Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 220920

Area Forecast Discussion
National Weather Service Aberdeen SD
320 AM CST Mon Jan 22 2018

.SHORT TERM...(Today through Tuesday Afternoon)
Issued at 317 AM CST Mon Jan 22 2018

Fog and low stratus today will be the main issue in the short term.

A strong area of low pressure currently over northeastern Kansas
will slowly track northeastward toward Chicago today through
tonight. While this system will bring breezy northerly winds to
eastern SD and western MN today, with no significant snow in our
southeast CWA, will remove the mention of blowing snow.

With an abundance of low level moisture and light winds along the
Missouri Valley, dense fog has developed, especially in north
central SD. NAM buffer soundings keep the dense fog and low stratus
through a better portion of the day before lifting later this
afternoon. Based on short blend of models, will issue a dense fog
advisory until 17Z in our northeast. In our eastern CWA, upslope
winds along the eastern side of the Sisseton Hills is producing
dense fog. A consensus among short term models suggest the fog in
our east will continue through the morning hours with gradual
improvement by early afternoon.

Fog may reform again this evening before drier, northwesterly winds
move into the region. An upper level trough will cross the Northern
Plains on Tuesday with light pcpn possible along the ND/SD border.
The NAM, along with the ARW and NMM support the possibility of light
pcpn with this trough. Other models suggest dry conditions. After
looking at the NAM`s moisture profile, will maintain a dry forecast
on Tuesday.

.LONG TERM...(Tuesday Evening through Sunday)
Issued at 317 AM CST Mon Jan 22 2018

Overall, pretty quiet long term period with limited precipitation
chances and above normal temperatures.

Upper ridge will slide over the area for the second half of the
week behind a weak shortwave and surface trough Tuesday
afternoon/evening. 850mb temps will warm into the single digits
above zero C by Thursday, so amount of warming will depend on the
appearance of low stratus and the amount of mixing that occurs
during the day. Both GFS/NAM are indicating the potential for low
stratus Wed/Thurs (below inversion around 900mb), but as usual the
NAM is the most aggressive. CMC/ECMWF are not as enthused, so
will continue to show partly cloudy skies for Wed/Thurs and more
for the high clouds streaming in ahead of the next low pressure
system and along the favorable right rear region of the departing
upper jet. Thursday will likely be the warmest day with the
increasing south-southeasterly flow aiding mixing and latest
blends have highs in the upper 30s to upper 40s. That aligns
fairly well with the ECMWF ensemble members, so no adjustments
were made.

Those stronger south-southeasterly winds on Thursday (gusts up to
20kts at this point) are ahead of a surface low that will move
east across the Dakotas and southern Canada Thursday night. At
this point, with the low interacting with abundant dry air still
in place on the back side of the departing upper ridge, not
really expecting much precipitation potential (just mid-high
clouds), at least until trailing shortwave and colder air slide
in on Saturday. Even then, best cold air pocket and steeper low
level lapse rates end up being to the northeast of the area. Will
also see gusty northwest winds Friday/Saturday afternoons behind
the cold front (gusts to 25-30kts over north central SD).

Behind that low and brief cold air push (850mb temps in the teens
below zero C), upper ridging develops again over the western
CONUS and moves east over the Northern Plains for early next
week. That will push temps well above normal for the start of
next week.


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1123 PM CST Sun Jan 21 2018

Fog and stratus has started to advect in from ND and MN tonight.
Expect all sites to be IFR by 9z. KMBG/KPIR/KABR will improve to
VFR Monday afternoon. KATY will not improve until Monday evening.


SD...Dense Fog Advisory until 11 AM CST /10 AM MST/ this morning for



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