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000
FXUS63 KGID 260628
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
128 AM CDT Fri Apr 26 2024

...Aviation Update...

.KEY MESSAGES...

- High confidence in a widespread strong to severe thunderstorm
  event across much of the forecast area this evening/tonight.
  Many areas will see over 1 inch of rain, with localized 2 to
  3 inch amounts.

- Primary severe weather threat this evening/tonight will be
  golf ball sized hail and thunderstorm wind gusts to around 70
  mph primarily along and south of I-80. There will also be an
  isolated tornado threat mainly in our southwest (Phillips,
  Rooks, Osborne Counties in Kansas).

- Upper low will be slow to exit the area on Friday and thus
  another round of severe thunderstorms are possible Friday,
  mainly between 11 AM and 4 PM across our east and northeastern
  areas, including the possibility for isolated tornadoes in
  addition to hail and winds.

- Expect a general lull in precipitation chances Friday night
  into at least the first half of the daytime Saturday.
  Thunderstorm chances will increase late Saturday afternoon
  into the evening, with more high end severe weather possible,
  especially from the Tri-Cities and points to the south and
  southeast.

- Areas of frost are possible Sunday night, mainly to the
  northwest of the Tri-Cities as we cool down behind the
  departing storm system.

&&

.DISCUSSION...
Issued at 318 PM CDT Thu Apr 25 2024

This Evening/Tonight (Severe Weather)...

The warm front will gradually lift north and could make it into
our far southwestern counties (Rooks, Osborne, Phillips) by
around or just after sunset. The tornado threat will be limited
to areas in close proximity to this warm front across our far
southeastern zones where storms may become surface based.

Thunderstorms will quickly develop southwest of our forecast
area late this afternoon and then track east northeast into our
southwestern areas primarily after 7 PM. These storms will then
continue to track across our forecast area bringing possible
severe weather and likely heavy rain at times through the late
night/early morning hours. There is some question as to where
the southern most extent of the line of thunderstorms will set
up. All of south central Nebraska is pretty much expected to
get in on these thunderstorms tonight, but it is more
questionable how far south they will extend into north central
Kansas. But even Kansas rain chances are 70-80 percent with near
100 percent rain chances across south central Nebraska.

Added the possibility for locally heavy rainfall including
localized flash flooding to our forecast as thunderstorms could
train over the same locations tonight. Although surface based
instability/CAPE is lacking, there is plenty of MUCAPE at over
2,000 J/KG ahead of these thunderstorms tonight, especially
along and south of I-80. Therefore, large hail is certainly
possible and can also not rule out some stronger wind gusts
making it to the ground behind bowing lines of thunderstorms.


Friday (Severe Thunderstorms East and Northeast)...

The upper low is slow to exit the area and as it slows down from
previous runs we have seen the SPC severe outlook expand further
and further back to the west on Friday to include more of our
forecast area with higher threat levels. There is a concern for
tornadoes near the low across our eastern and northeastern zones
as the warm front lifts north during the late morning and early
afternoon hours. There will be little to no CIN in close
proximity to the low, so thunderstorms could redevelop very
quickly around noon or shortly thereafter. I would not be
surprised to see the future severe outlooks bring the Friday
tornado potential even further west into our forecast area.
Eventually the surface winds will turn southwest by later in
the afternoon as the low lifts northeast and the severe weather
threat will pass off to our east and northeast. Greatest severe
weather threat across our northeastern zones will be between
noon-4 PM.


Saturday (Another Severe Weather Threat)...

The next upper low is quick to eject into high plains by
Saturday afternoon/evening. The main question will center around
where the warm front sets up, but current indications are that
the warm front will be located somewhere across the southern
half of our forecast area. The atmosphere will again be very
unstable along with strong wind shear. All forms of severe
weather including tornadoes will be possible in the warm sector
northward to around the warm front. Large hail will be the
primary severe weather threat north of the warm front. The
forecast may certainly change as this is a few days away, but
keep an eye on where that warm front sets up Saturday afternoon.


Sunday into Sunday Night (Cooling back/frost?)...

We will cool down behind the departing storm system. Some
showers and thunderstorms could linger into Sunday, but the
main concern will be possible frost northwestern areas as we
clear out Sunday night.


Monday through Wednesday (Warming back up)...

Great weather returns with most locations seeing highs back into
the 70s. There are some small rain chances (20-30%) Tuesday
afternoon through Wednesday, but not looking like a big deal at
this point.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 127 AM CDT Fri Apr 26 2024

UP FRONT NOTE REGARDING KEAR:
Have tagged KEAR TAF with "AMD NOT SKED" (amendments not
scheduled) given temporary loss of observations.

- General overview for KGRI/KEAR:
This is a somewhat complex period, as a strong low pressure
system passes through the region from southwest to northeast,
accompanied by several aviation concerns including: sub-VFR
ceilings, showers and thunderstorms (and associated sub-VFR
visibility), breezy to moderately-windy winds and a gradual
directional shift from southeasterly, to southwesterly, to
westerly.

- Ceiling/visibility/rainfall/thunderstorm details:
Although showers and (probably) non-severe thunderstorms will
remain possible at almost any point through these first 18 hours
(and have at least a VCTS or VCSH going throughout this time,
the most concentrated activity will be right away these first 3
hours, which is handled with a TEMPO group for TSRA and
visibility potential down to around 2SM. Truly severe
thunderstorms are not anticipated, but periods of brief heavy
rain, wind shifts and possibly small hail are all possible.

As for ceiling, they are currently "all over the place" due to
convective influences, but particularly the 09-18Z time frame
will likely feature prevailing IFR/MVFR before ceilings rise to
at least low-end VFR during the afternoon.

- Wind details (not accounting for any convective influences):
For the majority of the period, sustained speeds will average
15-25KT/gusts 20-30KT, with sustained speeds finally easing
under 15KT by very late in the period (beyond 03Z). Direction-
wise, passing low pressure will result in a gradual/general
shift from east-southeasterly this morning, to southerly mid-
morning to early afternoon, to southwesterly mid afternoon, to
westerly late afternoon and evening.

On one final wind-related note, considered introducing a
marginal low level wind shear (LLWS) group for early this
morning, but with shear magnitude within the lowest 2K ft. AGL
looking to average closer to 25KT than 30+KT, held off on formal
TAF inclusion.

&&

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

&&

$$

DISCUSSION...Wesely
AVIATION...Pfannkuch