Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 211743

Area Forecast Discussion
National Weather Service Sioux Falls SD
1243 PM CDT Fri Apr 21 2017

.SHORT TERM...(Today and Tonight)
Issued at 357 AM CDT Fri Apr 21 2017

The main forecast concern in the short-term is cool temperatures
expected tonight and possibility of frost.

For today, a ridge of high pressure will be over the area through
out the day. This will result in a persistent easterly flow which
will advect in drier air from Minnesota resulting dew points falling
into the mid 30s this afternoon. Except for some high clouds
primarily in the Missouri Valley, skies will be mostly sunny which
will allow for efficient mixing and will allow highs to rise within
a couple of degrees of 60.  Overnight, as the ridge settles over
and the upper low over the southern plains moves southeast, skies
will clear across the area and winds will become light and variable.
This will mean another cool night with lows across the area from 34
to 37. Opted not to add frost into the forecast even though lows
tonight will be the same as this morning. The reason is that today`s
mixing should leave less moisture near the surface so that dew or
frost is unlikely.

.LONG TERM...(Saturday through Thursday)
Issued at 357 AM CDT Fri Apr 21 2017

Another nice weekend on tap, as surface ridge across the area
Saturday slowly shifts southeast, with some increasing southerly
flow developing Sunday. Mixing will be more limited Saturday with
the light winds, but abundant sunshine should help warm afternoon
temperatures into the lower-mid 60s. Lingering ridge axis across
northwest Iowa Saturday night could allow for another cool night
with temperatures in the mid 30s in some locations, but otherwise
the beginning of return flow should hold lows in the upper 30s to
lower 40s.

This leads into a warmer, but breezy day Sunday, again with mostly
sunny skies and highs in the upper 60s-lower 70s. Low level jet and
some increasing clouds ahead of a weak wave will result in a mild
Sunday night, with lows in the upper 40s-lower 50s expected for most
areas. This wave and associated cool front slide across the region
on Monday. Could see some scattered showers, but instability remains
pretty limited, so only isolated thunder potential, mainly near and
southeast of Highway 60 in the late afternoon and evening. Highs on
Monday again look pretty mild with strong mixing in the southerly
flow ahead of the front, with highs again in the mid 60s-lower 70s.

Pattern remains a bit unsettled through the longer range of the
forecast Tuesday through Thursday, but Monday`s cool front pushes
well south of the area by late Tuesday, and remains south of I-80
through Thursday. As a result, moisture/instability this far north
will be limited, so despite some upper support with a couple of weak
waves sliding through, will largely hold pops in the chance range at
most through this period. Temperatures cool to below normal, with
highs back into the 50s and lows mid 30s to lower 40s.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1243 PM CDT Fri Apr 21 2017

Model underestimation of the moisture in the boundary layer today
and have seen a much greater expanse of diurnally driven cumulus
at VFR levels as mixed layer deepened late morning. Expect
coverage should peak in the next 1-2 hours, and dissipate fully
by around 00-01z.




SHORT TERM...Schumacher
AVIATION...Chapman is the U.S. government's official web portal to all federal, state and local government web resources and services.