Dunbar, Nebraska Weather Forecast Discussion

934
FXUS63 KOAX 212301
AFDOAX
Area Forecast Discussion
National Weather Service Omaha/Valley NE
601 PM CDT Sun Sep 21 2025
.KEY MESSAGES...
- Areas of fog are expected to develop again late tonight into
  Monday morning, mainly along and east of the Missouri River.
- Shower and thunderstorm chances increase late Monday afternoon
  into Monday night, with a few strong to severe storms
  possible. Rain chances continue Tuesday into Tuesday night,
  especially for locations along and south of I-80.
- Monday will be the warmest day, with highs of 80 to 85. Cooler
  afternoon temperatures in the 70s are expected through the
  remainder of the week.
&&
.DISCUSSION...
Issued at 317 PM CDT Sun Sep 21 2025
Rest of this afternoon and tonight:
Early-afternoon water-vapor imagery shows a well-defined,
mid/upper-level low over the upper MS Valley, with a weaker
disturbance moving through the base of the low across the lower
MO Valley. Forcing for ascent attendant to the latter system is
generating light shower activity across portions of northeast
KS, southeast NE, southwest IA, northwest MO, which will
shift east of the area within the next hour or two. Elsewhere,
visible satellite indicates low pressure developing in
southeast SD, with an associated area of deepening cumulus and
early thunderstorm development in southwest MN. A weak boundary
trails southwest from the low pressure to near the south-
central SD/north-central NE border as of 3 PM.
Latest CAM output suggests that thunderstorms will largely
remain confined to southern MN from late afternoon through this
evening, so only a small area of 15% PoPs will be retained into
this evening.
By late tonight into Monday morning, areas of fog are once again
expected to develop, with the most probable location being
along and to the east of the Missouri River.
Monday and Monday night:
A short-wave trough currently located over British Columbia into
WA/OR is forecast to dive south through the northern into
central Rockies this period. In the low levels, the models
indicate a surface low developing through central and southeast
NE Monday afternoon into Monday night. South winds ahead of the
surface low will draw a warmer air mass into the region, with
temperatures warming to 80-85; likely the warmest of the week.
The warm temperatures will combine with steep lapse rates and
boundary-layer dewpoints in the low/mid 60s to create a
moderately unstable air mass Monday afternoon into evening.
Large-scale forcing for ascent will remain relatively weak,
owing to the displacement of the mid-level trough well to our
west. That weak forcing is leading to considerable variability
in the CAM simulated reflectivity fields Monday afternoon into
Monday night. Current thinking is that a zone of enhanced, low-
level convergence near and east of the surface low will be the
primary focus for late afternoon and evening thunderstorm
development. The forecast thermodynamic environment will be
conducive to hail production in the strongest storms. Maximum
sizes up to 1.5" appear possible at most locations, with some
potential for isolated 2" hailstones in southeast NE, where the
strongest vertical shear (30-35 kt effective bulk shear) is
forecast to exist. Locally damaging winds are also possible, and
a brief tornado cannot be ruled out (mainly in southeast NE).
Thunderstorms are expected to become more numerous overnight
Monday into early Tuesday (PoPs increasing to 40 to 60%), with
an increasing threat for locally heavy rainfall.
Tuesday and Wednesday:
The mid-level trough initially over the central Rockies Tuesday
morning is forecast to weaken while tracking to the south of
our area through Tuesday night. By Wednesday, a broader,
mid/upper-level low is forecast to evolve across the upper
Midwest into mid MS Valley regions. At the surface, an area of
low pressure is projected to develop from the southern Plains
into mid MS Valley, with our area remaining in the cool sector
of that system. This forecast update will maintain the highest
PoPs (50-70%) along and south of I-80 on Tuesday, with
decreasing precipitation chances with northward extent in the
northern half of the area. Chance PoPs (20-40%) linger Tuesday
night into Wednesday morning for locations along and south of
I-80.
As alluded to above, temperatures will be cooler, with highs in
in the upper 60s to low 70s on Tuesday, and low/mid 70s on
Wednesday.
Thursday through Saturday:
Mid-level troughing from the Great Lakes into lower MS Valley
Thursday morning is forecast to shift east, with the majority of
ensemble mean solutions indicating building heights/ridging
over the central U.S. into the weekend. That upper-air pattern
evolution would support drier and progressively warmer
conditions.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 558 PM CDT Sun Sep 21 2025
Shallow mid clouds are becoming more sparse this evening as
southerly winds continue at around 10 kts or less, with a stray
shower/storm developing to the northwest of KOFK that should
avoid that terminal over the next few hours. Overnight, winds
will decrease in speed and allow for fog formation, mostly
across western Iowa and far southeast Nebraska, clipping KOMA in
the process. As of right now the most likely timeframe for fog
is 10-14z, but forecast trends will be evaluated to see if that
duration will change in a later update. Tomorrow, winds continue
to be southerly/southeasterly storm chances increasing from 21z
onward into the overnight hours. As of now, KLNK and KOMA seem
to be the most likely to see storms while KOFK may be too far
north.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Mead
AVIATION...Petersen

NWS OAX Office Area Forecast Discussion