Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 081132 AAA

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

Issued at 526 AM CST Fri Dec 8 2017

Aviation discussion updated below for 12Z TAFs.


.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 up 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

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 up 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 12Z TAFS through 12Z Saturday Morning)
Issued at 526 AM CST Fri Dec 8 2017

IFR/MVFR CIGs will affect the region this morning, especially
across KABR and KATY. These lower CIGs will likely remain in some
form over eastern SD into the afternoon and evening, likely
affecting KATY. KPIR and KMBG are on the edge of these lower
clouds, but could see periods of BKN conditions this morning
before clouds gradually erode to the east.




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