000
AXPZ20 KNHC 162115
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON FEB 16 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...
AXIS ALONG 05N77W TO 04N90W TO 02N105W TO 03N125W TO 03N140W.  
SCATTERED MODERATE CONVECTION WITHIN 60 NM S OF AXIS BETWEEN 
90W-92W.

...DISCUSSION...
A NEARLY VERTICALLY-STACKED DEEP LOW CONTINUES APPROACHING THE 
NW CALIFORNIA COAST. THE ATTENDANT LARGE AMPLITUDE DEEP TROUGH 
EXTENDS INTO THE NORTHERN PORTION OF THE DISCUSSION AREA...WITH 
A 100-110 KT UPPER LEVEL JET ROTATING AROUND THE BASE OF THE 
UPPER TROUGH INTO THE SW CONUS. AN ASSOCIATED SURFACE TROUGH 
EXTENDS SOUTHWARD INTO THE DISCUSSION AREA FROM 30N119W TO 
23N128W. W OF THE SURFACE TROUGH...W TO NW WINDS OF 20 TO 25 KT 
ARE OCCURRING BASED ON A QUIKSCAT PASS AROUND 16/1500 UTC...WITH 
LIGHTER SW TO W WINDS E OF THE TROUGH. THE SURFACE TROUGH WILL 
CONTINUE TO LOSE ITS IDENTITY WHILE SLOWLY DRIFTING 
SOUTHEASTWARD DURING THE NEXT SEVERAL HOURS AS IT ENCOUNTERS A 
1021 MB SURFACE HIGH NEAR 24N115W...AND THE UPPER JET DEPARTS 
THE REGION. IN THE MEANTIME...THE UPPER JET CONTINUES TO ADVECT 
COPIOUS AMOUNTS OF TROPICAL MOISTURE INTO THE CENTRAL BAJA 
CALIFORNIA. FARTHER TO THE S...SUBSIDENCE...DEEP LAYER DRY 
AIR...AND STABLE ATMOSPHERIC CONDITIONS ASSOCIATED WITH AN UPPER 
RIDGE S OF 20N BETWEEN 84W-112W ARE RESULTING IN FAIR WEATHER 
ACROSS SOUTHEASTERN PORTIONS OF THE DISCUSSION AREA.

A PROGRESSIVE UPPER PATTERN IS FORECAST TO CONTINUE INTO MIDWEEK 
AS ANOTHER DEEP LOW APPROACHES THE NORTHERN PORTION OF THE 
DISCUSSION AREA ON WEDNESDAY. AN ASSOCIATED COLD FRONT WILL 
ENTER THE NORTHWEST WATERS BY WEDNESDAY...WHICH WILL BE 
ACCOMPANIED BY SW TO W WINDS OF 20 TO 25 KT. THESE CONDITIONS 
WILL MAINLY BE CONFINED TO LOCATIONS N OF 26N W OF 128W...AS THE 
DEEP LOW STALLS NORTH OF THE AREA BY FRIDAY WHILE BECOMING 
DETACHED FROM MUCH OF THE SUBSTANTIAL UPPER LEVEL FLOW. 
HOWEVER...BY LATE THIS WEEKEND...AN UPPER LEVEL JET DIVING 
SOUTHEASTWARD TOWARD THE LOW WILL EJECT IT EASTWARD...WITH A 
REINFORCING AND STRONGER COLD FRONT ENTERING THE NORTHERN WATERS 
N OF 29N BY NEXT MONDAY. MEANWHILE...SURFACE RIDGING S AND E OF 
THE FRONTS WILL MAINTAIN EASTERLY TRADES GENERALLY UNDER 20 KT 
FOR MUCH OF THIS WEEK.

GAP WINDS...
IN THE WAKE OF THE DEEP LOW CURRENTLY APPROACHING THE NW 
CALIFORNIA COAST...STRONG SURFACE HIGH PRESSURE IS FORECAST TO 
BUILD OVER THE GREAT BASIN OF THE CONUS BY MIDWEEK...STEEPENING 
THE SURFACE PRESSURE GRADIENT OVER THE SW CONUS. IN TURN... 
NORTHWESTERLY WINDS ARE FORECAST TO INCREASE IN THE GULF OF 
CALIFORNIA BY LATE WEDNESDAY...WITH STRONG WINDS CONTINUING 
THERE THROUGH FRI. HOWEVER...THE FORECAST PRESSURE GRADIENT DOES 
NOT APPEAR STRONG ENOUGH TO SUPPORT A GALE EVENT IN THE GULF OF 
CALIFORNIA AT THIS TIME. THE ABSENCE OF ANY STRONG FRONTAL 
PASSAGE ALSO PRECLUDES THE GALE THREAT.

ADDITIONALLY...SURFACE RIDGING IN MEXICO IN THE WAKE OF A COLD 
FRONT CURRENTLY IN THE GULF OF MEXICO WILL INDUCE PERIODS OF 
20-KT WINDS IN THE GULF OF TEHUANTEPEC THROUGH MIDWEEK...WITH A 
MORE PROLONGED PERIOD OF STRONGER WINDS THERE LATE THIS WEEK. 
ALSO...TRADE WIND FLOW IN THE CARIBBEAN WILL LIKELY FUNNEL INTO 
THE GULFS OF PAPAGAYO AND PANAMA...MAINTAINING PERIODS OF 20-KT 
WINDS THERE DURING THE NEXT FEW DAYS. 

$$
COHEN