Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 171727 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1127 AM CST Tue Jan 17 2017

Issued at 1126 AM CST Tue Jan 17 2017

See updated aviation discussion below.

UPDATE Issued at 1053 AM CST Tue Jan 17 2017

With westerly low level flow, albeit weak, and a sharp inversion
with temperatures around freezing at 1.5kft - should see
temperatures a touch above climo despite the deep snowpack. Just
nudged highs upwards 1-3 degrees between the Missouri and the
James. Otherwise, with sublimation/melting we should see some
higher dewpoints this afternoon. Doubt that will carry over into
fog overnight thanks again to the light westerly flow. Coteau
downslope winds could top 40kts based on NAM BUFKIT soundings
overnight - so no changes in that respect and left in mention of
blowing snow.


.SHORT TERM...(Today through Thursday Afternoon)
Issued at 315 AM CST Tue Jan 17 2017

Low stratus and fog currently over the far SE portion of the CWA
will slowly push east of the region this morning. A surface high
pressure, currently centered over the CWA will sink southward today,
allowing for WAA and southwesterly winds to develop. While 925 mb
temps warm to around 0C, a strong inversion should keep valley areas
cool. Ridge tops, like the Prairie Coteau and Leola Hills, should
warm into the upper 20s or warmer today.

A weak downslope winds event is possible on the lee side of the
Prairie Coteau late tonight. Hi-res models are showing sustained
winds of 25 mph with higher gusts. These winds could produce patchy
to areas of blowing and drifting snow.

Warmer air will filter into the region on Wednesday with
temperatures reaching the low to mid 30s for most locations. Am a
bit concerned the deep snow pack and strong temperature inversion
could limit our heating. Have ignored the warmer GFS solution and
kept temperatures cool. By Thursday, winds should become southerly
wind the temperature inversion finally mixing out allowing highs to
reach the mid to upper 30s.

.LONG TERM...(Thursday Evening through Monday)
Issued at 315 AM CST Tue Jan 17 2017

With 500mb heights remaining above 540 in the extended and only weak
systems at the surface, temperatures will be above normal. Model
blends continue to post temps in the 30s, but expect these to be
moderated over areas with a deeper snowpack. Therefore, any melting
will be minimal. Also, as energy begins to eject out of a deep west
coast trough into the Plains, the potential for precipitation will
increase. With the temperature forecast hovering around the freezing
mark, the rain/snow line and any associated snow accumulations will
hang in the balance.

A deeper, sfc low moving into the Plains Monday night and Tuesday,
stacked atmospherically with an upper level low will be more likely
to bring better forcing and all snow to the region.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1126 AM CST Tue Jan 17 2017

VFR conditions will prevail across the area through the TAF




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