Winter Storm in Wyoming, March 28 to 30, 2007

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1110 AM MDT WED MAR 28 2007

.DISCUSSION...16Z SURFACE ANALYSIS HAS LOW PRESSURE OVER NORTH
CENTRAL COLORADO WITH INVERTED TROUGH ALONG THE WYOMING SOUTH DAKOTA
BORDER. COLD AIR IS CURRENTLY MOVING INTO MOST OF NORTHEAST WYOMING
WITH THUNDERSNOW REPORTED ACROSS MUCH OF CAMPBELL COUNTY. AREAS OF
FOG AND LOW STRATUS REMAIN OVER MOST OF WESTERN SOUTH
DAKOTA...INHIBITING SURFACE HEATING.

QUICKLY FALLING TEMPERATURES ACROSS CAMPBELL COUNTY HAS WARRANTED
ISSUING WINTER STORM WARNING A LITTLE SOONER THAN ANTICIPATED.
OBSERVATIONS FROM KGCC SHOWED CHANGE OVER TO SNOW BY 10 AM WITH
ELEVATED THUNDERSTORMS. WITH COMPLETE CLOUD COVER...DO NOT
ANTICIPATED ANY TEMPERATURE RECOVERY ACROSS THIS AREA...SO SNOW WILL
BEGIN TO ACCUMULATE...WITH 6 INCHES OR BETTER EXPECTED BY THIS
EVENING. TIMING OF SNOW ACROSS THE REMAINING PORTIONS OF NORTHEAST
WYOMING AND THE BLACK HILLS REMAINS UP IN THE AIR...WITH INVERTED
TROUGH REMAINING NEARLY STATIONARY THROUGH THIS EVENING. WINTER
STORM WATCH REMAINS IN EFFECT FOR THESE AREAS.

ON THE WARM SIDE OF THE TROUGH ACROSS WESTERN SOUTH DAKOTA...LOW
STRATUS IS TRYING TO BREAK UP...ESPECIALLY ACROSS SOUTHWESTERN SOUTH
DAKOTA. IF ENOUGH CLEARING AND SURFACE HEATING OCCURS ACROSS THE
PANHANDLE...SURFACE BASED THUNDERSTORMS SHOULD FIRE THIS AFTERNOON
AND TRAVEL NORTH INTO SOUTHWESTERN SOUTH DAKOTA. CURRENT
TEMPERATURES ARE IN THE 50S TO LOWER 60S...WITH DEWPOINTS AROUND 50
DEGREES. SOUTHEAST WINDS ARE HAVING A HARD TIME GETTING GOING THIS
MORNING. HAVE PARED BACK WIND ADVISORY TO CENTRAL AND SOUTH CENTRAL
SOUTH DAKOTA...WHERE BEST PRESSURE GRADIENT LINES UP.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY TODAY AND THIS EVENING FOR CENTRAL AND SOUTH
     CENTRAL SOUTH DAKOTA.
  ...WINTER STORM WATCH TONIGHT THROUGH THURSDAY FOR THE BLACK
     HILLS.
WY...WINTER STORM WARNING FOR CAMPBELL COUNTY THROUGH THURSDAY.
  ...WINTER STORM WATCH TONIGHT THROUGH THURSDAY FOR PARTS OF
     NORTHEASTERN WYOMING.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
1115 AM MDT WED MAR 28 2007

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-291300-
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-
1115 AM MDT (1215 PM CDT) WED MAR 28 2007

...WINTER STORM WARNING IN EFFECT THROUGH THURSDAY FOR CAMPBELL
   COUNTY IN WYOMING...
...WINTER STORM WATCH FROM TONIGHT THROUGH THURSDAY FOR THE
   REMAINDER OF NORTHEAST WYOMING ALONG WITH THE BLACK HILLS...
...WIND ADVISORY IN EFFECT THROUGH THIS EVENING FOR CENTRAL SOUTH
   DAKOTA...

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

.DAY ONE...TODAY AND TONIGHT

AN UPPER LEVEL STORM SYSTEM APPROACHING THE AREA WILL BRING A SLIGHT
RISK FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING TO MANY
PARTS OF WESTERN AND CENTRAL SOUTH DAKOTA. LARGE HAIL WILL BE THE
MAIN THREAT FROM ANY SEVERE STORM THAT DOES DEVELOP...THOUGH SOME
DAMAGING WIND GUSTS WILL ALSO BE POSSIBLE. THE AREA WITH THE BEST
CHANCES FOR SEVERE WEATHER WILL BE PORTIONS OF WESTERN AND SOUTH
CENTRAL SOUTH DAKOTA SOUTH OF A LINE FROM SPEARFISH TO FAITH. ALONG
WITH THE THREAT FOR LARGE HAIL AND DAMAGING WIND GUSTS...THERE WILL
BE THE POSSIBILITY FOR AN ISOLATED TORNADO...THOUGH THIS THREAT
IS EXPECTED REMAIN OVER THE FAR SOUTHWEST AND SOUTH CENTRAL SOUTH
DAKOTA COUNTIES THAT BORDER NEBRASKA.

ALONG WITH THE THUNDERSTORM THREAT...WINDY CONDITIONS ARE EXPECTED
OVER CENTRAL SOUTH DAKOTA. SOUTHERLY WINDS OF 25 TO 35 MPH WITH
GUSTS TO 45 MPH ARE EXPECTED THIS AFTERNOON AND WILL CONTINUE INTO
THE EARLY EVENING HOURS.

MEANWHILE BACK TO THE WEST...MUCH COLDER AIR WILL CONTINUE TO PUSH
INTO NORTHEASTERN WYOMING...AND WILL MAKE IT INTO THE BLACK HILLS
TONIGHT. SNOWFALL HAS ALREADY DEVELOPED OVER CAMPBELL COUNTY IN
WYOMING WHERE A WINTER STORM WARNING HAS BEEN ISSUED. THE SNOW WILL
SPREAD EASTERLY OVERNIGHT...WITH HEAVY SNOWFALL ACCUMULATIONS
POSSIBLE THROUGH THURSDAY AFTERNOON. THE HIGHEST SNOWFALL
ACCUMULATIONS CAN BE EXPECTED OVER WESTERN CAMPBELL COUNTY IN
NORTHEASTERN WYOMING. BLOWING SNOW COULD CREATE HAZARDOUS DRIVING
CONDITIONS IN THE AREAS WHERE THE HEAVY SNOW IS EXPECTED TO FALL.
THE EXACT STORM TRACK IS STILL UNCERTAIN AND THE STORM TOTAL SNOW
AMOUNTS WILL DEPEND ON WHEN THE RAIN CHANGES OVER TO SNOW FOR THE
REMAINDER OF NORTHEAST WYOMING AND THE BLACK HILLS...BUT DUE TO THE
POSSIBILITY OF HEAVY SNOW...A WINTER STORM WATCH WILL CONTINUE FOR
THIS AREA FROM TONIGHT THROUGH THURSDAY AFTERNOON.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THE WINTER STORM WARNING FOR CAMPBELL COUNTY...ALONG WITH THE WINTER
STORM WATCH FOR THE REMAINDER OF NORTHEAST WYOMING AND THE BLACK
HILLS CONTINUES THROUGH THURSDAY AFTERNOON OVER NORTHEASTERN WYOMING
AND NORTHWESTERN SOUTH DAKOTA WITH HEAVY SNOW POSSIBLE OVER THOSE
AREAS. THE SNOW IS EXPECTED TO TAPER OFF ON THURSDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER MAY BE NEEDED TODAY...PARTICULARLY OVER FAR SOUTHWEST AND
SOUTH CENTRAL SOUTH DAKOTA NEAR THE NEBRASKA BORDER.