000
AXPZ20 KNHC 250344
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU DEC 25 2008

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0330 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W TO 
05N80W TO 06N189W TO 10N118W TO 06N130W TO 08N140W. SCATTERED 
MODERATE WITHIN 60 NM S OF AXIS BETWEEN 78W AND 80W. 

...DISCUSSION...
W OF 115W...A STRONG SHORT WAVE TROUGH IS DIGGING INTO SOUTHERN 
CALIFORNIA...EAST OF A HIGHLY AMPLIFIED RIDGE NORTH OF HAWAII. A 
SURFACE LOW ASSOCIATED WITH THE UPPER TROUGH IS CENTERED NEAR 
33N123W...MOVING INTO SOUTHERN CALIFORNIA...WITH A TRAILING 
TROUGH TO 25N127W THEN TO 24N135W. SCATTEROMETER AND SHIP 
OBSERVATIONS CONTINUE TO SHOW STRONG WINDS BEHIND THIS 
FRONT...ALTHOUGH WINDS ARE LIKELY DIMINISHING TO BELOW GALE 
STRENGTH. THE STRONG WINDS ARE EMBEDDED IN THE PRESSURE GRADIENT 
BETWEEN THE LOW PRES AND 1036 MB HIGH PRES CENTERED NW OF THE 
AREA. THE UPPER RIDGE N OF HAWAII WILL SHIFT EAST...TO THE NORTH 
OF AN UPPER LEVEL CYCLONE SE OF HAWAII NEAR 17N147W THU FORMING 
A REX BLOCK PATTERN INTO SAT. THE UPPER RIDGE WILL FLATTEN AS 
ANOTHER STRONG SHORT WAVE DIGS FROM THE FAR NE PACIFIC INTO THE 
WEST COAST FRI INTO SAT. THIS WILL ALLOW THE SURFACE HIGH TO 
SHIFT SE BEHIND THE FRONT TO NEAR 35N125W BY SAT...INCREASING 
TRADE WIND FLOW ON THE ITS SOUTHERN EDGE AS WELL AS ALONG THE 
NORTHERN BAJA COAST. LONG PERIOD NORTHERLY SWELL TO 18 FT WILL 
FOLLOW THE FRONT AS WELL.

GULF OF CALIFORNIA...SW WINDS WILL INCREASE TO 20 KT OVER THE 
NORTHERN GULF WATERS TOMORROW AHEAD OF THE SURFACE LOW/FRONT 
PUSHING INTO SOUTHERN CALIFORNIA AND DIMINISH FRI AS THEY VEER 
WEST AS THE LOW LIFTS OUT. LOOKING AHEAD...NORTHERLY WINDS MAY 
INCREASE FRI NIGHT INTO SAT AS A SURFACE HIGH PRES AREA FORMS 
OVER THE GREAT BASIN THIS WEEKEND...IN RESPONSE TO A SHORT WAVE 
RIDGE BUILDING BEHIND THE SECOND SHORT WAVE TROUGH EXPECTED TO 
DIG INTO THE AREA LATE THU INTO FRI. GLOBAL MODELS SUGGEST 
SURFACE PRES OVER THE GREAT BASIN COULD REACH 1035 MB BY SAT...A 
POSSIBLE TRIGGER FOR NEAR GALE WINDS FUNNELING INTO THE NORTHERN 
GULF OF CALIFORNIA. 

E OF 110W...A QUIKSCAT PASS FROM EARLIER THIS MORNING SHOWED 
FRESH GAP WINDS PERSISTING THROUGH THE GULF OF PAPAGAYO...THE 
RESULT OF STRONG TRADE WIND FLOW OVER CARIBBEAN. FURTHER 
NORTH...THERE ARE SOME INDICATION THAT WEAK RIDGING OVER THE 
GULF OF MEXICO MAY INDUCE WINDS TO 20 KT IN THE GULF OF 
TEHUANTEPEC BY EARLY TOMORROW MORNING. CONFIDENCE ON THIS LOW 
HOWEVER CONSIDERING THE SOUTHERLY RETURN FLOW IN THE SW GULF OF 
MEXICO. OTHERWISE...MODEST CONVECTION ALONG THE ITCZ AT THE BASE 
OF AN UPPER TROUGH HAS DISSIPATED WITH GENERALLY DRY AIR 
PREVAILING IN THE MID AND UPPER REACHES OF THE ATMOSPHERE.

$$
CHRISTENSEN