Amherst, Nebraska Weather Forecast Discussion

673
FXUS63 KGID 212157 CCA
AFDGID
Area Forecast Discussion...CORRECTED
National Weather Service Hastings NE
457 PM CDT Sun Sep 21 2025
.KEY MESSAGES...
- Precipitation/thunderstorm-wise: BY FAR our main chances for
  at least scattered showers/thunderstorms are focused Monday
  evening-Tuesday evening as a large-scale upper system passes
  through.
- A few storms especially Monday evening could be severe (entire
  forecast area is still assigned an SPC Marginal Risk/level 1
  of 5)...but it`s starting to look a bit more likely that much
  of our area could be in a bit of a "lull" in severe chances,
  with better potential focused slightly east and south.
- Our forecast remains officially DRY (chances less than 15
  percent) area-wide Wed night-Sunday, and most places probably
  start this prolonged dry stretch by Wednesday afternoon.
- Temperature-wise: An overall-seasonably mild-to-warm weather
  pattern continues not only through the official 7-day forecast
  but likely beyond, with highs MOST days between the mid
  70s-low 80s, and lows MOST nights mid 50s-low 60s (no sign of
  an early-season frost/freeze in sight).
&&
.DISCUSSION...
Issued at 452 PM CDT Sun Sep 21 2025
- 7-DAY FORECAST BIG PICTURE COMMENTS, CHANGES, UNCERTAINTIES:
- In the very short term, the main question is whether (or not)
  at least patchy fog/dense fog materializes late tonight into
  Monday morning. There are pros/cons, and models/guidance
  continue to convey "mixed signals". For now will call for
  generic "patchy fog" all areas 4-10 AM Monday, but currently
  lack the confidence to even include fog as a highlighted
  concern in our Hazardous Weather Outlook (HWOGID).
- As mentioned above, BY FAR our main/bigger picture forecast
  issue/focus at this time is on the potential for perhaps a few
  severe storms mainly Monday evening. However, deep-layer wind
  shear is on the lower-end (mainly 30KT or less) of what would
  typically drive a potentially more widespread threat, and
  higher-res models/CAMS are starting to suggest that the
  primary areas of more concentrated severe potential could
  focus SLIGHTLY to both our east and south. Following suite,
  SPC has assigned its more-concerning Slight Risk categories
  (level 2 of 5) both slightly east/south of our forecast area
  (CWA) on their latest Day 2 severe storm outlook, while
  leaving our entire CWA in the level 1 Marginal Risk.
- Those watching very closely might notice that our high
  temperature forecast has nudged up very slightly (only a few
  degrees at most) for Wednesday-Saturday...but an upward trend
  nonetheless.
-- 7-DAY FORECAST CHRONOLOGICAL DETAILS (heavily short term
 focused):
- CURRENT/RECENT WEATHER SCENE AS OF 4 PM:
It`s truly been a "tale of two days" today. This morning
featured widespread cloud cover (CWA-wide) and at least spotty
showers (in Nebraska) and more widespread showers/non-severe
thunderstorms (in our KS zones). In fact, small parts of mainly
eastern Phillips/southwest Smith counties (near Agra/Kensington/Kirwin)
saw at least 2-3" of rain that fell over a few hours near-to-
beyond sunrise this morning per radar estimation and limited
gauge truth. However, by this afternoon not only were the
showers/storms dissipating rapidly and/or departing our CWA, but
skies cleared more efficiently than this forecaster
anticipated, with much of this afternoon featuring widespread
sun (although a fair amount of "fair weather" cumulus has
developed these past few hours mainly in counties along/south of
the KS border). Thanks to the sunshine and steady south-to-
southwesterly breezes of mainly 10-15 MPH, if anything high
temps this afternoon very slightly "overachieved", with most of
the CWA on track to top out 79-84.
In the big picture of the mid-upper levels, water vapor
satellite and short term model data confirm that we are "in
between" forcing aloft, with this morning`s activity driven by
the southern extension of lift from a well-defined upper
low/vort max currently spinning over northern MN, while our
next/upstream main system is still up over the Northern Rockies.
At least in the short term, that leaves us under benign west-
northwesterly flow aloft.
- THIS EVENING-OVERNIGHT:
Although a few sprinkles/light showers MIGHT try flirting with
our western counties very late overnight/early Mon AM, we
continue an officially-dry forecast CWA-wide at this time. At
the surface, light southerly breezes generally 4-8 MPH will
prevail through the night. While some limited mid-high level
clouds will increase somewhat from the west post-midnight, it`s
starting to look increasingly likely that tonight will be mainly
clear, leaving the "million dollar question" as to whether much
fog will be able to form. "Pros" for fog formation are fairly
high boundary-layer RH (and the aforementioned mainly clear
skies), while "cons" include the light-but-steady southerly
breezes keeping mixing up a bit. For what it`s worth, recent
HRRR runs have backed off a bit on its portrayal of patchy dense
fog for Mon AM versus earlier runs, but felt it was prudent to
at least cover the entire CWA with generic "patchy fog" after 4
AM to account for any pockets that might crop up. Low temps were
changed very little...most areas aimed 57-61.
- MONDAY DAYTIME:
At least for now, kept the morning-through-mid-afternoon period
void of any precip mention. However, there are some hints
(including in latest HRRR) that later shifts may need to include
potential for spotty sprinkles/light showers as the leading
edges of lift from the next incoming upper wave arrive. However,
the overall-bigger concern starts after 4 PM, when at least
slight chances for isolated thunderstorms (possibly strong to
severe?) enter the picture. That being said, latest higher-res
HRRR/NAMNest runs keep the vast majority of this potential at
least slightly outside our CWA until the start of the official
"evening" forecast period at 7 PM, so have kept late-afternoon
chances/PoPs low...only 20-30 percent.
In other daytime departments, southerly breezes look to average
5-15 MPH, and assuming that skies are no worse than partly
cloudy, this still looks to be the overall-warmest day of the
next week. If anything, highs were nudged up very slightly from
previous...with most of the CWA aimed 83-87 degrees.
- MONDAY EVENING-OVERNIGHT:
These 6-12 hours feature our overall-biggest concern for perhaps
a few severe storms, as lift increases out ahead of the larger-
scale/"parent" upper low diving south through the Central
Rockies, while in tandem a lower-level/surface cold front starts
slipping southward into our CWA with northerly winds in its
wake. From an instability/shear combo perspective, this forecast
agrees with the Marginal Risk designation from SPC, as although
instability/CAPE looks fairly healthy (at least 1500-2500 J/kg),
deep-layer shear is somewhat weak (mainly 25-30KT), likely
keeping storms a bit more on the multicell/cluster spectrum
instead of organized supercells. Furthermore, while one never
wants to take high-res models TOO literally 24+ hours out...both
the latest HRRR/NAMNest suggest that our CWA might see a
relative minimum in activity versus areas only SLIGHTLY off to
both our south/east. If we do get spotty severe, main hazards
look to be hail to around 1" size/winds to around 60 MPH...with
some localized 1-2" rain amounts possible as well (but does not
look like a higher-end flooding concern). Low temps aimed a few
degrees either side of 60.
- TUESDAY DAYTIME-NIGHT:
While any severe storm threat should steadily wane with time
(and SPC currently has us assigned only "general thunder),
widespread rain chances are present especially during the day
and especially in our south half...gradually diminishing
southward Tues night as the heart of the upper system slowly
tracks east-southeast farther into KS. We`ll have to watch for
localized heavy rain, but again, not expecting big issues with
most areas able to handle an inch or two.
The combo of widespread precip/clouds and somewhat breezy north
winds all but ensures that Tuesday should be the overall-coolest
of the next 7 days, with high temps mainly aimed 65-70 degrees.
- WEDNESDAY-THURSDAY:
We continue to carry some small chances for lingering showers
mainly in our southeastern 1/3 for Wednesday daytime, but then a
high-confidence stretch of dry weather begins as broad upper
level ridging arrives in the wake of the departing trough. High
temps were nudged up slightly from previous...mainly low-mid 70s
Wed and mid-upper 70s Thursday.
- FRIDAY-SUNDAY:
Although still not "set in stone" being 5-7 days out...this is
currently looking like a very pleasant and dry weekend by late-
September standards...albeit just a touch on the above normal
side of things temperature-wise with highs mainly upper 70s-low
80s.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 112 PM CDT Sun Sep 21 2025
For KGRI/KEAR Airports:
- General overview (including winds):
High confidence in VFR ceiling/visibility through the majority
of the period, and high confidence in dry/thunderstorm-free
conditions throughout (although suppose a rogue sprinkle cannot
be completely ruled out mid-late Monday AM). By far the main
challenge/question mark is whether or not at least patchy fog
and/or low stratus develops within the area early Monday
morning. Unfortunately, there is currently very little
confidence in how this plays out.
Winds will not be a significant issue, with sustained speeds
the majority of the period 6-11KT and any gusts mainly at-or-
below 16KT (and mainly right away this afternoon). Direction
will be fairly consistent/southerly, although KGRI will briefly
start off early this afternoon with a more west-southwesterly
component.
- Ceiling/visibility details/uncertainty:
Right out of the gate this afternoon, skies are mainly clear
over both KGRI/KEAR. There is at least some chance that
scattered MVFR-level clouds could develop with afternoon
heating, so have "hinted" at this with "FEW020 SCT035". However,
the real question marks arrive Monday morning mainly 09-15Z as
some higher-res model data suggests that at least patchy low
stratus/shallow fog will develop over the area, while
traditional numerical guidance sets are much less
suggestive...possibly due to boundary layer mixing/surface
breezes being JUST strong enough to keep it at bay. Needless to
say, the realm of possibilities for KGRI/KEAR range from
outright-VFR to perhaps at least brief IFR/LIFR. Given the
considerably uncertainty, and also given that these concerns are
beyond the first 12 hours, will simply "hint" at fog/stratus
potential fog/low stratus for now with "6SM BR SCT015" groups.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...Pfannkuch

NWS GID Office Area Forecast Discussion