Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Omaha/valley NE
1149 am CST Sat Feb 13 2016
Short term...(today through monday)
issued at 245 am CST Sat Feb 13 2016
Precipitation chances and temperatures will provide the primary forecast
challenges in this period.
Main features noted from the upper air charts last evening
included the following. At 300 mb...a jet streak of around 145
knots was punching southeast from southeast Minnesota. Winds of
about 100 knots from the southwest were over Oregon...associated
with the next shortwave trough of concern. At 500 mb...12 hour
height falls of up to 100 meters were over southwest British
Columbia...while a ridge stretched from The Four Corners region up
into Alberta and Saskatchewan. A modest thermal gradient was noted
over the northern and Central Plains at 700 mb and 850 mb. Coldest
values at 850 mb were around -39 c on the south side of James Bay.
Surface analysis at 08z showed a ridge of cold high pressure from
the eastern Dakotas and western Minnesota down into our area.
Winds were from the northeast or east...with temperatures in the
single digits and teens. Pressure falls were highest over the
High Plains. Radar echoes had been increasing over South Dakota
and parts of northern Nebraska.
Today...expect that some light snow will occur in northeast
Nebraska. Chance for measurable snow seems highest this afternoon
near the South Dakota border...where up to around half an inch of
snow may accumulate. Drier air over our southern counties should
limit precipitation there. A band of snow should develop in association
with an area of middle level frontogenesis on an axis from around
Yankton to Denison by middle to late afternoon. Look for highs in
the upper teens to middle 20s.
Best combination of lift and moisture with this next shortwave
trough should stay to our north across South Dakota...with the
highest chances for snow being there tonight. Best chances spread
into central and eastern Iowa by Sunday morning. Our area will be
in the fringes of the best dynamics for snow. 00z NAM was probably
a little too bullish with its snow amounts in our area tonight...
but will go with up to an inch of snow accumulation in some of
our northern zones and possibly parts of western Iowa tonight.
Some light snow should linger Sunday morning...mainly in western
Iowa...but that quickly moves east. Expect a decent temperature
recovery in the afternoon as winds turn to the west.
Currently have Sunday night and Monday dry for now.
Long term...(monday night through friday)
issued at 245 am CST Sat Feb 13 2016
00z runs of European model (ecmwf) and GFS were in good agreement bringing precipitation in
the area Monday night. Precipitation type likely rain or a mix...based on
model forecast soundings so will go with a chance of light rain
and light snow.
Precipitation chances seemed too low to mention for the rest of the week...
but may need to adjust that later. A fairly potent system should
move through Thursday night/Friday...but moisture may be limited.
Middle tropospheric ridge over the western United States Tuesday
should build eastward into our area by Thursday...while a trough
digs along the West Coast. Most model guidance is in very good
agreement with that. Temperatures are expected to moderate to the
40s and 50s...with some 60s possible late in the week.
Aviation...(18z tafs for kofk...klnk and koma.)
Issued at 1145 am CST Sat Feb 13 2016
VFR conditions are expected to prevail through most of the period.
A period of MVFR ceilings and visibility is possible at kofk and koma after
06z as surface trough and upper wave moves across the region.