428 
FPUS65 KPIH 102130 
AFDPIH
 
MODELS NOT INITIALIZED REAL WELL WITH MOISTURE FIELD ASSOCIATED WITH
NORTHEAST OREGON/CENTRAL IDAHO SHORTWAVE.  HOWEVER...ETA SEEMS TO
CATCH UP WITH WHAT SATELLITE AND RADAR SHOWING THIS AFTERNOON. 
SIGNIFICANT CHUNK OF MOISTURE AND WEAK DYNAMICS WILL OVERSPREAD THE
UPPER SNAKE HIGHLANDS TONIGHT WITH SOME LIGHT PRECIPITATION LIKELY. 
IN THE ABSENCE OF ANY OTHER DYNAMIC FORCING MECHANISMS...LOW LEVELS
DRY ENOUGH TO SUPPRESS PRECIPITATION IN VALLEYS.  HOWEVER...ANOTHER
FACTOR THAT MAY PLAY INTO THE LIGHT SHOWER THREAT TONIGHT IS THE
POSSIBLE DEVELOPMENT OF VERY WEAK CONVERGENCE IN THE SNAKE RIVER
PLAIN BETWEEN 9 PM AND EARLY TUE MORNING.  MODELS INFER SURFACE
PRESSURE GRADIENT WILL REVERSE WITH LIGHT WINDS DEVELOPING UP SNAKE
RIVER VALLEY. THIS ALREADY BEGINNING TO TAKE PLACE.  AT SAME
TIME...NORTHWEST WINDS ALOFT INCREASE WITH SOME CHANNELING DOWN LOST
RIVER AND BIRCH CREEK VALLEYS.  BELIEVE STABILITY WILL KEEP EVENT
MINIMAL.  HOWEVER... WILL NOT RULE OUT SHOWERS IN SNAKE RIVER PLAIN. 
NEXT SHORTWAVE WILL ENTER PICTURE WEDNESDAY AND WEDNESDAY NIGHT. 
SYSTEM ENTERING MEAN RIDGE POSITION AND WILL LIKELY WEAKEN AND SPLIT
BEFORE ENTERING EASTERN IDAHO.  BAUCK    
PIH EC 024/038 018/040 022 03221
IDA EC 022/035 015/037 020 03221