Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Springfield MO
549 am CST Tue Dec 10 2013
issued at 332 am CST Tuesday Dec 10 2013
The area of snow had moved southeast of the region this morning as
the mid and upper level trough shifted east this morning. General
snowfall amounts ranged from 1-4 inches, though a 5 inch reading
would not be out of the question. Dry air was filtering over the
region as per water vapor imagery which will allow for clearing
skies this morning.
Short term...(today and tonight)
issued at 230 am CST Tuesday Dec 10 2013
The main concern will be cold temperatures. The entrance region of
the upper jet that produced lift/resultant band of snow over the
region is shifting east and we will continue to see diminishing
snow over the southeast half of the cwfa over the next 2-3 hours.
We are already seeing clearing skies on satellite imagery and sfc
observations over Kansas into our western MO counties and that trend
will continue from west-east.
The influence of snow cover will affect temperatures over the next
few days. Already seeing single digits (deg f) at Joplin right now
with light winds and a clear sky (shallow ground based temperature
inversion), so a quick drop can still be expected before daybreak
where the sky clears. Will undercut MOS guidance temperatures somewhat,
but we should see a bit of a "warm up" with southwest winds and
sunshine today. That being said it will still be much colder than
normal, but the sunshine will be nice.
Another front will move through the region late tonight and early
in the daylight hours Wednesday. This front will go through dry.
Long term...(wednesday through monday)
issued at 230 am CST Tuesday Dec 10 2013
The main concern will be Friday as a cutoff low now off the coast
of northern baja will kick out and open up, shifting northeast
into the Southern Plains Friday.
Quiet weather is expected Wednesday/Thursday with sfc high
pressure moving through the area. Cold temperatures will continue
and with high pressure centered near/over the area Wednesday night,
temperatures will drop quickly after sunset with some areas
getting well down into the single digits for lows. However, as the
sfc high moves off, we will likely get a nice diurnal temperature bounce
during the day Thursday with south winds (and hopefully) sunshine.
Friday: guidance has been fairly consistent in bringing
moisture/precip northward ahead of what looks like a compact but
fairly vigorous southern stream shortwave moving into the
central/Southern Plains. Although some minor timing differences
exist, it looks like lift will be maximized as the left exit
region of a jet streak moves through the region Friday
afternoon/evening. The main concern will timing the onset of the
precip and how the vertical temperature profiles will influence
precip type. For now, have light precip moving into the area
Friday morning. During this time there will be strong warm
advection in the lower layers with GFS and European model (ecmwf) progged soundings
showing a strong warm nose at 850-750mb 12z Fri while sfc
temperatures remain at or below freezing early in the day.
Evaporative cooling will also be a contributor to the low level
temperatures during the day Friday, possibly cooling the warm nose
and further complicating the precip type forecast. The potential
for freezing rain/sleet/snow exists, with the possibility of an
eventual transition to rain Friday afternoon. For Friday night, it
looks like the potential for a transition back to snow/freezing
drizzle as precip diminishes. We are still 72+ hours out, and will
continue to watch trends.
Clouds and very light precip/snow may linger into Saturday,
otherwise it looks quiet with a modest warming trend Sunday into
Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 538 am CST Tuesday Dec 10 2013
High pressure building into the region in the wake of the
overnight snow will keep flight conditions VFR through the forecast
period. An approaching low level jet will allow for the
development of low level wind shear across the area for Wednesday
morning at all terminals.