588
FXUS63 KGID 291001
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
501 AM CDT Tue Sep 29 2026

.KEY MESSAGES...

- Wet weather pattern begins today and continues through
  Thursday. Widespread total rainfall amounts of 1.5-3" are
  expected over the next three days.

- Prospects for appreciable dry breaks in the rain are limited,
  effectively leading to "washout" type days Wednesday-Thursday.

- Ensemble 90th percentile QPF forecast (reasonable worst case
  scenario) maxes out between 4-5", which, if comes to fruition,
  could lead to areas of flooding given already wet soils from
  last week`s rain event. A Flash Flood Watch remains in effect
  for the entire forecast area.

- Much quieter weather arrives in time for the weekend. Slightly
  below normal temperatures are favored - highs 60s/70s, and
  lows in the 40s/50s.

&&

.UPDATE...
Issued at 445 AM CDT Tue Sep 29 2026

Forecast focus remains the upcoming persistent, and likely at
times heavy, rainfall over the next three days. Big picture, not
a whole lot has changed. The remnants of Hurricane Polo are
crossing the Baja now...and a deep upper trough is digging into
the Four Cornerns region. Several weak lead impulses within
broad, diffluent SWrly upper flow are already leading to several
areas of scattered to widespread showers/embedded weak
storms...with one such area currently moving through central
Nebraska. Still appears that areas from around the Tri-Cities,
and especially W and N, will be most affected by this lead
impulse this morning...with areas from around Osborne/Mitchell
Counties up towards York County perhaps staying mostly dry
through at least the morning hrs.

Rain coverage, and rates, are forecast to increase substantially
this afternoon into early evening, particularly along and S of
the NE/KS state line...then moreso into other parts of south
central Nebraska during the overnight. Bouts of moderate to
heavy rain are likely continue all day Wednesday and Wednesday
night...essentially making the day a complete "washout". Rain
will probably taper off some for areas N of I-80 on Thursday,
but at least moderate rates could continue elsewhere into
Thursday night. Should FINALLY clear out for Friday, and,
fortunately, the weekend into next week looks much much less
active. In fact, the entire first half of October may be dry.

Unseasonably high PWATs are already in place, per 00Z regional
ROABs, and values will only increase over the next 24 hours as
deep, tropical and sub-tropical, Pacific moisture associated
with the remnants of Hurricane Polo are drawn N/NE through the
Plains...ahead of the aforementioned Four Corners upper trough.
Latest 50-member EPS ensemble continues to support MEAN values
increasing into 1.75-2.00" range tonight into Wednesday. PWATs
of this magnitude are considered high during our
climatologically peak months of July/August, much less late
September into early October, and comes out to about +3 to +4
standard deviations. ***Simply put...atmospheric moisture
content will likely be as high, or higher, than ever sampled by
the upper air network, in our region, in late September.***
This aspect of the system/next few days is high confidence.

Now, translating the above into impacts and specific rain totals
is much more nuanced...and there is the potential for
significant spatial variability. To this point, several pieces
of numerical guidance fits a conceptual model of a moisture-
enhanced mid latitude cyclone, in which our region is located on
the northern side within persistent mid level deformation and
frontogenesis. These types of systems often have a very sharp
precip gradient on the northern side of the system, similar to
what we experience with winter storms. Exactly where and how
sharp the gradient with this system will be is still
uncertain...but it could come into play for our N zones. Also,
various pieces of hi-res modeling suggest multiple, relatively
narrow, swaths of very heavy rain (4-6"+) due to convective
enhancements. These are extremely difficult to pin down ahead
of time, owing to complex mesoscale interactions. However, the
IDEA of such heavy swaths makes sense given mean mid/upper level
flow that will be largely parallel to the deep layer
deformation and forcing, which would favor training cells and/or
stationary bands of enhanced rates. This is why we need to take
90th-95th percentile QPF output as a real possibility and
concern. 00z HREF max QPF through the 00Z (not even the end of
the event) is in the 5-7" range, and latest NBM 95th percentile
for same period is also in the same 5-7" range...focused S of
Hwy 6 into N KS. EPS values are slightly lower, but some of this
may explained by coarser model resolution.

Finally, from a hydrology perspective...the high-end potential
amounts mentioned above appear to be most favored within a
corridor that already received 3-5" of rain last week. Areas
such as areas in and around Harlan Co., and also from around
Osborne up towards Superior and Hebron. I know, personally, that
my yard in S Hall County and fields around my area are still
quite damp, even though we`ve had 72 hours to "dry out". Lack of
significant wind and sun, combined with shorter days in early
fall, means we just don`t dry out like we would in July/August.
Furthermore...row crops simply aren`t drawing nearly as much (if
any?) moisture from the ground, either. Adding another 3-5" on
top of last week`s rain would essentially push us into top 3-5
wettest September`s on record...with the impressive part being
most of it occurring in the later half/third of the month and
not the early part of the month.

Needless to say...the Flood Watch continues for the entire
forecast area, and this could turn into one of the larger
"weather stories/events" of the yr for at least a few of our
counties. Folks in flood prone areas, particularly along and S
of Highway 6 into northern Kansas, need to be prepared for
potential flooding Wednesday into Thursday.

&&

.DISCUSSION...
Issued at 343 PM CDT Mon Sep 28 2026


Rest of Monday and Tonight...

A few isolated showers and thunderstorms (primarily near and
north of the KS / NE state line) cannot be ruled out this
afternoon into evening, however a substantial cap casts a good
deal of doubt on these storms successfully initiating.
Regardless, if storms develop, no severe weather is expected.

As for tonight, a glancing blow of showers and a few
thunderstorms is expected for our far northwestern CWA as a
joint mid-level and low-level jet impinge on the area through
Wednesday morning. No flooding is expected from these showers.

Tuesday...

The main show of the week arrives on Tuesday. Our initial jet
streak will gradually pull off to the northeast through Tuesday
morning, but a secondary pulse will arrive round noon. Vorticity
advection is not expected to ever fully die down, and thus
broken rounds of showers and storms are expected through the
day. The likeliest times for precip will be from noon onwards,
with the likeliest time for a break in the mid-morning between
jet streaks.

Tuesday night (particularly 1 AM - 4 AM Wednesday morning) is
expected to strongly uptick the intensity of precip (and thus
flooding risk). At this time, the remnants of Hurricane Polo
will advance into our area after getting sucked into our main
trough. Vorticity advection, a favorable mid-level jet with
strong diffluence, a 35+ kt low-level jet, and warm air
advection all look to arrive with saturated profiles through the
depth of the troposphere. By sunrise on Wednesday morning, mean
24-hr precip of 0.5 - 1.5 inches (with the heaviest favored
south of I-80) is expected. As a potential worst-case scenario,
12z HREF 95th- percentile 24-hr totals by sunup on Wednesday
exceed 3.5 inches with the heaviest yet to come on WED. Given
antecedent wet soils, flooding will be a concern. WPC currently
holds us in a Level 2 out of 4 Slight Risk for flash flood
exceedance for TUE.

Wednesday...

Wednesday is highly likely to be a washout with rain and storms
carrying us through the day. Our trough, jets, and saturated
profiles with PWATs >150% of normal for this time of year will
continue to provide for additional flooding risk. WPC maintains
us us in a Level 2 out of 4 Slight Risk for flash flood
exceedance on WED. 13z NBM guidance suggests new Wednesday and
Wednesday night rainfall totals of 1.5 - 3 inches, with 95th-
percentile wosrt-case totals locally exceeding 5 inches in our
central CWA. Of note for our southern CWA, where forcing remains
more optimal, a few strong to severe thunderstorms will be
possible, with SPC currently outlining these counties in a Level 1
out of 5 Marginal Risk for severe thunderstorms.

Exactly where the heaviest rain falls will depend on how far
northward the nose of the jets can reach, and the northern edge
of the jet will likely produce a sharp cutoff in rainfall
totals. THE EPS and GEFS tend to favor our central CWA as the
northern edge, while the 12z REFS favors our northern counties.
In addition, some breaks in rainfall are expected, but dry time
will be the exception and not the rule.


Thursday...

Precip looks to linger on Thursday, primarily for our KS
counties. By evening, precip is expected to finally die off as
our favorable forcing ejects to the east. Despite the heavy
rainfall coming to an end, the trough core itself will likely
linger on Thursday, bringing cooler temperature in the low 60s F
with overnight lows into FRI able to dip into the mid 40s.
Additionally, breezier conditions with wind gusts of 25 - 30 mph
are expected.

In all, by sundown on Thursday when rain is expected to end,
likeliest cumulative totals across the CWA look to be 2.5 - 4
inches, with a worst-case scenario of 5+ inches per 13z NBM
guidance.

Friday into Weekend...

Friday, Saturday, and Sunday are expected to stay dry with
relatively cooler temperatures prevailing. The 06s GEFS suggests
that the next shortwave trough will move in from Canada on
Saturday, but right now precipitation associated with this
trough looks unlikely.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1240 AM CDT Tue Sep 29 2026

For KGRI/KEAR Airports:

Rain showers are expected to begin impacting KEAR and KGRI
shortly and will continue through the end of the period.
Continuous rain is not expected and there is some uncertainty if
and when there may be breaks in the rain showers. There is also
a possibility of thunderstorms but there is uncertainty if,
when, and where these storms will occur. Generally expect VFR
ceilings overnight, although there may be brief MVFR ceilings in
areas of heavier rain. There is expected to be some lowering of
ceilings around or after 18z and especially by 00z. Winds will
be out of the southeast through 12z then out of the south then
will turn towards the southwest around 18z. Southerly winds are
expected by 00z.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Flood Watch from this evening through Thursday evening for
     NEZ039>041-046>049-060>064-072>077-082>087.
KS...Flood Watch from this evening through Thursday evening for
     KSZ005>007-017>019.

&&

$$

UPDATE...Thies
DISCUSSION...Began
AVIATION...Schuldt