000
AXPZ20 KNHC 200919
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN JAN 20 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.
 
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N77W 4N82W 4N97W 11N132W 9N140W. 
WIDELY SCATTERED SHOWERS/ISOLATED TSTMS FROM 9N-14N W OF 120W.

...DISCUSSION...

N OF 20N...
THE MID-LATITUDE FLOW OVER NORTH AMERICA HAS FLATTENED OUT A BIT 
COMPARED TO THE PAST SEVERAL DAYS AS THE MEAN TROUGH AXIS SHIFTS 
TO THE EASTERN SEABOARD...A RIDGE BUILDS ALONG THE ROCKIES...AND 
A NEW CLOSED LOW SPINS OVER THE PACIFIC NORTHWEST. A SHORTWAVE 
TROUGH HAS BECOME CUT-OFF FROM THE MAIN FLOW AND LIES 
PREDOMINANTLY JUST N OF THE REGION FROM SOUTHERN CALIFORNIA SW 
TO 28N136W. THIS HAS LEFT ZONAL WESTERLY FLOW ACROSS THE ENTIRE 
SUBTROPICAL REGIME WITH A 90 KT JET EXTENDING FROM 22N120W EWD 
TO W/CENTRAL MEXICO. THE SUBTROPICAL RIDGE LIES ACROSS THE AREA 
FROM 30N131W TO 20N111W BUT IS NOT TOO STRONG DUE TO SURFACE 
TROUGHING OFF THE COAST OF SOUTHERN CALIFORNIA. THE UPPER 
PATTERN WILL BECOME MORE TROUGH-LIKE OVER THE AREA WITHIN THE 
NEXT 2-4 DAYS AS THE CLOSED LOW OVER THE PACIFIC NORTHWEST DROPS 
SW AND BECOMES NEARLY STATIONARY OFF THE CALIFORNIA COAST.

S OF 20N...
WESTERLY UPPER LEVEL FLOW CONTINUES ACROSS THE TROPICAL EAST 
PACIFIC WITH A 50-70 KT WIND MAXIMUM STRETCHING ROUGHLY ALONG 
6N. AN UPPER TROUGH W OF THE AREA ALONG 148W IS PRODUCING A 
THICK DECK OF MID/UPPER LEVEL CLOUDINESS...AND A GOOD PORTION OF 
THIS MOISTURE IS BEING ADVECTED EWD TOWARDS MEXICO IN A BAND 
BETWEEN 7N-20N W OF 100W. FARTHER E...A MID-LEVEL RIDGE AXIS 
EXTENDS FROM NICARAGUA SW PAST THE EQUATOR AT 110W AND IS 
PRODUCING WIDESPREAD SUBSIDENCE E OF 105W. AT THE SURFACE...A 
TROUGH IS LOCATED ALONG 132W S OF 14N AND IS INCREASING THE PRES 
GRADIENT WITHIN THE TRADE WIND REGIME. A WEAK LOW MAY FORM ALONG 
THE TROUGH AS DIFFLUENCE INCREASES IN THE UPPER LEVELS BUT THE 
GLOBAL MODELS ARE NOT EXCEPTIONALLY EAGER WITH THIS SCENARIO.

WARNING CONDITIONS BEGAN OVER THE GULF OF TEHUANTEPEC EARLIER 
THIS EVENING AND WINDS ARE NOW TO STORM FORCE BASED ON A 0030 
UTC QUIKSCAT PASS. THE LEADING ARC CLOUD ASSOCIATED WITH THE 
WIND SURGE IS VISIBLE IN SATELLITE IMAGERY AND NOW EXTENDS UP TO 
350 NM SW OF THE COAST OF TEHUANTEPEC...CONTINUING TO SPREAD S 
AND W. DANGEROUS SEA CONDITIONS WILL CONTINUE TO DEVELOP WITH 
MAXIMUM WAVE HEIGHTS POTENTIALLY REACHING 21 FT. WINDS WILL DROP 
TO JUST BELOW STORM FORCE WITHIN THE NEXT 18-24 HOURS AND THEN 
SHOULD DIMINISH BELOW GALE FORCE BY 42 HOURS (MON EVENING).

$$
BERG