846
FXUS63 KGID 281149
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
649 AM CDT Fri Jun 28 2024

.KEY MESSAGES...

- Warmer today with isolated to scattered storms possible
  (20-50% chance, highest W of the Tri-Cities) once again this
  evening into the overnight. There is a Slight risk (level 2 of
  5) that some of these storms could be severe.

- Very pleasant temperatures behind a cold front for the weekend
  along with low-end (20-30%), mainly overnight, thunderstorm
  chances.

- Warmer with continued storm chances next week, with highs in
  the 80s and 90s and mainly small chances for thunderstorms
  (20-40%) each day. Heat Index values could climb to 100-105F
  in spots both Monday and Tuesday afternoons.

- Early look at Independence Day is for rather seasonable
  conditions - warm temperatures in the 80s-90s and 30-40%
  chances for showers/storms.

&&

.DISCUSSION...
Issued at 505 AM CDT Fri Jun 28 2024

After a few storms in the Hebron area early this morning, skies
have turned clear to partly cloudy. Scattered elevated
convection has shifted E/SE of the forecast area in response to
a veering 45-50kt low level jet. Can`t completely rule out a few
more elevated storms from Beloit to Hebron next few hrs, but
this is only a 20% chance. A cold front will shift WNE to ESE
across the area this morning and this could also be a source for
some elevated, weak convection - as is currently noted over
extreme NE Colorado. Forecast soundings suggest this activity is
rooted around 10-12K ft with some dry air beneath it. So any
rain amounts during the day today would likely remain very
light. Winds will shift from S to NW with passage of the front,
but despite this, full aftn sunshine should still allow for warm
highs in the upper 80s to mid 90s for most spots. In fact, far S
zones (Rooks to Mitchell Cos) could make a run into the upper
90s and heat indices 100-105F. Opted against heat headlines
given largely marginal criteria and short-lived nature (today
only). Worth noting that far S/SE areas could see elevated Wet
Bulb Globe readings, though, given closer proximity to sfc front
and likely lighter winds, along with pooling moisture.

Expect two main areas for convective development late this aftn
and eve, both of which will likely - at least initially - be
outside of the local forecast area. One area will be along the
sfc cold front, which by the time the cap is eroded (21-23Z),
should be roughly along a line from OMA to SLN and only moving
further E/SE away from the area. Another area will be over the
High Plains (WY/CO/NE border area) within steep low level lapse
rate environment and sufficiently moist/unstable post-frontal
airmass, perhaps aided by slight upslope component. Capping will
likely be an issue with time and eastward extent, but appears
favorable post-frontal deep layer shear 35-45kt, consisting of
long, straight hodographs, and moderate 1000-1500 J/kg of MUCAPE
will be sufficient for at least some convective organization
(splitting supercells and/or multicell clusters) and opportunity
for activity to make it into W 1/3rd of CWA in the 00-03Z time
frame. Large hail and damaging wind gusts look to be the primary
threats. Activity will likely weaken after 03Z given lack of
LLJ and incr inhibition/nocturnal cooling, but the rate of
weakening will likely depend on storm scale processes. Given the
recent model trends, wouldn`t be surprised to see the Slight
risk (level 2 of 5) area trimmed a bit, esp. in our NE.

Cooler, quite pleasant, conditions filter in behind another cold
front tonight, setting the stage for an excellent late June
weekend with highs in the 70s-80s. Refreshing Nrly breezes on
Sat will help usher in seasonably low humidity which looks to
stick around even on Sun, despite a turn in winds to the SE.
Thunderstorm chances this weekend aren`t zero, but they`re not
all that high, either, at only 20-40% Saturday night into
Sunday. Slightly higher chances (30-50%) arrive Sun night.

Continued return flow will lead to another round of hot, humid
conditions for the start of the new work week as highs soar into
the 90s to low 100s on Monday, and upper 80s to upper 90s on
Tuesday. Off and on convection could throw a wrench into these
numbers, but assuming some breaks late AM into the aftn, pooling
low level moisture near a slow moving front could lead to
elevated heat indices in the 100-105F for at least southern
parts of the area each aftn. Elevated, warm air advection driven
thunderstorms could present our next severe risk as early as
early Mon AM (mainly large hail), but overall-highest chcs
should come with arrival of aforementioned slow-moving front
Mon aftn-eve. Portions of south central NE remains within 15%
risk area on latest Day 4 SPC convective outlook. Of course,
some refinements are likely as we get closer. Some models hint
at the front hanging up W to E somewhere over the central Plains
Tue into Wed - which if that pans out, could support a
localized hydro threat given pooling moisture and PWATs around
+2 standard deviations. Far too early to opine on specific areas
at more risk than others. Rest of the forecast appears fairly
seasonable in terms of highs in the 80s-90s and more off and on
chances for storms - including on Independence Day. Will have to
keep an eye on the specific timing of a potential upper
disturbance and associated cold front hinted at in some of the
model data - both deterministic and ensemble - as it pertains to
holiday celebrations.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 645 AM CDT Fri Jun 28 2024

For KGRI/KEAR Airports:

VFR through the period:

Today: Sfc winds will veer through the day along and behind a
weak cold front, from SSW this morning to NW this aftn, to NE
this evening. Speeds will be mainly 8-12kt. Can`t rule out a few
sprinkles this morning, but should be mainly mid to high level
cloud cover. Confidence: High.

Tonight: Main issue will be potential for iso-scat tstms to move
in from the W around 01Z-04Z. Will probably need a VCTS with the
next TAF cycle, but held off on this one given a possible track
mostly S of the terminals. Winds may go lgt and variable late in
the period. Confidence: Low to medium.

&&

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

&&

$$

DISCUSSION...Thies
AVIATION...Thies