000
AXPZ20 KNHC 252149
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE JAN 25 2011

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...

THE ITCZ AXIS FLUCTUATES BETWEEN 04N AND 05N FROM THE COAST OF 
COLOMBIA TO BEYOND 140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS NOTED FROM 01N TO 07N TO THE E OF 80W CURRENTLY 
DECREASING IN INTENSITY...AND ALSO WITHIN 30 NM EITHER SIDE OF A 
LINE FROM 07N89W TO 06N94W. SCATTERED MODERATE CONVECTION IS 
NOTED FROM 07N TO 08N BETWEEN 126W AND 140W.

...DISCUSSION...

AN UPPER TROUGH EXTENDS ACROSS THE NORTHERN PORTION OF THE 
DISCUSSION AREA FROM 32N96W TO 25N110W THEN CONTINUING W TO 
25N120W AND INTO AN UPPER CYCLONE AT 23N127W...WITH THE TROUGH 
EXTENDING W BEYOND 22N140W. DRY UPPER AIR IS INDICATED WITHIN 
150 NM OF THIS UPPER TROUGH AXIS AND ALSO AROUND THE UPPER 
CYCLONE. A BAND OF UPPER MOISTURE IS SPREADING SE OVER THE 
DISCUSSION AREA N OF 28N E OF 120W AND AS FAR E AS W TEXAS...BUT 
DRIER AIR IS ALSO NOTED ALONG 35N AND WILL QUICKLY REPLACE THIS 
MOIST AIR. 

FURTHER S...A BROAD UPPER RIDGE DOMINATES THE TROPICS BETWEEN 
140W AND 110W. A MOISTURE PLUME EXTENDS NE ACROSS THE EQUATOR 
BETWEEN 130W AND 150W AND MERGES WITH DEBRIS MOISTURE FROM THE 
SCATTERED MODERATE ITCZ CONVECTION NEAR 130W...RESULTING IN A 
MOIST UPPER LEVEL UNDER THE RIDGE. A BROAD TROUGH IS NOTED OVER 
THE SUBTROPICS BETWEEN 110W AND 95W WITH THE WESTERN EXTENSION 
OF AN UPPER RIDGE EXTENDING OVER THE DEEP TROPICS E OF 95W. 
UPPER DIFFLUENCE IS ENHANCING THE CONVECTION PREVIOUSLY 
DESCRIBED ALONG THE LINE 07N89W TO 06N94W...BUT THE DEBRIS 
MOISTURE QUICKLY EVAPORATES IN THIS AREA.   

AT THE LOW LEVELS A RIDGE EXTENDS ALONG 32N132W TO 12N94W. A 
SMALL AREA OF 15-20 KT NE TRADES IS OBSERVED FROM 08N TO 13N W 
OF 130W WHILE THE ENTIRE PACIFIC WATERS FROM 32N TO THE EQUATOR 
BETWEEN 100W AND 140W IS EXPERIENCING 8-10 FT SEAS IN NW SWELL 
MIXING WITH AND SOME NE WIND WAVE AROUND THE RIDGE. THE PARENT 
SURFACE HIGH PRESSURE WILL SHIFT SE INTO THE AREA NEAR 28N135W 
EARLY THU. THE HIGH WILL THEN WEAKEN AS SOUTHERLY SURFACE WINDS 
INCREASE IN ADVANCE OF A COLD FRONT REACHING NEAR 32N138W TO 
28N142W BUT QUICKLY STALLING.   

THE SURFACE PRESSURE GRADIENT IS FORECAST TO TIGHTEN OVER THE 
GULF OF CALIFORNIA IN 24 HOURS SUPPORTING AN INCREASE IN NW 
WINDS TO 20-25 KT OVER THE NORTHERN GULF WATERS...PERSISTING 
THROUGH EARLY FRI.

GAP WINDS...THE PASSAGE OF A COLD FRONT IN THE BAY OF CAMPECHE 
WILL RESULT IN NORTHERLY WINDS FUNNELING THROUGH THE CHIVELA 
PASS INTO THE GULF OF TEHUANTEPEC INCREASING TO 20-30 KT BY 
SUNRISE WED. THESE NORTHERLY WINDS WILL CONTINUE INTO THE 
WEEKEND. 

$$
NELSON