FXUS63 KUNR 221720
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1000 AM MST TUE DEC 22 2009
.DISCUSSION...SATELLITE IMAGES SHOW UPPER RIDGE OVER FORECAST AREA
THIS MORNING...AS STRONG STORM SYSTEM IS OVER WESTERN U.S. SMALL
SHORT WAVE MOVING FROM SRN WY OVER WRN SD THIS AFTERNOON MAY PRODUCE
LIGHT SNOW. SURFACE ANALYSIS PLACES HIGH PRESSURE OVER SRN CANADA
WITH E-SE FLOW AHEAD OF STATIONARY FRONT ACROSS CNTRL MT-WY.
EASTERLY LOW LEVEL UPSLOPE FLOW OVER WESTERN SOUTH DAKOTA WILL
CONTINUE TO PRODUCE FOG/FREEZING FOG...WITH VISIBILITIES LESS THAN A
MILE ALONG THE EASTERN AND NORTHERN FOOTHILLS. FOG WILL DISSIPATE
LATER THIS AFTERNOON.
TEMPS WILL REACH THE LOWER TO MID 30S OVER PARTS OF NORTHEASTERN WY
AND BLACK HILLS...BUT WILL NOT BE WARMING MUCH OVER THE REST OF
SOUTH DAKOTA WHERE THE FOG REMAINS.
&&
.AVIATION...IFR/LIFR CONDITIONS WILL CONTINUE ACROSS MUCH OF THE
SOUTH DAKOTA PLAINS TODAY DUE TO CIGS/FOG. DENSE FOG ACROSS SOME
AREAS INCLUDING KRAP MAY START TO LIFT THIS AFTERNOON...BUT CIGS
SHOULD REMAIN IN THE IFR CATEGORY THRU TONIGHT. SNOW WILL DEVELOP
LATE TONIGHT AND CONTINUE THRU CHRISTMAS DAY. VFR CONDS WILL CONT
THRU 00Z ACRS NERN WY...WITH CONDITIONS DETERIORATING AS SNOW DVLPS
ACRS THE REGION TONIGHT.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WARNING FROM 5 AM WED TO 5 PM MST THURS FOR
CNTRL-NRN-SRN BLACK HILLS.
WINTER STORM WARNING FROM 5 AM MST /6 AM CST/ WED TO 11 PM MST
/MIDNIGHT CST/ THURS FOR SOUTHERN AND SOUTH CNTRL SD.
WINTER STORM WATCH FROM THIS EVENING THROUGH THURS AFTN FOR
SWRN SD...HERMOSA AND SRN FOOT HILLS.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURS AFTN FOR
NWRN SD AND NRN-RAPID CITY-STURGIS/PIEDMONT FOOT HILLS.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURS EVENING
FOR WEST CNTRL SD.
WY...WINTER STORM WARNING FROM 5 AM WED TO 5 PM MST THURS FOR
WY BLACK HILLS.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURS AFTN FOR
CROOK-WESTON.
&&
$$
