Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 190816
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
316 AM CDT Wed Jul 19 2017

.SHORT TERM...(Today through Friday)
Issued at 251 AM CDT Wed Jul 19 2017

...Excessive Heat Expected Through Friday...

The main concern over the new few days will be the excessive heat
across the region, with afternoon heat index values 105-113 each
day.

Early this morning, the remains of a weak frontal boundary were
across eastern NE and central IA. Some convection has bubbled up
along/east of the Missouri River, where the air remained quite
unstable with up to 2000 J/kg of CAPE, along the nose of the low
level jet, within a PW maximum. These may have some small hail
this morning, but freezing and wet bulb zero values remain very
high thus severe storms seem unlikely. Brief downpours will be the
main hazard. These should continue move slowly east of the area
through daybreak, although there could be some spotty convection
in our extreme southeast counties for an hour or two past
daybreak.

Otherwise, highs today in the mid to upper 90s, and may even hit
100 at a couple of favored locations. Models seem to be underdoing
dewpoints especially in the afternoon, with corn/crop
evapotranspiration at peak efficiency. Should easily reach heat
advisory criteria today, with heat index readings around 110 in
the Missouri River valley in favored locations.

A new front tries to push into northeast NE tonight, which may
trigger spotty convection along it, but storms probably don`t make
it too far into the heat further south. Much more substantial
convection will be possible to our north overnight.

This boundary likely remains stationary on Thursday, may even
dissipate or lift north slightly. This sets us up for another very
oppressive day with highs again very hot, in the 95 to 103 range.
Afternoon heat index values again 103 to 112 across the forecast
area.

Strong convection again appears likely north of the forecast area
Thursday night, and may sneak into the NE/SD border area late
Thursday or early Friday, but should not make much southeastward
progress. Nighttime lows remain quite muggy, in the mid to upper
70s.

One more oppressive day on Friday, which may be the hottest day of
the week for us. Again, 96 to 103, with heat index values 103 to
111. Finally forecasting a high of 100 in Omaha on Friday, which
we haven`t hit officially since May 2013. There is that stalled
frontal boundary, which remains near the NE/SD border, which may
trigger isolated strong thunderstorms Friday afternoon/evening
north of I80.

.LONG TERM...(Friday night through Tuesday)
Issued at 251 AM CDT Wed Jul 19 2017

Aforementioned frontal boundary finally gets a slow push southward
into the area Friday night into Saturday. There may be some
overnight convection that could linger into Saturday morning. This
does help to lower temps just a little, and maybe enough to allow
the excessive heat warning to drop in some areas, although may
have to extend it along the KS/NE border region where afternoon
heat index values could still be near 105. Still plenty of time to
make headline adjustments as we get closer.

A stronger frontal push finally arrives by Sunday, which finally
brings our temps back down to normal for the remainder of the
extended period. Sunday and Monday look mostly dry, but more
organized precip chances return Monday night into Tuesday as the
next wave moves out of the Rockies.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1135 PM CDT Tue Jul 18 2017

IR satellite imagery indicates a weak front slowly settling south
through northwest IA and northeast NE with light southeast winds
present ahead of this feature. Latest model guidances hints at
this boundary edging a bit farther south overnight before lifting
back north of the area on Wednesday. Persistent low-level warm
advection near and north of the front could foster isolated storms
overnight which would likely be north of KOMA and east of KOFK.
Additionally, some light fog is possible at KOFK toward daybreak
Wednesday.

Expect winds to increase from the south by early Wednesday
afternoon with prevailing VFR conditions.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Excessive Heat Warning from 1 PM this afternoon to 8 PM CDT
     Friday for NEZ034-044-045-050>053-065>068-078-088>093.

     Heat Advisory from 1 PM this afternoon to 8 PM CDT Friday for
     NEZ011-012-015>018-030>033-042-043.

IA...Excessive Heat Warning from 1 PM this afternoon to 8 PM CDT
     Friday for IAZ055-069-079-080-090-091.

     Heat Advisory from 1 PM this afternoon to 8 PM CDT Friday for
     IAZ043-056.

&&

$$

SHORT TERM...DeWald
LONG TERM...DeWald
AVIATION...Mead


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