Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 190442
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1142 PM CDT Sun Aug 18 2019

.SHORT TERM...(Tonight through Wednesday)
Issued at 300 PM CDT Sun Aug 18 2019

At 3 PM, a patch of stubborn low clouds continued to sit over
eastern Nebraska and western Iowa in association with a weak
surface front. There were a few sprinkles/light showers with this
feature this morning, but these have since dissipated. Can safely
say that the cloud cover busted the temperature forecast today,
with many places still in the 70s this afternoon. So it goes,
probably better to be humbled in the "cool" direction in August
anyway.

After a couple nights with at least the potential for strong
thunderstorms, tonight should be uneventful. Surface high
pressure is expected to settle in over the Missouri River Valley.
This will bring light and variable winds, and could aid in patchy
fog development along the Interstate 80 corridor. Otherwise temps
in the low 60s are forecast by sunrise Monday, under partly to
mostly cloudy skies.

Warmer Monday, with partly cloudy skies and a building upper
level ridge over the Central and Southern Plains. Afternoon
temperatures should climb back into the upper 80s, while surface
dewpoints in the low 70s will keep the humidity up. As we
transition into Monday night, a couple showers/thunderstorms are
possible as a weak shortwave tracks eastward along the NE/SD
border. The best rain chances look to be in Iowa. At this time the
atmosphere doesn`t look receptive to any strong storms Monday
night.

Tuesday will be the hottest and muggiest day of the week as the
upper level ridge continues to build and 850 temps peak. High
temperatures should push back into the lower 90s and combine with
dewpoints in the mid 70s to produce heat indicies of 98 to 108
degrees (highest values toward the KS/NE border). Heat Advisory
conditions certainly look likely to our south over Kansas/Missouri.
Areas along and just south of the Interstate 80 corridor
(including Omaha and Lincoln) may also flirt with Heat Advisory
conditions for a couple hours Tuesday Afternoon. Later shifts will
likely need to consider issuing a Heat Advisory Tuesday
afternoon.

Thunderstorms, possibly widespread, return to the forecast
Tuesday evening/night as a cold front dives south into the region.
With surface dewpoints in the mid 70s and steep mid level lapse
rates, instability should be very high Tuesday evening/night
(MUCAPE >4,000 j/kg). Shear will be a bit lacking, but veering
wind profiles with height could help a couple supercells form
before convection grows rapidly upscale. DCAPE values near 1,500
j/kg certainly suggest strong cold pools. Initially the main
hazards should be damaging winds and large hail, with a transition
to more of a damaging wind and heavy rain threat as the night
progresses. Model consensus suggests a broad area of 0.50 inch
rain totals over our region, while individual ensemble members
hint a local amounts up to 3 inches. Forecaster confidence in
interesting weather Tuesday evening/night is moderate.

Lingering showers and thunderstorms are possible Wednesday
(especially in the morning), but model trends over the last 48
hours seem to be focusing in on the Tuesday evening/overnight
period for the most widespread activity. Afternoon highs should
fall back into the 75 to 81 degree range Wednesday. Putting an
end to our early weak heat.

.LONG TERM...(Thursday through Sunday)
Issued at 300 PM CDT Sun Aug 18 2019

A building upper level ridge over the Western U.S. should
dominated the weather pattern over the CONUS as we descend into
next weekend. This should allow our local temperatures to stay
within a couple degrees of average through next weekend (80s).
The models are hinting at a couple periods with a slight chance
for a shower/thunderstorm. However the timing/existence any weak
shortwaves is finicky in the models this far out and forecaster
confidence is low. Odds favor a mostly dry forecast Friday
through Sunday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1135 PM CDT Sun Aug 18 2019

Clouds cover has lingered in the area longer than expected.
Ceilings are at VFR, but OFK is currently overcast at 3500 AGL.
The primary forecast concern for the TAF period is whether MVFR
visibilities and ceilings will develop this morning. The
ingredients are in place for fog (recent rain, clear skies, light
winds, forecast low temps below crossover temperature). However,
forecast models are in low agreement on fog and inspire little
confidence. Reduced visibilities were put in TAFs at OMA and LKN
between 09-13Z. Cloud cover that lingered longer than expected and
lack of a strong temperature inversion may prevent widespread
fog. Will amend TAFs if confidence in fog increases.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Albright
LONG TERM...Albright
AVIATION...Fajman


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