Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Springfield MO
940 am CST Sat Dec 27 2014
issued at 940 am CST Sat Dec 27 2014
Forecast updated to account for thermodynamic and radar trends.
Deeper cold air has come in quickly and allowed for a mix/change
over to snow across the west/northwest half of the area (or so).
Most persistent area of light snow has been across southeastern
Kansas where a dusting of accumulation has been observed on grassy
areas. Air temperatures are holding in the low/mid 30s. Looking at
area obs and after making a few calls, Road temperatures are a bit
warmer (upper 30s in southeastern Kansas, warmer on the MO side).
Since snow showers will be on again/off again in nature, it does
not appear that we will receive persistent enough precipitation
rates to overcome relatively warm ground temperatures. As a
result, any snow accumulation will be on grassy areas and light
Timing the ending of the snow is proving somewhat tricky. Looking
at the 12z ktop sounding, there is a wedge of dry air in the
low/mid levels working southeastward (850-700mb layer). This is
already entering the northwestern portion of the outlook area and
meshes up nicely with surface observations in Kansas/Oklahoma. At
this hour, light snow reports are becoming more sporadic at kfsk
(fort scott) with rising cloud bases, which supports the idea of
tracking these mid level dewpoint depressions. As a result, have
followed this for timing the end of precipitation.
Across the eastern portion of the outlook area, the cold front has
exited east and temperatures will slowly, but steadily drop
through the day. Will look at the forecast for this evening
shortly to see if there is need to introduce a brief period of
light snow before ending around midnight.
Short term...(today and tonight)
Light rain was increasing in coverage over eastern Oklahoma this
morning, which will shift into southeast Kansas and the Missouri
We followed the hi-res arw with our precipitation and pop forecast
through today and tonight. This solution suggests placing light
rain further northwest by 12z, and translating an axis of light
rain eastward across southern Missouri with time.
We think the areal coverage of measurable rain will be high,
however, rainfall amounts will be low. Many locations will only
experience measurements less than one tenth of an inch.
Light rain should linger across south central Missouri this
evening and tonight, eventually exiting the entire region by
Long term...(sunday through friday)
A cooler air mass will have spread across southern Missouri by
Sunday bringing temperatures down into the 20s to start the day.
High pressure will be shifting directly overhead causing winds
to become light and variable under sunny skies.
An extended period of dry weather is expected heading into the
upcoming work week. Fast zonal flow will occur over most of the
nation's mid section as northerly winds persist at the surface.
This pattern will keep moisture at Bay, bringing dry weather.
These northerly winds will also allow some polar air to move into
the Ozarks. Temperatures will plummet by Tuesday and Wednesday
with highs only in the 20s and lows in the teens.
Rain chances finally increase by Thursday night and Friday as a
storm system slowly approach from the west. Thermal fields will be
border line rain or snow for precipitation type. Therefore we have
a rain or snow worded in our forecast for Thursday night and
beyond. Details regarding precipitation type late next week should
be better understood in time.
Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 558 am CST Sat Dec 27 2014
For the ksgf/kjln/kbbg tafs: a cold front moved through the taf
sites over the past few hours. Some Post frontal light
precipitation is occurring, but in general expect IFR/low end
MVFR ceilings to gradually improve somewhat over the next few
hours, especially at kjln and ksgf. Lower clouds and precip will
linger a bit longer at kbbg. In general, lower ceilings are
expected to push off to the east for the latter half of the taf
period as the front moves farther off to the east.