Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 180416
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1016 PM MDT FRI APR 17 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MDT FRI APR 17 2015

UPPER LEVEL ANALYSIS HAS GENERALLY ZONAL FLOW ACROSS SOUTHERN
CANADA WITH LARGE CUT OFF LOW OVER THE FOUR CORNERS REGION. SKIES
ARE CLOUDY ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA...WITH
PARTLY SUNNY SKIES TO THE NORTH. LIGHT BANDS OF MOISTURE HAVE BEEN
ROTATING NORTH OUT OF THE UPPER LOW AND INTO FAR SOUTHERN
PORTIONS OF SOUTH DAKOTA. AT THE SURFACE...HIGH PRESSURE RESIDES
ACROSS THE FAR NORTHERN HIGH PLAINS WITH LOW PRESSURE DEVELOPING
ACROSS THE COLORADO ROCKIES. TEMPERATURES ARE IN THE 60S WHERE THE
SUN IS MAKING IT THROUGH THE CLOUDS...AND IN THE 50S WHERE THICKER
CLOUD COVER PERSISTS.

AS THE UPPER LOW MOVES ACROSS CO TONIGHT...LOW LEVEL MOISTURE AND
UPPER LEVEL ENERGY WILL EXPAND NORTHWARD INTO THE NORTHERN
PLAINS...ESPECIALLY AFTER MIDNIGHT. RAIN/RAIN SHOWERS WILL
CONTINUE TO SLOWLY MOVE NORTH OVERNIGHT WITH WIDESPREAD COVERAGE
OF SHOWERS BY EARLY SATURDAY MORNING FROM THE BLACK HILLS SOUTH.
WITH THE UPPER LOW STAYING FAR ENOUGH SOUTH OF THE CWA...TEMPS
WILL STAY WARM ENOUGH FOR MOSTLY RAIN ACROSS EVEN THE BLACK
HILLS...BUT COULD SEE A MIX OVER THE HIGHEST ELEVATIONS...MAINLY
LATE TONIGHT/EARLY SATURDAY AND THEN SATURDAY NIGHT WHEN THE
SYSTEM EXITS. RAINFALL AMOUNTS OF ONE QUARTER TO HALF AND INCH
LOOK REASONABLE FOR MOST AREAS...WITH HIGHER AMOUNTS POSSIBLE
ACROSS PORTIONS OF SOUTH CENTRAL AND WEST CENTRAL SOUTH DAKOTA.

A STRONG COLD FRONT WILL TRACK ACROSS THE CWA LATE SATURDAY AND
SATURDAY NIGHT...HELPING TO PUSH THE SYSTEM OUT OF THE
REGION...BUT WILL BRING VERY GUSTY WINDS ACROSS THE AREA INTO
SUNDAY.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MDT FRI APR 17 2015

AFOREMENTIONED UPPER LOW WILL RACE INTO THE MIDWEST SUNDAY AS
NORTHERN STREAM KICKER MOVES ACROSS THE UPPER MIDWEST. SURFACE LOW
OVER NORTHERN MN SUNDAY MORNING WILL LEAVE A TIGHT PRESSURE
GRADIENT IN IT/S WAKE AS 1030MB HIGH SQUEEZES INTO MT/WY. GUSTY
NORTHWEST WINDS EXPECTED WITH MUCH DRIER AIR AND AN END TO
PRECIPITATION.

UPPER RIDGE EXPECTED OVER THE ROCKIES MONDAY THROUGH WEDNESDAY WITH
UPPER LOW JUST NORTH OF THE GREAT LAKES. RATHER DRY NORTHWEST FLOW
EXPECTED OVER THE CWA. LOOKS LIKE A BACK DOOR COLD FRONT WILL DROP
ONTO THE SD PLAINS LATER TUESDAY INTO WEDNESDAY WHICH MAY IMPACT
TEMPERATURE/CLOUD FORECAST. MODELS THEN DIVERGE SOMEWHAT FOR THE END
OF NEXT WEEK WITH A COL/BLOCKING-TYPE FEATURE OVER THE CWA LEAVING
MAIN WEATHER MAKES NORTH NORTHEAST AND SOUTHWEST OF THE
AREA...ALTHOUGH PRECIPITATION COULD DEVELOP ALONG FRONTAL BOUNDARY.
TEMPERATURES THROUGH THE PERIOD WILL BE SEASONAL...BUT IF THE BACK
DOOR COLD FRONT IS STRONG ENOUGH...COULD BE CHILLY EAST OF THE BLACK
HILLS MID-WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1011 PM MDT FRI APR 17 2015

A SLOW MOVING UPPER LOW WILL SLOWLY SPREAD RAIN FROM SOUTH TO
NORTH ACROSS THE AREA THROUGH SATURDAY. ACROSS WRN SD...MVFR
CIGS/VSBYS ARE EXPECTED ACROSS ALL BUT FAR NWRN SD. PARTS OF NERN
WY WILL ALSO REMAIN VFR. SOME LIFR CIGS/VSBYS EXPECTED OVER THE
HIGHER TERRAIN OF THE BLACK HILLS. CONDITIONS WILL IMPROVE FROM
NORTHWEST TO SOUTHEAST BEGINNING LATE SATURDAY AFTN BEHIND A
CDFNT.

&&

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

$$

SHORT TERM...15
LONG TERM...HELGESON
AVIATION...JOHNSON



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