053
FXUS63 KGID 171917
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
217 PM CDT Mon Aug 17 2026

...Aviation Update...

.KEY MESSAGES...

- There is a low chance (20% or less) of a shower/isolated storm
  moving across northern portions of the forecast area late
  tonight.

- There is a 40% to 60% chance of fog development overnight,
  especially across areas that received the most rainfall yesterday.

- There is a fairly high chance (around 70%) of strong to severe
  storms impacting the area this evening into tonight.

- The main hazards with storms this evening into tonight are
  large hail, damaging winds, and heavy rainfall.

- Severe storm threats continue for Tuesday and Wednesday.

&&

.UPDATE...
Issued at 205 AM CDT Mon Aug 17 2026

Currently watching storms across northern Nebraska moving southeast
toward northern portions of the forecast area (in and around Ord,
NE). Models are showing these storms weakening as they move
southeast so not expecting severe weather overnight. Some models
have them completely dissipating before reaching the forecast area,
but there remains a low chance (20% or less) of showers and perhaps
an isolated thunderstorm late tonight/after sunrise for mainly
Valley, Greeley, Sherman, and Howard Counties. There is a chance
(40% to 60%) of fog development overnight. The highest chances for
fog development will be across areas that received the most rain
yesterday morning. The hindering factor for fog development will be
high clouds moving across the area. Will be monitoring conditions
for fog development. Overnight low temperatures will range from the
upper 50s to mid 60s.

High temperatures today will range from the low 80s to low 90s.
Storms are expected to develop by late this afternoon across western
and northern Nebraska and move eastward and southward toward the
forecast area. Storms could impact northern portions of the forecast
area (primarily north of I-80) as early as 6 to 8 PM. These storms
will continue to develop and move southeastward through the evening
into the overnight hours. More storms will likely develop during the
overnight hours behind the initial cluster of storms. The storms may
be strong to severe with large hail and damaging winds being the
main threats. Heavy rainfall leading to localized flash flooding is
also possible. These storms are expected to continue through most,
if not all, of the overnight hours tonight and will likely continue
into the morning hours on Tuesday (especially across northern and
eastern portions of the forecast area). The forecast area is in a
marginal (level 1 out of 5) to slight (level 2 out of 5) threat of
severe weather for today and tonight. There is also a mostly slight
threat of severe weather on Tuesday although there is quite a bit of
uncertainty in placement and timing of storms. Portions of the area
are in a marginal threat of severe weather for Wednesday.

&&

.DISCUSSION...
Issued at 410 PM CDT Sun Aug 16 2026

Absolutely gorgeous late summer weather out there this afternoon
and evening. Get out and enjoy it if you can. Quiet conditions
look to persist tonight and through most, if not all, of the
daylight hours Monday. Highs should climb 3-5 degrees most
location for Monday given the quieter/sunnier start to the day,
but still seasonable in the 83-88 degree range.

Next chance for storms will come from convection that develops
along a cold front over north central Nebraska late Monday
afternoon, then moves SE during the evening and overnight.
Expect a general evolution - in terms of intensity - fairly
similar to recent weeks in that the strongest activity will be
prior to 9-10PM, then gradual weakening thereafter. This would
place the highest severe chances just NW of the local area,
right where SPC has a Slight Risk (level 2 of 5). What does make
it into the area would probably be in the form of one or two
small clusters and pose primarily a risk for 50-60 MPH gusts.

The aforementioned front looks to drape somewhere across the
area on Tuesday - with the ultimate location being somewhat
reliant upon how strong/widespread Monday night`s activity is.
Northern Kansas is most likely to remain storm/outflow free the
longest, so these locations could get quite warm by Tuesday
afternoon with forecast highs in the mid to upper 90s. Add in a
little bit of humidity (not as much as further E/NE, though) and
heat indices could sneak into the lower 100s. The weather
headline for Tuesday, however, will be chances for at least
scattered storms to develop over the area during the late
afternoon and evening. Pooling moisture and insolation ahead of
the composite outflow/front should support moderate to strong
instability with MLCAPE values in excess of 2-3K J/kg. Forecast
soundings from various guidance at 21Z Tue also show seasonably
strong deep layer shear of 30-40kt amidst relatively straight
hodographs above 1-2km. This should support initial splitting
supercells with both large hail and wind threat...then gradual
upscale growth into one or two clusters and transition to
primarily a damaging wind threat for the late evening into
early overnight hours. Agree with the latest SPC outlook showing
a broad Slight risk category across the area - including the
recent inclusion of a Cig 1 delineation.

Expect cooler temperatures behind the front Wednesday-Thursday,
and may see another couple rounds of showers and storms, most
favored during the evening and overnight hours. Confidence on
details, though, is quite low.

Pattern may quiet down some heading into next weekend and warm
back to, or even above, seasonable levels for temperatures.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 215 PM CDT Mon Aug 17 2026

For KGRI/KEAR Airports:
- General overview:
High confidence in VFR (both ceiling/visibility) through at
least the vast majority of the period. Also high confidence that
at least the vast majority of the period is dry, although there
is an small (deemed around 30%) chance for a few passing
showers/thunderstorms very late tonight into Tuesday
morning...slightly more favoring KGRI than KEAR. Aside from any
potential convective outflow influence/enhancement (which IS
possible), winds will not be a significant issue, with sustained
speeds prevailing under 12KT throughout. Later TAFs may need to
consider a formal inclusion of low level wind shear (LLWS) for
late overnight.

- Ceiling/visibility and thunderstorm potential details:
High confidence in VFR through at least the vast majority of the
the period, with the only potential caveats being perhaps a
brief period of MVFR visibility and/or ceiling mainly sometime
between 09-15Z...associated with passing showers/thunderstorms
and/or light fog. Speaking of thunderstorms, the very latest
higher-res models show overall-decreasing chances for either
terminal seeing any late-night/early morning convection...but IF
it were to occur would seemingly favor KGRI a bit more so than
KEAR. As a result, for now have removed a PROB30 group from
KEAR, but have maintained for KGRI, albeit "shifted later" to
09-15Z.

- Wind details:
- Surface winds:
This afternoon into early this evening, generally southerly
breezes will prevail with modest gusts up to around 17KT, but
prevailing speeds mainly at-or-below 11KT. This evening and
overnight, steady light south-southeasterly speeds should
prevail...BUT...there will be at least a small chance for
convective outflow to race through and abruptly turn winds more
northerly-to-easterly. Once winds recover from any potential
convective outflow, a generally southeasterly component should
re-establish late in the period.

- Potential low level wind shear (LLWS) late tonight:
Strongly considered introducing a formal LLWS group to TAFs for
mainly 06-12Z, as south-southwesterly winds within the lowest
1-2K ft. AGL are expected to accelerate up to around 38KT.
However, given this potential concern is mainly just beyond the
first 12 hours, and that it currently appears at least slightly-
too-weak/marginal for TAF inclusion, have held off for now.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.

&&

$$

UPDATE...Schuldt
DISCUSSION...Thies
AVIATION...Pfannkuch