Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 261549
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
949 AM MDT TUE APR 26 2016

.UPDATE...
ISSUED AT 932 AM MDT TUE APR 26 2016

UPPER LOW SPINS OVER NORTHWESTERN CO...WITH BAND OF RAIN/SNOW
ROTATING THROUGH SD. PRECIP IS CLEARING OUT OF SOUTHERN SD AS
DRIER MID-LEVEL AIR MOVES INTO THE REGION. LATEST NAM...ALONG WITH
HRRR AND OTHER HI-RES MODELS...ARE HINTING AT MORE SCATTERED
PRECIP TODAY INTO TONIGHT...WITH HEAVIEST BAND DEVELOPING ACROSS
CENTRAL SD. DECREASED POPS TO REFLECT RADAR AND MODEL TRENDS.
ACCUMULATING SNOWFALL STILL EXPECTED OVER NORTHEASTERN WY AND THE
BLACK HILLS...BUT DECREASED PRECIP CHANCES MAY REDUCE OVERALL
TOTALS...AND SO WILL HAVE TO CONSIDER THIS FOR AFTERNOON FORECAST
PACKAGE.

&&

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
ISSUED AT 349 AM MDT TUE APR 26 2016

UPPER LEVEL ANALYSIS HAS STRONG CLOSED LOW ENTERING THE CENTRAL
ROCKIES...WITH LARGE AREA OF PRECIP MOVING NORTH INTO SOUTHWESTERN
SOUTH DAKOTA AND NORTHEAST WYOMING. PER WEB CAMS/ASOS...SNOW HAS
STARTED ACROSS THESE AREAS. AT THE SURFACE...LOW PRESSURE IS
LOCATED ACROSS NORTH CENTRAL COLORADO. TEMPERATURES ACROSS THE
AREA AT 3AM ARE IN THE 30S...WITH LIGHT NORTHERLY WINDS.

TODAY...CLOSED LOW ELONGATES AND DEVELOPS TWO CIRCULATIONS AS IT
CROSSES THE CENTRAL ROCKIES. THE NORTHERN CIRCULATION LIFTS INTO
EASTERN WYOMING BY THIS AFTERNOON...WITH A DECENT SLUG OF MOISTURE
LIFTING THROUGH THE WESTERN PORTION OF THE FORECAST AREA.
TEMPERATURES ARE COOL ENOUGH THIS MORNING THAT A MAJORITY OF THE
MOISTURE WILL FALL AS WET SNOW ACROSS THE HIGHER ELEVATIONS OF
NORTHEAST WYOMING AND THE BLACK HILLS. SNOWFALL AMOUNTS OF 4 TO 6
INCHES COULD FALL THROUGH THE MORNING AND EARLY AFTERNOON HOURS
ACROSS SOUTHERN CAMPBELL COUNTY AND THE BLACK HILLS...WITH LIGHTER
AMOUNTS ACROSS THE REMAINDER OF THE NORTHEAST WYOMING PLAINS.
WINTER WEATHER HIGHLIGHTS ARE OUT FOR THESE AREAS.

ACROSS THE REMAINDER OF THE FORECAST AREA...PRECIP WILL BE MAINLY
RAIN OR A MIX OF RAIN AND SNOW...WITH LIGHT SNOW ACCUMULATIONS
POSSIBLE IN THE FOOTHILLS AND ADJACENT PLAINS THIS MORNING.
HIGHEST RAIN TOTALS WILL BE ACROSS FAR WESTERN SOUTH DAKOTA
TODAY...WITH SOME LOCATIONS POSSIBLY SEEING A HALF TO THREE
QUARTERS OF AN INCH OF QPF. HIGH TEMPERATURES WILL BE
CHILLY...MAINLY IN THE 30S...WITH SOME LOWER 40S FURTHER EAST
ACROSS THE SOUTH DAKOTA PLAINS WHERE PRECIPITATION WILL BE
LIGHTER.

TONIGHT...NORTHERN CIRCULATION OF THE UPPER LOW WILL SHEAR OUT
WITH THE SOUTHERN CIRCULATION TAKING OVER AND LIFTING INTO
CENTRAL NEBRASKA AFTER MIDNIGHT. MAIN AXIS OF PRECIP WILL SHIFT
INTO THE SOUTH DAKOTA PLAINS LATE TONIGHT...WITH PRECIP ACROSS
NORTHEAST WYOMING TAPERING OFF QUITE A BIT. SNOWFALL ACCUMULATIONS
ACROSS NORTHEAST WYOMING WILL COME TO AN END BY LATE IN THE
EVENING. WIDESPREAD RAINFALL IS EXPECTED ACROSS THE SD
PLAINS...WITH ANOTHER QUARTER TO HALF INCH EXPECTED FOR MANY
LOCATIONS...AND AMOUNTS CLOSER TO AN INCH POSSIBLE ACROSS FAR
SOUTH CENTRAL SOUTH DAKOTA. LOW TEMPERATURES WILL FALL INTO THE
LOWER TO MID 30S.

FOR WEDNESDAY...CLOSED UPPER LOW WILL SHIFT INTO EASTERN NEBRASKA
WITH THE MAIN PRECIP SHIELD FROM SOUTH CENTRAL SD INTO NORTHWEST
SD. LIGHT PRECIP/SNOW WILL LINGER ACROSS NORTHEAST WYOMING AND
SOUTHWESTERN SD. ADDITIONAL LIGHT ACCUMULATIONS OF SNOW WILL BE
POSSIBLE ACROSS THE HIGHER BLACK HILLS. ADDITIONAL RAINFALL
AMOUNTS AROUND HALF AN INCH WILL BE POSSIBLE ACROSS THE SOUTH
DAKOTA PLAINS. CLOUDS AND PRECIP WILL ONCE AGAIN KEEP HIGH
TEMPERATURES CHILLY...IN THE 30S TO LOWER 40S. UPPER LOW WILL
WEAKEN AND SHIFT EAST WEDNESDAY NIGHT...WITH PRECIP TAPERING OFF
AFTER MIDNIGHT. LOWS WILL FALL INTO THE UPPER 20S TO MID 30S.

.LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 349 AM MDT TUE APR 26 2016

ACTIVE WESTERLY FLOW WILL CONTINUE TO SUPPORT MEAN TROUGHING AND
COOL/WET CONDS THROUGH THE WEEKEND. GROWING INDICATIONS FOR MEAN
LONG WAVE RIDGING OVER WESTERN NOAM BY EARLY NEXT WEEK...AS A
STRONG/DEEP UPPER TROUGH SHIFTS EAST IN THE NORTHERN PAC. MUCH
UNCERTAINTY WRT TO THE STRENGTH/TRACK OF THESE FEATURES WHICH WILL
HAVE A SIG IMPACT OF THE EVOLUTION OF THE AFOREMENTIONED WESTERN
NOAM RIDGE AND POTENTIAL BLOCKING PATTERN...ALTHOUGH WARMER/DRIER
WEATHER LOOKS CERTAIN BY NEXT WEEK.

ANOTHER TROUGH WILL EJECT INTO THE PLAINS BY FRI...SETTING THE STAGE
FOR MORE CHANCES FOR PRECIP AS WELL AS POSSIBLE SNOW ACCUMS INTO
SUN. FORECAST MODELS REMAIN SLIGHTLY WARMER AND SOUTH WITH THE
CLOSED LOW TRACK THAN THE CURRENT SYSTEM OVER THE REGION...WHICH
PUTS THE FA ON THE WESTERN EDGE OF PRECIP. HOWEVER...THIS SYSTEM
LOOKS TO STALL OVER THE CENTRAL PLAINS SAT...WITH A COUPLE BANDS OF
PRECIP ROTATING AROUND THE SYSTEM...SUPPORTING A COUPLE DECENT
CHANCES FOR RAIN/SNOW. EASTERN PORTIONS OF THE FA LOOK TO SEE THE
BEST CHANCES FOR PRECIP...ESP SCENTRAL SD. SOME SNOW ACCUMS WILL BE
POSSIBLE ONCE AGAIN OVER MAINLY THE WESTERN HALF...ESP THE BLACK
HILLS. THIS WILL HIGHLY DEPEND ON THE AMOUNT OF CAA AND WETBULB
EFFECTS ASSOCIATED WITH THIS SYSTEM. COOL CONDS WILL CONTINUE
THROUGH THE WEEKEND...WITH HIGHS MAINLY IN THE 40S/LOWS IN THE LOWER
30S.

CONTINUED INDICATION TOWARD STAUNCH WESTERN NOAM RIDGING AND
POTENTIAL BLOCKING EARLY NEXT WEEK...WHICH COULD LEAVE THE REGION
UNDER A WEAK NEGATIVE HEIGHT ANOMALY...ALTHOUGH WARMER AND MUCH
DRIER THAN THE CURRENT PATTERN. OVERALL...TEMPS WILL BE WELL BELOW
SEASONAL NORMS THROUGH THE WEEKEND...WITH A WARM UP NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 519 AM MDT TUE APR 26 2016

RA AND SN WILL SPREAD OVER THE AREA THIS MORNING WITH WIDESPREAD
IFR LOCAL LIFR CONDS. SNOW SHOULD REMAIN CONFINED TO NE WY AND
IN/AROUND THE BLACK HILLS WHERE LOCAL VLIFR CONDS WILL BE
POSSIBLE. CONDS SHOULD IMPROVE SLIGHTLY THIS AFTERNOON WITH HIGH
END IFR TO LOW MVFR CONDS BEFORE DETERIORATING AGAIN OVERNIGHT
TONIGHT TO WIDESPREAD IFR/LOCAL LIFR.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WARNING UNTIL 6 PM MDT WEDNESDAY FOR SDZ024-028-029.

WY...WINTER STORM WARNING UNTIL 6 PM MDT WEDNESDAY FOR WYZ057.

     WINTER WEATHER ADVISORY UNTIL 6 AM MDT WEDNESDAY FOR WYZ054-056-
     058.

     WINTER STORM WARNING UNTIL 6 AM MDT WEDNESDAY FOR WYZ055.

&&

$$

UPDATE...POJORLIE
SHORT TERM...15
LONG TERM...JC
AVIATION...JC



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