Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 282315
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
415 PM MST SUN DEC 28 2014

.SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT
ISSUED AT 200 PM MST SUN DEC 28 2014

UPPER LEVEL ANALYSIS HAS BROAD TROF DROPPING SOUTH ACROSS THE
NORTHERN AND WESTERN CONUS...WITH SHORTWAVE CROSSING MONTANA AT
THE MOMENT. REGIONAL RADAR ECHOES ARE ON THE INCREASE ACROSS THE
FORECAST AREA...WITH MOST RETURNS JUST MID LEVEL MOISTURE. SOME
POCKETS OF HIGHER RETURNS ARE LIKELY PRODUCING LIGHT SNOW. AT THE
SURFACE...ARCTIC AIR IS SETTLING ACROSS THE NORTHERN PLAINS WITH
WEAK LEE TROF ACROSS EASTERN WYOMING. TEMPERATURES AT 2 PM ARE IN
THE UPPER TEENS AND 20S...WITH LIGHT EAST WINDS.

FOR THIS AFTERNOON AND TONIGHT...ARCTIC FRONT WILL CONTINUE TO
SLIDE SOUTH AND WEST ACROSS THE AREA AS SNOW DEVELOPS LATE THIS
AFTERNOON. MOST OF THE SNOWFALL SHOULD FALL AT A LIGHTER
INTENSITY AS THE BEST FRONTOGENESIS AND DYNAMICS ARE TO THE SOUTH
AND WEST OF THE FORECAST AREA TONIGHT...AND AVAILABLE MOISTURE
WILL BE MINIMIZED IN THE COLD AIR. HOWEVER...SNOWFALL RATIOS OF
20-25:1 WILL PRODUCE A FLUFFY SNOWFALL THAT SHOULD ACCUMULATE
RATHER EASILY. WIDESPREAD SNOWFALL IS EXPECTED TONIGHT...WITH 2 TO
4 INCHES OF ACCUMULATION ACROSS MUCH OF THE AREA BY MONDAY
MORNING. WINDS WILL REMAIN ON THE LIGHTER SIDE WITH THIS
SYSTEM...BUT SOME GUSTS TO 20 MPH ON THE PLAINS COULD PRODUCE
PATCHY BLOWING SNOW TONIGHT. TEMPS WILL DROP TO NEAR OR BELOW ZERO
BY EARLY MONDAY...WITH WIND CHILL VALUES ZERO TO 20 BELOW ZERO IN
THE MORNING.

ON MONDAY...SNOW WILL TAPER OFF FROM NORTHEAST TO SOUTHWEST ACROSS
THE CWA MONDAY AFTERNOON. LITTLE ADDITIONAL ACCUMULATION IS
EXPECTED FROM LATE MORNING THROUGH THE AFTERNOON. HIGHS WILL RANGE
FROM ZERO TO 10 ABOVE...COLDEST ACROSS NORTHWEST SD. WIND CHILLS
WILL REMAIN BELOW ZERO IN MOST AREAS DURING THE DAY. PATCHY LIGHT
SNOW AND FLURRIES ARE POSSIBLE INTO MONDAY NIGHT OVER NORTHEAST WY
AND FAR SOUTHWEST SD...BUT LINGERING SNOWFALL SHOULD MOVE OUT LATE
MONDAY NIGHT. SOME BREAKS IN THE CLOUDS ARE EXPECTED OVERNIGHT.
WITH FRESH SNOW COVER...TEMPS SHOULD DROP TO 5 BELOW TO 15 BELOW
ZERO. WINDS UP TO 10 MPH OVERNIGHT SHOULD PRODUCE WIND CHILLS OF
20 BELOW TO 30 BELOW ACROSS MUCH OF THE PLAINS. A WIND CHILL
ADVISORY WILL LIKELY BE NEEDED FOR A GOOD PORTION OF THE CWA LATER
MONDAY NIGHT INTO TUESDAY MORNING.

.LONG TERM...TUESDAY THROUGH SUNDAY
ISSUED AT 200 PM MST SUN DEC 28 2014

1055MB ARCTIC HIGH SETTLES INTO THE AREA TUESDAY WITH TEMPS
STRUGGLING TO GET ABOVE ZERO. WIND CHILLS IN THE MORNING COULD BE
AS COLD AS -35F...EVEN WITH RELATIVELY LIGHT WINDS EXPECTED. AFTER
ANOTHER BITTERLY COLD MORNING ON WEDNESDAY...SLIGHT MODERATION IN
TEMPS EXPECTED THROUGH THURSDAY. NEXT SHOT OF ARCTIC AIR ARRIVES
FRIDAY BRINGING ANOTHER ROUND OF LIGHT SNOW AND VERY COLD
TEMPERATURES FOR THE WEEKEND.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 412 PM MST SUN DEC 28 2014

WIDESPREAD SNOW WILL CONTINUE TO DEVELOP THIS EVE ACROSS NERN WY
AND NWRN SD...WITH THE SNOW SPREADING QUICKLY SOUTH/EAST AND
CONTINUING TONIGHT. WDSPRD IFR/MVFR CIGS AND IFR/LIFR VSBY
EXPECTED...WITH THE WORST CONDITIONS FROM NERN WY THROUGH SWRN SD.
CONDITIONS WILL SLOWLY IMPROVE FROM NORTH TO SOUTH MONDAY MRNG.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 11 AM MST MONDAY FOR SDZ012-013-
     024>026-028-029-031-072-073.

     WINTER WEATHER ADVISORY UNTIL 11 AM MST /NOON CST/ MONDAY FOR
     SDZ027-030-032-041>044-046-047-074.

WY...WINTER WEATHER ADVISORY UNTIL 11 AM MST MONDAY FOR WYZ054>058-
     071.

&&

$$

SHORT TERM...15
LONG TERM...JOHNSON
AVIATION...JC






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