103 
FXUS63 KFSD 272126
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
326 PM CST Wed Feb 27 2019

.SHORT TERM...(This evening through Thursday)
Issued at 326 PM CST Wed Feb 27 2019

Relatively weak and somewhat disorganized shortwave is expected to 
lead to increasing clouds tonight and light snow across the region. 
Short term hires models have trended south with this system, with 
the focus now south of the forecast area in Nebraska into Iowa. 
Within our forecast area, isentropic lift on the 290-295K surface 
concentrates the strongest dynamics in the lower portions of the 
atmosphere along the Missouri River Valley where models are 
producing a few hundredths of an inch of liquid across central South 
Dakota. Dendritic layer is focused much higher in the atmosphere at 
or above 600 mb limiting the amount of lift in the ice creation 
layer. As the wave works east, encounters dry air in the near 
surface layer limiting precipitation amounts. Generally have 1/2" 
forecast along and south of I-90 Thursday morning.  

Behind this disturbance, atmosphere dries out but may keep some 
lingering stratus around throughout the day. High temperatures will 
be slightly warmer than we have seen the past several days, with 925 
hpa temperatures around -10C leading to highs only 15 degrees below 
normal. 

.LONG TERM...(Thursday night through Wednesday)
Issued at 326 PM CST Wed Feb 27 2019

Second system breaks away from parent low off the Pacific NW coast 
Thursday evening and works into the plains on Friday.  Model timing 
differences with this system, with the American solutions faster than 
the European counterpart.  Based on WPC guidance, blended the EC 
ensemble timing with the GFS given the American systems are believed 
to be a little progressive, and the operational ECMWF is a little 
slow. This timing seems to agree with the German and French models. 
This system is focused across the northern half of the forecast 
area, with the greatest amounts focused along and north of highway 
14. 

Behind this system, freezer door opens and potential record cold is 
expected this weekend into next week.  Have blended temperatures 
with CONS_RAW, which results in wind chills of 30 to 35 below 
Saturday night and Sunday night.  In addition, sub-zero highs are 
looking increasingly likely on Sunday.  What is a bit unnerving are 
925 hpa winds on Sunday night into Monday with 30-40 knots forecast 
by both the GFS and ECMWF. Have started to nudge winds up in this 
time, and also have a mention of blowing snow.  Will need to keep an 
eye on this with both frigid air in place creating dangerous wind 
chills, and the potential for blowing snow.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1129 AM CST Wed Feb 27 2019

VFR conditions expected through 06Z Thursday. Thereafter, short
wave is expected to funnel down the Missouri Valley resulting in
reduced visibility at times. Lowest visibilities are expected
along the South Dakota/Nebraska line including the KSUX terminal.  
Light west- northwest flow at the surface will transition to the 
south into Thursday morning.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...BT
LONG TERM...BT
AVIATION...BT