000
FXUS63 KGID 221731
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1231 PM CDT Mon Apr 22 2024

.KEY MESSAGES...

- A frontal boundary will slide SE through the area this
  afternoon into tonight and will provide a focus for shower-
  storms, a few storms could be strong with small hail/gusty
  winds. Ahead of this front, expect gusty SW winds, especially
  this morning, and warm temperatures.

- High likelihood for widespread near-critical fire weather on
  Tuesday thanks to dry, breezy N winds gusting around 30 MPH.

- An active weather pattern develops mid week and continues into
  the weekend with multiple rounds of showers and thunderstorms
  possible - most notably Thu-Fri and Sun.

- Greatest risk for strong-severe storms (Slight Risk, level 2
  of 5) will be Thu-Thu night and possibly again Fri-Fri night
  (esp. E of Hwy 281) depending on overall evolution and timing.

&&

.DISCUSSION...
Issued at 440 AM CDT Mon Apr 22 2024

Quiet, mild and breezy morning in place currently thanks to
strong low level jet and deepening lee troughing in response to
next upper disturbance digging into N Rockies/Plains. A Pacific
cold front associated with this wave is noted in 08Z surface
analysis running from central ND into SE WY. Strong S-SW low
level flow will continue ahead of this front and help lead to
warm aftn high temps in the 70s to low 80s. Dry air (low to mid
20s RHs) will try to nose into far SW zones this aftn, but this
looks to coincide with a decr in winds immediately near/along
the front...which should preclude official near-critical fire
weather conditions. Nonetheless, even further SE where the winds
remain elevated for longer, RHs will still have a tendency to
fall to around mid 20s and lead to at least elevated fire
weather. Fortunately, these are areas that are likely the
greenest, so erred against inclusion in HWO for this reason.

Later this eve and especially overnight...
A LLJ is forecast to ramp up to 40-50kt and provide convergence
and lift along and atop the SE sinking cold front. Deep
moisture/instability, is quite limited...but various forecast
soundings still support ~250-750 J/kg of MUCAPE amidst very
steep mid level lapse rates and long mid-upper level hodographs
and 40-50+ knots of effective shear. Any shwrs/storms will
probably be pretty limited in coverage (iso to scat), but still
can`t rule out a couple/few strong cores producing small hail
and gusty winds - mainly E/SE of the Tri- Cities where H85-H7
flow is strongest - in roughly the 03Z to 09Z time frame.

Tuesday through Wednesday...
Main story on Tue will be cooler temperatures (though
still mild) on breezy N winds that will likely lead to
widespread near critical fire weather given continued dry low
levels. In fact, RHs continue to trend a bit lower (due in large
part to temps trending a few deg warmer) and now look to be
near 20% to 25% area wide during the afternoon. Wind gusts are
forecast to decr after 21Z as pressure gradient relaxes, but
particularly in the 18Z-21Z time frame, gusts around 30 MPH are
likely. Again, with the area trending towards more substantial
greenup, will forego a Fire Weather Watch at this time and
continue mention in HWO.

Tue night continues to be a bit tricky in terms of timing of mid
level warm air advection and potential for cloud cover/iso-scat
shwrs and how it relates to temps and frost potential. Latest
NBM didn`t change a whole lot on low temps and still runs mid
30s NE to low 40s S. Thus, widespread frost concerns still seem
unlikely, but the builder continues to include some frost in the
grids from around Greeley to York. The rest of Wed should be
fairly quiet, and actually fairly pleasant in the sense that
winds will be lightest they`ll be through at least the weekend
during the AM to early aftn. Srly flow will incr mid to late
aftn, esp. W of Hwy 281.

Thursday into the Weekend...
Most "interesting" portion of the forecast will come Thu into
Fri as low level moisture/instability rapidly incr ahead of an
ejecting strong shortwave from a rather broad W CONUS upper
trough. Broadly speaking, this setup will bring the potential for more
widespread preciptiation chances and concern for strong/severe
storms. The initial surge of WAA on nose of LLJ could lead to
elevated strong (severe?) convection with mainly a hail threat early
Thu AM, mainly S of the state line towards the I-70 corridor.
This is mostly strongly depicted in the 00Z EC QPF output in the
06Z-18Z time frame. With that said, it`s far from a certainty
as the NAM/GFS are nearly QPF free, likely owing to stronger
capping and warmer temps around 700mb. As such, PoPs are only
~30% in these areas prior to dawn.

Rain and thunderstorms chances, including potential for severe
storms, increases late Thu aftn, but especially evening and
overnight, as the main shortwave ejects from the Four Corners
region onto the central High Plains by 12Z Fri. Timing is less-
than-ideal for peak severe t-storm coverage/intensity - somewhat
similar to last Mon - but model consensus is still for moderate
instability (1500-2500 J/kg) and sufficient deep layer shear (on
the order of 30-40kt). Deterministic and ensemble solutions have
trended a bit higher and further N with these parameters, and as
such the SPC Day 4 15% contour (essentially a Slight Risk, level
2 of 5) has shifted a bit N to around the I-80 corridor. Seems
probable that a Marginal Risk will be introduced in later
outlooks to cover areas further N. Fri-Fri eve thunderstorm
timing, coverage, and severe potential will really be driven by
the evolution of Thu night`s convection and how it affects
pertinent sfc features. The main low (sfc and aloft) looks to
move through the Central Plains on Fri, but the question is how
quickly? Overall, not much change in this regard over the past
24 hrs in either deterministic or ensemble output, but worth
noting that the GFS is faster/more progressive (as usual)
compared to slower EC/Canadian. The slower solutions would
suggest continued severe threat for at least far E zones
(roughly Hwy 81 corridor) Fri aftn-eve. Wrap-around, non-severe
activity could persist into Fri night, esp over central NE.

Precipitation chances remain elevated for the upcoming weekend
considering it`s Day 6/7, though I don`t foresee it being a
complete washout, either. Saturday daytime, in particular,
looks to be mainly dry given latest model trends. More likely
time frame for shwrs/storms would be Sat night and esp. on Sun
as another upper trough ejects out of the broader W CONUS trough
and onto/thru the Plains. This wave has been pretty consistently
modeled to eject out a bit further S/SE, suggesting this is
also where the primary severe threat could set up. Officially,
however, there`s just too much uncertainty to delineate
particular threat areas this far out per latest SPC Day 6/7
outlooks. Seems most probable outcome is that majority of our
forecast area will be N of the sfc low/warm front, and thus in
cooler environment, or at least in one that instability is
mainly elevated and weaker. In fact, data seems to be honing in
on idea that this round could turn out to be a widespread rain
producer with a generally low severe threat. Obviously great
news for those looking for some much needed moisture ahead of
spring planting season. Many areas are sitting at only 15-75% of
normal for the past 30 days, with overall driest areas along/SE
of a line from Osborne to Hebron. Latest EPS guidance puts
7-day total precipitation probs at 60-90% for >0.5" and 30-70%
for >1" - highest SE of the Tri- Cities. There`s even a 10-30%
chc for more than 2" for these driest areas. As always, there
will be "winners" and "losers" when in comes to final amounts,
and locally higher amounts above 2" is certainly possible given
the convective elements and PWATs 2 to 3 standard deviations
above normal, at times...but in general, this looks to be one of
the best signals for widespread moisture we`ve had thus far
this spring! Temps will vary based on clouds/rain, but generally
remain in the 60s/70s for highs and 40s/50s for lows.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1223 PM CDT Mon Apr 22 2024

VFR conditions are forecast for this TAF period, with the main
concern being with winds. Gusty west-southwest winds start off
the period, but an approaching surface cold front will be
bringing a switch to the north-northwest within the first couple
of hours. Gusts of 30+ MPH continue ahead of the front, gusts
behind the front look to be more in the 25-30 MPH range, and
should diminish with time late in the day. Winds turn more
northeasterly this evening/tonight, with speeds around 10-15
MPH...switching back to the north for the final few hours of
this period, with gusts back up near 25-30 MPH once again. Kept
a VCSH mention going this evening, can`t totally rule out some
isolated precipitation around the terminal areas, but confidence
in it occurring is not high.

&&

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

&&

$$

DISCUSSION...ADP
AVIATION...Thies