Winter Storm in Wyoming, January 22, 2011

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
840 AM MST SAT JAN 22 2011

.DISCUSSION...AT 15Z SFC MAP SHOWS LOW PRES IN SERN MT WITH A
TROF EXTENDING SE THRU KRAP INTO CENTRAL NEBRASKA. ALOFT...UPPER
LOW NOW NEAR MILES CITY MONTANA. STRONG S/W IN CENTRAL MONTANA
WILL ROTATE THRU REGION LATER TODAY BRINGING ANOTHER ROUND OF
SNOW FOR THIS AFT/EARLY EVENING.

HAVE UPDATED ZONES TO LOWER POPS TO SCT SNOW SHOWERS THROUGH
MIDDAY OVER ALL BUT NWRN SD WHERE SNOW CONTINUES. ADDITIONAL
SNOW IN MONTANA WILL WRAP AROUND UPPER SYSTEM INTO WRN SD THIS
AFT AND UPPER LOW MVS SE.

PREVIOUS FORECAST DISCUSSION:(330 AM MST)...
SNOW WILL INCREASE IN COVERAGE AND INTENSITY LATE THIS MORNING AS
STRONG QG FORCING DEVELOPS AHEAD OF THE APPROACHING SHORTWAVE.
FAVORABLE UPSLOPE CONDITIONS WILL DEVELOP THIS AFTERNOON ACROSS
THE NORTHERN BLACK HILLS/NRN FOOTHILLS AND BEAR LODGE MOUNTAINS
AS WINDS BECOME NORTHWESTERLY. THE SFC LOW WILL MOVE SOUTHEASTWARD
ACROSS THE FORECAST AREA TODAY. A TIGHT SFC PRESSURE GRADIENT TO THE
WEST OF THE LOW WILL LEAD TO WINDY CONDITIONS WITH SOME AREAS OF
BLOWING SNOW ACROSS PARTS OF NORTHEASTERN WYOMING AND FAR
NORTHWESTERN SOUTH DAKOTA.

CURRENT WINTER HEADLINES STILL LOOK REASONABLE. WINTER STORM
WARNING HAS BEEN POSTED FOR 6-10 INCHES OF SNOW OVER THE FAVORED
UPSLOPE AREAS OF THE NRN BLKHLS/FOOTHLS AND BEARLODGE MOUNTAINS BY
LATER THIS EVENING AS IT APPEARS THERE SHOULD BE 4-6 HRS OF GOOD
UPSLOPE CONDITIONS THIS AFTERNOON. QPF SUPPORTS 3-5 INCHES OF SNOW
FOR PORTIONS OF NERN WY/ NWRN SD SO WINTER WX ADVISORY THERE STILL
LOOKS GOOD THERE. ELSEWHERE EXPECT GENERALLY 1-3 INCHES OF SNOW.
SNOW SHLD TAPER OFF IN THE EVENING.

TEMPERATURES WILL FALL THROUGH MOST OF THE DAY TODAY AS THE SFC
LOW MOVES THROUGH DRAWING IN COLDER AIR FROM THE NORTH AND EAST.
TEMPERATURES WILL BEGIN TO RISE AGAIN TONIGHT...CONTINUING THROUGH
SUNDAY. SUNDAY WILL START OUT DRY WITH MILD TEMPS AS WARM AIR ALOFT
MVS INTO REGION. ANOTHER S/W WILL DIVE SOUTH OUT OF SRN CANADA SUNDAY
NIGHT...BRINGING AN INCREASED CHC OF SNOW TO NERN WY/ NWRN SD AND
NRN BLACK HILLS ON SUNDAY NIGHT. SOME LIGHT SNOW MAY LINGER INTO
MONDAY MORNING ON THE WESTERN SOUTH DAKOTA PLAINS. HIGHS ON MONDAY
WILL BE NEAR NORMAL...GENERALLY IN THE MID 20S TO UPPER 30S.

EXTENDED...NORTHWEST FLOW WILL REMAIN ACROSS THE REGION THROUGH THE
LONG TERM. MODELS CONTINUE TO SHOW A SHORTWAVE CROSSING THE AREA
TUESDAY...BRINGING A CHANCE FOR PRECIP TUESDAY INTO TUESDAY NIGHT.
MAINLY DRY WEATHER STILL LOOKS ON TAP FOR THE SECOND HALF OF THE
WORK WEEK. TEMPERATURES WILL BE NEAR NORMAL THROUGH MIDWEEK...THEN
MODELS ARE BEGINNING TO TREND WARMER FOR THE END OF THE WORK WEEK AS
850 MB TEMPS OF +10C CROSS THE AREA. THAT WOULD RESULT IN TEMPS WELL
ABOVE SEASONAL AVERAGES.

&&

.AVIATION...MVFR/IFR CONDITIONS WILL DEVELOP ACROSS THE AREA TODAY
AS A STORM SYSTEM BRINGS SNOW TO THE REGION. VFR CONDITIONS WILL
RETURN LATE TONIGHT AS THE STORM SYSTEM DEPARTS TO THE SOUTHEAST.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WARNING UNTIL 11 PM MST THIS EVENING FOR NORTHERN
     BLACK HILLS.

     WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR BUTTE-
     CENTRAL BLACK HILLS-HARDING-NORTHERN FOOT HILLS-NORTHERN
     MEADE CO PLAINS-PERKINS-ZIEBACH.

WY...WINTER STORM WARNING UNTIL 11 PM MST THIS EVENING FOR WYOMING
     BLACK HILLS.

     WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR
     NORTHEASTERN CROOK-NORTHERN CAMPBELL-WESTERN CROOK.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
307 AM MST SAT JAN 22 2011

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-231400-
BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON-
HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK-
NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS-
NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-
SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS-
SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-
WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH-
307 AM MST (407 AM CST) SAT JAN 22 2011

...WINTER STORM WARNING TODAY THROUGH THIS EVENING FOR THE
   NORTHERN BLACK HILLS AND BEAR LODGE MOUNTAINS...

...WINTER WEATHER ADVISORY TODAY THROUGH THIS EVENING FOR
   NORTHWESTERN SOUTH DAKOTA...PARTS OF NORTHEASTERN WYOMING
   ...AND THE CENTRAL BLACK HILLS...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND
NORTHEASTERN WYOMING.

.DAY ONE...TONIGHT

AN UPPER LEVEL WEATHER SYSTEM WILL BRING SNOW TO THE AREA TODAY.
SNOW ACCUMULATIONS OF 6 TO 10 INCHES WITH LOCALLY HIGHER AMOUNTS ARE
EXPECTED BY LATE THIS EVENING ACROSS THE NORTHERN BLACK HILLS AND
BEAR LODGE MOUNTAINS. IN THE CENTRAL BLACK HILLS...2 TO 6 INCHES OF
SNOW ACCUMULATION IS EXPECTED WITH THE HIGHER AMOUNTS WEST OF
ROCHFORD AND DEERFIELD. ON THE PLAINS...SNOWFALL OF 3 TO 5 INCHES IS
EXPECTED OVER NORTHWESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING.
ELSEWHERE...SNOWFALL OF 1 TO 3 INCHES IS EXPECTED. AREAS OF BLOWING
SNOW CAN BE EXPECTED ACROSS NORTHEASTERN WYOMING TODAY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THERE IS A CHANCE OF SNOW ON SUNDAY NIGHT WITH A CHANCE OF RAIN OR
SNOW ON TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.