000
AXPZ20 KNHC 212124
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT FEB 21 2009

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...
THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...04N77W TO 
04N105W TO 05N140W. SCATTERED MODERATE CONVECTION IS JUST NORTH 
OF THE ITCZ WITHIN 60 NM OF THE POINT 05N125W.

...DISCUSSION...

DEEP LAYER TROUGH IS OVER THE NORTHWESTERN PART OF THE AREA. 
STRONG COMPLEX CUTOFF LOW IS CENTERED NORTH OF THE WESTERN PART 
OF THE AREA NEAR 38N140W. ASSOCIATED WEATHER IN THE FORM OF A 
PLUME OF UPPER LEVEL MOISTURE WITH MULTI LEVEL OVERCAST CLOUDS 
WITH SOME EMBEDDED RAIN IS WITHIN 150 NM EITHER SIDE OF A LINE 
FROM 22N140W TO BEYOND 32N125W. THIS MOISTURE EMANATES FROM 
DIFFLUENT UPPER FLOW TO THE EAST OF A DEEP TROPICS TROUGH 
LOCATED WEST OF THE AREA NEAR 148W. THE CUTOFF LOW AND THE 
TROUGH OVER THE NORTHWEST PART OF THE AREA WILL CONTINUE THROUGH 
SUNDAY WITH THE CUTOFF WEAKENING LATE SUNDAY BUT REMAINING OVER 
THE NORTHWEST PART OF THE AREA THEN LIFTING NORTHEAST MONDAY 
WITH THE TROUGH REMAINING OVER THE NORTHWEST PART BEYOND MONDAY.

REMAINDER OF THE MIDDLE AND UPPER LEVELS IS COVERED BY A BROAD 
RIDGE. THE AREA SOUTH OF A LINE FROM NEAR 20N90W TO 15N120W 
00N125W IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS. 
AN EXCEPTION IS A NARROW BAND OF SHOWERS 40 NM EITHER SIDE OF A 
LIND FROM 11N94W TO 07N100W. THIS FEATURE IS HARD TO EXPLAIN BUT 
MAY BE RELATED TO THE FLOW OF NORTHEASTERLY WINDS ACROSS THE 
CENTRAL AMERICA ISTHMUS. A PLUME OF UPPER LEVEL MOISTURE WITHOUT 
AMY CLOUDS IS MOVING ACROSS MEXICO NORTH OF 20N. THIS MOISTURE 
IS EMANATING FROM ITCZ CONVECTION THAT WAS LOCATED WEST OF ABOUT 
130W AND HAS SINCE DIMINISHED. 

SURFACE FRONTAL TROUGH IS OVER THE NORTHWEST PART OF THE AREA 
AND IS ASSOCIATED WITH THE MIDDLE AND UPPER LEVEL TROUGH AND 
CUTOFF. THE SURFACE TROUGH SHOULD CONTINUE THROUGH THE NEXT 
SEVERAL DAYS BUT SLOWLY WEAKEN AS THE UPPER FEATURE WEAKENS.
OTHERWISE WEAK RIDGE IS NORTH OF 15N W OF 105W. REMAINDER OF THE 
AREA IS ANALYZED AS A BROAD SURFACE TROUGH CENTERED NEAR THE 
ITCZ.

GAP NORTHEAST TO EAST WINDS IN AND WEST OF THE GULF OF PAPAGAYO 
OF 20 TO 25 KT WILL CONTINUE THROUGH THE NEXT SEVERAL DAYS. 

GAP NORTHERLY WINDS WILL BEGIN AGAIN IN THE GULF OF TEHUANTEPEC 
REGION LATE TONIGHT AND WILL INCREASE TO GALE SUNDAY AND STORM 
FORCE SUNDAY NIGHT THEN DIMINISH TO A GALE MONDAY.

$$
LL