533
FXUS63 KGID 150641
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
141 AM CDT Sat Jun 15 2024

...Aviation Update...

.KEY MESSAGES...

- A complex of thunderstorms is expected to move across the
  area late this evening and overnight. Storms will be strong to
  marginally severe, especially W/SW of the Tri-Cities, with
  damaging wind gusts the main threat.

- Thunderstorm chances of some degree continue off and on nearly
  every day/night over the next week, which is not uncommon for
  this time of year. Beyond tonight, mid to late next week
  currently appears to be most favored time for more frequent
  and/or widespread rainfall.

- Storms may be strong to severe from time to time, but any
  decent amount of forecast confidence in specifics will be
  limited to only 1-2 days out. Rain may be heavy next week.

- Very warm LOW temps in the 70s most areas both Sun night and
  Mon night COULD at least approach record-warm values for June
  17-18. Sun and Mon also look to be the warmest highs of the
  next week with widespread 90s and even some low 100s.

&&

.UPDATE...
Issued at 653 PM CDT Fri Jun 14 2024

Thunderstorm chances increase heading into this evening and
tonight. A Severe Thunderstorm Watch has been issued for
counties along and west of Highway 281 through 2AM Saturday. For
additional details, please see the watch product.

&&

.DISCUSSION...
Issued at 445 PM CDT Fri Jun 14 2024

Temperatures have warmed well into the 80s across most of the
area this afternoon, with even some low 90s noted over portions
of north central KS. Easterly surface flow kept humidity levels
seasonably low for most this AM, but a shift to SErly winds this
afternoon has allowed for some moisture return - dew points into
the mid to upper 60s, especially over the S/SW third of the
forecast area. Outside of a stray, generally weak, shower or
storm, think most areas will remain dry through around sunset.
Latest forecast expectations are largely unchanged from the
previous forecast in that thunderstorms that are currently
developing along the Front Range of the Rockies will organize
into an MCS over the High Plains this evening, then roll E/NE
into our W/SW zones around 9-10PM. Strong to severe storms will
be possible with this activity, particularly W of Hwy 281 where
instability will be strongest, with damaging wind gusts 60-65
MPH the main threat given expected linear storm mode. Perhaps
some marginally severe hail, too, in the strongest cores.
Instability has trended higher in the models for more of our
area overnight, so storms may not dissipate quite as quickly,
though I do think the severe risk will still dissipate with time
and eastward extent given lack of strong LLJ convergence and
modest deep layer shear only 25-30kt. This should be good news
for most as latest HREF produces a fairly broad swath of
0.25-0.75" of rain - which will be much appreciated given the
upcoming hot/windy conditions Sun-Mon. Of course, some locally
heavier amounts are likely, but don`t think flooding will be an
issue given the progressive nature of the broader complex.
Finally, want to mention that 0-3km shear values 30-35kt,
oriented favorably (perpendicular) to the expected line, along
with sufficient 0-3km CAPE, could present a non-zero risk for a
couple/few QLCS tornadoes overnight, as well.

Saturday:
Most, if not all, of the rain should be out of the area by
around sunrise, with mainly dry conditions expected rest of the
morning and most of the afternoon. Anytime after 4-5pm, isolated
to widely scattered thunderstorms may develop over mainly E 1/3
of the CWA within the departing mid level trough axis and along
a sfc moisture gradient. Upper height changes will be neutral or
slightly rising and sfc convergence is weak, so coverage should
be pretty limited. Models that do generate convection have
generally trended most E/NE, now mostly along and E of Hwy 81.
This is depicted well in the SPC Day 2 outlook, though the
western extent of the Marginal may be generous. Otherwise,
expect a typical warm and somewhat muggy mid-June day with highs
in the mid 80s to low 90s. If any storms develop they will
shift E by late evening, leaving dry wx for rest of the night.

Sunday - Monday:
Main story for these days will be increasing heat - with
afternoon high temps in the 90s to even low 100s each day. There
will be some humidity present, so heat indices may approach 105F
in spots, particularly near and S of the state line. However,
moisture doesn`t look to be too oppressive and there will be at
least breezy conditions each day. In fact, Monday could be
outright windy and feel like a furnace with winds gusting 30-40
MPH. Worth noting, though, that the experimental Heat Risk index
will be in the RED (level 3 on scale of 0 to 4) for areas around
the Tri-Cities S and E both days - likely owing to the warm
overnight lows and it being pre-July/August. In fact, overnight
lows in the 70s most areas both Sun night and Mon night COULD at
least approach record-warm values for June 17-18. Convective
potential is highly uncertain, though probably not zero. Mid to
upper height rises and H7 temps 12-15C will be fairly hostile to
convective development in a broad sense...but locally intense
heating/low level mixing/lapse rates and convergence along a
gradually southward sinking boundary could both be potential
triggers for iso storms during the late aftn/eve. This type of
setup makes storm development at all HIGHLY conditional, but IF
something develops, then strong instability and modest shear
could support hail and gusty winds. Some model guidance suggests
scattered storms developing SW of the area where those two
triggers overlap the most, then some sort of MCS moving NE along
the boundary Sun eve/night - but confidence in this specific
scenario is low.

Rest of the forecast:
Generally speaking, the upper level pattern looks to become one
that favors frequent chances for showers/storms - featuring
broad/persistent troughing over the Rockies and strong upper
ridging over the NE CONUS. This would keep our area in SW upper
flow amidst increasingly cool mid level temps and less capping.
Also, there is multi-ensemble agreement that a persistent fetch
of moisture-rich Gulf of Mexico air will arc it`s way into the
Plains and upper Midwest in a "ring of fire" type fashion, with
multiple days of PWAT values 125-150% of normal. Combine this
with weaker capping, "dirty"/active SW upper flow, and perhaps a
quasi-stationary surface front and there could be a setup for
heavy rain. Obviously, specifics on day-to-day details is still
very low, but would say that I`m becoming increasingly
confidence in this type of general pattern setting up for mid to
late next week given the model-to-model and run-to-run
consistency. Unsure of severe weather potential, but
probabilities already north of 50% for at least 2" of rain on a
global ensemble argues that heavy rain will be a threat worth
monitoring over the coming days, though an even stronger signal
lies over the Upper MS Valley region. Temperatures, in general,
should cool off some from the HOT Sun/Mon, but specifics will
likely be highly tied to clouds/rain and any stalled front(s).

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 140 AM CDT Sat Jun 15 2024

For KGRI/KEAR Airports:
- General overview:
Very high confidence that the vast majority of the period
features VFR ceiling/visibility and rain/thunderstorm-free
weather, with the overall-main feature of the period being
moderately-breezy south winds especially during the day
Saturday. That being said, these first 2-3 hours right away this
morning will feature lingering light rain and possibly a few
weak thunderstorms, and there is a roughly 4-hour window of
opportunity for possible MVFR/IFR ceiling in the wake of the
departing rain.

- Ceiling/visibility/rain and thunderstorm details:
Right out of the gate early this morning, both KGRI/KEAR are
down to no more than 2-3 more hours of steady light rain
(visibility mainly VFR) and perhaps a rogue/weak thunderstorm,
but any threat of 40+KT gusts or possible hail has clearly
passed for the night. In the wake of departing rain, have
assigned a TEMPO BKN015 group to the 10-14Z time frame to handle
possible low ceiling development, as still hinted at by various
models/guidance. IF this low ceiling does form, MVFR is most
probable, but brief IFR probably cannot be ruled out. Once any
possible low ceiling scatters out, the remainder of the period
is high-confidence VFR, although at least a lower-VFR scattered
cumulus field is possible during the day. There is also the
slightest possibility for a late afternoon thunderstorm, but
with most models suggesting this activity would focus at least
50-75 miles to the east-southeast, have left out of TAFs.

- Winds:
Once short-term convective influences ease up over these next
few hours, the general expectation is for early morning breezes
to become established out of the southeast at generally 10-15KT.
Then, during the daylight hours and particularly between 17-23Z,
moderately breezy south winds will kick in...mainly sustained
15-20KT/gusts 25-30KT. Following a brief lull in speeds late
afternoon/early evening, another modest increase is likely very
late in the period (mainly after 03Z), with gust potential back
up around 20KT.

&&

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

&&

$$

UPDATE...Wekesser
DISCUSSION...Thies
AVIATION...Pfannkuch