673
FXUS63 KGID 301010
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
510 AM CDT Thu May 30 2024

.KEY MESSAGES...

- More active pattern expected for the rest of the week and
  through early next week, though official forecast likely
  sounds worse/wetter than what reality will be for most.

- Some of the thunderstorms may be strong to severe, at times,
  but there currently aren`t any strong indications for
  organized and/or widespread severe weather.

- Rainfall amounts will be HIGHLY variable across the region, as
  is typical for the warm season. Reasonable high end amounts
  over the next 5 days (ensemble 90-95th percentile) are 3-5",
  which could lead to isolated hydro concerns if that pans out.

- Temperatures will remain remarkably steady in the 70s-80s and
  50s-60s for most of the next 7-10 days, though areas SW of the
  Tri-Cities may make a run into the low 90s at times Sun-Tue.

&&

.DISCUSSION...
Issued at 450 AM CDT Thu May 30 2024

Much more "messy", almost summer-like, upper pattern is
forecast to settle in for the next several days with shower and
thunderstorm chances for at least portions of the forecast area
essentially a daily/nightly occurrence. The pattern won`t come
with the summer-like heat, however.

Today - Tonight:
Convection has largely played out as expected over the past 9-12
hours and is indeed scattered and fairly weak currently. Several
MCVs are evident in regional mosaic radar loops, and to some
extent surface observations, which will "muddy the waters" for
forecasting convective trends today. The most obvious MCV
locally is currently just NW of Kearney, but additional MCVs are
also noted in northern Neb. and central Kan. These will slowly
shift E throughout the morning and continue to provide weak
ascent for iso-scat new development within a generally uncapped,
weak elevate CAPE environment. Shear is also weak through at
least midday, so really not much of a severe risk this morning.

Assuming some subsidence behind departing MCVs allows for at
least a few hrs of mixed sunshine, should be able to develop
some moderate instability (1000-1500 J/kg MLCAPE) immediately
along and just ahead of the front by late aftn/early eve as low
levels gradually moisten on continued Srly flow. SREF deep layer
bulk shear increases to ~30kt this eve, but appears the
strongest mid-level flow will remain well post-frontal.
Nonetheless, this CAPE/shear parameter space will probably be
adequate for marginally severe hail and wind. Capping is weak
thanks to H7 temps of 8C or less, so would expect relatively
early development along the sfc convergence zone from near Ord
to Lexington around 20Z. Activity should move E and SE through
the evening, probably still on a scattered basis through 03Z.
Some uptick in coverage will be possible thereafter, either from
MCVs moving off the high plains, or from increasing low level
jet. This could keep the marginal severe threat going well into
the overnight. PWATs are forecast to pool around 1.5" along the
frontal zone this eve/overnight, so with complex storm mergers
and/or slow effective forward motions, could have some locally
heavy rainfall. General consensus of model data suggests areas
along and S of the state line would be most at risk for isolated
2-4" of rain in short amount of time. Rainfall amounts,
however, will be HIGHLY variable across the region with many
areas staying mostly dry. This looks to be general idea each of
the next several days - some see isolated heavy rain, many
others miss out completely.

Friday-Friday Night:
Lingering showers and thunderstorms in the morning should
gradually end/shift S-SE with the composite front/outflow
through the daytime hours as upper support becomes increasingly
meager. Can`t rule out an iso pop-up storm anytime in the aftn
or eve thanks to uncapped moist BL, as evident by light and
spurious QPF in various model output. Also, EC has been
insistent that an MCS could clip areas SW of the Tri-Cities Fri
night, though confidence on this is low given weak 850mb flow.

Weekend:
Rain chances continue through the entire weekend, but definitely
don`t want to give the impression that either day is a washout.
In fact, think most will stay dry through late aftn Sat as the
main risk locally should come from scattered storms that develop
in central Nebraska then move SE during the evening - perhaps in
the form of one or two MCSs. Belt of stronger deep layer shear
remains just off to the N, so think severe threat should be
fairly similar to today and mostly of the marginal variety.
Overnight convection should have more LLJ to work with. Kind of
a wash, rinse, repeat for Sunday in terms of expecting timing
and location of initial development. This round of activity
could have more organization/intensity with it, though, given
higher values of both instability and shear, as well as more
coherent shortwave trough and possibly a front. Confidence in
the higher CAPE/shear overlap occurring this far S is too low
for a formal outlook from the SPC, but something to monitor for
potential impacts to Sunday evening outdoor activities.

Next week:
Forecast confidence continues on the low side early week, at
least in terms of shower/thunderstorm details on Monday, thanks
to weak zonal flow and potential for one or more boundaries to
linger in the region from previous rounds of convection.
Ensembles have started to come into better agreement regarding a
stronger shortwave trough moving through the central/northern
Plains in the Tuesday-ish time frame - which would likely send
at least a moderately strong cold front through the region and
possibly bring an end to the frequent rain chances for a few
days. Ahead of this front, some areas could make a run at the
low 90s Sun-Tue, but otherwise much of the next 7-10 days look
to be mainly mid 70s to 80s for high temperatures. Fairly
seasonable for late May - early June.



&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1255 AM CDT Thu May 30 2024

Primarily VFR during the period, though non-zero chance for MVFR
CIGs afternoon into overnight.

Tricky forecast due to uncertainties regarding thunderstorm
timing, coverage, and intensity. First this morning, cluster of
weakening thunderstorms will push in from the W next few hrs.
This activity is forecast to weaken beyond 09Z, but isolated
pop-up thunderstorms will be possible to redevelop just about
anytime through the remainder of the overnight, and even through
much of the daytime hrs. Tried to back off the VCTS to VCSH
during periods where chances are lowest. Conceptually speaking,
would expect an increase in thunderstorm chances by late
afternoon and into the evening, but very low confidence in
details (timing/coverage) continue as forcing is nebulous. CIGs
will fluctuate lower in and near convection, but should remain
primarily VFR 4-8K ft. There are some indications for CU with
MVFR worthy bases to develop this aftn, but coverage is
uncertain. At least MVFR CIGs become increasingly probable
(50-60%) beyond 00Z Friday, but will tackle this in later TAFs.

Winds outside of convection should be primarily SErly 9-14kt
with gusts near 20kt. Convection this morning should give at
least a 2-3hr window for a wind shift to gusty W/SW winds, but
think a turn back to SErly will occur by sunrise. This evening
winds will gradually back to E then NE at 5-9kt.

&&

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

&&

$$

DISCUSSION...Thies
AVIATION...Thies