Hail in Kansas, August 28, 2020

AREA FORECAST DISCUSSION
National Weather Service Hastings NE
821 PM CDT Fri Aug 28 2020

...Short Term Update...

.UPDATE...
Issued at 821 PM CDT Fri Aug 28 2020

Some comments on thunderstorm/severe storm potential overnight
mainly for our KS zones:

- Main message: Our KS zones still stand a chance for a few severe
  storms this evening-overnight, with large hail up to around ping
  pong ball size (perhaps even slightly larger?) being the main
  threat. We fully agree with SPC maintaining their Marginal Risk
  on the just-updated 01Z Day 1 outlook, although this local
  forecaster probably would have kept it nudged it north a bit
  more into more of Phillips/Smith/Jewell counties.

- More details: While it's a given that the majority of our CWA
  (especially Nebraska zones) is truly "in the clear" from any
  severe storm threat overnight given that the LONG-anticipated
  cold front is working through and scouring out appreciable
  instability from north-to-south, it's a different story in our
  KS zones. Although a very isolated (thus far non-severe) storm
  has actually just popped up along the main cold front within the
  last half hour in northern Osborne County (despite fairly decent
  lingering capping to low-level parcels), believe we are still at
  least 2-4 hours away from a possible "main show" in our southern
  CWA, with better storm chances focused near/after midnight as
  upper forcing increases somewhat in response to the approach of
  a low-amplitude wave approaching from eastern CO. This later
  activity will surely be fairly elevated/high-based with forecast
  soundings indicating convection rooted in the 800-700 millibar
  layer. Even so, RAP13 soundings overnight in our KS zones (and
  perhaps creeping up toward Hebron as well) indicate healthy CAPE
  of 1000-2000 J/kg, with respectable effective deep shear of
  30-40 knots. Thus, at least a few strong to severe storms with
  mainly a large hail threat (due to the elevated nature) appear
  quite possible, and have nudged up hail size potential from
  quarters to ping pongs in our latest Hazardous Weather Outlook
  (HWOGID).

&&

.SHORT TERM...(This evening through Saturday)
Issued at 200 PM CDT Fri Aug 28 2020

High pressure across the region is finally giving way to a cold
front crossing the local area this afternoon. Ahead of this
front...temperatures have spiked across the local area...with
temperatures meeting if not exceeding values of the past couple
of afternoons. This marks the 9th consecutive day of temperature
over 90 degrees across the tri-cities...something we have not seen
since the significant drought year of 2012.

Speaking of drought...this afternoons front does not appear to be
a drought buster...as a strong CAP in place across the area will
likely prevent any further development along the cold front
through the afternoon hours. This evening...as the front pushes
into north central Kansas and weak forcing is realized
aloft...could see some elevated thunderstorm activity across north
central Kansas...where a marginal risk for severe storms
continues and is supported by such model runs as the 18Z RAP. If
little activity is realized along the front during the evening
hours...an MCS moving out of Colorado is expected to ride over the
front late in the night...but this activity should be non-severe
locally and most likely south of the local area in the first place.

While a small chance of storms exists across north central Kansas
to start the day Saturday...this activity will be associated with
the aforementioned MCS and should be ending before mid-day. The
main story for tomorrow will then be the much cooler
temperatures...with highs forecast to top out right around 80.

.LONG TERM...(Saturday night through Friday)
Issued at 200 PM CDT Fri Aug 28 2020

Overall...a significantly different extended period of weather is
expected than we have seen the past week or so. Expect noticably
cooler temperatures and multiple...real/more significant...chances
for showers and thunderstorms across the local area.

Starting Saturday night...expect an area of decaying convection
from the high plains to approach the local area during the
overnight hours. While there is a small chance of thunderstorms in
the forecast...there is not great model consensus supporting it
making it into our area...and would not be surprised if this
period eventually remains dry.

That said...there will be a much greater chance of thunderstorms
Sunday night when a second...stronger cold front...makes its way
across the local area. Given the nearly 2K J/kg of instability to
work with and decent forcing...could see some elevated severe
thunderstorms across the local area...with hail and winds being
the main concern. Not surprisingly...nearly the entire area is
highlighted in a slight risk for severe weather Sunday night...and
we have some fairly highly chances for precipitation in the
forecast. Despite the high looking chances for rain...do not have
a great feel for precipitation amounts given the highly variable
nature of convection and discrepancies in the model data. Some
areas will likely see a good rain event...and others may remain
mostly dry.

Beyond Sunday...a cool start to the work week is expected with
temperatures expected to run 10+ degrees below normal Monday
afternoon. In addition...there will be multiple chances for
showers and thunderstorms...the next best shot of which will be
during the Monday night/early Tuesday timeframe with a fairly
decent upper level wave moving out of the northern Rockies.
Temperatures will moderate some by mid to late week...but with
northwesterly flow aloft continuing...they will still likely
average just on the cool side of normal...in the low to mid 80s.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 712 PM CDT Fri Aug 28 2020

High confidence in VFR ceiling/visibility through the period,
although mid-high level clouds will be plentiful especially
through the first 12-15 hours, and will need to watch for an
outside chance of perhaps scattered lower clouds near the upper
MVFR range (around 3K ft.) passing through overnight.
Precipitation- wise, cannot rule out a few passing sprinkles this
evening, but any chance for actual thunderstorm activity tonight
should focus at least 50-75 miles south of KGRI/KEAR. As for
winds, no big issues foreseen here either as the strongest speeds
of the entire period are occurring right away these first few
hours (northerly gusts 15-20KT). Thereafter, speeds through the
majority of the period will prevail below 10KT, as direction
gradually transitions from northerly, to easterly and eventually
southeasterly as surface high pressure slides across and
eventually east of the area.

&&

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

UPDATE...Pfannkuch
SHORT TERM...Rossi
LONG TERM...Rossi
AVIATION...Pfannkuch

Hazardous Weather Outlook...CORRECTED
National Weather Service Hastings NE
741 PM CDT Fri Aug 28 2020

KSZ005>007-017>019-NEZ082>087-291200-
Phillips-Smith-Jewell-Rooks-Osborne-Mitchell-Furnas-Harlan-
Franklin-Webster-Nuckolls-Thayer-
741 PM CDT Fri Aug 28 2020

This Hazardous Weather Outlook is for portions of north central
Kansas, along with south central Nebraska counties along the
Kansas border.

.DAY ONE...Overnight.

Thunderstorm development is possible through the overnight hours,
particularly within north central Kansas, but possibly brushing
up into extreme south central Nebraska as well. Should storms get
going, some could be strong to severe, especially within north
central Kansas. The main threat with any possible severe storms
would be large hail, up to around ping pong ball size.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Intermittent thunderstorm chances exist throughout the Saturday
through Wednesday night time frame, with the best chance for more
widespread...and potentially severe thunderstorms...expected
Sunday night through early Monday morning. At this time...large
hail and damaging winds are the primary concerns Sunday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation should not be needed through tonight...but
any reports of possible large hail would be very appreciated.

&&

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

NEZ039>041-046>049-060>064-072>077-291200-
Valley-Greeley-Nance-Sherman-Howard-Merrick-Polk-Dawson-Buffalo-
Hall-Hamilton-York-Gosper-Phelps-Kearney-Adams-Clay-Fillmore-
741 PM CDT Fri Aug 28 2020

This Hazardous Weather Outlook is for south central Nebraska
counties mainly along and north of Highway 6.

.DAY ONE...Overnight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Intermittent thunderstorm chances exist throughout the Saturday
night through Wednesday night time frame, with the best chance
for more widespread...and potentially severe
thunderstorms...expected Sunday night through early Monday
morning. At this time...large hail and damaging winds are the
primary concerns Sunday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

&&

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

Pfannkuch