440
FXUS63 KGID 010255
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
955 PM CDT Tue Apr 30 2024

.KEY MESSAGES...

- There is a slight chance (around 20%) of thunderstorms this
  afternoon across far eastern and northeastern portions of the
  forecast area. These storms may become severe.

- Shower and thunderstorm chances increase (up to near 70%
  during the afternoon) on Wednesday areawide with storm chances
  increasing up to 95% Wednesday night.

- There is a 20% to 30% chance of strong to severe storms during
  the day Wednesday but much higher chances (up to around 70%)
  Wednesday evening and night.

- After today, high temperatures will mostly be in the 60s and
  70s and low temperatures in the 30s to 50s.

&&

.UPDATE...
Issued at 955 PM CDT Tue Apr 30 2024

Quick update regarding thunderstorm potential tomorrow...

Latest model guidance is really honing in on the ongoing
activity across KS/OK and how it will affect our sensible
weather on Wed. In general, seems less and less likely that the
surface warm front will return northward anywhere close to the
local CWA, owing to persistent convection over central/SE Kansas
into N OK through the overnight and even into Wed AM. Sfc winds
will turn SE, but all this will do is advect a convectively
overturned airmass from these areas into south central Nebraska
and north central Kansas. This is not overly uncommon for this
area at this time of year, as we`re still several weeks from
peak sun angle and don`t have the help of surface ET. In fact,
latest hi-res guidance suggests an expanding area of only 50s
sfc temps by the aftn hrs thanks to more Erly/upslope sfc flow
and thickening cloud cover. Prior to that, will probably see
incr scat elevated convection from S to N by late AM or early
aftn. Forecast soundings are generally unimpressive, at least
from a thermo environment, as MUCAPE largely remains less than
1K J/kg. Could see some small hail (pea to penny-ish) from
strongest cores, thanks to seasonably low WBZ heights and strong
effective shear.

Appears our "highest" risk for severe convection will come
during the late evening and overnight from activity that
initially develops over NE CO, then shifts E. Due to
aforementioned stabilized effects from earlier in the day, any
tstms tmrw eve/night will likely be elevated...around 800mb per
00Z HRRR forecast soundings. These soundings continue to be
somewhat modest from an instability perspective (MUCAPE
1000-2000 J/kg, perhaps locally higher W/SW of the Tri-Cities),
but 50kt of SWrly flow at H5 atop incr 35-45kt Srly LLJ should
yield a substantial amount of effective shear. Even after
excluding the stable lowest 1km, 1-6km hodographs are still
quite long, and straight, with around 60kt of effective shear.
This suggests some sort of combination of splitting supercells
and/or linear segments. Axis of MUCAPE is highest W/SW of the
Tri-Cities, so these areas may have highest risk in the 00Z-06Z
time frame, with lessening risk with time and eastward extent.
Large hail will likely be the primary risk. If linear storm mode
indeed transpires, then dmg wind risk isn`t zero...but a
relatively deep stable layer (around 1km) argues against much
high wind making it to the sfc. This seems to be reflected in
00Z HRRR by lack of significant gusts near this convection. Any
tornado threat looks to remain well S/SW of the area.

&&

.DISCUSSION...
Issued at 312 PM CDT Tue Apr 30 2024

Today and tonight...

An upper trough is over the Pacific Northwest and Northern Plains
and extends southward over the Central Plains. A cold front is
pushing through south central and central Nebraska and north central
Kansas from the northwest. Showers and thunderstorms are expected to
develop along and ahead of this cold front this afternoon into this
evening as it moves southeastward. Most models are showing the
convection developing east of the forecast area, but there is about
a 20% chance of storms developing across the far eastern and
northeastern part of the forecast area later this afternoon. Any
storm that develops will have the potential (60% to 70% chance) to
become severe given fairly high CAPE, wind shear, and instability.
Gusty northwest winds are present behind the front with temperatures
in the 60s and 70s. A surface high will be present across the area
tonight with fairly light winds. Low temperatures will range from
the low 40s to low 50s.

Wednesday and Wednesday night...

Showers and thunderstorms may develop across mainly north central
Kansas into far south central Nebraska Wednesday morning as the cold
front lifts northward a bit and interacts with an upper level
disturbance. Widespread severe storms are not expected with this
activity but a few strong to severe storms will be possible (about a
20% to 30% chance). An upper trough to the west will move closer to
the region Wednesday afternoon further increasing the upper level
lift. There is uncertainty as to whether the activity during the
morning and early afternoon hours will be strong to severe. Lift
from the upper trough will increase across the area Wednesday night
with the stalled front receiving a push southeastward. This will
likely result in a complex of storms moving across the forecast area
Wednesday evening into Wednesday night. The threats with these
storms will be large hail, damaging winds, localized flash flooding,
and a low tornado threat. High temperatures Wednesday will be in the
mid 60s to low 70s. Low temperatures Wednesday night will be in the
mid 40s to mid 50s.

Thursday through Monday night...

Lingering showers and storms are possible (up to a 50% chance)
mainly east of Highway 281 Thursday morning. The rain and storms are
expected to be out of the area Thursday afternoon. Winds will be
gusty out of the northwest Thursday morning into Thursday afternoon
as the colder air pushes through the area. High temperatures
Thursday are expected to be in the mid 60s to low 70s. Winds will
weaken during the evening hours with partly cloudy to mostly clear
skies overnight. Low temperatures Thursday night are expected to
drop into the mid 30s to mid 40s. Winds will increase out of the
south to southeast on Friday as an upper trough covers the northern
and central Plains. High temperatures on Friday are expected to be
fairly similar to the previous day. An upper trough will move over
the Central Plains Friday night and will provide increased chances
(up to around 60%) of showers and thunderstorms. Low temperatures
Friday night are expected to be in the mid 30s to upper 40s. The
showers and storms will end by Saturday afternoon with high
temperatures in the mid 60s to lower 70s. Low temperatures Saturday
night will mostly be in the 40s. Winds across south central and
central Nebraska and north central Kansas will increase out of the
south to southeast with an upper trough dominating the western part
of the country on Sunday. High temperatures on Sunday will mostly be
in the 70s across the area. Gusty south to southeast winds will
continue into Sunday night with lows in the 50s. The upper trough to
the west will begin to move over the Central Plains on Monday with
increasing rain and storm chances (up to near 50%). Low temperatures
Monday night are expected to be in the mid 40s to mid 50s.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 658 PM CDT Tue Apr 30 2024

Tonight: W-NW winds will decr around sunset, then veer
substantially through the overnight...becoming lgt and somewhat
variable after midnight. Skies should be clear to mostly clear
with just some FEW-SCT high clouds. Confidence: High.

Tuesday: Expect incr mid level clouds by mid to late AM, then
lower clouds, perhaps MVFR, towards the last 3-6 hrs of the
valid period. The lowering CIGs could also be accompanied by
some lgt shwrs. Winds will become ESE-SE for daytime hrs, and
incr to 12-16kt, with gusts towards 20kt, esp for the aftn.
Confidence: Medium.

&&

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

&&

$$

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