829
FXUS63 KGID 151812
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
112 PM CDT Mon Jul 15 2024

...Aviation Update...

.KEY MESSAGES...

- A Heat Advisory remains in effect for all counties along and
  south of Interstate 80 as well as Merrick and Polk counties in
  Nebraska, and for the entirety of north central Kansas,
  through 8PM this evening. Heat index values as high as 110
  degrees are expected.

- Cooler temperatures are expected Tuesday through the weekend,
  with high temperatures in the 80s across Nebraska and the low
  90s across north central Kansas Tuesday and then in the 70s
  and 80s Wednesday through the weekend.

- Several at least small (20%) chances for precipitation are in
  the forecast through next weekend, mainly during the evening
  and overnight hours. The best chances for this will be Tuesday
  evening into Tuesday night (30-50%) and Friday evening into
  Friday night (30-50%).

&&

.DISCUSSION...
Issued at 238 AM CDT Mon Jul 15 2024

Today and tonight...
Aloft, high pressure will persist over the southwestern CONUS
and into the southern and central Plains with a trough extending
from Canada into the northern Plains. At the surface, weak
southerly flow will be present this morning, but a cold front
will move into the region today, causing a shift in winds to
northeasterly this afternoon and an increase in wind speeds to
15 to 20 mph. So this will be the last hot day for a while, at
least a week, and a Heat Advisory is in effect for counties
along and south of Interstate 80. Heat index values up to 105
degrees are expected in the Tri-Cities and up to 110 degrees
across north central Kansas this afternoon. Additionally, there
will be a chance of thunderstorms this evening and overnight.
There is high confidence that thunderstorms will develop over
high terrain in Colorado this afternoon and move eastward, but
how much makes it into our forecast area is still in question.
The HRRR remains the most aggressive in coverage and perhaps in
thunderstorms strength, but models currently appear to be
trending toward north central Kansas as having the greatest
chance. Models are also trending toward whatever storms we do
get occurring during the late evening and overnight timeframe,
likely after 8 or 9 PM. A few of these storms may be strong to
severe with winds and hail being the primary threat as they
enter the forecast area, but these should weaken as they
continue eastward. The entire area is under at least a Marginal
Risk (1 of 5) for severe weather this evening, while areas west
of Lexington are in a Slight (2 of 5) risk this evening.

Tuesday...
The upper trough to the north will dive southeast, pushing the
area of high pressure further west into the desert Southwest.
This will bring cooler and potentially wetter weather to the
area. As the ridge will be to the west of the forecast area, we
will see cooler temperatures. Highs will be in the 80s across
most of south central Nebraska and in the low 90s across north
central Kansas. As far as wetter weather is concerned, there is
not great model consensus regarding how far east into the
forecast area the greater rainfall amounts will be. There is
stronger model consensus supporting areas west of Highway 281
having a better chance at rain (40-55%) with areas east of that
having a 20-30% chance. With this will be the chance for
thunderstorms and the entire area has been outlooked by SPC for
a Marginal Risk (1 of 5) for severe weather.

Wednesday through the weekend...
A persistently northwesterly upper level flow pattern will keep
the area cool and high temperatures will be in the 70s and 80s
through this time. Numerous shortwaves are expected to move
across the area, so there will be multiple periods of at least a
20% chance of rain/thunderstorms. Starting with Wednesday and
Thursday, there will be a 20% chance of precipitation over far
western portions of the forecast area, but the majority of this
(perhaps all of it) is expected to remain over western Nebraska
and Kansas. Friday evening into Saturday will be the next best
chance at precipitation (40-50%) as a more pronounced shortwave
is currently expected to develop, with a 20% chance through the
remainder of the weekend. Of course, at this point we are
looking beyond 5 days out, so this portion of the forecast may
well change by then.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 112 PM CDT Mon Jul 15 2024

For KGRI/KEAR Airports:
- General overview:
Overall-high confidence in VFR ceiling/visibility through at
least the vast majority of the period, with the main caveats
being possible/brief reduced visibility in any passing
showers/thunderstorms overnight, and also the possibility for at
least brief fog around sunrise Tuesday (both of these possible
caveats are low-medium confidence in occurrence). Otherwise
winds should not be a big issue, as outside of any possible
thunderstorm-related outflow, sustained speeds should prevail
under 12KT throughout, with direction out of the north-northeast
the majority of the period.

- Ceiling/visibility/rain-thunderstorm potential details:
Very high confidence in VFR and rain/thunderstorm-free
conditions through at least 05Z, with only varying degrees of
passing mid-high level clouds. However, anytime mainly 05-12Z,
the potential exists for mainly isolated/scattered
showers/thunderstorms. Models are a bit diverse regarding both
storm likelihood/intensity, so for now have simply introduced a
generic "vicinity thunderstorm" (VCTS) for now and will allow
later issuances/possible amendments to fine tune. Cannot rule
out some lingering shower/weak thunderstorm potential beyond
12Z, but not enough confidence to indicate shower/thunderstorm
potential beyond this at this time.

As for ceiling/visibility, aside from possible brief reduced
visibility in any convection, there is probably at least a small
(non-zero) chance for some brief fog/low ceiling development
around sunrise Tuesday...especially if any convection has
departed by then. However, not enough of a signal to introduce
prevailing sub-VFR at this time, so will simply "hint" at the
possibility with a low-end VFR "6SM BR".

- Wind:
Aside from any possible thunderstorm-related outflow overnight,
winds should not be a major issue. Right out of the gate this
afternoon, a weak cold front is in the process of passing
through, switching direction to some variation of northerly for
the rest of the afternoon-evening. Although there could be a
brief period of gusts mainly 15-20KT, sustained speeds should
largely average under 12KT. There is some uncertainty in "exact"
wind direction especially late tonight into Tuesday morning, but
it should be rather light so have mostly run with generic
"VRB06KT".

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory until 8 PM CDT this evening for NEZ048-049-
     060>064-072>077-082>087.
KS...Heat Advisory until 8 PM CDT this evening for KSZ005>007-
     017>019.

&&

$$

DISCUSSION...Hickford
AVIATION...Pfannkuch