Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 232028
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
228 PM MDT Sun Apr 23 2017

.SHORT TERM...(This Evening Through Monday Night)
Issued at 224 PM MDT Sun Apr 23 2017

Upper flow is nearly zonal across the northern plains,
and a trough is moving into the western CONUS, with the upper low
just off the Pac NW coast. Clouds are clearing ahead of an 85 kt
jet. Fog over northwestern SD took a while to dissipate today, and
with a cold front draped west to east across SD, have lowered
expected highs to the north. Southwest winds are gusty across
south central SD. Temperatures at 2PM range from the 40s across
far northwestern SD to the lower 70s across parts of central SD.

The first of several upper waves to affect the area this week will
bring showers tonight, with isolated thunderstorms possible this
evening. Breezy winds will continue across south central SD. Lows
will range from the upper 30s across northwestern SD to near 50
across south central SD.

A brief break in precip is expected Monday between waves. Then
chances of showers and isolated thunderstorms return Monday
afternoon, spreading eastward overnight. The 700 mb low is progged
to move into northeastern WY by Tuesday morning, placing the higher
QPF amounts across far northeastern WY and the Black Hills area.
Colder air will be pulled in from the north, and rain will mix with
and change to snow overnight. Models have continued the cold trend,
giving the CWA more snow than yesterday`s runs. Snow will change
back to rain across most locations Tuesday afternoon, and precip
will diminish Tuesday evening. Precip may remain all snow for the
northern Hills through the event. Overall the Black Hills and areas
just north of the Hills could see up to 6 inches of snow.
Accumulating snow of lesser amounts is expected on the plains, with
some melting as it reaches the ground. WPC has warning criteria snow
in the forecast for the Hills, but latest SREF has actually trended
down on snow amount probabilities. Forecast snow amounts indicate
advisory criteria/borderline warning criteria, but will hold off on
headlines at this point because of the model inconsistency.

Monday will be the warmest of the upcoming week, with highs in the
upper 50s to upper 60s. Tuesday`s highs will reach only the 30s and
40s. Widespread 20s are expected for lows Tuesday night.

.LONG TERM...(Tuesday Through Sunday)
Issued at 224 PM MDT Sun Apr 23 2017

Cool and unsettled weather will continue for the rest
of the week and into the weekend. The next significant low pressure
system to affect the region will begin moving in Thursday night,
bringing another round of rain and snow. ECMWF and GFS are currently
showing the upper low sinking south over the Four Corners region by
Saturday morning, and then slowly sliding northeastward across the
central plains during the weekend. This could bring a long duration
of rain/snow to the area, depending on the track and timing of the
system. Below average highs in the 40s and 50s are expected into
next weekend.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1111 AM MDT Sun Apr 23 2017

Areas of IFR/LIFR conditions over far nwrn SD will dissipate early
this afternoon and will redevelop after 04Z this evening. VFR
conditions will continue over the rest of the region. Scattered
showers and a few thunderstorms are expected to develop over
northeastern Wyoming and the Black hills starting late this
afternoon and spread into much of the rest of western South
Dakota overnight. Local MVFR conditions are expected near any
showers or thunderstorms.


&&

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

$$

SHORT TERM...Pojorlie
LONG TERM...Pojorlie
AVIATION...10



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