Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 251737
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1137 AM MDT MON APR 25 2016

.UPDATE...
ISSUED AT 1042 AM MDT MON APR 25 2016

MADE SMALL ADJUSTMENTS BASED ON LATEST RADAR TRENDS ALONG WITH
SDDOT WEBCAMS SHOWING SHOWERS UP IN THE NORTHERN PARTS OF ZIEBACH
AND PERKINS COUNTIES. TEMPERATURES ARE STRUGGLING TO GET OUT OF
MID 40S RIGHT NOW... BUT WARMING SHOULD OCCUR QUICKLY AS CLOUDS
THIN OUT SOME. ONLY OTHER CHANGE WAS TO ADD ISOLATED TO SCATTERED
THUNDER TOMORROW JUST NORTH OF NE/SD LINE AS MODELS SHOWING AT
LEAST 200-400 J/KG CAPE IN THESE AREAS.

&&

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
ISSUED AT 234 AM MDT MON APR 25 2016

UPPER LEVEL ANALYSIS HAS CLOSED LOW OVER EASTERN SOUTH DAKOTA WITH
PRECIP SHIELD EAST AND NORTH OF THE FORECAST AREA. SKIES ARE
CLOUDY ACROSS THE AREA...WITH A FEW BREAKS IN THE CLOUDS ACROSS
FAR SOUTHWEST SD. AT THE SURFACE...LOW PRESSURE IS LOCATED ACROSS
SOUTHEAST SD...WITH HIGH PRESSURE NOSING INTO NORTHEAST WYOMING.
TEMPERATURES AT 2AM ARE IN THE 30S AND 40S...AND WINDS ARE OUT OF
THE WEST TO NORTHWEST AT 5 TO 20 MPH...HIGHEST ACROSS THE SD
PLAINS.

FOR TODAY...CLOSED UPPER LOW WILL WEAKEN AND BECOME AN OPEN
SHORTWAVE AS IT MOVES INTO MINNESOTA THIS AFTERNOON. LOW CHANCES
FOR PRECIP WILL CONTINUE ACROSS THE FAR NORTHERN PORTIONS OF THE
CWA...BUT BEST UPPER ENERGY AND MID-LEVEL MOISTURE WILL BE OVER
ND. BRIEF RIDGING BETWEEN SYSTEMS WILL BRING DRIER WEATHER TO MOST
OF THE AREA. HIGH TEMPERATURES WILL RANGE FROM THE 40S ACROSS
NORTHWESTERN SD...TO NEAR 60 ACROSS SOUTHERN PORTIONS OF SD.

TONIGHT...NEXT UPPER LOW TO AFFECT THE FORECAST AREA MOVES ACROSS
THE CENTRAL ROCKIES TONIGHT...WITH RAIN/SNOW EXPANDING ACROSS
NORTHEASTERN WY AND FAR SOUTHWESTERN SD OVERNIGHT. LITTLE OR NO
ACCUMULATION IS EXPECTED ACROSS THE LOWER ELEVATIONS...BUT AN INCH
OR TWO WILL BE POSSIBLE ACROSS THE HIGHER ELEVATIONS OF THE BLACK
HILLS BY TUESDAY MORNING. LOW TEMPERATURES WILL BE IN THE 30S.

ON TUESDAY...CLOSED UPPER LOW SHIFTS INTO THE CENTRAL PLAINS ON
TUESDAY...WITH THE CWA ON THE NORTHERN SIDE OF THE LOW. THIS WILL
PUT THE AREA IN THE OPTIMAL POSITION FOR PRECIPITATION CHANCES
WITH SOME UPSLOPE ENHANCEMENT OCCURRING WITH THE EAST TO
NORTHEAST BOUNDARY LAYER FLOW. MOST LOCATIONS ACROSS THE AREA
SHOULD SEE 1 TO 2 INCHES OF PRECIPITATION THROUGH WEDNESDAY NIGHT.
UPPER AIR TEMPERATURES WILL BE CHILLY WITH THIS SYSTEM...SO
SIGNIFICANT SNOWFALL IS A GOOD POSSIBILITY ACROSS THE HIGHER
ELEVATIONS OF THE BLACK HILLS. THEREFORE...WILL BE ISSUING A
WINTER STORM WATCH FOR THE BLACK HILLS FROM TUESDAY MORNING
THROUGH WEDNESDAY AFTERNOON FOR THE POSSIBILITY OF 6 OR MORE
INCHES OF SNOW. TEMPERATURES ON TUESDAY WILL RANGE FROM THE 30S
ACROSS NORTHEAST WYOMING AND THE BLACK HILLS...TO THE MID 50S
ACROSS FAR SOUTH CENTRAL SOUTH DAKOTA. LOWS TUESDAY NIGHT WILL BE
IN THE 30S TO LOWER 40S.

.LONG TERM...WEDNESDAY THROUGH SUNDAY
ISSUED AT 234 AM MDT MON APR 25 2016

ACTIVE JET AND ASSOCIATED IMPULSES WILL TRACK INTO THE SW CONUS
AND EJECT NE INTO THE PLAINS...WITH THE FA REMAINING ON THE NW
SIDE OF THE MEAN STORM TRACK...SUPPORTING COLD CONDS WITH DECENT
CHANCES FOR PRECIP. CONTINUED TO SIDE TOWARD THE COOLER SIDE OF
THE GUIDANCE SPECTRUM GIVEN CLOUDS/PROGGED PRECIP/AND A HEAVY
TREND IN MODEL DATA TOWARD E/NE UPSLOPE FLOW. RAIN/SNOW WILL
CONTINUE OVER MUCH OF THE AREA WED...WITH A THE FA BEING SITUATED
UNDER THE STRONGEST FGEN COLLOCATED WITH A LEFT EXIT REGION OF AN
UPPER JET STREAK. THE GFS REMAINS THE WARMEST MODEL PER LL TEMPS
AND AN OUTLIER...THUS SIDED TOWARD THE COOLER
NAM/GEM/ECMWF...WHICH SUPPORTS SNOW OVER THE WESTERN THIRD THROUGH
MORNING AND INTO THE AFTERNOON. PRECIP TILL TAPER OFF WED NIGHT
WITH LINGERING PRECIP POSSIBLE THUR AS THE UPPER LOW STALLS OVER
THE REGION. ANOTHER TROUGH WILL EJECT INTO THE PLAINS BY
FRI...SETTING THE STAGE FOR MORE CHANCES FOR PRECIP AS WELL AS
POSSIBLE SNOW ACCUMS. FORECAST MODELS ARE WARMER AND FURTHER SOUTH
WITH THE CLOSED LOW TRACK...WHICH PUTS THE FA ON THE WESTERN EDGE
OF PRECIP. SOME INDICATION TOWARD STAUNCH WESTERN NOAM RIDGING AND
POTENTIAL BLOCKING EARLY NEXT WEEK...WHICH COULD LEAVE THE REGION
UNDER A WEAK NEGATIVE HEIGHT ANOMALY AND UNSETTLED NORTHERLY
FLOW...ALTHOUGH SLIGHTLY WARMER. OVERALL...TEMPS WILL BE WELL
BELOW SEASONAL NORMS IN THE PERIOD...ESP WED-THU.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 1129 AM MDT MON APR 25 2016

AREAS IFR CIGS/VSBYS EXPECTED ACROSS FAR NORTHEAST WY INTO FAR
NORTHWEST SD THROUGH THE PERIOD WITH SOME -SHRA/DZ/BR THIS
AFTERNOON. MVFR CIGS EXPECTED THROUGH THIS EVENING FROM EAST
CENTRAL WY INTO NORTH CENTRAL SD. VFR CONDITIONS EXPECTED ACROSS
FAR SOUTHERN SOUTH DAKOTA THROUGH THIS EVENING. CONDITIONS ALL
AREAS WILL THEN DETERIORATE OVERNIGHT AS A LARGE STORM SYSTEM
MOVES FROM SOUTH TO NORTH WITH WIDESPREAD IFR CIGS/VSBYS DUE TO
-RASN THROUGH TUESDAY WITH LOCAL LIFR CONDITIONS OVER THE HIGHER
ELEVATIONS WITH ST/FG.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY
     AFTERNOON FOR SDZ024-028-029.

WY...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY
     AFTERNOON FOR WYZ057.

&&

$$

SHORT TERM...15
LONG TERM...JC
AVIATION...HELGESON



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