Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KUNR 020433
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
933 PM MST SUN MAR 1 2015

.UPDATE...
ISSUED AT 912 PM MST SUN MAR 1 2015

MAIN REASON FOR UPDATING WAS TO ISSUE A WINTER STORM WATCH FOR SW
THROUGH SCNTRL SD LATE MON NIGHT THROUGH TUE MRNG. MODELS IN GOOD
AGREEMENT THAT A FEW INCHES OF SNOWFALL...PROBABLY 4 INCHES OR
LESS...WILL FALL ACROSS THAT AREA. MORE WORRISOME ARE THE GUSTY NW
WINDS EXPECTED THAT COULD PRODUCE A PERIOD OF NEAR WHITEOUT
CONDITIONS IN OPEN AREAS. CONTEMPLATED PUTTING RAPID CITY IN THE
WATCH BUT BELIEVE THERE WILL BE ENOUGH SHELTERING IN TOWN FROM
THE WORST CONDITIONS. THE CURRENT WATCH AREA MAY NEED TO BE
BORDERED WITH WINTER WX ADVISORIES ON THE WRN AND NRN EDGES. STAY
TUNED.

&&

.SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT
ISSUED AT 235 PM MST SUN MAR 1 2015

UPPER WAVE IS SHIFTING OUT OF THE NORTHERN PLAINS WHILE CLOSED
LOW CONTINUES TO SPIN OVER CA. CUMULUS CLOUDS HAVE SPREAD
ACROSS THE CWA WITH SOME SNOW SHOWERS OVER PARTS OF SOUTHWEST
ND/SOUTHEAST MT. AT THE SURFACE...AN AREA OF HIGH PRESSURE
STRETCHES FROM CENTRAL MT INTO NE...AND A SOMEWHAT TIGHT PRESSURE
GRADIENT OVER SD IS KEEPING NORTHWEST WINDS BREEZY. TEMPS ARE
RISING INTO THE 20S AND LOWER 30S.

RETURN FLOW WILL DEVELOP TONIGHT AS HIGH PRESSURE SHIFTS
EASTWARD...AND WARM AIR WILL BEGIN TO ADVECT INTO THE AREA. UNDER
PARTLY CLOUDY SKIES...LOWS WILL BE 5 TO 15.

A WEAK UPPER RIDGE WILL BRIEFLY COVER THE CENTRAL STATES AS THE
TROUGH ASSOCIATED WITH A STRONG CANADIAN UPPER LOW BEGINS TO SWEEP
THE CALIFORNIAN LOW EASTWARD. SURFACE LOW PRESSURE PUSHES INTO THE
REGION AND PRESSURE GRADIENT TIGHTENS BETWEEN THAT AND THE EXITING
HIGH PRESSURE...PRODUCING SOME STRONG SOUTHERLY WINDS ACROSS SOUTH
CENTRAL SD AROUND MIDDAY MONDAY. WINDS AROUND 25 KTS WITH GUSTS OF
35 KTS ARE EXPECTED FOR A FEW HOURS BUT WILL QUICKLY DIMINISH MONDAY
AFTERNOON AS THE TROUGH AXIS MOVES THROUGH THE CWA. LOOKS LIKE ONLY
A MARGINAL WIND ADVISORY EVENT SO WILL HOLD OFF ISSUING HEADLINES
FOR NOW. HIGHS MONDAY WILL BE IN THE MID 30S TO MID 40S...WITH
CLOUDS INCREASING FROM THE SOUTH.

UPPER TROUGH WILL MOVE EASTWARD OVER THE ROCKIES AND COLD FRONT WILL
PUSH INTO THE REGION MONDAY EVENING. NORTHWEST WINDS WILL INCREASE
TO 20-30 KTS WITH HIGHER GUSTS BY TUESDAY MORNING...STRONGEST ACROSS
THE SD PLAINS...AND STRONG CAA WILL COMMENCE. SNOW WILL BEGIN MOVING
INTO NORTHEAST WY/SOUTHWEST SD BY MIDNIGHT AND SPREAD NORTHEASTWARD
AS THE NIGHT PROGRESSES. BEST FRONTOGENESIS CROSSES THE CWA BETWEEN
06Z AND 12Z. GENERALLY 1-3 INCHES OF SNOW IS EXPECTED BY 12Z TUESDAY
IN MOST PLACES...WITH LESSER AMOUNTS ACROSS NORTHWEST SD. STRONG
NORTHWEST WINDS WILL CREATE BLOWING SNOW AND REDUCED VISIBILITIES.
ALTHOUGH SNOW AMOUNTS WILL BE FAIRLY LIGHT...MAY NEED AN ADVISORY
LATER WITH BLOWING SNOW CONCERNS. FOR NOW WILL JUST EMPHASIZE THE
EVENT IN WXSTORY AND HWO. LOWS WILL RANGE FROM NEAR ZERO ACROSS THE
NORTHWESTERN CWA TO THE MID TEENS IN SOUTH CENTRAL SD.

.LONG TERM...TUESDAY THROUGH SUNDAY
ISSUED AT 235 PM MST SUN MAR 1 2015

UPPER TROF LOCATED ACROSS THE DAKOTAS ON TUESDAY. LEADING SHORTWAVE
TRACKS INTO SOUTHERN MINNESOTA TUESDAY MORNING...WITH SECONDARY WAVE
DROPPING THROUGH THE WESTERN DAKOTAS LATE TUESDAY/TUESDAY NIGHT.
BEST ISENTROPIC LIFT/SNOWFALL ACCUMULATIONS WILL BE ACROSS THE
SOUTHERN HALF OF THE FORECAST AREA TUESDAY MORNING. SOME MID LEVEL
DRYING WORKS INTO THE AREA TUESDAY AFTERNOON...BUT WITH STEEP LOW
LEVEL LAPSE RATES...-SHSN/FLURRIES WILL CONTINUE THROUGH THE
AFTERNOON. GUSTY NORTHWEST WINDS...AIDED BY 5-7MB/3HR PRESSURE RISES
WILL CREATE SOME AREAS OF BLOWING SNOW. HIGH FROUDE/1-2KM RH
FAVORABLE FOR SOME UPSLOPE ENHANCEMENT. HOWEVER...SHORT DURATION OF
FAVORABLE CONDITIONS WILL LIMIT SNOWFALL AMOUNTS. ARCTIC HIGH
SETTLES IN ACROSS THE DAKOTAS FOR WEDNESDAY...HIGHS 20-25F BELOW
AVERAGE.

GFS/ECMWF HAVE BEEN TRENDING SLOWER WITH WARMUP FOR THE END OF THE
WEEK...WITH RIDGE A LITTLE FURTHER WEST. THIS KEEPS NORTHWEST FLOW
ACROSS THE FORECAST AREA...WITH WEAK COLD FRONT PASSAGE LATE
FRIDAY/EARLY SATURDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 912 PM MST SUN MAR 1 2015

VFR CONDITIONS ARE EXPECTED THROUGH MONDAY AFTERNOON. A FAST
MOVING WINTER STORM WILL BRING RAPIDLY DETERIORATING CONDITIONS TO
PARTS OF NERN WY AND SWRN SD BY LATE MONDAY EVENING.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING
     FOR SDZ030>032-042>044-046-047-049.

WY...NONE.
&&

$$

UPDATE...JOHNSON
SHORT TERM...POJORLIE
LONG TERM...7
AVIATION...JOHNSON





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.