605
FXUS63 KGID 041004
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
504 AM CDT Mon Aug 4 2025

.KEY MESSAGES...

- Gradually strengthening upper ridge over the Desert SW will
  lead to increasingly hot and humid conditions and lower rain
  chances as the week progresses.

- During the transition over the next few days, a "ring of fire"
  or "ridge runner" pattern will continue to bring nightly
  chances for thunderstorms to portions of the area.

- The highest heat indices this week will come on Thursday and
  Friday, with peak values around 98-105 degrees.

- Our next cold front and higher confidence chance for rain is
  on track to arrive Saturday evening/night.

&&

.DISCUSSION...
Issued at 445 AM CDT Mon Aug 4 2025

Starting to feel like a broken record as yet again we`re dealing
with the after effects of high plains afternoon/evening
convection. This time around we have two new MCVs, one centered
on the Siouxland region, and another near HJH/BIE/CNK area. Both
are moving SE and should have decreasing impacts on our local
weather. Nonetheless, could still see some iso convection bubble
up along the Hwy 81 corridor for another few hrs thanks to
veering low to mid level flow (evident on UEX VAD) that`s
contributing to just enough isentropic ascent to tap into the
~1000 J/kg of MUCAPE. Not expecting severe weather this morning,
but small hail, gusty winds, and heavy downpours could accompany
the strongest activity.

Didn`t make this one of the "key messages" above as I think the
coverage will be limited...but could see some patchy areas of
dense-ish fog through ~8AM. Light ESE/SE flow (subtle upslope
component), in conjunction with clearing on the backside of
departing MCV, has resulted in little to no T/Td spreads as of
09Z. GOES nighttime RGB and area sfc obs confirm a fair amount
of stratus already, especially for W thru NW portions of the
area, and suspect the favorable conditions could allow for
SEward expansion through around dawn. Will keep an eye on
trends, but think any dense fog will be fairly patchy and that
most areas will just experience very low cloud bases. This
notion seems to be supported by recent HRRR runs. Any
fog/stratus should clear out by late AM and allow for plenty of
time to warm into the low to upper 80s (from E to W).

The biggest question for this forecast revolves around the
potential for continued nightly rounds of convection that
develops over the high plains, then tracks E or SE around the
core of the high pressure. These types of patterns are common
with strong upper ridges - where weak mid level shortwaves ride
the proverbial edge of the ridge and periodically strike a
balance where boundary layer instability is strong enough to
break the cap on the edge of the warmest mid level temps.
Typically, initial development happens over the higher terrain
W/NW of here (where steeper lapse rates upslope low level flow
can break the cap the easiest/quickest) then propagate E or ESE
with the mean mid/upper level wind and onto the central Plains.
So location of initial development, rate at which storms
organize into a cluster (MCS), and orientation of ridge and
associated mean wind field all play a role in where these
systems track. An additional "curve ball" can be if/when/where
the MCS will take on more of a Corfidi vector and dive S into
the pool of moisture/instability - often coincident with the NE
"corner" of the ridge and on the nose of the mid level thermal
ridge. Long story short...this could happen each night tonight
through Wednesday night, or not at all...or somewhere in
between. These mid level waves are notoriously difficult to
predict/time, and if storms are too slow to organize during the
evening, they`ll just fall apart with loss of daytime heating
and succumb to the warm mid level temps/cap.

Conceptually speaking...think overall-best chances for a ridge-
running MCS affecting our area would be on the front end of
strengthening ridge process - i.e. tonight - or with any
POTENTIALLY stronger shortwaves, which as already noted above is
quite difficult. SPC has our western areas in a Slight Risk for
tonight, and a good chunk of our area in a Marginal Risk for
Wed. Tonight`s risk is highly conditional but seemingly
warranted based on some hi-res guidance. Hail and wind would be
the primary threats. I would perceive the Wed outlook to be of
very low confidence at this time.

MCS chances appear to wane late in the week as the ridge reaches
peak strength. Thu and Fri continue to look like the hottest
days of this next stretch of hot and humid weather with peak
heat indices topping out around 98-105F each day. We`re pretty
accustomed to the heat by Aug, so not sure if this will warrant
an advisory.

Latest extended ensembles/blends continue to show our next cold
front and more "synoptically-evident" rain chance coming Sat eve
or overnight. This front should knock us back down to more
seasonable levels in the 80s for Sun and Mon.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1245 AM CDT Mon Aug 4 2025

For KGRI/KEAR Airports:

Line of showers/weak storms is exiting to the SE and expect dry
conditions for the remainder of the night and through the
daytime hours Monday. Short term models still hint at potential
for some stratus to develop near dawn, though it`s certainly not
a slam dunk. If it does indeed develop, will probably be IFR
CIGs. Have included a tempo IFR group for EAR, but held off on
GRI as signal is greater just to the W/NW. Any stratus should
lift and transition to stratocu ~mid AM, then cu late AM into
early aftn. Slight chance that weakening convection could once
again approach the area late Mon eve/Mon night, mainly EAR,
though too uncertain to include attm. Winds will be SE-S around
5-10kt, with "gusts" near 15kt. Confidence: Medium.

&&

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

&&

$$

DISCUSSION...Thies
AVIATION...Thies