527 
FXUS63 KUNR 120140
AFDRAP

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY 
NATIONAL WEATHER SERVICE RAPID CITY SD
740 PM MDT THU OCT 11 2001

THE ZONE FORECAST WAS UPDATED TO LOWER THE CHANCE OF PRECIPITATION 
IN PARTS OF WESTERN SD...AND ALSO TO MAKE ADJUSTMENTS TO THE WINDS 
BASED ON THE LATEST SURFACE TRENDS. RADAR AND SATELLITE DATA SHOWED 
TWO MAIN AREAS OF SHOWERS...ONE ACROSS EASTERN MT SOUTH INTO THE BIG 
HORNS...AND THE OTHER SMALLER AREA OVER WESTERN NEB AND EASTERN CO.
THESE CORRESPONDED REASONABLY WELL TO THE 300-MB DIVERGENCE 
PATTERNS...WHICH THE 18Z AVN/ETA AND 00Z RUC HAD A GOOD HANDLE ON. 
THE 12Z ETA MISREPRESENTED THE 00Z JET CONFIGURATION FROM WY INTO 
SOUTHERN CANADA...AND THE NGM UNDERFORECAST THE 140-KT JET OVER THE 
NORTHWESTERN UNITED STATES. BASED ON THE 18Z/00Z MODELS...THE BULK 
OF THE SYNOPTIC-SCALE LIFT AND PRECIPITATION WILL BYPASS MUCH OF THE 
CWFA. HOWEVER...UPSLOPE FLOW WILL LEAD TO ENHANCED LIFT OVER THE 
NORTHERN BLACK HILLS LATER TONIGHT...WITH MUCH OF THE CURRENT LIFT 
BEING WASTED DUE TO THE DRY LOWER ATMOSPHERE. ANOTHER UPDATE MAY BE 
NEEDED LATE THIS EVENING TO ACCOUNT FOR FRONTAL PASSAGE IN SOME 
AREAS.

.UNR...WIND ADVISORY PORTIONS OF WESTERN SOUTH DAKOTA LATE TONIGHT 
THROUGH FRIDAY MORNING.

MJB