Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 201513 AAB

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1013 AM CDT Wed Sep 20 2017

Issued at 1011 AM CDT Wed Sep 20 2017

Current forecast is on track, therefore no changes made at this


.SHORT TERM...(Today through Friday Afternoon)
Issued at 348 AM CDT Wed Sep 20 2017

A cooler, and very dry airmass will work into the area today. This
will be while an area high pressure skirts across Nebraska and
eastern South Dakota. Afternoon relative humidity will fall into the
20 to 30 percent range, with south central South Dakota relative
humidity values in the teens. This dry air will be accompanied by
west winds of 10 to 20 mph. The strongest winds will be behind the
exiting area of high pressure, with some gusts in the 20 mph range
across central South Dakota this afternoon. Very high grassland fire
danger index values remain for our southwest counties today.

The dry weather will not last the entire short term period. The sfc
high will quickly exit across southern MN tonight, with the next
slow pushing into western SD Thursday morning. Highs on Thursday
will jump from the 70s today to the 80s. The 500mb low over much of
southwestern Canada will shift across Saskatchewan with the trough
focusing over the Pacific Northwest, and strong southwesterly flow
set up from California through the Northern Plains and Ontario by
daybreak Thursday. The southwesterly flow will stay in place through
Friday, as a cut off low sinks across the interior west.

Severe weather may again return to eastern SD and western MN
Thursday night into Friday. An elongated sfc trough will be set up
from northeastern CO through south central SD by 06Z Friday, with a
frontal boundary extending through northeastern SD and northern MN.
Assisted by a low level jet and plenty of low level moisture as
dewpoints jump into the mid 60s south of this boundary, showers and
thunderstorms will be possible. The best chance looks to be
northeast of the forecast area. The slight chance pops Friday
afternoon may again be accompanied with strong to potentially severe
thunderstorms, as the boundary will not move much. Will include the
thunderstorm and severe weather potential in the HWO, but with
limited certainty and low probability of occurring, will not get
into too much detail yet.

.LONG TERM...(Friday Evening through Tuesday)
Issued at 348 AM CDT Wed Sep 20 2017

The extended period begins with a wet weekend. A persistent low
pressure trough at the sfc from Hudson Bay to the desert southwest
will be aided by numerous shortwaves ejecting out of a deep longwave
trough across the western CONUS. Off and on showers and
thunderstorms and continuous cloud cover will suppress temperatures
on Saturday and Sunday. Highs will be well below average in the 50s
and lower 60s.

Below normal temperatures will continue into early next week as the
upper trough shifts farther into the Plains.


.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
Issued at 625 AM CDT Wed Sep 20 2017

VFR conditions are expected through the period.




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