Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 261046
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
446 AM MDT Sun May 26 2019

.DISCUSSION...(Today Through Saturday)
Issued at 315 AM MDT Sun May 26 2019

Thunderstorms have been developing over southwest South Dakota
over the past hour, in area of weak 850-700mb theta-e advection.
This activity will continue to move northeast early this morning
before diminishing after sunrise. Strongest cells may produce
some small hail. For the rest of today, warmer temperatures
expected with highs into the 70s for most locations outside of the
Black Hills. A few high resolution models show expanding area of
stratus over western South Dakota this morning. If stratus
develops and persists into this afternoon, current high
temperature forecast will be too warm. MLCAPE of 1500-2500 J/KG
across the area this afternoon. With marginal shear, a few severe
storms are possible....mainly large hail. Slow storm motion will
result in locally heavy rain. Thunderstorms coverage will increase
this evening as potent shortwave lifts through the area.

Upper low moves through the central Rockies Monday and into
central Nebraska Tuesday. After widespread thunderstorm activity
tonight/early Monday, most areas will see a break in rainfall on
Monday. Deep/moist upslope flow will maintain some shower
activity, especially around the Black Hills. Heavier widespread
rain develops Monday into and continues into Tuesday. Most
locations along and south of I-90 will see 1-2" of rain through
Tuesday, with locally heavier amounts around the Black Hills.
Upper low lingers in eastern Nebraska on Wednesday, some rain
showers from the Black Hills into south central South Dakota.
Drier and warmer conditions expected for the end of the week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Monday Morning)
Issued At 439 AM MDT Sun May 26 2019

Showers and thunderstorms with gusty winds and small hail across
portions of western SD will gradually dissipate later this
morning. Some MVFR conditions will be possible this morning
in low clouds/fog around the Black Hills area and southwestern
SD. A more widespread and stronger round of thunderstorms is
expected this afternoon and overnight. Thunderstorms will shift
eastward overnight, but then MVFR/IFR conditions in fog will
develop by early Monday morning, especially around the Black Hills
area.

&&

.HYDROLOGY...
Issued at 315 AM MDT Sun May 26 2019

Heavy rain will move into the region beginning tonight night and
continue through Tuesday. Widespread rainfall amounts of 1-2"
look likely, with some amounts over 2" especially south of I-90.
Flood Watch remains in effect for northeast Wyoming and much of
western South Dakota.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch from this evening through Tuesday afternoon for
     SDZ012>014-024>032-041>044-046-047-049-072>074.

WY...Flood Watch from Monday afternoon through Tuesday afternoon for
     WYZ054>058-071.

&&

$$

DISCUSSION...7
AVIATION...Pojorlie
HYDROLOGY...7


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