Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 081723 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1123 AM CST Fri Dec 8 2017

Issued at 1122 AM CST Fri Dec 8 2017

See updated aviation discussion below.

UPDATE Issued at 1015 AM CST Fri Dec 8 2017

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


.SHORT TERM...(Today and Tonight)
Issued at 347 AM CST Fri Dec 8 2017

An area of stratus continues to move south through the CWA, although
it was expected to be a bit more expansive by this point. In fact,
several models are overdoing cloud cover across the area currently.
Although, there are indications of expansion across the eastern CWA,
but nothing much upstream. Soundings and ceiling grids indicate a
much more expansive cloud cover this morning and lasting several
hours. Reality does not match up quite to this thinking, but will
monitor trends over the next few hours to see if upstream locations
begin to cloud up. Temperatures have held fairly steady over the
past few hours with the cloud cover in place and even a bit of
mixing as well.

For later today, will see low pressure drop south into the arrowhead
of MN and into WI. This looks to only bring some cloud cover to at
least eastern portions of the area, while breezy northwest winds
develop all across the CWA. It appears most of the snow potential
with this system will remain in MN, although cannot rule out a
couple flurries over the eastern CWA. Overall confidence in this is
fairly low, so opted to leave out of the forecast at this time.
925mb temps remain in the single digits below zero today for eastern
areas, so likely remaining in the upper 20s to around 30 degrees
there. But for central SD, 925mb temps rise to around +1C along with
good mixing. Therefore, should be able to see highs rise into the
upper 30s to around 40 degrees. Will be able to erode a bit more
snow cover today.

Fairly good shot of cold air advection moves back in tonight with
the passage of a frontal boundary. Models suggest some more cloud
cover lingering across eastern area with a bit of a breeze. Lows
look to drop into the teens east, with lower 20s across the
southwest CWA.

.LONG TERM...(Saturday through Thursday)
Issued at 347 AM CST Fri Dec 8 2017

The highly amplified long wave pattern over the conus will continue
through most of the long term. That pattern consisting of a far west
conus mid level ridge, and downstream central/eastern conus trof. It
appears that the best chances for any meaningful pcpn will be Sunday
night into Monday, and possibly again Wednesday night into Thursday.
Of those two periods, the wave for Sunday night appears the
strongest in model progs, particularly the ECMWF. In coordination
with adjacent offices, did increase POPs over the northeast CWA
to account for stout wave. The system for Wednesday night does not
have unanimous consensus between the models and thus confidence
in the finer details is low. For now have stuck with the in-house
model blend.

Despite the strong northwest flow aloft, the temperatures
actually appear as if they`ll favor near, to perhaps a bit above,
normal for the period, especially over the central and western
portions of the state where modified air of Pacific origin will
reside. For the most part the model blend was used, but did
increase highs on Sunday based on temps aloft. If we mix better
than expected on Sunday, we`ll blow right through the current
forecast highs.


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1122 AM CST Fri Dec 8 2017

IFR/MVFR cigs will linger over parts of the east through the
afternoon hours, including KATY. Otherwise, VFR conditions will
prevail through midday Saturday.




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