Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 152327 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
527 PM CST Wed Feb 15 2017

Issued at 526 PM CST Wed Feb 15 2017

See updated aviation discussion below.


.SHORT TERM...(This Evening through Thursday Afternoon)
Issued at 316 PM CST Wed Feb 15 2017

No major changes to the weather pattern translates to a similar
forecast from tonight through Thursday. A large, dominant upper
level ridge will keep winds light and skies clear tonight, and while
a few models have hinted at a bit of fog development across and east
of the James Valley, have left it out of the forecast for the time
being. As for Thursday, persistent snowpack across the Missouri
River valley north of Stanley county should once again have a
dampening influence on temperatures. Have adjusted highs down
therefore, but it may not be enough despite impressive upper level
temperatures. Values at 700 and 850 mb during the afternoon hours
look to be between 2-3 standard deviations above normal, which
helps translate to 50+ degree surface temperatures across the CWA.
This is generally 20-25 degrees above average for this time of
year, and values may approach record territory for a few locations
as well. Light winds and clear skies continue into Thursday
evening as lows dip just a few degrees below the melting point.

.LONG TERM...(Thursday Evening through Wednesday)
Issued at 316 PM CST Wed Feb 15 2017

Mild and mainly dry from the end of the work week through the middle
of next week. The only system, a wave embedded within the northern
branch of split flow, features negative tilt and thus is rather
progressive. The track/timing of the wave and associated low
pressure system still varies rather significantly between the
Canadian, ECMWF and GFS deterministic runs and thus have low
confidence in POPS/QPF. Given the track and temperatures aloft, will
persist with a majority PTYPE of rain with this system.

The main aspect of the extended range is the mild air, with
highs/lows some 10 to 30 degrees above average - with near record
warmth on several of the days. Early in the period, 850mb
temperatures are topping out around +14C, which is above the daily
max according to SPC sounding climatology page. The degree of mixing
is uncertain as a weak surface low moves across the CWA. Winds will
be weak, but also shifting to a westerly component with weak cold
advection in the wake of the low. Regardless, with a good portion of
the CWA experiencing snow melt we should see highs in the 50s.

Saturday will initially start with weak cold advection at 850mb, but
with temperatures still into the low single digits above zero
Celsius. Thus, a bit cooler than compared to Friday but still well
above climo. There is another surge of warm advection that begins
west river late Saturday. Sunday features 850mb temperatures up to
+12C though with south winds mixing will not be at peak efficiency.
These 850mb readings will also be close to the daily max. Another
low, mentioned above, will deepen and cross the Dakotas and result
in strong mixing. Temperatures may in fact remain in the 30s and 40s

There is less certainty in the temperature forecast for the first
half of next week, though the consensus is for temperatures to
remain much above average.


.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 526 PM CST Wed Feb 15 2017

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




LONG TERM...Connelly
AVIATION...Parkin is the U.S. government's official web portal to all federal, state and local government web resources and services.