Hail and Damaging Winds in Nebraska, June 3, 2020

AREA FORECAST DISCUSSION
National Weather Service Hastings NE
630 PM CDT Wed Jun 3 2020

.SHORT TERM...(This evening through Friday night)
Issued at 443 PM CDT Wed Jun 3 2020

Focusing on the first 5 night/day periods in this section, BY FAR
the main concern is the tricky thunderstorm/severe weather
chances mainly for tonight, but potentially also for various
points during the Thurs-Fri time frame (although confidence in the
actual likelihood of storm development for most of the area is
very much in question beyond tonight). In other departments,
confidence is high that our continued, seasonably-hot weather
pattern continues right on through the next few days, as we
continue one of the warmest starts to June in recent memory.

Briefly covering the here-and-now as of 4 PM:
Other than a few rogue showers/weak thunderstorms that briefly
flared up late this morning in our extreme southeast CWA (Mitchell
County KS area), it's been very much as expected today with mostly
sunny skies, SLIGHTLY-cooler high temperatures than the past few
days (highs mainly 88-93) and fairly light easterly to southerly
breezes mainly around 10 MPH or less. In the mid-upper levels,
water vapor satellite and short term model data depicts broad
west-northwest flow over the Central Plains, with the main low-
amplitude shortwave trough of interest dropping east-southeast
across the SD/NE border area.

Now looking ahead forecast-wise through the next 5 periods...

This evening/tonight:
The main focus by far is the Slight Risk of severe storms for the
entire coverage area (CWA). Confidence is fairly high that most of
our CWA will remain dry/storm-free through around 7 PM, although
isolated-to-scattered activity already underway to our west-
northwest will be on a gradual approach through that time. Based
on consensus of various short term models (including HRRRV4), our
main 6-hour block of concern for severe storms pretty clearly
looks to be 7pm-1am, during which time at least isolated-scattered
storms will drift in from the west and northwest, in an
environment characterized by up to around 2000 J/kg mixed-layer
CAPE and modestly-decent deep-layer shear of 30-40 knots. This
will easily support organized multicell structures with brief
supercell characteristics possible. The big question is whether
activity remains more isolated-scattered or perhaps becomes more
widespread in the form of a larger scale complex/MCS. At the very
least, hail of quarter to golf ball size and wind gusts of 60+ MPH
are on the table, but any organized complex with a good cold pool
could easily bring 70+ MPH winds into the picture. The bottom
line: confidence is high that at least parts of the CWA will see
an active evening, but just how much of it is in question? After 1
AM and through the late-night, some strong to marginally-severe
activity could linger, but the "main show" should be over by then.
In other departments, low temps tonight are aimed low-mid 60s most
areas. Not too concerned about patchy fog formation in the wake of
storms, but suppose some limited coverage not completely out of
the question.

Thursday daytime-night:
Confidence is high that the majority of the CWA stays dry, and
this is strongly supported by NAM/HRRR solutions. Despite lack of
forcing aloft and capping trying to reign, models such as the
ECMWF are more aggressive in trying to pop late afternoon (and
potentially severe) storms mainly in our far east-northeast zones.
If anything goes, severe is possible, but agree that the overall
CHANCES of storms developing/lack of coverage support SPC
downgrading the entire CWA to only a Marginal Risk on the latest
Day 2 outlook. For the evening/overnight hours, will carry low-
confidence/slight chance PoPs across the area, as there could be a
bit better chance of hit-and-miss activity versus the late
afternoon hours. Temp-wise, based on our recent trends of slightly
under-forecasting highs, have nudged up highs Thursday a few
degrees, with mainly low-mid 90s. Winds will average 5-15 MPH from
a generally southerly to southwesterly direction.

Friday-Friday night:
As if there isn't enough uncertainty in the Day 2 storm chances,
this sentiment only grows for this Day 3 time frame. As upper
ridging starts to build aloft, odds are fairly high that most of
the CWA remains dry/storm-free. However, with continued
significant instability around, will need to watch for "mesoscale
accidents" that could potentially pop isolated severe weather.
That being said, am not overly-confident in SPCs Day 3 Marginal
Risk in our east (would expect some typical modifications as it
gets closer). Otherwise, the early-summer heat continues, with
highs perhaps just barely cooler than Thursday but still mainly
low-mid 90s for highs. Daytime breezes look to average 10-15 MPH
from the east- northeast.

.LONG TERM...(Saturday through Wednesday)
Issued at 443 PM CDT Wed Jun 3 2020

General overview of this 5-day period:
The two main stories during this time frame remain/are:

1) Temperature-wise, a pronounced cool-down from continued well-
above-average heat Saturday-Monday (highs mainly upper 80s to mid
90s), to cooler and potentially even slightly BELOW normal
readings Tues-Wed in the wake of a seasonably-strong cold front
(highs only 70s to low 80s).

2) As for rain/thunderstorm chances, the truth is that although
many of these day/night periods carry at least slight chances/PoPs
somewhere within the CWA, many of these chances most definitely
carry a medium-high degree of uncertainty, and it's just not worth
putting too much stock in them yet. See "daily details" below for
a bit more insight, but from a large-scale forcing standpoint, the
chances during the Mon night-Tues time frame look to carry the
overall-highest confidence of coming to fruition (on at least a
somewhat widespread basis). On the flip side, barring a pretty
big shift in the latest ECMWF/GFS model trends, our going
rain/thunderstorm chances for Tuesday night into Wednesday are
looking rather questionable and may ultimately need removed.

With the big points covered, will finish with some brief/day-to-
day-basics:

Saturday-Saturday night:
This is currently a dry forecast for the majority of the CWA,
which favors the latest ECMWF solution much more so than the
considerably-wetter/stormier GFS. With ridging aloft the main
influence, the main question is whether any weak forcing can
overcome warm temps aloft/capping to spark any activity. If so,
severe storms certainly appear possible. In higher-confidence
departments, this is expected to be another very warm day with
highs aimed mainly low-mid 90s, and also looks rather breezy out
of the south-southeast.

Sunday-Sun night:
This 24-hour block officially carries a dry forecast CWA-wide as
upper ridging/warm air aloft/capping looks to prevail. Another hot
and quite-breezy (windy?) day out of the south with highs aimed
mainly mid 90s.

Monday-Mon night:
This time frame marks the beginning of a pattern/temperature
change as both ECMWF/GFS are in good agreement on a large-scale
trough and associated surface cold frontal passage. The day looks
mostly dry, with better storm chances kicking in Mon night. Temp-
wise, another hot one, currently aimed low-mid 90s.

Tuesday-Wednesday:
High confidence in cooler temperatures behind the aforementioned
cold front, with highs very preliminarily aimed mid 70s north to
low 80s south, which will probably feel fairly refreshing after
the ongoing/upcoming heat between now and then. As earlier
mentioned, our currently-advertised rain chances for Tues night-
Wed are looking pretty questionable, at least by Day 7 standards.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 621 PM CDT Wed Jun 3 2020

The main aviation forecast concern will be thunderstorms in the
next 6 hours. A line of thunderstorms will move in from the west
this evening. The HRRR has a decent handle on timing and followed
that fairly close, expect it to be a 02-04z timeframe at both
terminals, with lingering precip possible after. Expect most
activity out by 06z, but have held on to VCTS until 07z as a
buffer. Winds will be variable as the storms move through and are
expected to remain variable through the overnight hours. Winds
will be southerly again tomorrow with few clouds and VFR
conditions.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

SHORT TERM...Pfannkuch
LONG TERM...Pfannkuch
AVIATION...Billings Wright

Hazardous Weather Outlook...CORRECTED
National Weather Service Hastings NE
336 PM CDT Wed Jun 3 2020

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-
041200-
Phillips-Smith-Jewell-Rooks-Osborne-Mitchell-Valley-Greeley-Nance-
Sherman-Howard-Merrick-Polk-Dawson-Buffalo-Hall-Hamilton-York-
Gosper-Phelps-Kearney-Adams-Clay-Fillmore-Furnas-Harlan-Franklin-
Webster-Nuckolls-Thayer-
336 PM CDT Wed Jun 3 2020

This Hazardous Weather Outlook is for south central Nebraska and
portions of north central Kansas.

.DAY ONE...This Evening and Tonight.

The entire outlook area is under a Slight Risk of severe
thunderstorms. Storms are expected to move in from the west and
northwest this evening, and eventually depart east-southeast local
counties late tonight. At least a few severe thunderstorms are
likely, especially between 7 PM and 1 AM, with the main hazards
expected to be hail up to around golf ball size, wind gusts of at
least 60 MPH and brief heavy rainfall, perhaps in excess of 1
inch. There is some uncertainty regarding whether storms will
remain more isolated to scattered in nature, or perhaps form into
a larger, more organized complex. If a larger storm complex forms,
the threat for damaging winds would likely increase, with gusts
to around 70 MPH possible.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

There are a number of thunderstorm chances throughout much of
this time frame, with at least small chances somewhere within the
outlook area nearly every day and night, with the exception of
Sunday and Sunday night, which currently has a dry forecast.
Although strong to severe thunderstorms appear possible at times,
there is a significant amount of uncertainty regarding the timing
and location of any severe activity, so please be sure to keep up
with the latest forecasts.

As it currently stands, the entire outlook area is under a
Marginal Risk of severe storms late Thursday afternoon into
Thursday night. Although the coverage of storms could be very
sparse Thursday, if any do form, they could become severe and
capable of producing large hail and damaging winds.

Looking ahead into next week, some of the higher chances for
thunderstorms currently appear to focus around the Monday night
into Tuesday time frame as a cold front arrives.

.SPOTTER INFORMATION STATEMENT...

Storm spotters may be needed this evening and tonight, especially
during the 7 PM to 1 AM time frame.

&&

More information may be obtained at the following web page:
   https://www.weather.gov/hastings

Pfannkuch