Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 171126 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
626 AM CDT Tue May 17 2022

Issued at 622 AM CDT Tue May 17 2022

See updated aviation discussion below.


.SHORT TERM...(Today through Wednesday Afternoon)
Issued at 356 AM CDT Tue May 17 2022

The main challenge in the near term deals with ongoing showers and
thunderstorms, and timing when they will come to an end. Weak upper
level ridging currently over the area will slide east by sunrise
with a more zonal flow setting up through the remainder of the
period. At the surface, scattered showers and thunderstorms are
ongoing across much of the CWA in association with a warm front
extending from a low over the western High Plains, and on the nose
of a 30-40 knot low level jet. Per the SPC mesoanalysis, there is
some weak CAPE, which is likely aiding in keeping the thunderstorms
going. Expect the precipitation to hold together this morning, then
affect mainly the eastern CWA this afternoon as the low begins to
track southeast, dragging the frontal boundary back to the south
with it. The remainder of the period looks to be dry as weak high
pressure settles in over the region.

High temperatures today will range from the lower 60s across west
central Minnesota and far northeastern South Dakota, to the mid 70s
across south central South Dakota. Low temperatures tonight will be
in the upper 40s to lower 50s. Highs on Wednesday will be in the 70s.

.LONG TERM...(Wednesday Evening through Monday)
Issued at 356 AM CDT Tue May 17 2022

The long term period is fairly quiet except for some strong to
severe storms possible Thursday. This weekend is expected to be
cooler than average with high temperatures in the low 50s.

A surface low forms off the Rockies Thursday and moves across the
region Thursday night providing some potential for strong to severe
storms. The SPC has far eastern SD and west central MN in a 15
percent chance of severe weather. Lots of energy moves through the
region late Thursday night and into Friday morning reaching down
from a 500mb low over northern ND/southern Canada. Mid level
moisture moves in ahead of the low and moves out of the region with
it. As for low level moisture, it sticks around and increases ahead
of the low level low and cold front. Abundant WAA exists ahead of
this cold front. Timing of frontal passage differs between the
deterministic models with the NAM moving it into the region last at
around 00Z Friday. MUCAPE values range from 200 to 3000 J/kg
depending on the model with 0-6km shear mostly over 50kts over
eastern counties. Starting Thursday night and continuing through the
day Friday, winds increase with gusts around 30kts.

Behind this surface low, winds shift around to the north and bring
in some cooler air to give us below average temperatures through the
weekend. Otherwise, for Friday clusters have an upper trough over
the region. As several surface highs move through the region, the
low levels dry out and stay relatively dry through the rest of the

For Saturday, some more progressive clusters show the upper level
trough moving out of the region while the majority show the trough
centered over the area. NAEFS percentiles show below average
temperatures above the surface. NBM v4.0 shows high temps in the low
50s Saturday and Sunday. Expecting clouds Saturday, but as mid
level moisture moves out ahead of some high pressure Sunday,
clouds decrease. Clusters show the upper level trough continuing
to move out Sunday as a ridge builds in for Monday. To start the
work week, Monday has a chance for some precipitation as low
pressure moves through the region but low confidence on amounts.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 622 AM CDT Tue May 17 2022


Scattered showers, and a few thunderstorms, will affect mainly the
eastern part of the area this morning. Additional shower and
thunderstorm development is expected this afternoon, again mainly
across the eastern part of the area. Periods of MVFR vsbys are
possible with any thunderstorms. The precipitation will exit the
area by this evening. Some MVFR cigs may develop over far eastern
South Dakota and west central Minnesota during the evening. VFR
conditions will prevail during the overnight hours.




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