High Wind in South Dakota, January 8, 2007

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1030 AM MST MON JAN 8 2007

.DISCUSSION...17Z SFC ANALYSIS SHOWS HIGH PRESSURE OVER NORTHERN
ROCKIES WITH LOW PRESSURE OVER THE GREAT LAKES. SFC LOW THAT WAS
DROPPING SOUTHEASTWARD OUT OF CANADA INTO MINNESOTA HAS WEAKENED
INTO A TROUGH THIS MORNING...ALTHOUGH A VERY TIGHT SFC PRESSURE
GRADIENT STILL EXISTS ACROSS OUR FORECAST AREA. REGION OF STEEP
850/500MB LAPSE RATES HAS DEVELOPED INTO AN AREA OF SCT/NMRS SHRASN
EXTENDING FROM EASTERN MONTANA NORTHEASTERN WY AND FAR WESTERN SD.

THIS AFTERNOON/TONIGHT...UPPER WAVE WILL ROCKET ACROSS THE NORTHERN
PLAINS BRINGING STRONG WINDS TO MUCH OF THE AREA LATER THIS
AFTERNOON...PROBABLY BETWEEN 19 AND 21Z. 45-50KT BOUNDARY LAYER
WINDS COMBINED WITH STEEP LAPSE RATES...MODEST COLD AIR ADVECTION
AND DEVELOPING SURFACE PRESSURE RISES PAINTS PICTURE FOR CONTINUING
CURRENT WIND HIGHLIGHTS. THE MAIN UPPER LEVEL FEATURE WILL PASS JUST
NORTH OF REGION...SO SUBSIDENCE SHOULD KICK IN BEHIND COLD FRONT
FURTHERING JUSTIFICATION FOR WARNINGS. THIS WILL ALSO CUT DOWN ON
POPS FOR LATE THIS AFTERNOON AS MAIN FRONTOGENESIS EAST OF CWA...BUT
NOT BEFORE CURRENT RADAR ACTIVITY IN MT/WY/SD BRINGS SCT -SHRASN TO
THE AREA. COULD SEE ADDITIONAL 2 INCHES OF SNOW IN THE HIGHER HILLS
BY THIS AFTERNOON GIVEN UPSLOPE SIGNATURE. HIGHS WILL BE REACHED
MIDDAY WITH STEADY OR SLOWLY FALLING TEMPERATURES...IN FACT SOME
PLACES ARE NEAR FORECAST HIGHS ALREADY GIVEN DOWNSLOPING WINDS.
WINDS WILL QUICKLY DIMINISH TONIGHT AS GRADIENT SLACKENS AND WARM
AIR ADVECTION BEGINS ANEW.

TUESDAY/EARLY WEDNESDAY...UPPER RIDGE BUILDS INTO THE NORTHERN
PLAINS. POTENTIAL TEMPERATURES IN THE LOWER 50S WEDNESDAY WITH
WESTERLY FLOW BRINGING WARMISH OVERNIGHT LOWS TUESDAY NIGHT. THUS
HAVE RAISED TEMPERATURES.

WEDNESDAY AFTERNOON THROUGH THURSDAY...NAM/GFS BOTH SLOWING
PROGRESSION OF ARCTIC AIR OUTBREAK. NAM SLOWEST AND SEEMS TO BE THE
PREFERRED MODEL. GIVEN THIS SCENARIO...WILL SEE WARMER TEMPERATURES
IN THE AFTERNOON AND WILL PUSH BACK POPS LATER WEDNESDAY. THURSDAY
MORNING PROMISES TO BE A RUDE AWAKENING FOR MANY DURING THE MORNING
COMMUTE. GFS HAS BEEN ADVERTISING GENTLE LIFT OVER THERMAL RIBBON
ALONG NE/SD BORDER...SO DO EXPECT SOME LIGHT SNOW IN THE
SOUTH...WHERE BEST SFC-700MB FRONTOGENESIS FORESEEN.

EXTENDED...ARCTIC AIR WILL BE ENTRENCHED ACROSS THE NORTHERN PLAINS
BY FRIDAY AND LINGER ACROSS THE REGION THROUGH AT LEAST THE EARLY
PART OF NEXT WEEK. LARGE UPPER TROF WILL ALSO SINK INTO THE ROCKIES
AND PLAINS LATE IN THE WEEK AND REMAIN IN PLACE THROUGH THE WEEKEND.
THIS WILL KEEP THE WEATHER RATHER UNSETTLED WITH A GOOD DEAL OF
CLOUDINESS AND SOME CHANCES FOR LIGHT SNOW THROUGH MOST OF THE
PERIOD. DURING THIS PERIOD...THE BETTER CHANCES FOR SNOW WITH SOME
MINOR ACCUMULATION STILL LOOK TO BE ACROSS THE HILLS AND SOUTHERN
PARTS OF SOUTH DAKOTA.

&&

.AVIATION...AREAS OF MVFR CONDITIONS WITH SNOW SHOWERS CAN BE
EXPECTED ACROSS THE BLACK HILLS AREA THROUGH THIS AFTERNOON
...MAINLY AFFECTING TWEB ROUTES 259 AND 285. GUSTY NORTHWEST WINDS
RIGHT WILL BECOME VERY STRONG ACROSS ALL ROUTES THIS AFTERNOON AND
PERSIST INTO THE EVENING HOURS BEFORE GRADUALLY TAPERING OFF.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WARNING NW THROUGH SC SD THROUGH EARLY EVENING.
  ...WIND ADVISORY FAR SW SD THROUGH EARLY EVENING.
WY...NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
456 AM MST MON JAN 8 2007

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-091400-
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-
456 AM MST (556 AM CST) MON JAN 8 2007

...HIGH WIND WARNING UNTIL 7 PM MST /8 PM CST/ THIS EVENING FOR MOST
OF THE SOUTH DAKOTA PLAINS...
...WIND ADVISORY UNTIL 7 PM MST THIS EVENING FOR SOUTHWESTERN SOUTH
DAKOTA...

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

.DAY ONE...TODAY AND TONIGHT

A TIGHT PRESSURE GRADIENT WILL BRING STRONG WINDS TO PORTIONS OF THE
REGION TODAY. OVER THE SOUTH DAKOTA PLAINS...NORTHWEST WINDS WILL
INCREASE TO 30 TO 50 MPH WITH GUSTS TO 60 AT TIMES BY AFTERNOON.
SEVERAL INCHES OF SNOW OVER THE HIGHER ELEVATIONS OF THE BLACK
HILLS WILL RESULT IN SOME BLOWING SNOW THIS MORNING. WINDS WILL
DIMINISH RAPIDLY TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

ARCTIC AIR WILL OOZE INTO THE NORTHERN PLAINS LATER WEDNESDAY...
BRINGING AN ABRUPT END TO WARMER THAN NORMAL TEMPERATURES. HIGHS
WILL BE 10 TO 20 DEGREES BELOW NORMAL THURSDAY THROUGH SUNDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.