Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 222036
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
236 PM MDT TUE APR 22 2014

.SHORT TERM...THIS EVENING THROUGH WEDNESDAY NIGHT
ISSUED AT 221 PM MDT TUE APR 22 2014

UPPER LEVEL ANALYSIS SHOWS BROAD RIDGING OVER THE
CENTRAL US...AND A TROUGH DIGGING INTO THE WEST COAST. SURFACE
TROUGH/WARM FRONT CONTINUES TO PUSH INTO THE NORTHERN
PLAINS...CREATING BREEZY SOUTHERLY WINDS ACROSS CENTRAL SOUTH
DAKOTA. RAIN SHOWERS CONTINUE TO DEVELOP ACROSS WY...MOVING INTO
SOUTHWEST SD. TEMPS ARE RISING INTO THE 70S...WITH DEW
POINTS IN THE 30S.

UPPER WAVE WILL APPROACH THE NORTHERN PLAINS TONIGHT...WITH THE
SURFACE LOW MOVING INTO WESTERN SD BY 12Z. ML CAPE OF 200-500 J/KG
COMBINED WITH UPPER LEVEL ENERGY ROUNDING THE TROUGH MAY RESULT IN A
FEW SHOWERS AND THUNDERSTORMS TONIGHT INTO TOMORROW MORNING...BUT
LOW LEVELS ARE PRETTY DRY AND CONDITIONS ARE NOT FAVORABLE FOR
ANYTHING SEVERE. LOCATION OF THE LOW INDICATES A POTENTIAL DRY SLOT
SETTING UP ACROSS THE SOUTHWEST PORTION OF THE CWA OVERNIGHT...WITH
MOST PRECIPITATION TO THE NORTH AND EAST. SOUTHERLY WINDS WILL
REMAIN BREEZY AHEAD OF THE SURFACE TROUGH THROUGH THE
NIGHT...ESPECIALLY ACROSS SOUTH CENTRAL SD. LOWS TONIGHT WILL BE
MAINLY IN THE 40S.

A COLD FRONT WILL BEGIN CROSSING THE REGION EARLY WEDNESDAY MORNING.
PRESSURE RISES OF 4-5 MB/3HR AND SIGNIFICANT COLD AIR ADVECTION
SUGGEST GUSTY NORTHWEST WINDS BEHIND THE FRONT...ESPECIALLY ACROSS
NORTHWEST SOUTH DAKOTA AND NORTHEAST OF THE BLACK HILLS INTO RAPID
CITY. MODELS INDICATE 25-30 KT WIND SPEEDS LATE MORNING THROUGH THE
AFTERNOON IN THESE AREAS...SO DECIDED TO ISSUE A WIND ADVISORY FOR
THE USUAL WINDY SPOTS. TEMPS WILL BE TRICKY TOMORROW DEPENDING ON
THE COLD FRONT...BUT HIGHS ARE FORECAST TO RANGE FROM THE 50S ACROSS
NORTHEAST WY AND NORTHWEST SD...TO THE UPPER 70S IN SOUTH CENTRAL
SD. MAY BE SOME SHOWERS AND THUNDERSTORMS AS PRECIP WRAPS AROUND THE
LOW...BUT AGAIN NOTHING SIGNIFICANT IS EXPECTED. WINDS WILL DIMINISH
IN THE EVENING AND PRECIP WILL MOVE OUT...AND LOWS WILL BE MAINLY IN
THE 30S.

&&

.LONG TERM...THURSDAY THROUGH TUESDAY
ISSUED AT 221 PM MDT TUE APR 22 2014

GENERALLY MILD CONDITIONS WILL PREVAIL ON THU AND FRI
AS THE UPPER LOW SHIFTS EWD ALONG THE CNDN BORDER AND TRANSITORY
UPPER RIDGE MOVES EASTWARD INTO THE PLAINS. THERE COULD BE A FEW
-SHRA ACRS FAR NWRN SD THU MORNING BEFORE DRIER AIR WORKS IN. VERY
WINDY CONDITIONS ARE EXPECTED AGN THU DUE TO A TIGHT SFC PRESS GRAD.

FOCUS THEN TURNS TO A STRONG UPPER TROF WORKING THROUGH THE WEST
EARLY IN THE WEEKEND...AND INTO THE PLAINS LATER IN THE WEEKEND AND
EARLY NEXT WEEK. THE ECMWF/GFS/GEM ALL AGREE IN SHOWING A VIGOROUS
UPPER LOW TRACKING ACROSS THE CNTRL ROCKIES SAT/EARLY SUN AND INTO
THE CNTRL/NRN PLAINS SUN/MON. WIDESPREAD PRECIPITATION IS LIKELY
BY LATE IN THE WEEKEND...WITH LATEST THERMAL PROFILES BOOSTING
CONFIDENCE THAT TEMPS SHOULD BECOME QUITE COLD...20 DEGREES OR MORE
BELOW AVERAGE FOR HIGH TEMPS. THIS COULD LEAD TO ACCUMULATING
SNOW...MOST LIKELY OVER THE BLACK HILLS...BUT POSSIBLY ON THE PLAINS
AS WELL. AT THIS TIME IT REMAINS MUCH TO EARLY TO KNOW HOW MUCH SNOW
MIGHT ACCUMULATE AS THAT WILL BE DEPENDENT ON THE EXACT
TRACK...STRENGTH AND TIMING OF THE UPPER LOW. STAY TUNED.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY
ISSUED AT 221 PM MDT TUE APR 22 2014

AN UPPER LEVEL DISTURBANCE WILL CREATE A FEW HIGH BASED
SHOWERS/TSTMS THIS EVENING CONTAINING LOCALLY GUSTY WINDS.
OTHERWISE...VFR CONDITIONS WILL PREVAIL TONIGHT THROUGH WEDNESDAY.
A COLD FRONT WILL CROSS THE AREA ON WEDNESDAY MORNING...FOLLOWED
BY GUSTY NORTHWEST WINDS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 9 AM TO 6 PM MDT WEDNESDAY FOR SDZ001-002-012-
     013-026-031-072-073.

WY...NONE.
&&

$$

SHORT TERM...POJORLIE
LONG TERM...10
AVIATION...10





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