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000
FXUS63 KOAX 051726
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1226 PM CDT Tue Jul 5 2022

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 425 AM CDT Tue Jul 5 2022

Still warm across the area early this morning with about half of
the reporting stations still holding on to lower 80s as of 3 am.
Heat indices are warmer by a couple of degrees. A/C units are
still working hard and for that reason the heat advisory continues
now and through the evening.

Some convection has developed over central Nebraska and is
approaching the border of the CWA. This convection is relatively
weak, but may intensify by mid-day today. Some guidance suggests
instead that new convection will emerge. Either way, these storms
will have nearly 4000 J/kg of CAPE by mid-day with a moisture
pool just south of the stationary front draped across the SD/NE
state line. These mid-day storms would be capable of large hail
and strong wind gusts (DCAPE is AOA 1200 J/Kg). Any mid-day
convection will be relatively isolated, but have plenty of energy
at their disposal.

The best chance of convection will wait for the arrival of storms
from the northwest. Guidance clashes on timing and placement, but
upscale growth seems likely with the storms as they push ESE out
of central South Dakota. These storms, driven by a cold pool, may
clip the area north of I-80 and will be capable of damaging
winds. PWAT values of 1.5-2.5" leave heavy rain possible which in
turn will bring hydro concerns (see WPC Excessive Rainfall Outlook
[ERO]). Timing with this wave will be best from 4 pm to 10 pm,
though any mid-day convection could throw a wrench in the plans.

High temps this afternoon should approach 100F for most, with
some mid to upper 90s in western Iowa. My latest forecast has
Eppley peaking at 100F, but the NBM suggests only a 20% chance of
hitting the century mark. We`ll see, NBM, we`ll see. Dewpoints
will have lost a couple of degrees vs. yesterday afternoon.
Overall, heat indices will equal or best the scorching numbers of
the holiday to push well above 100 for most locations. Heat
indices of 110 are possible with little to no cloud cover.

Lingering convection will likely wrap up by sunrise Wednesday
morning. Wednesday`s temps will still be hot, but a significant 10
degrees cooler or so as that front sags south. Low level humidity
will remain high and with the 500 hPa pattern mostly unchanged,
afternoon and evening convection will remain possible. Another
ridge rider may work off the higher terrain out west and find its
way to the Missouri River and beyond. In fact, until this pattern
changes, chances of afternoon / evening convection will continue
to populate the forecast. Thursday will be no exception.

Near normal temps are expected for the end of the work week with
the CWA on the cooler side of the front. Those temps begin nudging
upward for the weekend before another cold front pushes through on
Sunday. This will be driven by an upper level trof which will
increase our chances of convection as it cools things down a bit.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1216 PM CDT Tue Jul 5 2022

The main concern this TAF period is convection that is expected to
expand south into the area this afternoon into the evening. A
ongoing complex of storms is moving SE across South Dakota, with
the far western edge of the system expected to affect KOFK after
2230z, while KOMA and KLNK are expected to see later convection
after 02z but could shift earlier an hour or so.

An additional round of rain does look likely early Wednesday
morning, but there is a considerable amount of uncertainty after
the first two rounds of storm chances, so we`ve opted to keep
those chances out of the TAF for this issuance.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory until 8 PM CDT this evening for NEZ011-012-015>018-
     030>034-042>045-050>053-065>068-078-088>093.

IA...Heat Advisory until 8 PM CDT this evening for IAZ043-055-056-069-
     079-080-090-091.

&&

$$

DISCUSSION...Nicolaisen
AVIATION...Petersen