Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 122302
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
502 PM MDT SAT APR 12 2014

.SHORT TERM...THIS EVENING THROUGH SUNDAY NIGHT
ISSUED AT 320 PM MDT SAT APR 12 2014

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER NORTHWESTERN
KS...WITH CANADIAN COLD FRONT SINKING SOUTHWARD ACROSS THE CWA
NOW. UPPER LEVEL ANALYSIS SHOWS WEST-SOUTHWEST FLOW ACROSS THE
REGION...WITH TROF SINKING SOUTHEASTWARD ACROSS THE NORTHERN
ROCKIES AND INTERMOUNTAIN WEST. CLOUDS ARE INCREASING FROM WEST TO
EAST...WITH SKIES MOSTLY CLOUDY NOW FROM NORTHEAST WY INTO THE
BLACK HILLS AREA AND NORTHWESTERN SD. TEMPS GENERALLY RANGE FROM
THE 50S OVER NORTHEAST WY...THE BLACK HILLS...AND FAR NORTHWEST
SD...TO THE LOWER 70S ACROSS SOUTH CENTRAL SD. BRISK NORTH TO
NORTHWEST WINDS ARE IN PLACE ACROSS THE PLAINS. KUDX RADAR IS
SHOWING SOME WEAK RETURNS AND PERHAPS SOME SPRINKLES ACROSS
NORTHWESTERN SD...WITH SHOWERS DEVELOPING FURTHER SOUTH AND WEST
ACROSS WY AND SOUTHERN MT.

UNSETTLED WEATHER CAN BE EXPECTED TONIGHT INTO SUNDAY AS THE TROF TO
THE WEST MOVES SOUTHEAST INTO THE CENTRAL ROCKIES AND HIGH PLAINS BY
SUNDAY AFTERNOON. THIS SYSTEM WILL BRING AT LEAST SOME PCPN TO
SOUTHERN AND WESTERN PORTIONS OF THE CWA...ESPECIALLY NORTHEAST WY
INTO SOUTHWESTERN SD. MOST OF THE SHORT RANGE MODELS ARE IN GOOD
AGREEMENT ON GENERAL TRACK OF THE UPPER LEVEL SYSTEM...WITH NAM
REMAINING AN OUTLIER. THE TRENDS HAVE BEEN TO DIG THE TROF A BIT
FURTHER SOUTH AND WEST ACROSS THE ROCKIES TONIGHT...WHICH WILL FOCUS
THE HEAVIER PCPN FURTHER OUT OF OUR CWA...WITH PORTIONS OF NORTHEAST
WY AND SOUTHWESTERN SD SEEING THE BEST POTENTIAL FOR MORE
SIGNIFICANT PCPN AMOUNTS. THE BIGGEST ISSUE WITH THIS SYSTEM IS THE
TIMING OF CHANGEOVER TO SNOW...WHICH WILL AFFECT SNOWFALL TOTALS
ACROSS THE AREA. AS WITH MOST SYSTEMS THIS TIME OF YEAR...ELEVATION
WILL PLAY THE BIGGEST ROLE IN TIMING AND EVENTUAL SNOWFALL
AMOUNTS.

PCPN WILL START OFF AS RAIN LATE TODAY INTO THIS EVENING...WITH RAIN
CHANGING TO SNOW IN MOST AREAS OVERNIGHT AS COLDER AIR FILTERS IN
BEHIND THE PASSING COLD FRONT. THE TIMING OF THIS WILL BE
TRICKY...BUT THE CHANGEOVER WILL BE QUICKEST OVER THE HIGHER
ELEVATIONS...SPECIFICALLY THE BLACK HILLS AND THE HIGHER TERRAIN OF
NORTHEASTERN WY. THIS SHOULD TAKE PLACE DURING THE EVENING...WITH
SNOW LEVELS LIKELY DROPPING TO NEAR 4000 FT AROUND MIDNIGHT. THE
CHANGEOVER SHOULD OCCUR ACROSS THE REST OF THE AREA LATE TONIGHT
INTO EARLY SUNDAY...THOUGH TIMING LOOKS TO BE A BIT SLOWER THAN WAS
EXPECTED ACROSS THE PLAINS SOUTHEAST OF THE BLACK HILLS. WITH MOST
OF THE PCPN FALLING ACROSS NORTHEASTERN WY AND SOUTHERN SD LATE
TONIGHT AND EARLY SUNDAY...ANY SIGNIFICANT SNOWFALL SHOULD BE
LIMITED TO THE HIGHER ELEVATIONS OF NORTHEAST WY...THE BLACK
HILLS...AND PERHAPS FAR SOUTHWEST SD. SOME UPSLOPE ENHANCED SNOWFALL
IS ALSO EXPECTED ACROSS THE NORTHERN BLACK HILLS OVERNIGHT AS
NORTHERLY WINDS INCREASE. HAVE DECIDED TO ISSUE A WINTER WX ADVISORY
FOR A GOOD PORTION OF NORTHEAST WY...THE NORTHERN AND CENTRAL BLACK
HILLS...AS WELL AS THE FALL RIVER COUNTY PLAINS. GENERAL 2 TO 4 INCH
AMOUNTS ARE EXPECTED...BUT COULD OBVIOUSLY BE MORE OR LESS DEPENDING
ON THE TIMING OF CHANGEOVER AND WHERE ANY HEAVIER BANDS COULD
DEVELOP.

PCPN LOOKS LIKE IT WILL TAPER OFF PRETTY QUICKLY ACROSS THE AREA BY
LATE MORNING...WITH ANY ACCUMULATING SNOW DONE WITH BY MIDDAY. HIGHS
WILL BE IN THE 30S AND LOWER 40S...WARMEST OVER FAR EASTERN PORTIONS
OF THE CWA. GUSTY NORTHERLY WINDS WILL DEVELOP ACROSS THE PLAINS IN
THE MORNING AND PERSIST INTO THE AFTERNOON. A WIND ADVISORY MAY BE
NEEDED FOR THE WEST CENTRAL SD PLAINS IF WINDS ARE PROJECTED TO BE
ANY STRONGER.

CLOUDS WILL DECREASE FROM NORTH TO SOUTH SUNDAY AFTERNOON...WITH
PARTLY CLOUDY SKIES EXPECTED SUNDAY NIGHT. CHILLY TEMPS CAN BE
EXPECTED SUNDAY NIGHT...WITH LOWS MOSTLY IN THE 20S...SOME TEENS
OVER THE BLACK HILLS AS WELL AS SHELTERED AND SNOW COVERED
AREAS.

&&

.LONG TERM...MONDAY THROUGH SATURDAY
ISSUED AT 320 PM MDT SAT APR 12 2014

A WEAK UPPER LEVEL RIDGE WILL BRING DRY AND COOL WEATHER TO THE
REGION MONDAY. A SHORTWAVE TROUGH WILL APPROACH TUESDAY WITH
WARMING TEMPERATURES AHEAD OF IT. THIS FEATURE WILL CARVE OUT A
LARGER UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS FOR THE SECOND
HALF OF NEXT WEEK WITH CYCLONIC FLOW AND PERIODIC CHANCES FOR
PRECIPITATION. GUIDANCE IS STARTING TO CONVERGE ON SIMILAR
SOLUTIONS...BUT SOME TIMING AND STRENGTH DIFFERENCES CONTINUE.
THEY ARE IN DECENT AGREEMENT FOR BELOW NORMAL TEMPERATURES. WILL
KEEP PREVIOUS FORECAST LARGELY INTACT WITH CHANCES FOR NOTICEABLE
SNOW MAINLY AT NIGHT.

&&

.AVIATION...FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING
ISSUED AT 500 PM MDT SAT APR 12 2014

A COLD FRONT WILL EASE THROUGH THE AREA TONIGHT WITH INCREASING
CHANCES FOR RAIN. AS COLD AIR ARRIVES OVERNIGHT...RAIN WILL CHANGE
TO SNOW. WIDESPREAD MVFR CIGS AND IFR/LIFR VSBYS WITH
PRECIPITATION WILL THEN OCCUR THROUGH SUNDAY MORNING. CONDITIONS
WILL SLOWLY IMPROVE SUNDAY AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON MDT
     SUNDAY FOR SDZ024-028.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON MDT
SUNDAY      FOR SDZ041.

WY...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON MDT
     SUNDAY FOR WYZ054-055-057.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON MDT
SUNDAY      FOR WYZ058.

&&

$$

SHORT TERM...26
LONG TERM...HELGESON
AVIATION...HELGESON









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