Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 231756 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1156 AM CST Tue Jan 23 2018

.UPDATE...
Issued at 1145 AM CST Tue Jan 23 2018

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 934 AM CST Tue Jan 23 2018

Visibility is improving throughout the region. The Dense Fog
Advisory has been cancelled. Shortblend/NationalBlend numerical
guidance compliments the current official forecast today for
temperature, wind and skycover. No notable changes planned for
today for those forecast elements. Updates are out.

&&

.SHORT TERM...(Today through Thursday Afternoon)
Issued at 249 AM CST Tue Jan 23 2018

Stratus, fog and the occasional flurry/drizzle-sprinkle (although
at current the flurries have stepped up a notch) are the main
forecast challenges this morning - and are the main conditions
that are occurring to start the day off. The western edge of all
this follows the Missouri valley north to south across South
Dakota. While the western edge is somewhat obscured by high clouds
on Satellite, we can detect a slight eastward drift. This makes
the forecast high temperatures a challenge as it all depends on
how much sunshine each location can get before the sun sets. The
expectation is that this transition area will probably be between
the James and Missouri valleys with clearing getting in here and
points east too late to have a sizable impact on the high
temperature forecast. There will be a gap in coverage before
another area of clouds in Canada pokes into northeast South Dakota
late. With no real airmass change, we could be looking at clouds
and fog (which several CAMS suggest in the James valley) tonight
which should limit temperature drop.

The rest of the forecast is mainly weak warm advection dominated,
culminating in another mild day Thursday, thanks to 925mb
temperatures nudging up toward a standard deviation above climo.
Mixed temps Thursday are in the 40s to 50s so have gone a few
degrees above blended guidance. The only caveat is that low level
winds are south/southeast ahead of a lee low in the northern
Rockies, but this less favorable mixing direction will be
countered by a lack of snowfall.

.LONG TERM...(Thursday Evening through Monday)
Issued at 249 AM CST Tue Jan 23 2018

Overall, fairly quiet long term forecast. Above normal temps will
be in place for the start of the period as the upper ridge shifts
off to the east on Thursday night. As that occurs, a surface low
riding on the back side of the ridge will move northeast from the
western Dakotas to the Lake of the Woods area on Friday
afternoon. That will drag the first of two cold fronts across the
area.  The first on Friday morning will bring northwesterly winds
that will aid mixing into the warmer air aloft and should produce
highs in the lower 40s for much of the area. It probably won`t
feel as warm as that though with gusty northwest winds up to
30kts (maybe a little higher if we can maximize mixing).

Colder air will settle into the area on Saturday, lowering temps
back into the upper 20s to mid 30s under continued gusty
northwest winds (only to 20-25kts). The secondary cold front and
shortwave/PV anomaly will drop southeast across the area on
Saturday night, lowering temps a little more, but generally near
or slightly above normal highs for this time of year. Will keep
the forecast dry for now with that shortwave, but there is a
little better moisture associated with the wave so wouldn`t be
surprised to see a few flurries Sat night into Sunday over the
northwest part of the CWA.

Upper trough departs Sunday and an upper ridge builds in for the
first part of the work week, bringing a return to the above
normal temperatures we`ve seen recently. Still a wide variety of
solutions in the deterministic models on the surface details for
early next week, so will just follow a general blend for most
elements on Mon/Tue.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1145 AM CST Tue Jan 23 2018

KPIR is VFR and is expected to remain so over the next 24 hours.

KMBG is VFR and is expected to remain so for much of the next 24
hours. There could be a brief period tonight between 06Z and 12Z
when some fog forms over or backs into the terminal.

KABR is just about out of the sub-VFR fog/low stratus, will remain
out of it for the rest of the afternoon, but probably fall back
into either sub-VFR fog developing later this evening/overnight
or low stratus advecting in from North Dakota, or both.

If the western edge of the sub-VFR low stratus field doesn`t slow
down or stop, it should clear the KATY terminal by 03Z. Guidance
suggests KATY will either fall back into sub-VFR fog developing
later this evening/overnight or the low stratus won`t ever clear
KATY (or both). KATY has the highest probability of any of the
four terminals of staying sub-VFR for duration of the TAF valid
period.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Dorn
SHORT TERM...Connelly
LONG TERM...SRF
AVIATION...Dorn



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