Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 222318
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
618 PM CDT Thu Jun 22 2017

.UPDATE...
Issued at 615 PM CDT Thu Jun 22 2017

So far, the cap has been holding. The synoptic scale cold front
is still northwest of Omaha and Lincoln, so still potential yet
this evening. Even after the front passes, there may be some
activity behind the boundary. 22Z SPC mesoanalysis suggests cap
is weakest to the north and northeast of Omaha, with lowest
100 mb MLCAPE around 2000 J/kg and CINH less than 25. RAP model
may be a bit overdone with precipitation coverage and amounts,
based on what happened last evening. 21Z ESRL HRRR suggest some
activity developing by 01Z and then even into tonight.

&&

.SHORT TERM...(Tonight through Sunday)
Issued at 302 PM CDT Thu Jun 22 2017

12z upper-air analysis revealed a belt of stronger cyclonic flow
from the northern Rockies into the Dakotas with an embedded short-
wave trough over the northern High Plains. This disturbance will
track southeast into the mid MO Valley tonight into early Friday,
enhancing forcing for ascent and vertical shear ahead of it. In
the low levels, mesoanalysis depicted a cold front stretching from
north-central IA through northeast into south-central NE as of
early afternoon. The boundary layer ahead of this front has been
warming and moistening today, which when coupled with the steep
lapse rates aloft is yielding a moderately unstable air mass this
afternoon.

Considerable elevated convection is ongoing across the area as of
19z, likely rooted within the EML/steep lapse-rate plume. And
latest convection-allowing model guidance remains relatively
consistent in suggesting that surface-based storms will become
increasingly probable in the 22-00z time frame, generally along
the I-80 corridor. A few of these storms could become strong to
severe this evening with locally damaging winds and hail being
the primary hazards.

Showers and thunderstorm chances should diminish from north to
south tonight into early Friday as a cooler, continental-polar
air mass advances south into the region. This air mass will remain
in place over the mid MO Valley through the weekend with daytime
highs in the 70s.

.LONG TERM...(Sunday night through Thursday)
Issued at 302 PM CDT Thu Jun 22 2017

Longwave troughing from Hudson Bay into the OH Valley at the onset
of the long-term forecast period will gradually shift east ahead
of an evolving trough over western Canada into the northwestern
states. The latter trough will subsequently progress east into the
north-central Plains, supporting an increase in precipitation
chances by about the middle of next week. Daytime highs will
gradually warm back through the 80s during the early to middle
part of the upcoming work week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 615 PM CDT Thu Jun 22 2017

Wind shift will move through the KOMA and KLNK areas early this
evening. Generally expect VFR conditions through the period.
Ceilings with any TSRA could drop below 2500 feet and vsby could
drop below 3 miles, but confidence on exactly when and where is
not high enough to include in TAFs. Will amend as needed. Expect
variable mid clouds after 06z. North winds may be a bit gusty
right behind the cold front for a while, then decrease.

&&

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

$$

UPDATE...Miller
SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Miller


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