Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

FXUS63 KFSD 260348

Area Forecast Discussion
National Weather Service Sioux Falls SD
1047 PM CDT Sat Mar 25 2017

.SHORT TERM...(This evening through Sunday)
Issued at 354 PM CDT Sat Mar 25 2017

Stratus and fog will be the main concerns for tonight and Sunday,
with light east northeast low level flow continuing to tap into low
level moisture. Stratus will expand westward this evening,
blanketing the entire forecast area. With stratus lowering and
increasing low level moisture overnight, fog will also redevelop
late evening through Sunday morning. Much like this morning, there
may be localized areas of a mile or less visibility. Not confident
enough at this point to issue a dense fog advisory for any
particular area, given the lack of widespread dense fog this

With the big upper low centered over northern Missouri
slowly wobbling eastward, we could see enough forcing for some
isolated light rain to linger in our far eastern counties, near
north central Iowa and south central Minnesota. Lows tonight remain
above freezing in the mid to upper 30s. Highs will again be tricky
tomorrow, with stratus sticking around into the afternoon. With this
in mind, have lowered highs slightly, especially in the east where
stratus is most likely to stick around through the day. Highs will
be in the 40s to lower 50s.

.LONG TERM...(Sunday night through Saturday)
Issued at 354 PM CDT Sat Mar 25 2017

Lingering clouds Sunday night as meek low-level flow will be
inefficient toward removal. Likely will not have great mixing on
Sunday, and with winds diminishing, threat for any partial clearing
of skies will be met with a stronger likelihood of at least some
patchy fog redeveloping, if not a greater coverage threat for areas
near/west of I-29.  After split energy trough passes longitudinally
through Sunday night, will have a period of ridging aloft and quiet
overall weather, with usual difficulty in determining if the
persistent easterly component will allow any meaningful clearing.
Would expect by Tuesday.  Suggestions are that a somewhat drier
trajectory could sneak in by Tuesday, which may prove to be the best
bet at limited sunshine in the shorter term.  Next closed low in the
series will already be gracing the Four-Corners area by later
Tuesday, with broad mid-level warm advection pushing out into the
central Dakotas and Nebraska.  While the drier trajectories should
protect most of the area from lower clouds/precip, there is a
suggestion that a little rainfall could spread into the Lower Brule
areas during the afternoon.

Little has changed over the last 24 hours in terms of certainty in
the longer ranges of the forecast. GFS and a majority of ensemble
members continue to suggest a healthy split to the flow as next
trough works eastward, with enough northern stream component to
limit the northward wandering of precipitation threat to the
Missouri valley, and over a much shorter period of time from Tuesday
night to early Thursday.  The more closed-low dominant solutions in
ECMWF and GEM (most northern track) bring up a persistent chance for
precipitation on Tuesday night, lingering with wrapping all the way
north and westward through the CWA. Only GEM leaves precipitation
lingering into Friday, so for now have removed and kept forecast dry
from Friday into Saturday.  At least it is fairly safe to say that
solid precipitation would be highly unlikely given the fairly mild
off-surface temps, if there even is any precipitation for some areas


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1047 PM CDT Sat Mar 25 2017

IFR-LIFR stratus will continue to dominate most of the forecast
area through this TAF period, with areas of low visibility in fog
again developing through the night and easing by midday/early
afternoon Sunday.

Exception will be in far western portions of our area, including
KHON. where conditions are expected to improve to VFR again Sunday
afternoon as stratus retreats to the east.




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