000
AXPZ20 KNHC 201552
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN FEB 20 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE IS ANALYZED FROM 04N77W TO 
THE EQUATOR AT 95W...CONTINUING S OF THE EQUATOR TO 04S105W... 
THEN TURNING NW AND CROSSING THE EQUATOR AGAIN AT 117W...THEN NW 
TO 05N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
NOTED WITHIN 120 NM EITHER SIDE OF A LINE FROM 04N87W TO 02S96W. 
SCATTERED MODERATE CONVECTION IS OBSERVED FROM 02N TO 07N 
BETWEEN 120W AND 126W. ISOLATED MODERATE AND STRONG CONVECTION 
IS DEVELOPING ALONG THE COAST OF COLOMBIA NEAR 02.5N79W.

...DISCUSSION...
A LONGWAVE TROUGH DOMINATES WESTERN N AMERICA AND THE NE PACIFIC 
WITH ITS MEAN AXIS OVER THE DISCUSSION AREA FROM 32N121W TO 
20N132W AND SSE INTO A SMALL UPPER CYCLONE OVER THE DEEP 
TROPICAL PACIFIC AT 05N128W. UPPER DIFFLUENCE E OF THE TROPICAL 
CYCLONE IS ENHANCING MODERATE CONVECTION IN THE AREA FROM 02N TO 
07N BETWEEN 120W AND 126W. DEBRIS MOISTURE FROM THIS ACTIVITY IS 
ADVECTED NE...BUT EVENTUALLY EVAPORATES NEAR 17N115W. FURTHER N 
A NARROW TROPICAL MOISTURE PLUME EXTENDS FROM 18N129W TO 25N122W 
WHERE IT MERGES WITH A WELL DEFINED SUBTROPICAL PLUME DIVING SE 
THROUGH THE LONGWAVE TROUGH. THESE TWO BANDS OF UPPER MOISTURE 
CONCENTRATE INTO A SINGLE BAND ROUGHLY WITHIN 210 NM EITHER SIDE 
OF LINE FROM 27N122W TO BEYOND 32N110W...AND ACROSS THE S 
CENTRAL CONUS. OTHERWISE THE UPPER LEVELS APPEAR VERY DRY W OF 
120W. 

THE EASTERN PORTION OF THE DISCUSSION AREA IS DOMINATED BY AN 
UPPER RIDGE EXTENDING NW FROM COLOMBIA THROUGH AN UPPER 
ANTICYCLONE NEAR 12N110W...WITH A GENTLE RIDGE CREST FROM 
20N125W TO BEYOND 35N105W. CONVECTION ALONG THE ITCZ IS ENHANCED 
S OF 05N BETWEEN 85W AND 95W AS PREVIOUSLY DESCRIBED...AND ALSO 
NEAR THE COAST OF COLOMBIA. DEBRIS MOISTURE FROM THESE AREAS IS 
ADVECTED NORTHWARD...BUT SEEMS TO EVAPORATE BEFORE REACHING THE 
UPPER LEVELS OVER CENTRAL AMERICA. THE UPPER LEVELS ARE DRY 
ELSEWHERE S OF 22N E OF 112W.  
 
AT THE LOW LEVELS...A COLD FRONT IS MOVING ACROSS THE NORTHERN 
BAJA CALIFORNIA PENINSULA AND ACROSS THE GULF OF CALIFORNIA 
ALONG 30N ACCOMPANIED BY SHOWERS. LATEST GUIDANCE IS NOT AS 
AGGRESSIVE WITH THE NORTHERLY FLOW BEHIND THE COLD FRONT IN THE 
GULF OF CALIFORNIA...THUS DROPPED MENTION IN THIS MORNINGS 
FORECAST PACKAGE. A POST FRONTAL RIDGE EXTENDS FROM 32N138W TO 
NEAR 12N102W. NE TRADES ARE ENHANCED AT 15 TO 20 KT OVER THE 
AREA SW OF THE RIDGE...ROUGHLY FROM 07N TO 14N W OF 125W...WITH 
SEAS 8 TO 10 FT PRIMARILY IN NW SWELL. THE PREDOMINATE SWELL 
DIRECTION IS NW OVER THE REMAINDER OF THE AREA W OF 105W DRIVING 
SEAS TO 10 FT EXCEPT 11 TO 14 FT NEAR 30N125W. A SECOND COLD 
FRONT WILL MOVE INTO THE NORTHERN WATERS NEAR 30N125W MON NIGHT 
ACCOMPANIED BY A 20 TO 25 KT WIND SHIFT AND A NEW TRAIN OF N 
SWELLS DRIVING SEA HEIGHTS TO 15 FT NEAR 30N130W BY LATE TUE. 

GAP WINDS...
GULF OF TEHUANTEPEC...N TO NE WINDS AT 20 KT THIS MORNING ARE 
EXPECTED TO DIMINISH TO LESS THAN 20 KT BY EARLY AFTERNOON AND 
BECOME LIGHT SOUTHERLY WINDS TONIGHT. 

GULF OF PAPAGAYO...NE TO E WINDS AT 20 TO 25 KT EXPECTED TO 
CONTINUE IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO TODAY...BUT 
DIMINISH TO 15 TO 20 KT PULSES LATE TONIGHT THROUGH TUE.

GULF OF PANAMA...N TO NE WINDS ARE EXPECTED PULSE AT 15 TO 20 KT 
IN AND DOWNSTREAM OF THE GULF OF PANAMA TO ALONG 05N THROUGH TUE.

$$
NELSON