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000
FXUS63 KUNR 151712
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1112 AM MDT Mon Apr 15 2024

.KEY MESSAGES...

- Warm weather continues today, with threat for strong to severe
  storms later this afternoon and evening across much of the area.

- Showery and windy on Tuesday, with strong winds expected from southern
  portions of northeast Wyoming to the southwest South Dakota
  plains.

- Unsettled, windy, and colder weather expected for the rest of the
  week and into the weekend.

&&

.DISCUSSION...(Today Through Sunday)
Issued at 423 AM MDT Mon Apr 15 2024

Current surface analysis shows low pressure over north central
WY, with frontal boundary/warm front extending south- southeast
across eastern WY into southwest NE and northeast CO. Pacific cold
front extends south-southwest across the Rockies. Tight pressure
gradient across the Dakotas and strong low level southerly jet is
helping to produce gusty winds across portions of the western SD
plains, and in particular along the Pine Ridge, where gusts to
around 45 mph are noted. Upper level analysis shows negatively
tilted ridge across the plains, with trough across the western US
and embedded low pressure over northwest AZ early this morning.
Skies are variably cloudy across the area with a few showers noted
on KUDX radar across northwest into central SD on edge of low
level jet. Temps are in the 40s and 50s.

An active couple of days ahead as the upper low moves quickly east-
northeast across the southern Rockies today and through the central
Plains later tonight into Tuesday night. Warm weather will persist
today in most areas as frontal boundaries only move slowly east into
the high Plains today. Highs will range from the upper 60s over
parts of northeast WY and the higher Black Hills to the 80s south
and east of the Black Hills. By later this afternoon, main area of
low pressure along the cold front should develop across the NE
panhandle, with warm front setting up across northern NE.
Southeasterly flow will persist across most of the area into the
afternoon, with the strongest winds east of the Black Hills and
especially over south central SD, where gusts to near 45 mph are
expected. Moisture will increase across the area as well, with
dewpoints rising through the 40s and into the lower 50s to the east-
southeast of the Black Hills. This will help to produce MLCAPE
values of 500 to around 1500 j/kg, highest toward south central SD.
Shear will increase later today, with a corridor of more favorable
shear progged from near the Black Hills to south central SD, north
of the warm front. Robust shortwave energy should push north-
northeast through the area this afternoon and evening as the upper
low moves across CO. Showers and thunderstorms will develop and
increase in coverage generally from southwest to northeast by mid to
late afternoon. Parameters support at least isolated strong to
severe storms later this afternoon and evening across much of the
forecast area, with supercell potential and large hail most
favorable to the east and southeast of the Black Hills. Strong wind
gusts will be a primary threat as well for the marginal and slight
risk areas. Would not rule out an isolated tornado threat with
stronger storms that develop closer to the warm front near the NE
border. Precipitable water values will be above average, near or
above one inch across much of western and south central SD, so at
least locally heavier rainfall can be expected, with many areas
having high potential (above 50 percent) of a half inch or more of
beneficial rainfall later today into Tuesday. Severe storm threat
should diminish by late evening in most areas, but could linger into
the overnight over south central SD as the low tracks east across
NE.

The main concern after this evening will be strong N-NW winds on the
back side of the system as the surface low tracks across NE and into
IA by Tuesday evening. Winds will increase initially across
northeast WY late tonight and then across western SD Tuesday
morning. Most of the forecast area will see wind gusts ranging from
40 to 55 mph on Tuesday, with areas along the eastern foothills and
west central plains having potential for wind gusts to 65 mph during
the midday and afternoon hours. Have issued a high wind watch for
these areas. Winds should drop off fairly quickly by early evening.
Showers can be expected across most of the area on Tuesday, with
isolated thunderstorms expected, mainly east of the Black Hills.
Upslope enhanced rainfall will develop for a period across the
northern Black Hills. Highs will mostly be in the 50s and lower 60s,
with 40s over the higher Black Hills. Threat for severe storms
should remain east of the forecast area. Pcpn with the upper low
will dissipate from west to east during the afternoon and evening
hours.

The rest of the week looks to be unsettled, cool, and windy at
times. A Canadian upper low passes well north of the region midweek,
with northwest flow aloft developing across the region by late week.
A disturbance rotating well southwest of the Canadian low will bring
chances for rain and snow Wednesday and Wednesday night, mainly from
northeast WY to the Black Hills and southern SD. Some minor snow
accumulations are possible, especially across the higher Black Hills
and over Campbell County. Blustery winds can be expected Wednesday
and Thursday, with below average temperatures Wednesday through at
least Saturday. Drier weather expected late week into the weekend,
but a couple of disturbances could bring low chances for rain/snow
Friday and over the weekend.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Tuesday)
Issued At 1112 AM MDT Mon Apr 15 2024

Windy southeasterly winds will continue over much of western
South Dakota through the afternoon. VFR conditions will persist through
much of this afternoon. Scattered showers thunderstorms will then
develop late this afternoon and become numerous this evening and
overnight. Areas of MVFR conditions this evening will deteriorate
to widespread IFR conditions after 06Z tonight. Strong and gusty
northwest winds may develop on Tuesday, especially on the plains
to the east of the Black Hills.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Watch from Tuesday morning through Tuesday afternoon
     for SDZ026-030-031-042-072>074.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...26
AVIATION...SE