554
FXUS63 KGID 061118
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
618 AM CDT Mon May 6 2024

.KEY MESSAGES...

- Enhanced risk for severe thunderstorms Monday
  afternoon/evening. Very large hail, strong winds, and
  tornadoes will all be possible.

- There will be additional periodic small chances (20-30%) of
  showers and non-severe thunderstorms Tuesday evening through
  Thursday night.

- Temperatures will be near normal through the 7-day forecast
  period with highs in the 60s and 70s.

&&

.DISCUSSION...
Issued at 330 AM CDT Mon May 6 2024

To start out, severe thunderstorms are expected across the
central and southern Plains this afternoon and evening, with
very large hail, strong winds, and tornadoes possible. Even as
far north as our forecast area, it needs to be stressed to have
multiple ways to receive weather alerts and to have a plan of
action if severe weather does impact your area.

Monday/Today...

The SPC Enhanced Risk of severe weather remains in place for the
forecast area today mainly along and south of I-80, including
the entire tri- cities area, and a Slight Risk elsewhere in the
forecast area. A large negatively tilted upper trough will move
across the Plains today with a closed 500 mb low over eastern
WY/western South Dakota. A cold front will extend south across
Nebraska and Kansas with dewpoints in the 60s ahead of the front
and in the 30s behind the front.

Forecast models are in good agreement of thunderstorms
developing along the dryline/front between noon and 2 PM west of
Kearney either late this morning or early this afternoon...the
latest CAMs are suggesting thunderstorm initiation potentially
as early as 11AM. These storms will track east through the
forecast area through the afternoon and into the evening.
Thunderstorms may initially develop as supercells but should
quickly evolve into a more linear QLCS-type system.
Thunderstorms are expected to move eastward quickly enough that
widespread flooding is not much of a concern (localized flooding
or ponding may be possible, however). That being said, tornadoes
and very large hail will be possible with any supercell that
develops. As the system becomes more linear, the very large hail
threat should diminish somewhat, but the tornado threat will
persist (although the main threat will still be the winds in a
linear system)...especially if any supercells are embedded
within the line...and strong winds, potentially gusting to 75+
mph, will be possible with the line of storms. The most likely
time frame for the storms to reach Highway 281 will be 3-5 PM,
and then moving east out of the forecast area around 6-8 PM.

The main two points of uncertainty regarding this system will be
how much the cloud cover and light rain this morning impacts
storm development later this morning and early this afternoon.
Models have consistently had this in the forecast for the past
few runs, so believe that storms will initiate as forecast, but
it is one point of uncertainty. The other point would be how
quickly thunderstorms transition from discrete supercells to a
linear system...thinking it will be rather quickly across NE at
least due to the deep layer shear being oriented closer to
parallel to the boundary...whereas farther south in KS/OK
discrete storms may last longer and instability will be greater,
hence the greater tornado and large hail threat in those areas.

Tuesday through Thursday...

The upper trough will meander across the central Plains through
Thursday, but cut off from the better low level moisture after
Monday as the surface low continues east across the CONUS.
Still, a couple of weaker disturbances will allow us to see a
few rain showers and/or isolated thunderstorms periodically
between Tuesday evening and Thursday night...with the best
chance currently looking to be Tuesday evening/night (~25-35%).
Precipitation amounts will be light. High temperatures will be
in the 60s and 70s.

Friday through Sunday...

Conditions are currently expected to be mostly dry, with the
possible exception of a few showers/thunderstorms late in the
day Sunday. That being said, there is a lot of model
disagreement this far out, especially over the weekend. The GFS
has a broad upper ridge over the western CONUS whereas the ECMWF
has a narrower upper ridge over the western CONUS and a trough
over the northern and central Plains, hence the 20% chance of
precipitation Sunday. Highs will be in the 60s and 70s,
potentially to the upper 70s Sunday if a broader ridge sets up
over the region.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 606 AM CDT Mon May 6 2024

Gusty SSE winds are expected this morning up to 35+ kts...with
IFR CIGS and perhaps some light BR this morning. Around
midday...expect a line of thunderstorms to develop west of
KEAR...and propagate eastward during the afternoon through the
early evening hours. In addition to some of these storms being
severe, expect a continuation of IFR CIGS through the day along
with very strong S to SSE winds gusting to near 40 kts ahead of
the front. Introduced a VCTS/+TSRA group as well as a TEMPO
group to capture the worst conditions as the thunderstorms move
through Monday afternoon. Behind this system, winds will turn to
the southwest Monday evening and CIGS are expected to return to
VFR by mid- to late Monday evening. Wind speeds will also
diminish to around 10-12 kts as winds become southwesterly later
Monday evening.

&&

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

&&

$$

DISCUSSION...Hickford
AVIATION...Hickford