Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 231720
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1120 AM MDT SAT APR 23 2016

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 313 AM MDT SAT APR 23 2016

UPPER LEVEL ANALYSIS HAS VERY STRONG CLOSED LOW ACROSS THE GREAT
BASIN...WITH RIDGING ACROSS THE CENTRAL CONUS. SKIES ARE PARTLY
CLOUDY ACROSS THE NORTHERN PLAINS...WITH MID TO HIGH LEVEL CLOUD
COVER STREAMING IN FROM THE SOUTHWEST. AT THE SURFACE...LOW
PRESSURE IS LOCATED ACROSS SOUTH CENTRAL MONTANA...WITH WEAK
BOUNDARY STRETCHING EAST ACROSS NORTHWESTERN SOUTH DAKOTA.
SOUTHERLY BOUNDARY LAYER FLOW HAS KEPT TEMPERATURES VERY MILD
OVERNIGHT...WITH READINGS AT 3 AM IN THE 50S AND 60S.

TODAY...UPPER RIDGE AXIS SHIFTS EAST OF AREA...BUT CORE OF VERY
WARM AIR WILL REMAIN OVER THE REGION DURING THE DAY. MAJORITY OF
MODELS STILL SHOWING 850MB TEMPERATURES BETWEEN 20 TO 24 DEGREES
CELSIUS THIS AFTERNOON...WITH WARMEST AIR ALOFT GENERALLY OVER
SOUTHWESTERN SOUTH DAKOTA. WILL LIKELY SEE LOWER 80S FOR HIGHS
ACROSS THE SOUTH DAKOTA PLAINS. BREEZY SOUTHERLY WINDS WILL
PERSIST ACROSS SOUTH CENTRAL SOUTH DAKOTA...WITH SOUTHWEST WINDS
EXPECTED ACROSS NORTHEAST WYOMING THIS AFTERNOON.

TONIGHT...UPPER LOW CROSSES THE NORTHERN ROCKIES...AND MOVES INTO
THE FORECAST AREA AFTER MIDNIGHT. STEEP LAPSE RATES AND ENERGY
LIFTING OUT OF THE LOW DURING THE EVENING WILL LIKELY PROVIDE
ENOUGH LIFT TO INITIATE SHOWERS AND THUNDERSTORMS ACROSS NORTHEAST
WYOMING AND THE BLACK HILLS EARLY THIS EVENING. REGARDING THE
SEVERE WEATHER POTENTIAL...THERE IS A MARGINAL RISK FOR SEVERE
STORMS ACROSS THE AREA...WITH GUSTY WINDS AND MARGINALLY SEVERE
HAIL A POSSIBILITY WITH THESE STORMS. STORMS WILL BE FIGHTING FOR
MOISTURE...AS NEAR 50S DEWPOINTS WILL HAVE A DIFFICULT TIME
ADVECTING THIS FAR NORTH BY THIS EVENING. ANTICIPATED LOW LEVEL
JET SHOULD ASSIST THE CONVECTION WELL INTO THE OVERNIGHT HOURS.
LATER INTO THE NIGHT...UPPER LOW MOVES INTO THE REGION. STRONG
ISENTROPIC LIFT ON THE BACKSIDE OF THE LOW WILL CREATE WIDESPREAD
PRECIPITATION ACROSS NORTHEASTERN WYOMING AND NORTHWESTERN SOUTH
DAKOTA BY SUNDAY MORNING.

SUNDAY...UPPER LEVEL LOW CROSSES THE FORECAST AREA...WITH
WIDESPREAD RAIN EXPECTED ACROSS MUCH OF NORTHEAST WYOMING AND
NORTHWEST SOUTH DAKOTA...MORE SHOWERY RAIN EXPECTED FROM RAPID
CITY SOUTH AND EAST. PRECIP TOTALS FROM THIS SYSTEM RANGE FROM
NEAR AN INCH ACROSS FAR NORTHERN AREAS...TO ONLY A FEW HUNDREDTHS
ACROSS FAR SOUTH CENTRAL SOUTH DAKOTA. WITH THE PRECIP AND
WIDESPREAD CLOUDINESS...TEMPERATURES WILL RANGE FROM THE 40S IN
THE HEAVIER PRECIP AREAS...TO AROUND 70 IN SOUTH CENTRAL SD.
SYSTEM WILL SHIFT EAST SUNDAY NIGHT...WITH PRECIP TAPERING OFF
QUICKLY AFTER MIDNIGHT. COULD BE SOME VERY LIGHT ACCUMULATIONS OF
SNOW ACROSS THE HIGHER ELEVATIONS OF NORTHEAST WYOMING AND THE
BLACK HILLS...BUT PRECIP SHOULD BE WRAPPING UP BY THE TIME TEMPS
FALL TO NEAR FREEZING LATE SUNDAY NIGHT.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 313 AM MDT SAT APR 23 2016

ACTIVE/SEMI-PROGRESSIVE FLOW EXPECTED THROUGH THE PERIOD WITH A
TRAIN OF DISTURBANCES PROGGED IN ALL GUIDANCE TO AFFECT THE
REGION. ACTIVE JET AND ASSOCIATED IMPULSES WILL TRACK INTO THE SW
CONUS AND EJECT NE INTO THE PLAINS. H7 STORM TRACK WILL SHIFT
SOUTH WITH EACH SYSTEM...SUPPORTING BETTER CHANCES FOR PRECIP AS
WELL AS COOLER CONDS WITH EACH SYSTEM WITH PERSISTENT NORTHERLY
COMPONENT TO THE LL FLOW. THIS WILL SET THE STAGE FOR INCREASING
CHANCES FOR SNOW...ESP ON THE HIGHER TERRAIN OF NE WY AND THE
BLACK HILLS...EVEN PORTIONS OF THE SD PLAINS. HAVE SIDED TOWARD
THE COOLER SIDE OF THE GUIDANCE SPECTRUM GIVEN THE CLOUDS/PROGGED
PRECIP/AND A HEAVY TREND IN MODEL DATA TOWARD E/NE UPSLOPE FLOW.
THERE IS THE POTENTIAL FOR WIDESPREAD APPRECIABLE QPF...ESP IF MID
LEVEL CLOSED CIRCULATIONS DEVELOP AND TRACK OVER NEBRASKA. THIS
PATTERN WILL ALSO NEED TO BE MONITORED FOR ACCUMULATING
SNOWS...ESP BY MID WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1118 AM MDT SAT APR 23 2016

VFR CONDITIONS WILL CONTINUE THROUGH THIS AFTERNOON. A FEW
THUNDERSTORMS ARE POSSIBLE LATE AFTERNOON ACROSS NORTHEAST
WYOMING INTO FAR WESTERN SOUTH DAKOTA...WITH INCREASING COVERAGE
OF SHRA/TS THIS EVENING. MVFR/LCL IFR CONDITIONS WITH THE
THUNDERSTORMS. MVFR CIGS WILL SHIFT SE INTO THE AREA SUNDAY
MORNING BEHIND A COLD FRONT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

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



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