Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 190934
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
334 AM MDT THU MAY 19 2016

.SHORT TERM...Today Through Friday Night
Issued at 258 AM MDT Thu May 19 2016

Zonal flow across the northern plains this morning with shortwave
crossing MT starting to generate showers. Deepening surface
low/lee trof across eastern MT and strong southerly pressure
gradient over forecast area.

Wave will continue to track eastward, reaching western SD during
the peak heating of the afternoon, where it will encounter CAPE
values .5-1K J/kg over the Black Hills and southeasterly upslope
surface winds advecting higher dewpoints, leading to thunderstorm
development over the higher terrain. Wave will move onto the
plains east of the Hills this evening and overnight, where CIN is
high, but low level jet may provide sufficent forcing for some
elevated convection over far southern SD. Upper trof deepens over
CA Friday, with southwest flow over the area bringing another
shortwave to the region. Again the Black Hills will be uncapped,
so thunderstorms will develop over the higher elevation, but CIN
and low shear on the plains will inhibit progression of storms.
Thermal ridge remains over the high plains, and temperatures will
continue to warm today and Friday.

.LONG TERM...Saturday Through Wednesday
Issued at 258 AM MDT Thu May 19 2016

Upper low over the Pacific NW early in the weekend will
begin to slowly move east-northeast over the weekend as ridge shifts
east of the area. Chances for showers and thunderstorms will
continue to gradually increase through the weekend from west to
east. Medium range models in better agreement on pushing the low to
the north and west of the area, into the Canadian Prairie Provinces
by Monday morning. Several shortwaves will slide through the area,
with a cold front also slowly passing through late Saturday night
and Sunday. The potential for strong to severe storms looks greatest
over far northeast WY into far western SD late Saturday, then
possibly across areas east of the Black Hills on Sunday, especially
toward central SD. Potential on Sunday will highly depend on
location of the cold front and pre-frontal trough in the afternoon,
with latest models hinting the better potential could be mostly east
of the cwa.

The first half of next week still looks somewhat unsettled at times
as another upper trough digs into the western states and west-
southwest flow aloft remains over the region. Will keep broadbrushed
slight chance to chance pops across much of the area through the
period, with timing of individual disturbances being difficult to
pinpoint right now. Temperatures early next week will be near or
slightly above average, mostly mid 60s to mid 70s.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 258 AM MDT Thu May 19 2016

VFR conditions generally expected through the forecast
period. Isolated to scattered showers and thunderstorms are expected
to develop across the Black Hills area this afternoon, with isolated
activity possible east of the Black Hills tonight as southerly low
level jet intensifies. Local mvfr conditions are possible in and
near any showers.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...55
LONG TERM...26
AVIATION...26



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