840
FXUS63 KOAX 132040
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
340 PM CDT Sat Jul 13 2024

.KEY MESSAGES...

- Dangerous heat is expected for much of the area this weekend
  into Monday, with heat index readings of 100 to 110+ degrees
  likely. Sunday and Monday will be the hottest days.

- More widespread storm chances (20-40%) arrive Monday night and
  linger through Wednesday.

&&

.DISCUSSION...
Issued at 340 PM CDT Sat Jul 13 2024

A large ridge continues to spin high pressure over the western
US and is extending the record breaking heat. (Vegas just
averaged a high of 117 over the past week. Hottest 7 day period
in it`s recorded history).

Temperatures at 2 PM are near 90F with heat indices over 100 in
about half of our locations. A heat advisory is in affect for
the entirety of the area until 8 PM when the last of the heat
indices will slip below 105F. The area will be headline free
overnight as apparent temps slip into the upper 60s and low 70s.
Urban areas may remain a bit warmer due to the concentration of
asphalt, steel and glass. Still, expect most homes with no A/C
to briefly cool down overnight.

Again, dewpoints this afternoon have bested our forecast which
was already above the 90th percentile of model solutions. Have
boosted dewpoints for Sunday afternoon and Monday afternoon as
well. Remember, there is typically a lag of a few days for bias
corrected models to catch on to a trend... this time driven by
corn`s climatological peak in evapotranspiration.

Isotropic upglide is responsible for the possible convection in
northeast Kansas / northwest Missouri overnight. As of now,
I`ve got no showers in the forecast for nearby areas overnight
tonight, but it won`t take much shift in the action for a few
showers in far southeast Nebraska.

Expect dewpoints to slip over the southern half of the forecast
area overnight thanks to a nocturnal summer jet that has a
significant westerly component to it. It`ll allow southeast
Nebraska to get a short break from the air impacted by corn
sweat. I don`t expect much mixing, so strongest winds should
remain off the surface overnight. It`ll be rather pleasant
after dark and meteorologically the best time to walk the dog.

H5 northwest flow over the mid-Missouri River valley will
become more westerly over the course of the next 48 hours as the
West Coast ridge becomes less amplified and broader as it noses
into the Corn Belt. The warmest temps will be in western Kansas
and Nebraska, but a thermal axis will stretch from Denver
through Council Bluffs, just south of the surface front.
Guidance has brought temp forecasts down a degree or two over
the past 36 hours and my forecast has reflected this. It will
still be dangerously hot with high temps 1-2 degrees warmer than
today. A heat advisory remains for most of the area. But areas
from the Kansas / Missouri state lines north to Fremont, Omaha,
and Pottawattamie County, Iowa will be under an excessive heat
warning from noon Sunday through 8pm on Monday. We may fall just
shy of excessive heat warning criteria with the slightly cooler
forecast. But with minimum apparent temps slipping only into
the mid-70s for much of that area, am glad to let that warning
continue. It`ll be difficult to cool off without an A/C unit,
especially in our most populous downtowns. Find a way to cool
off and stay hydrated. Avoid extended time outdoors.

Sunday should remain dry with a stout EML / warm layer at H7.

Monday will still be hot, but temps will slip for areas north of
I-80 where a "cold" front will have more time to impact temps.
Triple digit temperatures and heat indices over 105 are forecast
for areas along and south of I-80. Expect low to mid-90s north
of the interstate.

That slowly sinking front will give a good indication where
20-30% PoPs are possible. Late Sunday night`s LLJ may bring
enough isotropic upglide for a few showers in far northwest
corner of the forecast area and Monday afternoon may see more.
Storms capable of 1" hail and damaging winds look possible but
not likely Monday afternoon or evening (Pops max out at 30%).

I`m looking forward to the weather of Tuesday and you probably
should, too, with temps running 10-20 degrees cooler than the
day prior. Northwesterly flow at H5 will keep both temps and
dewpoints lower than this weekend.

This flow will keep temps cooler for the rest of the week, but
will also direct shortwaves overhead. Wednesday and next
Saturday are currently saddled with the best chances of showers
/ storms ... but even then, odds suggest most will remain dry.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1224 PM CDT Sat Jul 13 2024

VFR conditions are forecast through the TAF period with winds
generally out of the south. The winds become light and
disorganized in northeast Nebraska overnight.

The primary concern will be the strong winds at 2000 feet. Have
added some LLWS to the TAFs at OMA and LNK from about 03Z to 12Z
Sunday.

&&

.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.
     Heat Advisory from noon to 8 PM CDT Sunday for NEZ011-012-
     015>018-030>034-042>045-050-065-078-088.
     Heat Advisory from noon to 8 PM CDT Monday for NEZ015-033-034-
     042>045-050-065-078-088.
     Excessive Heat Warning from noon Sunday to 8 PM CDT Monday for
     NEZ051>053-066>068-089>093.
IA...Heat Advisory until 8 PM CDT this evening for IAZ043-055-056-
     069-079-080-090-091.
     Heat Advisory from noon to 8 PM CDT Sunday for IAZ043-055-056.
     Heat Advisory from noon to 8 PM CDT Monday for IAZ043-055-056.
     Excessive Heat Warning from noon Sunday to 8 PM CDT Monday for
     IAZ069-079-080-090-091.

&&

$$

DISCUSSION...Nicolaisen
AVIATION...Nicolaisen