Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 200431

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1131 PM CDT TUE JUL 19 2016

.SHORT TERM...(tonight through Friday)
Issued at 259 PM CDT Tue Jul 19 2016

...excessive heat expected for the remainder this week...

Upper level short wave will continue to move east of the region
today with lingering sprinkles or showers ending across the area
by 06-07 pm. Water vapor imagery suggests there is a weak
circulation moving off the front range of the Rockies which could
trigger convection to our west overnight. A couple of models have
hinted that an isolated storm could also develop further east
along what remains of weak boundary that is lifting north through
the region along the NE/SD border. Not convinced we`ll see
anything in our area thus will leave the forecast dry for tonight
but will monitor development to our west and update forecast if

Focus shifts to building heat over the next couple of days with
build ridge, and elevated dewpoint levels, partially from corn
evapotranspiration. This should push heat index values to around
105 degrees on Wednesday, give or take a degree or two, with
actual air temps in the mid to upper 90s, and low 90s across
western IA. It will be breezy Wednesday, which will help a
little, but it will still be quite uncomfortable outdoors.

While there may be convection to our west Wednesday night, it
should remain dry in our area with muggy lows in the mid to upper
70s, so no real cooling relief expected at night.

The Nam does hint at a weak wave moving off the front range
Thursday with a small chance for storms. GFS and ECMWF remain dry
in our area, but hint at convection just to the west. There is
some concern that if convection does develop to the west, it could
throw some cloudiness over the area, which would not allow temps
to rise as high as forecast. For now, will maintain consistency
and go with highs in the mid 90s to around 100. Again, combined
with oppressive humidity, heat index values could range from 105
to 115 that day. Would not be surprised to see an 80 degree
dewpoint near a cord field in western Iowa.

Thursday night and Friday pose an interesting challenge against
the ongoing heat. A weak frontal boundary is progged by all
models to drop into northeast Nebraska Thursday night, then
further south of Friday. Feel there could be an isolated storm
along this boundary that could linger into Friday morning.
Will still be a very muggy night Thursday night with muggy lows
still in the mid to upper 70s. Then, the orientation of this
front and how far south it moves could also have an impact on
afternoon temps.

Regarding heat, because of the prolonged period of excessive
temps, will convert the heat advisory to an excessive heat
warning, rather than worrying about patchworking various products
with surrounding offices who have differing criteria and threshold
for heat impacts.

.LONG TERM...(Friday night through Tuesday)
Issued at 259 PM CDT Tue Jul 19 2016

The aforementioned frontal boundary will lift back to the north
Friday night into Saturday, as a weak wave moves off the front
range. Will have a small chance of storms along/north of the
boundary as it moves north. Temps will again be in the mid to
upper 90s over much of the area, thus heat warning may need to be
extended for some areas, but it`s far enough away that we`ll worry
about when we get there. That front then moves back south as a
cold front Saturday night which finally brings temps back to
normal. Will have a small chance of rain with that frontal
movement. We could see additional waves move off the front range
of the Rockies Sunday night into Monday bringing more chances for
rain. Confidence is low on Tuesday. New 12z guidance suggests all
features could be east of the region with weak upper level ridging
in place. Given uncertainty that far out, will trend more toward
climo with a slight chance of storms but with normal temps.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1130 PM CDT Tue Jul 19 2016

VFR conditions will prevail through the period with broad upper
high pressure centered over the southern plains.


.OAX Watches/Warnings/Advisories...
NE...Excessive Heat Warning from 1 PM Wednesday to 8 PM CDT Friday
     for NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-

IA...Excessive Heat Warning from 1 PM Wednesday to 8 PM CDT Friday
     for IAZ043-055-056-069-079-080-090-091.



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