Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 221103
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
503 AM MDT FRI APR 22 2016

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 249 AM MDT FRI APR 22 2016

UPPER LEVEL ANALYSIS HAS RIDGE OVER THE CENTRAL CONUS...WITH
CLOSED LOW AND ASSOCIATED TROF JUST OFF THE WEST COAST. SKIES ARE
MOSTLY CLEAR ACROSS THE CENTRAL PLAINS WITH JUST SOME VERY THIN
CIRRUS CROSSING THE FORECAST AREA. AT THE SURFACE...WEAK LOW
PRESSURE IS LOCATED ACROSS CENTRAL MONTANA...WITH WEAK SURFACE
BOUNDARY DRAPED ACROSS THE BLACK HILLS AREA. HIGH PRESSURE IS
LOCATED ACROSS NORTH CENTRAL SD. WINDS ARE LIGHT ACROSS MUCH OF
THE AREA...WITH SOME BREEZY SOUTHERLY WINDS ACROSS NORTHEAST WY.
TEMPERATURES AT 3 AM ARE IN THE UPPER 30S TO UPPER 40S.

FOR TODAY...WARMER AIR WILL CONTINUE TO PUSH INTO THE REGION
TODAY AS RIDGE MOVES OVER THE HIGH PLAINS AND WEAK SURFACE
BOUNDARY SHIFTS NORTH AND EAST OF THE AREA AS A WARM FRONT. HIGHS
WILL BE IN THE 70S ACROSS THE AREA...WITH SOME LOCATIONS OVER
NORTHEAST WY AND FAR WESTERN SD NEAR 80 DEGREES. TIGHTENING
PRESSURE GRADIENT WILL BRING BREEZY SOUTH-SOUTHEAST WINDS ACROSS
MUCH OF THE SD PLAINS BY THE AFTERNOON. MILD CONDITIONS CONTINUE
INTO TONIGHT...LOWS IN THE MID 40S TO MID 50S...WITH BREEZY
WINDS LINGERING ACROSS PORTIONS OF THE SD PLAINS AS LOW LEVEL JET
INTENSIFIES OVER THE WESTERN DAKOTAS AND CENTRAL PLAINS.

SATURDAY...UPPER RIDGE SHIFTS INTO THE MIDWEST AS CLOSED LOW MOVES
INTO THE GREAT BASIN AND CENTRAL ROCKIES. WEAK SURFACE LOW MOVES
FROM MONTANA INTO WESTERN SOUTH DAKOTA BY AFTERNOON...WITH BREEZY
SOUTHERLY WINDS ACROSS SOUTH CENTRAL SD...AND GUSTY SOUTHWEST
WINDS ACROSS NORTHEAST WYOMING. LATE IN THE DAY...UPPER LEVEL
ENERGY AND WEAK INSTABILITY WILL SHIFT INTO WESTERN PORTIONS OF
THE FORECAST AREA...WITH SOME SHOWERS AND THUNDERSTORMS POSSIBLE
IN THE EVENING. BETTER CHANCES FOR PRECIPITATION CROSSES WESTERN
AND NORTHERN PORTIONS OF THE AREA AFTER MIDNIGHT. LOW TEMPERATURES
WILL FALL INTO THE MID 40S TO MID 50S.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 249 AM MDT FRI APR 22 2016

SUNDAY THROUGH THURSDAY. THE FIRST UPPER LOW WILL MOVE SLOWLY E-W
ACROSS SOUTH DAKOTA FROM SUNDAY MORNING THROUGH SUNDAY EVENING
BRINGING CLOUDS...WIDESPREAD SHOWERS AND THUNDERSTORMS AND COOLING
TEMPERATURES. TEMPERATURE PROFILES IN MODEL SOUNDINGS INDICATE
THAT CONDITIONS MAY BE COOL ENOUGH FOR A LITTLE SNOW OVER THE
HIGHER ELEVATIONS OF THE BLACK HILLS LATE SUNDAY NIGHT/EARLY
MONDAY MORNING WITH A RAIN/SNOW MIX POSSIBLE OVER PARTS OF FAR
NORTHWESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING. MODELS DIFFER
SLIGHTLY ON PRECIP CHANCES FOR MONDAY BUT SEEM TO BE CONVERGING ON
DEVELOPING A TRANSIENT UPPER RIDGE DEVELOPING BETWEEN THE FIRST
DEPARTING UPPER LOW AND THE SECOND UPPER LOW WHICH WILL BE
DEEPENING OVER THE FOUR CORNERS REGION. THEREFORE HAVE STARTED TO
LOWER POPS ON MONDAY...ESPECIALLY ACROSS THE SOUTHERN PARTS OF THE
FORECAST AREA. LEFT SLIGHTLY HIGHER POPS ACROSS THE NORTH WHERE
THE ECMWF CONTINUES TO SHOW LIGHT PRECIP IN THE CYCLONIC CURVATURE
ZONE BEHIND THE FIRST UPPER LOW AND WHERE THE BEST INSTABILITY
WILL OCCUR DUE TO COLDER ROTATING IN ALOFT. INSTABILITY AND
PRECIPITATION COVERAGE WILL INCREASE AGAIN ON MONDAY NIGHT AS THE
SECOND UPPER LOW APPROACHES FROM THE SOUTHWEST. THE RELATIVELY
SLOW MOVEMENT OF THE SECOND UPPER LOW WILL KEEP CHANCES OF SHOWERS
AND THUNDERSTORMS...ALONG WITH COOLER TEMPERATURES...IN THE
FORECAST FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT. TEMPERATURES
ALOFT AND AT THE SFC MAY AGAIN BE COOL ENOUGH FOR SOME LIGHT SNOW
OVER THE HIGHER BLACK HILLS EARLY EACH MORNING. DRY WEATHER IS
EXPECTED THURSDAY BEFORE THE THIRD UPPER LOW BRINGS ANOTHER CHANCE
OF PRECIPITATION ON FRIDAY.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 503 AM MDT FRI APR 22 2016

VFR CONDITIONS WILL CONTINUE TODAY AND TONIGHT. BREEZY SOUTHERLY
WINDS WILL DEVELOP ON THE PLAINS OF WESTERN SOUTH DAKOTA TODAY.

&&

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

$$

SHORT TERM...15
LONG TERM...10
AVIATION...10



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