000
AXPZ20 KNHC 072154
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON JAN 07 2008

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 
2145 UTC.
 
...ITCZ...
INTERTROPICAL CONVERGENCE ZONE...AXIS 5N77W 5N82W 9N87W 9N96W 
5N104W 8N140W. SCATTERED MODERATE OBSERVED WITHIN 60 NM 4N79W 
AND ALSO NOTED WITHIN 60 NM EITHER SIDE OF LINE 7N118W 8N129W.

...DISCUSSION...
AN UPPER LEVEL LONGWAVE TROUGH LIES N TO S ACROSS WESTERN N 
AMERICA ALONG 107W WITH AN ASSOCIATED SHORTWAVE TROUGH EXTENDING 
INTO THE AREA ALONG 32N107W 23N111W THEN SW TO A SMALL UPPER 
CYCLONE AT 12N133W. AN UPPER ANTICYCLONE CENTERED NEAR HAWAII 
HAS A RIDGE AXIS EXTENDING NNE TO BEYOND 32N140W AND APPEARS TO 
BE COLLAPSING SE WITH TIME. UPPER MOISTURE CONTINUES TO SPILL E  
ACROSS THE RIDGE AND OVER THE DISCUSSION AREA GENERALLY N OF 22N 
W OF 130W AND N OF 26N BETWEEN 130W AND 108W. THE MOISTURE IS 
THE HEAVIEST OVER SOUTHERN CALIFORNIA AND THE BAJA PENINSULA AND 
THE GULF OF CALIFORNIA N OF N OF 27N. A BAND OF DRY UPPER AIR 
LIES ALONG THE UPPER TROUGH AXIS WITHIN 150 NM EITHER SIDE OF 
LINE 32N95W TO 25N107W WHERE THE BAND BROADENS 240 NM EITHER 
SIDE OF LINE 20N123W 19N140W.

A TROPICAL UPPER ANTICYCLONE IS QUASI STATIONARY NEAR 11N112W
WITH A RIDGE AXIS EXTENDING W TO A SHARP CREST NEAR 9N127W. 
THIS RIDGE LIES JUST N OF THE ITCZ AND IS ENHANCING CONVECTION 
ALONG ITS AXIS FROM 119W TO NEAR 132W. THE RESULTANT DEBRIS 
MOISTURE IS SPREADING NE IN A NARROW PLUME TO NEAR 20N105W.

A LARGE UPPER ANTICYCLONE IS WELL S OF THE AREA AT 22S69W WITH A 
RIDGE EXTENDING NW ACROSS THE EQUATOR TO A CREST ALONG 1N99W 
16N92W 16N71W. A SMALL UPPER CYCLONE IS NOTED NEAR 5N100W AND 
AND ANOTHER NEAR 4N108W...TOGETHER SEPARATING THIS LARGE UPPER 
RIDGE FROM THE TROPICAL RIDGE OVER THE SW PORTION DESCRIBED 
ABOVE. SOME UPPER MOISTURE HAS BEGUN TO SPREAD NE ALONG THE 
PERIPHERY OF THE RIDGE BETWEEN THE EQUATOR AND 16N FROM 85W TO 
101W. OTHERWISE THE UPPER LEVELS ARE VERY DRY S OF 25N E OF 104W 
AND IS SUPPRESSING CONVECTION ALONG THE ITCZ...EXCEPT FOR A FEW 
CELLS OF MODERATE CONVECTION THAT FLARED NEAR 5N78W. THE DEBRIS 
MOISTURE FROM THIS CONVECTION IS NOW SPREADING NE ALONG 7N77W TO 
11N69W.

AT THE LOW LEVELS...HIGH PRES HAS STALLED NEAR 27N138W 1026 MB 
WITH A RIDGE ESE TO NEAR 25N108W. TO THE S OF THIS RIDGE NE 
WINDS ARE 20 TO 25 KT WITH SEAS 9 TO 15 FT IN MIXED WIND WAVE 
AND NW SWELL. N OF THE RIDGE...A FRONTAL TROUGH HAS SWUNG SE 
INTO THE AREA ALONG 32N114W 27N118W 29N130W. W TO NW 20 TO 25 KT 
WINDS ARE OBSERVED N OF THIS TROUGH WITH SUBSIDING 00NW SWELLS 
RANGING FROM 9 TO 14 FT. THIS HIGH PRES IS EXPECTED BLOCK THE SE 
ADVANCE OF THE NEXT SERIES OF COLD FRONTS...BUT FRESH NW SWELL 
IN THE 12 TO 16 FT RANGE SHOULD ARRIVE NEAR 32N136W IN ABOUT 
48 HOURS.

GULF OF TEHUANTEPEC GAP WINDS HAVE DECREASED TO ABOUT 15 KT. 
UPWELLING FROM THE PAST NORTHERLY WIND HAS CREATED A COLD POCKET 
OF SEA WATER AND DENSE FOG IS NOW NOTED WITHIN 90 NM OF 
12.5N96.5W. STRONG NE TRADES IN THE W CARIBBEAN SEA ARE EXPECTED 
TO SURGE THROUGH THE GULF OF PAPAGAYO GAP THROUGH SUNRISE WED 
THEN DIMINISH TO LESS THAN 20 KT.  

$$
NELSON