Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Omaha/valley NE
516 PM CST Sat Nov 22 2014
Short term...(tonight through tuesday)
issued at 330 PM CST Sat Nov 22 2014
The short term forecast concerns will be low level moisture return
tonight and resultant fog and low cloud re-development along with
some light rain/showers and drizzle along with hourly
temperatures and dewpoints...isolated thunder
potential?...secondary band of light rain or a rain/snow mix may
develop Sunday into Sunday night. Strong northwest winds and
flurries/chance light snow with reinforcing cold air for Monday.
At the surface...south winds with mild temperatures in the 40s and
50s were common locally and dewpoints in the 30s and 40s. The
bank of stratus has been eroding allowing temperatures to warm
into the 50s. Even 50s were noted in southeast Nebraska and
southwest Iowa under the stratus.
One storm system is passing to our south and another shortwave
trough is approaching from the west. With the approach of this next
system...it will pull deeper moisture into the forecast area
resulting in low clouds...fog...and drizzle...light rain and some
showers possible isolated thunder redeveloping ahead of the
windshift/cold front. The surface front moves into the northwest
part of the forecast area by 09z and is through much of the
forecast area by 18z with winds picking up from the northwest.
Hourly temperatures and dewpoints will be quite mild ahead of the
Lapse rates are steep...6.5-7 degree c/km with Omega increasing.
Some elevated cape to work with and the sref has a 5-10% probability for
parts of western Iowa. Will continue to mention low probability of precipitation with
light rain and drizzle and may include a few hours for the spotty
showers and isolated thunder late tonight and early Sunday
The models do show a secondary area of precipitation developing
and moving through the forecast area. There has been thunder
associated with this upper level disturbance over Idaho...so did
increase probability of precipitation to account for this frontogenetic band and can
further refine probability of precipitation as needed. Models are leaning toward all
rain...however could be enough lift to have a rain snow mix.
Northwest winds will be strong sustained at 15 to 25kts behind the
Sunday night...reinforcing cold air moves in with gusty northwest
winds behind it. Added flurries and also could produce some light
snow Sunday night and Monday with colder highs in the 30s. For now
have winds below Wind Advisory criteria.
Long term...(tuesday night through saturday)
issued at 330 PM CST Sat Nov 22 2014
Tuesday night a clipper type system tracks to the northeast with a
slight chance for light snow clipping the area. A reinforcing cold
front moves through Thanksgiving. There may be some light snow or
flurries with this...but confidence too low to mention. Cold high
pressure lingers for Friday and shifts off somewhat for Saturday.
Below normal temperatures are forecast Thursday through Friday.
Aviation...(00z tafs for kofk...klnk and koma.)
Issued at 511 PM CST Sat Nov 22 2014
Another night of complicated tafs especially at klnk/koma as
IFR/LIFR conditions redevelop within the next couple of hours.
Should also see some patchy drizzle mainly at koma through the
night...but temperatures remain well above freezing. Kofk again remains
on the northern periphery of the low cloud deck but believe it
will make it there before 06z...but probably just MVFR. Secondary
concern is the arrival of the cold front. South winds around 10-14
knots ahead of the cold front...with an abrupt shift to northwest...
by 11z at kofk...and 13-14z at klnk/koma. Could also be some
showers for a few hours after the frontal passage as well.