Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 252030

Area Forecast Discussion
National Weather Service Aberdeen SD
330 PM CDT Tue Apr 25 2017

.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 328 PM CDT Tue Apr 25 2017

The main issue in the very short range will be pcpn...type and
amounts. System currently over the southern high plains will lift
northeast tonight and Wednesday. Meanwhile, an upper circulation/pv
anomaly over western South Dakota is expected to slowly eject
northeast. Energy associated with this feature is expected to bring
a mix bag of pcpn to the eastern parts of the region late tnt and
Wednesday. Temperatures remain relatively warm aloft over the
eastern cwa in vcnty of the Glacial Lakes/Sisseton Hills. This is
where the highest potential for any mixed pcpn will take place in
the next 24 hours. The GEM/GFS/HRRR all show some sort of a trowal
like feature forming over southeast North Dakota tnt and early
Wednesday, extending south into the far northeast part of the cwa.
H3 progs also indicate some potential for uvm associated with the
right entrance region of jet stream.  Model blend came up with
potentially a inch or more snow over these areas, and based on sfc
temps that certainly seems possible. Later shifts will have to
monitor for any mesoscale bands that might set up. On Wednesday slow
clearing from west to east is expected with temperatures eventually
recovering nicely west of the James Valley.  Temperatures overall
will be cold and below normal through mid week.

.LONG TERM...(Wednesday Evening through Tuesday)
Issued at 328 PM CDT Tue Apr 25 2017

A ridge of high pressure extending from Canada will remain
across northeastern SD and west central MN through much of the
period. Light snow will be exiting the northeastern counties
Wednesday night, with little to no additional snowfall. This will be
while the 500mb trough set up from the eastern Dakotas down through
OK exits only slightly to the east. The main 500mb low will continue
to spin across northern MN and Ontario into Thursday night.

The next chance of wet weather will arrive Thursday night over south
central SD, as the sfc ridge remains in place across the northeast.
With borderline temperatures, a mix of rain or snow will be
possible, transitioning to just rain during the day Friday. The GFS
has trended drier/farther south with this system, as a 500mb ridge
noses across the area, embedded within a broad trough set up across
much of the nation.

Will look for the large trough over the U.S. to stay in place, as
the main low dives across New Mexico on Saturday and begins to eject
northeastward from OK up through IA Sunday through Sunday night.
Will need to monitor the latest trends for this potent and rapidly
evolving system, as a prolonged period of precipitation looks more
and more likely over our extreme southeast or just to our east.
Mixed precipitation will be possible over that area late Saturday
night as temperatures fall into the low to mid 30s. Otherwise, the
GFS and ECMWF do agree on rain returning to western and central SD
by late Monday night into Tuesday as the 500mb low shifts across the
Upper Great Lakes and into Canada.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1230 PM CDT Tue Apr 25 2017

A mix of mvfr/ifr cigs is expected through the night at all
terminals. Vsbys should favor VFR but in the east may slip into
MVFR due to pcpn later today and tonight.




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