Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 240548 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1248 AM CDT Thu May 24 2018

.UPDATE...
Issued at 1244 AM CDT Thu May 24 2018

Aviation discussion updated below for 06Z TAFs.

&&

.SHORT TERM...(This Evening through Thursday)
Issued at 318 PM CDT Wed May 23 2018

The threat for severe storms over the next 30 hours will be the main
forecast challenge.

As of 19Z, an area of low pressure is located near Pierre with a
warm front draped east-southeast across the region. With dew
points in the 60s, surface based cape values exceed 3K J/KG.
While 0-6 KM bulk shear values are lacking, deep layer shear is
around 25-30 knots. CAMS still support convection developing in
south- central SD within the next few hours. These storms should
track northeastward through this evening, pushing into North
Dakota around 3Z. With high DCAPE values, damaging winds are
possible with these storms. Hail is also possible.

After the first round of convection this evening, attention then
turns westward. Thunderstorms currently developing over Wyoming
should push across western SD after 0Z, potentially reaching our CWA
around 3Z. These storms should progress eastward across the CWA with
diminish intensity expected. There could be lingering pcpn in the
eastern CWA Thursday morning.

The NAM, as well as the HREF seems to suggest a break in convection
Thursday morning through Thursday afternoon before additional storms
develop along a cold front. As of now, convective initiation looks
best along the James River Valley after 21Z. There storms should
push eastward across the rest of the CWA Thursday evening.

.LONG TERM...(Thursday Night through Wednesday)
Issued at 318 PM CDT Wed May 23 2018

A shortwave trough and surface cold front should be on their way out
of the area by Thursday evening, taking a very moist environment
with them. Before that happens, thunderstorms are possible across
eastern SD and west central MN through Thursday evening. An unstable
atmosphere will provide the potential for strong updrafts with any
activity. Shear does not look to be too favorable, however large
hail and damaging winds will be possible. By Friday, a Western U.S.
upper level ridge begins makings its presence known by spreading
east towards our across our CWA, resulting in much above
temperatures. This will be the story through Memorial Day Weekend
into early next week as well. Models indicate highs in the 90s
during this time. Meanwhile, a large and slow-moving upper-level
trough across the western U.S. will churn towards the High Plains.
Pieces of energy may begin ejecting northeastward by late Saturday,
leading to on-and-off thunderstorm chances. The trough itself may
begin working into the High Plains by Tuesday/Wednesday, leading
generally better precip chances.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1244 AM CDT Thu May 24 2018

KPIR and KMBG will be affected by showers and thunderstorms early
on in the TAF forecast period, otherwise expect mainly VFR
conditions. Across KABR and KATY, VFR conditions are forecast,
with the possibility for showers and thunderstorms Thursday
afternoon and evening.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...TMT
SHORT TERM...SD
LONG TERM...Lueck
AVIATION...TMT



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