textproduct: Hastings

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 /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 650 AM CDT Tue Sep 29 2026

For KGRI/KEAR Airports:

Complex TAF period with off and on rain chances and overall uncertainty in ceilings.

Today: Expect off and on rain showers today, but doesn't appear any of it will be particularly heavy or persistent. Thus, decided to paint the daytime hours with mainly VCSH in the prevailing groups along with TEMPO or PROB30 groups. Best chance for an actual storm will be next couple hours at GRI, but even this may stay to the N. CIGs should remain mainly VFR for the daytime hours, with winds out of the SSE to SW 8-12kt. Confidence: Medium to high for specific aviation impacts.

Tonight: Specific rain timing and coverage remains uncertain into the overnight hours - owing to expected scattered nature of the coverage. CIGs also remain uncertain given wide range in guidance. On one hand, could envision a scenario where stratus sets in after sunset and most of the night is IFR amidst light and variable winds. On the other hand, some hi-res guidance holds off on any sub-VFR CIGs until late in the overnight when perhaps a stronger surge in low level moisture, and attendant chcs for storms, arrives from the S. Overall confidence for the overnight period is LOW.

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.