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Area Forecast Discussion (AFD)

Issued by Springfield, MO (SGF)

                            
000
FXUS63 KSGF 181141
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
541 AM CST Fri Jan 18 2019

...12Z AVIATION UPDATE...

.SHORT TERM...(Today through Saturday) 
Issued at 313 AM CST Fri Jan 18 2019

Conditions were overcast with patchy drizzle and fog across the
area early this morning. Temperatures were generally in the mid 
30s to around 40. In the upper levels, a pronounced 120+ knot jet 
streak was punching southeast through the western US with mid 
level shortwave energy taking shape as well. This interaction has 
already induced lee side surface cyclogenesis in the western plains.
Therefore we should begin to see southerly winds pick up across 
the area as we head through the day. 850mb warm air advection will
begin in earnest as we head through the day as a low level jet 
develops. Therefore even with cloud cover, southerly winds will 
bring some warmer temps to the area with highs ranging from low 
40s in central Mo to the lower 50s around Joplin. 

Evening 00z models have trended much faster with this incoming 
storm system as it moves into the rockies today. Expectations are
for precipitation to develop across the area by late afternoon or 
more likely evening across the area as lift increases across the 
area. Models have indicated some MU cape values approaching 
500j/kg across southern Missouri, therefore a few thunderstorms 
will be possible this evening into the early overnight hours,
especially south of I-44. There will be a limited risk for 
flooding due to saturated soil conditions however currently 
thinking any flooding will be isolated given a slight decrease in 
total qpf. 

Surface low pressure will move from the I-40 region of Oklahoma,
northeast into central/northern Arkansas overnight into early
Saturday morning. As this occurs, an inverted trough/front will
pass through with very strong north winds ushering in colder temps
behind it. It now appears that the transition from rain to snow
will occur as early as 12am-3am in se KS/Western Missouri with 
the transition making it to the US Highway 65 corridor by 4am-8am 
and the eastern counties by mid morning. This is slightly earlier
than previous forecasts and is important because there will be 
less effects of solar insulation and improved snowfall 
accumulation efficiency. 

Roughly between 4am and 10am, the region will be in the left exit
region of the upper level jet and the 500mb low tracking directly
over the area. Therefore sufficient lift looks to occur across 
the area in the colder air. Therefore we are thinking that a 
general 1-2 inches of snow will be possible across most of the 
area Saturday morning with the heaviest amounts northeast of 
Springfield. Surface pressure gradient will be very strong and 
winds will increase dramatically with sustained winds of 25mph and
gusts to 40mph possible. This could create very low visibilities 
during the snowfall. Future forecast updates will need to look at 
the possibility of a Wind Advisory. 

Surface temps look to drop all day Saturday with morning temps in
the lower 30s to lunch time temps in the lower 20s. Wind chill
readings will drop into the single digits during the day making it
a very cold day. It is advised to not get too hung up on snow 
amounts, whether it is a dusting or two inches, roads/ground will 
cool dramatically given forecasted temps, allowing for 
quick accumulation to occur. Impacts to roadways are expected 
Saturday and a Winter Weather Advisory is in effect for a good 
chunk of the area. Lastly, it should be noted that some model 
guidance does show slightly higher/lower amounts with 03Z SREF 
snow plumes still showing several inches of spread across the area
therefore please continue to monitor forecasts throughout the day
for any changes.

Low temps Saturday night/Sunday morning will tank into the teens
as 850mb temps drop into the -5 to -10C range and the possibility
of some snow on the ground. Would not be surprised to see single
digit low temps in some areas.

.LONG TERM...(Sunday through Thursday) 
Issued at 313 AM CST Fri Jan 18 2019

An active pattern looks to continue into next week. However models
are struggling to handle individual shortwaves in the northwest
flow. Arctic airmass will slowly retreat Sunday and Monday as a
mid level ridge builds in. A strong shortwave trough will dig 
into the Rockies Monday and will be the next system to hone in on.
Some models split the energy as it moves east Tuesday with energy
moving north of the area and the other piece cut off to the 
southwest. Regardless, a front and reinforcing cold air does look 
likely by mid week with at least some precip chances however still
plenty of time to look at that system along with another system 
by the end of the week. 

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 524 AM CST Fri Jan 18 2019

IFR conditions are expected for at least the first six hours of
the forecast. Conditions could briefly improve to mvfr by
afternoon however IFR conditions and rain will move in tonight.
Winds will increase during the day out of the southeast and become
gusty. Cant rule out some thunder this evening or tonight however
confidence is not high enough to include in taf. Winds will switch
around to the northwest by the end of the taf period with rain
changing to snow at JLN and BBG along with wind gusts over 30kts.
Low level wind shear will be possible overnight as well at the taf
sites.


&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Winter Weather Advisory from midnight tonight to 6 PM CST 
     Saturday for MOZ055>058-066>071-077>083-088>092-094>096.

KS...Winter Weather Advisory from midnight tonight to 6 PM CST 
     Saturday for KSZ073-097.

&&

$$

SHORT TERM...Burchfield
LONG TERM...Burchfield
AVIATION...Burchfield