000
AXPZ20 KNHC 202154
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 
2205 UTC FRI APR 20 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 2145 UTC.

...ITCZ...

AXIS IS ALONG 9N78W 6N110W 2N125W 2N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION NOTED WITHIN 150 NM EITHER SIDE OF 
LINE 6N78W 7N88W AND LINE 4N94W 5N100W AND WITHIN 90 NM EITHER 
SIDE OF LINE 7N106W 6N117W. 

...DISCUSSION...

A SHORTWAVE UPPER RIDGE IS COLLAPSING SE NEAR 34N136W. OTHERWISE 
A BROAD UPPER LEVEL TROUGH DOMINATES DISCUSSION AREA N OF 20N W 
OF 110W. AN EMBEDDED CYCLONE IS NEAR 35N120W WITH A TROUGH SE TO 
NEAR 27N113W. THE ASSOCIATED SURFACE FRONT LIES ALONG 32N118W 
27N130W 30N140W. UPPER LEVEL MOISTURE IS INDICATED N OF POINTS 
32N110W 24N124W 27N140W. A BAND OF DRY UPPER AIR IS INDICATED 
WITHIN 240 NM EITHER SIDE OF LINE 32N104W 24N114W 22N140W. 

AN UPPER LEVEL ANTICYCLONE IS JUST SW OF THE AREA AT 4S142W WITH 
ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDING N TO ALONG 13N W OF 
127W. 

AN UPPER ANTICYCLONE IS ESTIMATED NEAR 10N75W WITH A DEEP 
LAYERED RIDGE EXTENDING NW TO BEYOND 32N92W INTO A BROAD RIDGE 
DOMINATING CENTRAL N AMERICA. AN UPPER TROUGH EXTENDS S FROM 
11N105W TO AN UPPER CYCLONE NEAR THE EQUATOR AT 105W. WEAK UPPER 
DIFFLUENCE IS INDICATED IN CLOUD MOTION WINDS WITH SLIGHT 
ENHANCEMENT OF ITCZ CONVECTION BETWEEN 107W 135W...WITH MOST OF 
THE DEBRIS MOISTURE ADVECTED S OF THE EQUATOR. UPPER DIFFLUENCE 
IS ALSO ENHANCING ITCZ CONVECTION E OF 103W WITH THE RESULTANT 
DEBRIS MOISTURE SPREADING N ACROSS CENTRAL AMERICA BUT 
EVAPORATING UNDER THE UPPER RIDGE AXIS. A MOISTURE PLUME 
CONTINUES THROUGH THE UPPER RIDGE...ROUGHLY WITHIN 300 NM EITHER 
SIDE OF LINE 14N137W 17N109W 26N93W 38N92W. 

$$
NELSON