000
AXPZ20 KNHC 080353
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE JAN 08 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 
0345 UTC.
 
...ITCZ...
INTERTROPICAL CONVERGENCE ZONE...AXIS 5N77W 5N82W 9N87W 9N96W 
5N104W 8N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
NOTED WITHIN 120 NM 9N124.5W.

...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 23N110W THEN SW THROUGH AN UPPER 
CYCLONE AT 21N127W THEN THE TROUGH CONTINUING S TO A BASE NEAR 
10N128W. AN UPPER ANTICYCLONE CENTERED W OF AREA NEAR 22N151W  
HAS A RIDGE AXIS EXTENDING NE TO BEYOND 32N138W AND IS 
COLLAPSING SE WITH TIME. UPPER MOISTURE CONTINUES TO SPILL E  
ACROSS THE RIDGE AND OVER THE DISCUSSION AREA GENERALLY N OF 21N 
W OF 130W AND N OF 26N BETWEEN 128W AND 104W. THE MOISTURE IS 
THE HEAVIEST JUST N OF AREA OVER SW CONUS. A BAND OF DRY UPPER 
AIR LIES ALONG THE UPPER TROUGH AXIS WITHIN 150 NM EITHER SIDE 
OF LINE 32N95W TO 24N110W WHERE THE BAND BROADENS TO ABOUT 240 
NM EITHER SIDE OF LINE 22N120W 16N140W.

A TROPICAL UPPER ANTICYCLONE IS QUASI STATIONARY NEAR 12N112W
WITH A RIDGE AXIS EXTENDING W TO A SHARP CREST NEAR 10N124W. 
THIS RIDGE LIES JUST N OF THE ITCZ AND IS ENHANCING CONVECTION 
ALONG ITS AXIS FROM 122W TO 128W. THE RESULTANT DEBRIS 
MOISTURE IS SPREADING NE IN A NARROW PLUME TO NEAR 22N100W.

A LARGE UPPER ANTICYCLONE IS WELL S OF THE AREA AT 22S69W WITH A 
RIDGE EXTENDING NW ACROSS THE EQUATOR TO A CREST ALONG 1N98W 
14N98W 17N79W. A SMALL UPPER CYCLONE IS NOTED NEAR 8N100W AND 
AND ANOTHER NEAR 4N106W...EFFECTIVELY SEPARATING THIS LARGE 
UPPER RIDGE FROM THE TROPICAL RIDGE OVER THE SW PORTION 
DESCRIBED ABOVE. SOME UPPER MOISTURE IS SPREADING NE ALONG THE 
PERIPHERY OF THE RIDGE BETWEEN THE EQUATOR AND 17N FROM 85W TO 
100W. OTHERWISE THE UPPER LEVELS ARE VERY DRY S OF 20N E OF 105W 
AND IS SUPPRESSING CONVECTION ALONG THE ITCZ...EXCEPT FOR A FEW 
CELLS OF MODERATE CONVECTION THAT FLARED E OF 96W. THE DEBRIS 
MOISTURE FROM THIS CONVECTION IS NOW SPREADING NE ACROSS CENTRAL 
IN THE ANTICYCLONIC FLOW.

AT THE LOW LEVELS...HIGH PRES HAS STALLED NEAR 27N138W 1023 MB 
WITH A RIDGE ESE TO NEAR 14N100W. TO THE S OF THIS RIDGE NE 
WINDS ARE 20 TO 25 KT WITH SEAS 9 TO 14 FT IN MIXED WIND WAVE 
AND NW SWELL. N OF THE RIDGE...A FRONTAL TROUGH IS LOSING 
IDENTITY ALONG 32N114W 24N119W. W TO NW 20 TO 25 KT WINDS ARE 
OBSERVED N OF THIS TROUGH WITH SUBSIDING NW SWELLS RANGING FROM 
12 TO 14 FT. THIS HIGH PRES IS EXPECTED TO 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