Text Products for AFD Issued by GID

Area Forecast Discussion
Issued by NWS Hastings, NE
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FXUS63 KGID 231008
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
508 AM CDT Tue Apr 23 2024

.KEY MESSAGES...

- Near critical, to perhaps localized/brief critical, fire
  weather conditions are likely across majority of south
  central Nebraska and north central Kansas this afternoon.

- 20-30% chance for patchy/scattered frost late tonight into Wed
  AM, mainly NE of the Tri-Cities. Increasing mid-high clouds
  from the SW should preclude a greater threat.

- Thunderstorms become possible as early as late Wed night or
  early Thu AM, but are more likely (60-80% chance) Thu evening
  and overnight, some of which could be strong/severe. There is
  a Slight Risk (level 2 of 5) for areas south of I-80, with a
  Marginal Risk (level 1 of 5) elsewhere.

- Another round of strong to severe thunderstorms is possible
  Fri afternoon, mainly near/E of Hwy 81 corridor, but
  specifics will really depend on timing of a front and surface
  low pressure. Additional off and on, largely non-severe,
  thunderstorms expected this weekend, most notably Sat night.

&&

.DISCUSSION...
Issued at 445 AM CDT Tue Apr 23 2024

Overnight iso-scat showers and a few strong thunderstorms have
largely exited the forecast area as of 4AM. Have lingered some
low end shower chances over the far NE for another 1-2 hrs, but
most areas are actually seeing quite a bit of clearing. This
will set the stage for a mostly sunny day with breezy N winds
behind a departing cold front. Little to no changes in forecast
high temperatures in the mid 60s to lower 70s, which when
combined with dew points mostly in the upper 20s to lower 30s,
yields afternoon relative humidity (RH) values around 20-25%.
Thus, at least near critical fire weather is likely for nearly
entire forecast area. May even see some pockets of
briefly/locally critical fire levels with RHs in the upper
teens...but given the somewhat marginal setup and fact that
there has been a considerable amount of greenup in the last 7-10
days, opted NOT to issue a formal Red Flag Warning. This is
supported by internal GFDI output that is largely in the "High"
category (8-20) when taking into account even just a 10% drop in
curing, vs. typical "Very High" or "Extreme" for most RFWs.

Maintained some frost mention in the grids and HWO for far NE
zones late tonight as lows attempt to drop into the mid 30s in
these locations, closer to sfc ridge axis. Models have been
consistent showing a fair amount of mid/high clouds increasing
from SW to NE Wed night, which should keep this a fairly minor
threat and keep rest of the forecast area in the upper 30s to
low 40s. In fact, latest NBM suggests only 20-30% chance of
falling to or below 35 degrees, and with the expected incr in
mid to high clouds, opted NOT to issue any Frost headlines. The
areas with the most (albeit limited) risk are really the same
areas that are least susceptible from a climatology and GDD
perspective. With the incr clouds could also come some light
showers, esp SW of the Tri-Cities, late tonight, then lingering
elsewhere into the daytime hrs Wed.

More impactful weather in terms of thunderstorms and the
potential for strong to severe weather will come late in the
week. EC continues to be most aggressive with elevated
convection signal, potentially on the strong to severe side,
across central KS late Wed night and into Thu AM. Greatest risk
will probably reside S of I-70, but the more aggressive EC tries
to edge the stronger activity into mainly Rooks and Osborne
Counties. As was the case 24 hrs ago, confidence on this is low
due to high model spread and differences in location and
magnitude of instability and mid level capping.

Higher dew points in the 50s to lower 60s with surge N during
the day Thu on increasingly breezy SErly low level flow.
However, with the increased moisture could also come a
considerable amount of stratus (low level cloud cover). NBM
precipitation chances are quite high during the daytime hours
Thu, despite the primary upper level system still WELL W/SW of
the area towards the Four Corners region, but this may be
pointing to the potential for drizzle and/or light showers,
instead of deep convection. This is evident in forecast
soundings showing an increasingly deep layer of saturation
beneath a mid level capping inversion and amidst strong warm air
advection. So outside of the AM strong thunderstorm potential
over the far S, tend to think that for most areas the current
forecast is a bit overly pessimistic and that most will just see
cloudy/drizzly/light showery conditions during the daytime hrs
Thu with not much accumulation.

Timing of the upper level trough ejection and arrival of
associated sfc low pressure system remains consistent that for
us, it will be in the late Thu eve and into the overnight.
Would think aftn/early eve convection develops mainly over W KS
along dry line, then grows upscale as it moves NE into the local
area after sunset, aided by increasing low level jet. This
would suggest a timing/evolution somewhat similar to last Mon
in that it`s largely an overnight event (potentially well after
midnight E/NE of Hwy 281) with mainly a wind and hail threat.
Guidance tends to keep the primary axis of instability
entrenched W of Hwy 281, so this potential MCS may tend to
"outrun" the low level instability axis and weaken E/NE of the
Tri-Cities very late Thu night. The new SPC Day 3 Outlook is
largely what was anticipated from even a couple days ago, with a
Slight Risk (15%, level 2 of 5) focused S of I-80 and esp. for
KS/OK/TX, with a Marginal Risk (5%, level 1 of 5) covering the
rest of the forecast area. "Significant Severe" probabilities
are currently focused SW of the CWA.

There`s also been very little change to the overall thinking of
general evolution/impacts for Fri and into the weekend. Latest
SPC Day 4 outlook is largely unchanged for our area and hints at
Hwy 81 corridor as a potential initiation point for a new round
of convection Fri aftn. However, this will REALLY depend on
timing of sfc low and associated fronts (particularly the dry
line), and to some extent the effects from Thu night`s round.
Sometimes these strong upper disturbances become more negatively
tilted and slow down, but there`s also times where convection
will be more progressive than the models anticipate (esp. when
it`s an organized MCS) and the moisture/instability sweeps to
the E much faster. So it`s tough to lean one way or the other at
this point. Given the consistency in the model output, tend to
think the greatest risk will align SE of the area along the I-35
corridor. Could actually see a fairly pronounced dry break from
Fri night through the daytime hrs Sat before the next
disturbance approaches from the SW Sat eve/night. This should
bring another round of fairly widespread rainfall. Guidance also
remains consistent that this wave will eject further S/SE
compared to Thu night`s system, so no change to overall thinking
that greatest severe risk Sat night into Sun will be from the S
Plains into Mid MS Valley. Perhaps...SE zones could get in on
enough elevated instability for some hail cores Sat eve/night
with the cooler mid-level temps, but don`t think this would be a
significant and/or widespread threat. Rain chances should wind
down Sun aftn/eve, with dry conditions expected for Monday.
Temps in the Fri-Mon time frame will really be dependent on
cloud/precipitation coverage, but generally remain in the
60s-70s for highs and 40s-50s for lows. Far S zones could crack
80F just about any day but Sun. Still think most areas will be
able to manage a solid 0.5-1.5" of rainfall over the next 7
days, which is very close to latest EPS 25-75th percentile. Any
>40% chances for total QPF over 2" have mostly shifted SE, in
line with the trend for the weekend system.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1245 AM CDT Tue Apr 23 2024

Band of mid level clds with bases 10-15k ft and iso shwrs/storms
will continue for a few more hrs before shifting E/SE. Kept VCTS
at GRI, but removed from EAR as vast majority should remain to
their E. Expect decr clds near/after sunrise such that most of
the daytime hours will be at least mostly clear. NErly winds now
will bec gusty out of the N/NW after sunrise once again.
Sustained winds 15-20kt and gusts 25-30kt are expected from mid
morning through mid to late aftn. Winds will decr to 5-9kt and
turn slightly to N/NNE around sunset. Confidence: High.

&&

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

&&

$$

UPDATE...Pfannkuch
DISCUSSION...Thies
AVIATION...Thies
National Weather Service Regional Headquarters
