONSIBLE FOR AN AREA 
OF FRESH TO STRONG N TO NE WINDS OVER THE NORTHERN WATERS SEEN 
IN THE 0530 UTC ASCAT PASS. WINDS ARE EXPECTED TO BE STRONGEST 
TODAY WHEN THE PRES GRADIENT IS TIGHTEST BETWEEN THE SURFACE LOW 
AND THE SUBTROPICAL HIGH. THE LOW ALOFT WILL BE OVERTAKEN BY THE 
NEXT DEEP LAYER TROUGH TO MOVE INTO NE WATERS OVERNIGHT SAT 
NIGHT. THIS TROUGH WILL QUICKLY BE RELOADED WITH ANOTHER SYSTEM 
DROPPING S ALONG THE CALIFORNIA COAST BY EARLY MON. THIS PATTERN 
ALOFT WILL KEEP THE SUBTROPICAL RIDGE WEAK OVER THE EASTERN HALF 
OF THE AREA...ALLOWING THE STRONGEST PRES GRADIENT TO REMAIN 
PRIMARILY OVER NW WATERS. 

GAP WINDS...

GULF OF TEHUANTEPEC...AN UPPER LOW MOVING EASTWARD ACROSS 
NORTHERN MEXICO WILL WEAKEN AS IT TURNS NORTHEASTWARD INTO TEXAS 
TODAY. THE SURFACE REFLECTION OF THIS LOW WILL DEVELOP IN THE SW 
GULF OF MEXICO TODAY AS HIGH PRES MOVES INTO SOUTHERN TEXAS AND 
NE MEXICO. THE BUILDING PRES GRADIENT OVER THE SW GULF OF MEXICO 
AND THE CHIVELA PASS WILL SEND NORTHERLY WINDS INTO THE GULF OF 
TEHUANTEPEC THIS MORNING...WITH WINDS INCREASING TO GALE FORCE 
THIS AFTERNOON AND PEAKING AT 40 KT BEFORE DIMINISHING BELOW 
GALE FORCE SUN AFTERNOON AS HIGH PRES OVER NE MEXICO WEAKENS.

GULF OF PAPAGAYO...THE AFOREMENTIONED HIGH PRES OVER SOUTHERN 
TEXAS AND NE MEXICO TODAY WILL SHIFT NORTHEASTWARD THOUGH THE 
TENNESSEE VALLEY BY SUN MORNING AND OFF THE U.S. MID ATLC COAST 
BY MON MORNING. THE INCREASED PRES GRADIENT BETWEEN THIS HIGH 
PRES SYSTEM AND TROUGHING OVER NW SOUTH AMERICA WILL ALLOW 
SUSTAINED FRESH TO STRONG NE WINDS TO PASS THROUGH THE GULF OF 
PAPAGAYO BEGINNING OVERNIGHT TONIGHT AND CONTINUING THROUGH THE 
END OF THE PERIOD EARLY MON MORNING.

GULF OF CALIFORNIA...FRESH SW WINDS ARE EXPECTED EARLY MON 
MORNING IN THE NORTHERN GULF OF CALIFORNIA AHEAD OF A COLD FRONT 
ASSOCIATED WITH THE SYSTEM DROPPING S ALONG THE CALIFORNIA COAST 
EARLY MON. 

$$
SCHAUER