000
AXPZ20 KNHC 210335
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED NOV 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

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

THE MONSOON TROUGH IS ALONG 08N83W TO 05N95W TO 05N100W. THE 
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N100W TO 
08N118W TO 07N125W TO 08N130W TO 06N140W. SCATTERED MODERATE 
CONVECTION IS NOTED WITHIN 150 NM S OF AXIS BETWEEN 83W AND 85W. 
SCATTERED MODERATE CONVECTION IS NOTED WITHIN 180 NM N OF THE 
ITCZ BETWEEN 120W AND 125W.

...DISCUSSION...

A PAIR OF MID/UPPER LEVEL SHORT WAVE TROUGH ARE THE MAIN WEATHER 
INFLUENCES N OF 20N. OFF CENTRAL BAJA...A WELL DEFINED MID/UPPER 
LEVEL CYCLONE CENTERED NEAR 25N115W IS MIGRATING EASTWARD TOWARD 
CENTRAL BAJA. UPPER LIFT AHEAD OF THE CYCLONE CONTINUES TO 
ENHANCE THICK DECKS OF CLOUDINESS OVER THE GULF OF CALIFORNIA 
AND SOUTHERN BAJA...AND SHARPENING RESIDENT TROUGHING OVER NW 
MEXICO. AT THE SURFACE...THE PRES GRADIENT BETWEEN THE TROUGH 
AND 1022 MB SURFACE HIGH PRES CENTERED NEAR 28N127W IS ALLOWING 
FRESH TO STRONG NW WINDS DOWN THE LENGTH OF THE SOUTHERN GULF OF 
CALIFORNIA...AS EVIDENCED BY SHIP OBSERVATIONS AND A 1650 UTC 
ASCAT PASS. SHIP AND ASCAT DATA ALSO INDICATED MODERATE TO FRESH 
NW WINDS ON THE PACIFIC COAST OF THE BAJA PENINSULA...ON THE 
WESTERN EDGE OF THE SURFACE HIGH PRES. 

FARTHER WEST...THE SECOND MID/UPPER LEVEL SHORT WAVE TROUGH 
EXTENDS FROM 30N128W TO 24N140W...WITH A WEAK SURFACE 
FRONT/TROUGH IN TOW. THROUGH 48 HOURS...THE SHORT WAVE TROUGH 
OFF BAJA WILL LIFT NE THROUGH ARIZONA...WITH THE SECOND SHORT 
WAVE TROUGH REACHING AS FAR EAST AS 120W...RESULTING IN THE 1024 
MB SURFACE HIGH PRES NEAR 29N127W DISSIPATING IN THE NEXT 24 TO 
48 HOURS...AND NW FLOW TO DIMINISH OFF BAJA AND THE GULF OF 
CALIFORNIA.

DEEP LAYER RIDGING FOLLOWING THE WESTERN MOST SHORT WAVE TROUGH 
WILL BUILD N OF 30N...AHEAD OF A ANOTHER MORE VIGOROUS LONG WAVE 
TROUGH OVER THE N CENTRAL PACIFIC MOVING INTO THE NE PACIFIC. 
THE REINFORCED SURFACE HIGH PRES WILL ALLOW FRESH TO 
OCCASIONALLY STRONG TRADES IN A BROAD AREA FROM ROUGHLY 12N TO 
22N W OF 120W. COMBINED SEAS OF UP TO 9 FT IN A MIX OF FRESH NW 
AND LONGER PERIOD NW SWELL PERSIST IN THE AREA OF FRESH TO 
STRONG TRADES. ANOTHER ROUND OF NW SWELL IS STARTING TO MOVE 
INTO THE AREA FROM THE N CENTRAL PACIFIC...AND WILL MIX WITH THE 
SUBSIDING SEAS IN THE AREA OF TRADES OVER THE NEXT 48 HOURS.

N WINDS TO 30 KT WERE REPORTED EARLIER THIS MORNING SALINA CRUZ 
NEAR THE PACIFIC TERMINUS OF THE TEHUANTEPEC 
ISTHMUS...SUPPORTING THE CASE FOR GALE CONDITIONS OVER THE GULF 
OF TEHUANTEPEC. THE PRES GRADIENT BETWEEN THE NORTHERN AND 
SOUTHERN ENDS OF THE ISTHMUS IS AROUND 5 MB...ENOUGH TO SUPPORT 
GALE CONDITIONS A LITTLE LONGER...ESPECIALLY DURING THE LATE 
NIGHT AND EARLY MORNING HOURS WHEN DRAINAGE IMPACTS CONTRIBUTE 
TO THE AGGREGATE GAP FLOW. LOOKING AHEAD...WINDS MAY DIMINISH 
BELOW GALE BY THU INTO FRI AS HIGH PRES OVER THE GULF OF MEXICO 
WEAKENS AHEAD OF THE NEXT COLD FRONT. GALES ARE LIKELY AGAIN 
THIS WEEKEND HOWEVER AFTER THE COLD FRONT MOVES INTO THE SW GULF 
OF MEXICO. 

PULSING OF NOCTURNAL WINDS ARE ALSO EXPECTED TO CONTINUE ACROSS 
THE GULF OF PAPAGAYO...WITH WINDS TO 25 KT AND SEAS OF 8-9 FT 
THROUGH LATER THIS AFTERNOON...THEN WILL DIMINISH TO 20 KT OR 
LESS WITH ANOTHER SURGE FORECAST BY THU MORNING.

$$
CHRISTENSEN