543
FXUS63 KGID 212146
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
446 PM CDT Tue May 21 2024

.KEY MESSAGES...

- Can`t rule out additional showers and a few non-severe
  thunderstorms across mainly the southwestern half of the area
  late this evening/tonight...but chances for most areas are
  low (20-30 percent).

- Wednesday looking to be a pleasant day, with winds of 10-15
  MPH, mostly sunny to partly cloudy skies, and highs in the
  mid 70s. Much of the overnight hours look to be dry, but a few
  showers/non-severe storms may clip far western areas.
  Confidence in these chances is not high (20 percent).

- Our next shot at potentially more widespread (and
  unfortunately potentially severe) thunderstorms returns
  Thursday evening- overnight, and our entire coverage area
  (CWA) is currently under an SPC Marginal Risk (level 1 of 5).

- Compared to the previous forecast, there are a few more dry
  periods beyond Thursday night (including Friday daytime-
  night), and although there are still intermittent thunderstorm
  chances over the weekend, at least for now any severe threat
  appears to remain relatively low.

- Peeking ahead to Memorial Day (Monday), current indications
  point toward a somewhat cooler (highs only upper 60s-low 70s
  most places) and mainly dry holiday. That being said, we are
  carrying small chances for rain showers...but NOT
  thunderstorms...as the airmass looks to be seasonably-dry and
  stable.

&&

.DISCUSSION...
Issued at 445 PM CDT Tue May 21 2024

-- CURRENTLY...

After a hectic overnight period, a brief early morning  lull,
then yet another round of thunderstorms mid morning to
midday...things have been relatively quiet this afternoon.
Aloft, upper air and satellite data show the region under north-
northwesterly flow, set up on the backside of a low pressure
system/trough axis moving from NE/SD into IA/MN. Satellite
imagery also showing another shortwave disturbance sliding east
along the WY/CO border this afternoon. Activity last night had
pushed the brunt of instability east- southeast of the forecast
area, but as the last round that developed over central portions
of the area pushed further east, enough lingered (and deeper
layer shear was sufficient) that a few storms became strong to
severe...but fortunately didn`t take too long to push off to our
east. At the surface, we sit on the backside of the main
surface low over IA and southward extending cold front into OK.
Gusty northwest winds continue area-wide this afternoon, with
gusts at times near 40 MPH. While temps for most locations
looking to fall just a little short of expectations, the fact we
are getting a little bit more sun will help readings
recover...at 3PM most of the area are in the low-mid 60s, with
upper 60s further south. Expecting the rest of this afternoon to
remain dry.

-- THIS EVENING ON THROUGH WED NIGHT...

Overall no notable changes were made to the forecast through
tonight. Expecting dry conditions to continue on into this evening,
but do have some small chance precipitation chances (mostly 20-30
percent) returning later this evening/overnight. That above
mentioned upper level shortwave disturbance currently over WY/CO is
expected to continue pushing east with time, with models in
generally good agreement showing roughly the southwest half of the
forecast area having those better chances of precipitation. Can`t
rule out a few thunderstorms, but models showing little instability
overall. Winds are expected to taper off with time tonight and
turning more westerly, as the pressure gradient weakens with higher
pressure building in. Cloud cover also gradually diminishes...and
overnight lows tonight are forecast to drop into the mid 40s to low
50s.

Wednesday looking to not be too bad of a day across the area, with
the forecast currently dry until late Wednesday night when another
weak disturbance may bring another round of precipitation to mainly
western locations. If anything models have trended back with that
potential, so forecast chances are low (20 percent). Expecting
partly cloudy to mostly clear skies...and winds remain on the
lighter side (10-15 MPH) as the surface pattern across the area
remains on the weaker side...westerly for much of the day but
turning more southerly by evening. No notable changes were made to
forecast highs, which are in the mid 70s.


-- THURSDAY DAYTIME-NIGHT:
Although the primary daytime hours (before 7 PM) are not
guaranteed dry, it should be a mostly dry day, with only some
spotty (probably non-severe) thunderstorm potential during the
afternoon. The main daytime story will be stronger south winds
(sustained 15-20 MPH/gusts around 30 MPH) drawing in increasing
low-level moisture (dewpoints back well into the 50s to around
60). High temps will also climb roughly 5-7 degrees warmer than
Wed, with most areas aimed a few degrees either side of 80.

Things look to turn more active during the evening-overnight
(particularly post-sunset), as a vigorous shortwave trough
drives out of the Northern Rockies into the Dakotas/northern
Nebraska, in turn driving a fairly strong cold front
southeastward across our CWA. Although still a few days away, we
are already under a Marginal Risk of severe from SPC...which
looks reasonable given current NAM/GFS expectations of 1000-2000
J/KG CAPE and 40KT of deep layer-shear. Given the fairly strong
frontal/low level forcing, and as supported by the far end hours
of latest 18Z NAMNest, we are probably looking more at a complex
or line of storms tracking through, as opposed to more discrete
supercells, but again, we have a few more days to pin down
details.


-- FRIDAY DAYTIME-NIGHT:
This entire 24-hour period is now a dry forecast, as we
experience weak shortwave ridging in between upper waves. It
does however looks like a cooler and breezy day (out of the
northwest), with highs only mid 60s to low 70s.


-- SATURDAY-SUNDAY NIGHT (the weekend):
Intermittent thunderstorm chances return to our forecast, as at
least a few separate upper disturbances look to track through
our region in renewed active flow aloft. While at least a low-
end severe storm threat cannot be ruled out at this time range,
current model instability progs and CSU Machine Learning severe
forecasts suggest only a lower end severe threat at worst (at
least for now). High temps mainly 70s.


- MONDAY-TUESDAY (including Memorial Day):
Overall, this looks like a mainly dry period (especially Tuesday
as upper ridging takes hold), but our forecast for the Memorial
day holiday does currently contain some low-end rain shower
chances. At this time, instability appears very meager, and thus
have pulled any thunderstorm mention at this time. Plenty of
time for adjustments, but for now this Memorial Day looks to be
on the cooler side of "normal" (highs a few degrees either side
of 70), with breeze north-northwest winds. Temps then trend up a
bit for Tuesday (mainly mid 70s).

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1133 AM CDT Tue May 21 2024

The EAR AWOS is OTS as of this TAF writing, so will carry AMD
NOT SKED for the EAR TAF. Over the next few hours expect
-SHRA, I am thinking the -TSRA chances are diminishing, so will
drop VCTS mention at this time. The winds will be gusty this
afternoon with gusts into the upper 20s to the low 30s. The
winds will taper off this evening and become more westerly.
Clouds are expected to move off by mid-morning tomorrow.

&&

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

&&

$$

DISCUSSION...ADP/Pfannkuch
AVIATION...Beda