Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 171629
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1029 AM MDT SUN JUL 17 2016

.UPDATE...
Issued at 1028 AM MDT Sun Jul 17 2016

Most of forecast still on track for today/tonight. Adjusted PoPs
and timing slightly based on new model guidance. Looking like
showers/storms will form in Eastern Wyoming shortly after noon,
with additional showers/storms forming in NE Wyoming around 2pm
to 3pm. All of this activity will trek eastward across the CWA
through the remainder of the afternoon and evening.

Despite seasonably strong deep layer shear, instability could be
a limiting factor today for severe weather, with the most
aggresive models putting close to 1kJ/kg in the extreme southwest
portions of the CWA. Models also show a substantial cap in place
in areas outside of NE Wyoming. Regardless, some of the high-res
CAMs do show a few strong/severe storms in the CWA late this
afternoon and evening, so this will be closely monitored.

&&

.SHORT TERM...(Today Through Monday Night)
Issued at 228 AM MDT Sun Jul 17 2016

Water vapor shows wsw flow through the nrn plains with upper wave
responsible for yesterday`s convection pushing into the upper
midwest. At the sfc...frontal boundary extends from the ern
Dakotas through ncntrl NE...with high building into MT.

Today...Relatively quiet wx expected through mid aftn with flat
upper ridge building into wrn portions of the nrn plains. Next
upper wave embedded in nearly zonal flow aloft expected to move
into the region near max heating. Return flow expected in our wrn
zones as sfc high shifts into the cntrl/ern Dakotas...allowing
increasing instability over nern WY and far wrn SD. Mid level
winds/shear sufficient for some svr storm potential. Any storms
that develop should be able to move onto the SD plains overnight
as LLJ/theta-e advection increases.

Monday...Temps should heat into the 90s most locations with upper
ridge amplifying over the wrn Dakotas. A more robust wave
expected to arrive later in the day as upper ridge axis shifts
into the cntrl/ern Dakotas. This will provide another chance for
aftn/eve storms.

.LONG TERM...(Tuesday Through Saturday)
Issued at 228 AM MDT Sun Jul 17 2016

Upper level ridge of high pressure will build across
the central CONUS for much of next week, bringing hot and mainly dry
conditions to the area. Weak energy moving through the ridge may
bring a few showers and storms to south central SD Tuesday night.
Ridge amplifies over the Northern Plains mid week, with 850mb temps
climbing above 30C over the CWA. Several locations across the plains
will likely see triple digit heat Wednesday and Thursday. The upper
ridge breaks down slightly by next weekend as a weak impulse crosses
the northern Rockies. This may bring a slight chance of afternoon
and evening showers and thunderstorms to parts of the forecast area,
along with slightly cooler temperatures.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Sunday Night)
Issued At 228 AM MDT Sun Jul 17 2016

VFR conditions are expected through much of this morning
and into the early afternoon. Strong thunderstorms are expected
again across Northeast Wyoming and southwestern SD by late
afternoon, translating eastward across SD during the evening and
overnight hours. Areas of IFR/LIFR conditions expected in the
vicinity of thunderstorms.


&&

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

$$

Update...McKemy
SHORT TERM...Johnson
LONG TERM...15
AVIATION...15


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