Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 231000
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
400 AM CST Thu Nov 23 2017

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 357 AM CST Thu Nov 23 2017

Upper level ridge building into the region, along with westerly
winds will bring much above normal temperatures into the region
today. Highs temperatures will range from the upper 40s, in
western Minnesota, to the upper 60s and low 70s, along and west of
the Missouri Valley. Am a bit concerned with our highs in the
James Valley where our 0Z sounding shows a substantial inversion.
The NAM keeps the inversion in the valley until after peak
heating. A few CAMS support the idea of warm temps along the
western rim of the valley, and on the eastern side of the Sisseton
Hills. Thus have lowered highs slightly in the eastern CWA from
the previous forecast. A few locations will likely see record to
near record high temperatures today. Record highs for
Thanksgiving will be possible for a few locations as well.

Warm temperatures will remain over the region tonight with lows only
in the 30s and 40s. An upper level trough and surface front will
cross the region on Friday. This system will bring very strong
northwesterly winds, along with a chance for light rain. The
strongest winds will likely occur between 12-18Z, for our western
CWA, and 18-0Z for our east. Buffer soundings, along with half km
winds support advisory level winds for the region on Friday. Pcpn
looks best in the eastern CWA during the morning hours. While 925
and 850 mb temps cool off on Friday, highs will still reach the 50s.

A Canadian high pressure sliding southwest across the region on
Saturday will bring cooler temperatures with highs in the 40s and
low 50s.

.LONG TERM...(Saturday Evening through Wednesday)
Issued at 357 AM CST Thu Nov 23 2017

The larger-scale signal for flow pattern in the models remains
unchanged in the out periods, a positive PNA pattern (ridge/warm out
west and trof/cool out east) with this CWA situated in between in,
more often than not, some form of northwest flow aloft, which
promotes a prevailing dry forecast with fluctuations back and forth
between periods of warmer than normal and cooler than normal
temperatures.

The 00Z GSM output tonight continues to leave questions surrounding
precip potential Monday night through Tuesday night unanswered. In
this installment, the ECMWF has returned to looking more like
solutions from a couple of nights ago, leaving a much weaker more
progressive shortwave to move through the northern plains, while
taking a separate/larger chunk of longwave trof energy southeastward
into the southern plains early to mid week next week. The GFS looks
similar to the ECMWF tonight, while the Canadian model takes a turn
at being the strongest/slowest and farthest north solution in
handling the treatment of said energy eastward across the country.

Monday night through Tuesday night is now moving into the day 5/day
6 portion of the forecast, but there is just as much uncertainty now
regarding strength and track of this energy moving through the
western CONUS ridge and out into the middle section of the country
as there was back when it was in the day 7/day 8 timeframe. For now,
it`s safe to say "there is still a signal" lurking the out periods
for some precipitation potential early next week. Will continue to
wait out the models and see if they start to come into better
agreement/timing/strength of low pressure energy early next week.

As for temperatures, much above normal warmth (1.5 to 2.5 standard
deviations above normal under the NAEFS Ensemble SA standardized
anomaly table) appears to reside over this region until Monday night
when colder air is progged to move in from the north and stick
around for a couple of days. That being said, these cooler
temperatures will probably end up being right around climo-normal
for late November/early December.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1122 PM CST Wed Nov 22 2017

VFR conditions will prevail across the area overnight and through
the day Thursday.

&&

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

$$

SHORT TERM...SD
LONG TERM...Dorn
AVIATION...Parkin


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