000
AXPZ20 KNHC 312125
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU JAN 31 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 
2100 UTC.
 
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 2N78W 5N86W 4N110W 9N140W. NO 
SIGNIFICANT CONVECTION.

...DISCUSSION...
A DEEP LONGWAVE TROUGH OVER THE CENTRAL UNITED STATES REACHES S OVER 
NORTHERN MEXICO. CONFLUENCE INTO THE BASE OF THE TROUGH IS PRODUCING 
SUBSIDENCE AND CLEAR SKIES.  A CUT-OFF UPPER TROUGH EXTENDING S FROM 
TEHUANTEPEC 9N98W IS COLLOCATED WITH A MID-LEVEL RIDGE ALONG 17N. AS 
A RESULT...LARGE SCALE SUBSIDENCE ALREADY PRESENT IS STRONGEST E OF 
THE TROUGH AXIS. QUIKSCAT SHOWS SURFACE WINDS ARE GENERALLY LIGHT... 
ALTHOUGH WINDS CONTINUE TO PULSE TO 20 KT IN THE GULF OF PAPAGAYO.

A GALE WARNING IS IN EFFECT FOR THE GULF OF TEHUANTEPEC FOR WINDS 
INCREASING TO 30-40 KT FRI AFTERNOON. A COLD FRONT MOVING OFF THE 
TEXAS COAST WILL REACH SOUTHERN MEXICO FRI AND WILL PROVIDE A QUICK 
SURGE OF N WINDS OVER TEHUANTEPEC. GALE CONDITIONS ARE EXPECTED TO 
LAST FOR ONLY 18 HRS OR SO. CONFIDENCE IS HIGH THAT THE EVENT WILL 
OCCUR BUT TIMING/STRENGTH IS A LITTLE UNCERTAIN. OUR FORECAST TAKES 
A BLEND OF THE MIXED-LAYER WINDS FROM THE GFS AND NAM MODELS.

UPPER LEVEL SPLIT FLOW IS ENTRENCHED OVER THE WESTERN PART OF THE 
AREA...WITH RIDGING N OF 17N ALONG 130W...AND A WEAK UPPER TROUGH S 
OF 17N. BROAD UPPER DIFFLUENCE IN THE REGION W OF THE RIDGE AXIS IS 
PRODUCING WIDESPREAD CIRRUS N OF 10N. SOME EMBEDDED MODERATE SHOWERS 
ARE POSSIBLE NEAR THE ITCZ...BUT DEEP CONVECTION IS NOT OBSERVED. A 
SURFACE TROUGH ALONG 140W S OF 18N IS GENERATING SCATTERED SHOWERS.

$$
MUNDELL