Area Forecast Discussion
Issued by NWS Springfield, MO
FXUS63 KSGF 311958
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
158 PM CST Sat Jan 31 2015
.SHORT TERM...(This Evening through Tuesday)
Issued at 158 PM CST SAT JAN 31 2015
Rainfall has been mighty hard to come by today, in spite of
increasingly mid/high level moisture. The flies in the ointment
for rainfall today has been a pocket of very dry air in the 925mb
to 850mb layer (seen best on the 12z KLIT sounding), southeast
winds and the mixing down of this drier air. Amazingly, we have
seen a steady decline in surface dewpoints over the past few
hours, with locations along and southeast of the plateau
observing values as low as the mid teens. The better quality
moisture is just within reach to our west and southwest, but it
has made very little progress east so far today. As a result,
outside of far western and northern portions of the forecast area,
conditions will remain dry heading into this evening.
All model output agrees that moisture will finally get forced
eastward tonight as two upper level disturbances converge on the
region. One from the northwest and one from the southwest. It will
take a good chunk of the evening to moisten up completely, but
once it does, we will receive a decent rainfall. The initial round
of rain will steadily progress eastward, but a reinforcing shot of
precipitation will quickly follow for at least the northeast half
of the area as the northern stream upper level disturbance enters
Temperatures will fall through the day as a much colder airmass
invades from the northwest. As this happens, rain will mix with or
change over to light snow. Given relatively warm ground
temperatures and light precipitation rates, accumulation more than
just a light dusting will be hard to come by. Deeper cold air will
move into the region Sunday night. Lingering low level moisture
will result in flurries for much of the night, ending by daybreak
Monday. Once again, a light dusting is possible.
Monday will be cold, starting out in the teens and warming into
the 30s. This is a good 15 or so degrees below average. Wind
chills for the Monday morning rush will be in the single digits
above zero. As has been the case lately, the cold air won`t last
long and southerly flow will return as early as Monday afternoon.
This will set the stage for a breezy but seasonably mild Tuesday
before the next front approaches at midweek.
.LONG TERM...(Tuesday Night through Saturday)
Issued at 158 PM CST SAT JAN 31 2015
There will be a system mid week to watch for the potential of light
snow across the area. A cold front with a Canadian airmass behind it
will move through during the day on Wednesday. Depending on the
timing of the passage of the front will depict which locations will
warm up slightly and which locations temperatures will actually fall
Wednesday afternoon. Gusty northerly winds up to 25 mph will
ushering in colder air Wednesday afternoon and night.
Some of the models are showing the potential for an upper level wave
to move across the area Wednesday night into early Thursday morning.
They are also indicating some good lift and mid level frontogenesis.
The 12z ECMWF is not showing this but the 12z GFS and GEM are
showing this. The models are also indicating QPF around a quarter an
inch which would translate into several inches of snow possible.
At this time...will maintain a chance for light snow across the
entire area Wednesday evening...night...ending Thursday morning.
There is potential for light accumulations with this system as this
system will be happening overnight and snow ratios could be slightly
higher because of the colder temperatures down into the upper teens
to lower 20s. There is some uncertainty this far out about the
system but some potential is there.
The upper level flow flattens out somewhat and heights appear they
will rise a little bit by the end of next week. This means milder
temperatures and dry weather will return again.
.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1125 AM CST SAT JAN 31 2015
Flight conditions will deteriorate over time across the region as
widespread begins to move into the area later this afternoon and
evening. Ceilings should gradually lower to MVFR and then IFR
late tonight, with visibility dropping to around 3 miles or so in
the heaviest areas of rain.
A cold front will then arrive mid to late morning tomorrow, with
winds shifting to west-northwest and increasing significantly as
it passes. Lingering rain showers will likely begin to mix with
and perhaps eventually change over to all snow late in the TAF
period. No accumulations are expected.