000
AXPZ20 KNHC 040926
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU JAN 4 2007

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 
0900 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N77W 5N85W 8N120W 4N140W. ISOLATED 
SHOWERS/TSTMS WITHIN 90 NM OF THE AXIS E OF 96W. SCATTERED 
MODERATE CONVECTION WITHIN 90 NM OF THE AXIS BETWEEN 
105W-109W...AND 118W-126W. SCATTERED MODERATE WITHIN 60 NM OF 
THE AXIS W OF 132W.

...DISCUSSION....

STRONG SURFACE HIGH PRES LOCATED ABOUT 1000 NM NNE OF THE 
HAWAIIAN ISLANDS CONTINUES TO SHIFT E TOWARDS THE CALIFORNIA 
COAST AND IS PUSHING A COLD FRONT TO THE NW CORNER OF THE 
DISCUSSION AREA. A MID/UPPER LEVEL HIGH AND RIDGE SYSTEM LIES 
OVER THE AREA SE OF THE APPROACHING FRONT AND HAS LED TO MAINLY 
CLEAR SKIES WITH MODERATE EASTERLY TRADES. AS THE SURFACE HIGH 
SLIDES E...THE PRES GRADIENT WILL TIGHTEN FROM THE CALIFORNIA 
COAST SWWD THROUGH THE DISCUSSION AREA WITH GALE CONDITIONS 
EXPECTED TO DEVELOP IN THE NORTHERN TRADES BY THU NIGHT...MAINLY 
N OF 25N THEN SHIFTING S. AFTER THE FRONT MOVES INLAND ACROSS 
THE DESERT SW...HIGH PRES OVER THE GREAT BASIN COUPLED WITH 
LOWER PRES ALONG THE PACIFIC COAST OF MEXICO WILL ALSO GENERATE 
GALE CONDITIONS OVER THE GULF OF CALIFORNIA BY FRI NIGHT.

IN THE MEANTIME...A MID/UPPER LEVEL CUT-OFF LOW IS CENTERED NEAR 
CHIHUAHUA MEXICO AND IS FINALLY BEGINNING TO LIFT ENE INTO TEXAS 
WITH A DANGLING TROUGH AXIS EXTENDING ACROSS SRN BAJA TO 
14N130W. STRONG UPPER LEVEL CONFLUENCE NEAR THE TROUGH AXIS IS 
PRODUCING STRONG SUBSIDENCE FROM 10N-20N W OF 120W WHILE AT THE 
SAME TIME THE SUBTROPICAL JET IS ADVECTING LARGE AMOUNTS OF 
PACIFIC MOISTURE INTO S/CENTRAL MEXICO...S OF LINE FROM 10N127W 
TO MAZATLAN MEXICO THEN DEL RIO TEXAS. TEMPERATURES OVER THE 
MEXICAN PLATEAU HAVE COOLED INTO THE 30S F WITH THE COLD LOW 
OVERHEAD...WHILE MORE MILDER 50S/60S ARE IN CONTROL OVER 
S/CENTRAL MEXICO.

AN UPPER LEVEL HIGH HAS DEVELOPED NEAR EL SALVADOR AHEAD OF THE 
CUT-OFF LOW/TROUGH WITH MODERATE/STRONG SUBSIDENCE STILL IN 
CONTROL E OF 98W ACROSS CENTRAL AMERICA. CONSEQUENTLY...SKIES 
ARE VIRTUALLY CLOUD-FREE N OF THE ITCZ. THERE IS A LITTLE MORE 
CONVECTION ALONG THE ITCZ THAN THERE HAS BEEN OVER THE PAST FEW 
NIGHTS POSSIBLY DUE TO STRONGER LOW-LEVEL CONVERGENCE. THE GAP 
WINDS HAVE CONTINUED TO DIMINISH IN INTENSITY...AND SHOULD FALL 
BELOW 20 KT OVER THE GULF OF TEHAUNTEPEC BY THIS AFTERNOON. 
STRONGER WINDS WILL CONTINUE OVER THE GULF OF PAPAGAYO DUE TO 
THE ENHANCED GRADIENT OVER THE CARIBBEAN.

$$
BERG