000
AXPZ20 KNHC 070356
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON JAN 07 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 5N92W 3N98W 8N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 
NM EITHER SIDE OF LINE 5N114W 8N125W AND ALSO NOTED WITHIN 45 NM 
EITHER SIDE LINE 8N130W 8N140W.

...DISCUSSION...
AN UPPER LEVEL LONGWAVE TROUGH LIES ALONG THE WESTERN SEABOARD 
OF N AMERICA WITH AN ASSOCIATED SHORTWAVE TROUGH EXTENDING INTO 
THE AREA ALONG 32N112W 22N119W THEN SW TO A SMALL UPPER CYCLONE 
AT 13N138W. AN UPPER ANTICYCLONE CENTERED NEAR HAWAII HAS A 
RIDGE AXIS EXTENDING NNE TO BEYOND 32N145W 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 24N 
W OF 130W AND N OF 27N BETWEEN 130W AND 108W. ALTHOUGH THIS 
MOISTURE APPEARS TO BE EVAPORATING OVER THE AREA N OF 25N A GOOD 
DEAL OF THE MOISTURE IS ADVECTED E OVER HE WESTERN CONUS. A BAND 
OF DRY UPPER AIR LIES ALONG THE UPPER TROUGH AXIS WITHIN 210 NM 
EITHER SIDE OF LINE 32N97W TO 24N113W WHERE THE BAND BROADENS TO 
COVER THE AREA FROM 15N TO 25N W OF 120W.

A TROPICAL UPPER ANTICYCLONE IS QUASI STATIONARY NEAR 9N108W
WITH A RIDGE AXIS EXTENDING W TO A SHARP CREST NEAR 10N130W. 
THIS RIDGE LIES JUST N OF THE ITCZ AND IS ENHANCING CONVECTION 
ALONG ITS AXIS FROM 117W TO BEYOND 140W. THE RESULTANT DEBRIS 
MOISTURE IS SPREADING NE TO ALONG 19N BETWEEN 125W AND 112W.

A LARGE UPPER ANTICYCLONE IS WELL S OF THE AREA AT 25S70W WITH A 
RIDGE EXTENDING NW ACROSS THE EQUATOR TO A CREST ALONG 6N85W 
17N76W 16N60W. A SMALL UPPER CYCLONE IS NOTED NEAR 5N97W AND 
SEPARATES THIS LARGE UPPER RIDGE FROM A TROPICAL RIDGE DESCRIBED 
ABOVE. GENERALLY THE UPPER LEVELS ARE VERY DRY S OF 25N E OF 
105W AND IS SUPPRESSING CONVECTION ALONG THE ITCZ...EXCEPT FOR A 
FEW CELLS OF MODERATE CONVECTION FLARING NEAR 5N85W. THE DEBRIS 
MOISTURE FROM THIS CONVECTION IS NOW SPREADING NE ACROSS COSTA 
RICA.

AT THE LOW LEVELS...HIGH PRES 27N143W 1025 MB RIDGES ESE TO NEAR 
13N100W. TO THE S OF THIS RIDGE NE WINDS ARE ABOUT 20 KT WITH 
SEAS 9 TO 15 FT IN NW SWELL. N OF THE RIDGE W WINDS TO 20 KT AND 
NW SWELLS RANGING FROM 10-17 FT CONTINUE TO PROPAGATE S OVER THE 
WATERS N OF THE RIDGE TO THE BAJA PENINSULA N OF 23N. THIS HIGH 
PRES IS EXPECTED BLOCK THE SE PUSH OF THE NEXT SERIES OF COLD 
FRONTS BUT A FRESH NW SWELL IN 12-18 FT RANGE SHOULD ARRIVE NEAR 
32N140W IN ABOUT 48 HOURS.

GULF OF TEHUANTEPEC GAP WINDS EXPECTED TO SURGE ONE LAST TIME 
AFTER SUNRISE MON TO 20 KT THEN DIMINISH. STRONG NE TRADES IN 
THE W CARIBBEAN SEAS ARE EXPECTED TO SURGE THROUGH THE GULF OF 
PAPAGAYO GAP THROUGH 42 HOURS THEN DIMINISH TO LESS THAN 20 KT.  

$$
NELSON