Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 242314 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
614 PM CDT Wed May 24 2017

.SHORT TERM...(This Evening through Thursday Afternoon)
Issued at 345 PM CDT Wed May 24 2017

The 500mb ridge extending from the southwest up through the Northern
Plains will move east into Minnesota by daybreak Thursday, in
response to the next low over southwestern Saskatchewan that will be
shifting a trough into the region. Taking a look at the surface
features, the pressure gradient continues to increase between the
exiting ridge over much of MN, and the nearing low extending from
Saskatchewan with a trough down through eastern MT and WY. A
secondary low looks to slide along the trough as it moves into
western SD tonight. It`s eastward progress is slow. While there will
be a slight chance of showers over mainly north central SD
overnight, there is a smaller chance of thunderstorms. While not
completely impossible, will leave the mention of thunder out of the
forecast for now, as we continue to watch the line of showers
nearing from eastern MT. The main impact for our area will be
continued gusty winds out of the southeast tonight, especially for
areas west of the James River Valley. LLWS is a concern aviation
wise as the llj sets up ahead of the sfc low, with winds of 35-
45kts. With the addition of daytime heating, did keep slight chance
pops going over our eastern areas for Thursday afternoon, as the sfc
low moves to southeastern Saskatchewan and the trough divides our
area into 2 halves by late afternoon. Dry west, slight chance of
showers east. Breezy conditions should continue through much of the
day, both ahead of the sfc trough, and then well behind as winds
shift out of the west-northwest.

.LONG TERM...(Thursday Evening through Wednesday)
Issued at 345 PM CDT Wed May 24 2017

At the beginning of the long term the models show an upper level low
pressure area straight to our north in southern Canada with a high
pressure ridge off the west coast. This upper low pressure area
meanders slowly east into the weekend as several short wave vorts
follow in behind. The low pressure area/trough then develops
southeast and over the eastern U.S. into early in the week while
upper level ridging builds over the western U.S. into western
Canada. What this all means is our region will be under prevailing
north to northwest flow through much of the period with cooler
Canadian air moving across the region. Temperatures through the
period at this time appear to be from just below to about 10 degrees
below normal. Highs look to be mainly in the mid 60s to the lower

A system moving across to our south may bring some showers into our
far southwest CWA Friday night into Saturday morning. Otherwise,
diurnally driven clouds and showers may occur Saturday afternoon. A
more significant short wave trough coming out of the northwest will
bring scattered showers and storms Sunday. Expect another round of
short wave/diurnal showers/storms again on Monday mainly east in the
CWA. Most of the rest of the period looks to be dry into Wednesday.


.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 613 PM CDT Wed May 24 2017

Vfr and breezy conditions are expected through tonight.




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