Scientific Forecaster Discussion
fxus63 koax 210438
Area forecast discussion
National Weather Service Omaha/valley NE
1138 PM CDT Fri Oct 20 2017
Short term...(tonight through monday)
issued at 315 PM CDT Fri Oct 20 2017
Warm and very windy conditions this afternoon with surface winds
just below advisory criteria. Wind gusts this past hour have
reached 30 to 40 mph, and this will continue for another few hours
late this afternoon. When the sun GOES down around 635 PM, we
should lose the high end of the wind gustiness, but sustained
southerly winds overnight still remain high at 20 to 28 mph.
Next concern overnight will be increasing chances for showers and
thunderstorms as the first southern-latitude trough, now exiting
the Texas Panhandle, moves into the region. Moisture will be increasing
tonight, along with a slight increase in the low level jet.
Latest esrl hrrr/operational hrrr/rap suggest that most of the
evening should be dry, so Friday night football games will
probably not be affected. However, by 04-05z, convection chance
should increase, eventually reaching 40-60% across the central
part of the County Warning Area in a SW/NE corridor through daybreak. Overnight
lows remain very mild lower to mid 60s.
Whatever convection develops overnight could be lingering in the
morning as it lifts northeast of the area. At the same time, the
cold front will begin moving in from the northwest, which will
help trigger additional showers/rumbles of thunder from northwest
to southeast through the day. Cold front crosses the MO river by
19-20z, and should begin to clear the forecast area to the east by
22-01z. Storm Prediction Center has the extreme southeastern forecast area in a slight risk of
severe storms with wind the primary hazard. Thus, while there will
instability over the area tomorrow with a 40-80% chance of showers
and storms, right now, the best severe threat appears to be
setting up southwest Iowa and a handful of counties in southeast
NE, but a higher threat of severe just east and southeast of our
counties. Precip should clear the forecast area altogether in the
Return southerly flow sets up quickly behind the front for Sunday,
but another cold front arrives by daybreak Monday, which shifts
our winds back to the northwest. Dry weather for both Sunday and
Monday with near normal highs in the mid to upper 60s.
Long term...(monday night through friday)
issued at 315 PM CDT Fri Oct 20 2017
Colder air behind the previously mentioned front settles in for
Tuesday, with much below normal highs in the mid to upper 50s. A
brief slight warmup occurs on Wednesday with temps back to the mid
to upper 60s. However, another sharp cold front arrives early
Thursday. This brings a small chance of rain to the forecast area,
with h85 temps making a strong push for below zero values by
daybreak Friday. If any precip lingers south of i80 early Friday
morning, it could end as rain/snow mix with 850 mb well below zero.
Sharply colder temps into the area for Friday with highs in the
upper 40s to lower 50s.
Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1138 PM CDT Fri Oct 20 2017
Mosaic radar data as of 0430z indicate a gradual increase in
elevated convection over south-central NE into north-central and
northeast Kansas. This activity is likely associated with a weak
short-wave trough lifting northeast toward the mid-MO valley.
Expect the convection to gradually increase in areal coverage
early Saturday as it overspreads eastern NE and western Iowa.
Confidence in this activity impacting the taf sites is low enough
such that we will only include thunderstorms in the vicinity at this juncture.
A broad zone of warm thermal and moisture advection will yield the
development of MVFR ceilings toward 12z Saturday ahead of a cold
front moving into eastern NE. Showers and thunderstorms should
increase in coverage Saturday morning into afternoon in the
vicinity of the front as it moves through the area. South winds
ahead of the front will veer to northwest with its passage.