Shenandoah, Iowa Weather Forecast Discussion

502
FXUS63 KOAX 111040
AFDOAX
Area Forecast Discussion
National Weather Service Omaha/Valley NE
540 AM CDT Thu Sep 11 2025
.KEY MESSAGES...
- Highs will mostly be in the 80s into next week, though a few
  spots are expected to see lower to possibly mid 90s Friday
  and Saturday.
- Mostly dry conditions expected through Saturday. Shower and
  storm chances return Saturday night into next week, with the
  highest chances late Saturday night into Sunday evening
  (30-50%).
&&
.DISCUSSION...
Issued at 324 AM CDT Thu Sep 11 2025
Pretty quiet across the region early this morning with upper
level ridging building in and weak surface boundary stretched
northwest to southeast across the area. Guidance continues to
suggest we may see some fog this morning, but we do have some
high level clouds to contend with and model soundings show winds
aloft may be too strong to see much more than some patchy
development. Otherwise we should see a quiet and warm day with
southeasterly flow continuing to usher in more summer-like air
and temperatures topping out in the mid 80s.
Heading into early Friday morning, a few pieces of guidance
(e.g. 11.00Z HRRR) suggest we could see some spotty showers
develop in association with strengthening low level warm air
advection and increasing moisture transport interacting with the
aforementioned boundary. However, model soundings reveal very
high cloud bases with a very dry sub-cloud layer, so if we do
get anything, it would probably be very light/sprinkles. For now
have just a 20-25% chance in eastern NE through about 6 AM. The
rest of Friday and Saturday will be quiet, but almost downright
hot for this time of year with highs in the upper 80s to lower
90s. Looking at NAEFS/EPS guidance, those may not even be high
enough as 850 mb temperatures of 22-24 C are good for the
90th-99th percentile of climatology and highs in the mid 90s
assuming we can mix that deep. However, model soundings are
somewhat divided on this, with the NAM suggesting we get close,
the ECMWF keeping it to around 900 mb, and the GFS doing its
typical over-mixing to near 700 mb. In addition, guidance is
hinting at some shortwave energy skirting the northwestern
periphery of the area both Friday and Saturday and possibly
bringing some cloud cover that could limit temps. Therefore,
don`t see any strong reason to make any major changes from model
consensus/NBM. Finally, dewpoints look to be in the mid 60s for
most locations, so definitely not a dry heat, but not downright
oppressive either, with heat index values expected to be only a
few degrees higher than actual temperatures.
Attention then turns to increasing precip chances late Saturday
night into Sunday as the upper level ridge pushes east and a
large scale upper level trough starts approaching with a surface
low moving through western NE and into the Dakotas dragging a
cold front toward the area. Trends have been toward a slightly
later arrival time, favoring precip chances more into the
daytime hours on Sunday. Instability and shear still look fairly
modest, but possibly just enough for a few stronger to isolated
severe storms and various machine learning severe weather
algorithms continue to indicate about a 5% chance. Otherwise,
given the incoming precip and cold front, we`ll fall back down
into the mid 70s to mid 80s for much of the area on Sunday.
The pattern for next week favors southwesterly flow aloft with
continued bits of shortwave energy sliding through and giving us
on and off shower and storm chances. Daytime hours on Monday
and Tuesday are largely favored to be dry (only a 10-20% of
anything in that period), but a larger scale trough axis starts
to approach by Tuesday night and bring more widespread 30-40%
chances from then through Thursday. Otherwise, high temperatures
will remain in the mid 70s to mid 80s, warmest Monday and
Tuesday with a gradual cooling trend thereafter.
&&
.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 540 AM CDT Thu Sep 11 2025
Some patchy fog has developed in portions of the area with MVFR
to IFR visibility. However, incoming high clouds and a little
wind aloft should prevent it from becoming too widespread, so
did not include mention at TAF sites. Any fog that does develop
should dissipate by around 14Z and give way to VFR conditions
with passing high clouds. Winds will remain southeasterly, with
gusts of 18-25 kts through this afternoon, highest in northeast
Nebraska/OFK.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...CA
AVIATION...CA

NWS OAX Office Area Forecast Discussion