Severe Thunderstorm Warning 293, NWS Hastings, NE

Area Forecast Discussion
National Weather Service Hastings NE
952 PM CDT Sun Aug 11 2019

.UPDATE...
Issued at 952 PM CDT Sun Aug 11 2019

New PDS Severe watch has been issued including south central
Nebraska from the I-80 corridor south and all of north central
Kansas. The primary threat is strong straight line winds, but hail
and a brief tornado or two cannot be ruled out. The way this event
is evolving looks like the NE/KS line will be the primary path,
but evolution to the north and south of this area are possible as
this storm becomes cold pool dominant and new development with the
LLJ. Thus with the uncertainty and possibility for strong winds,
decided to include the counties along the I-80 corridor. Hydro
concerns continue as well. These storms are excellent rain
producers with high PWATs. Hopefully the saving grace for
significant flooding concerns will be that this system will be
fairly progressive, moving through the forecast area by 4-5am.

&&

.SHORT TERM...(This evening through Monday)
Issued at 243 PM CDT Sun Aug 11 2019

The main concern in this forecast is the threat for severe
thunderstorms and heavy rainfall tonight.

Models continue to advertise scattered thunderstorms developing
over eastern Colorado and western Kansas late this afternoon and
evening. Coverage will initially be isolated to scattered in
nature, but there is good agreement amongst the models that storms
will merge into one or more multicell clusters or bowing segments
as they move into the local forecast area. Timing of these storms
should be between 11pm tonight and 5am Monday morning. With
30-40kts of deep layer shear and MUCAPE of up to 3500J/kg, storms
should remain intense and capable of very strong wind gusts as
they move through the area. Exact storm track is a bit uncertain,
but appears to have trended southward with today's model
runs...more closely following the instability gradient.

In addition, precipitable water values are expected to once again
be near 2 inches. This will promote very efficient and heavy
rainfall at times. 1 to 3 inches with locally higher amounts are
expected which may lead to localized flooding...especially in
areas that remain saturated from rain over the past week or so.
With the uncertainty in the exact storm track and heavy rain that
fell last night, I went ahead and expanded the Flash Flood Watch
to cover the remainder of the CWA.

Storms are expected to exit the area fairly quickly Monday
morning, but convective development for the rest of the day
is fairly uncertain. A few models show isolated thunderstorms
developing in our north with a marginal risk for severe weather,
but the main area of thunderstorms will be along the front...which
should be south of the area. Therefore, I have just maintained
slight chance PoPs for these areas through Monday afternoon and
evening.

.LONG TERM...(Monday night through Sunday)
Issued at 243 PM CDT Sun Aug 11 2019

Dry and seasonable conditions are expected during the daytime on
Tuesday, but a marginal risk for severe weather returns overnight
as thunderstorms move in from the west. Chances for rain and
storms then linger through Wednesday as well as we remain in
northwesterly flow aloft.

Mainly dry conditions are currently forecast for Thursday through
Saturday, but there is some considerable uncertainty. Both the
GFS and Euro have a wave move through Thursday night into Friday
morning bringing a round of thunderstorms to the area, so I
wouldn't be surprised if precipitation chances increase in future
forecasts.

Beyond that, we should see a quieter pattern and a gradual
warming trend as midlevel ridging moves overhead into the weekend.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 645 PM CDT Sun Aug 11 2019

The main aviation forecast concern is the thunderstorm chances
during the late evening and overnight hours. The high-resolution
guidance has been consistent in bringing the convection into the
region that has already begun in the High Plains of Colorado. The
convection is expected to become a squall line with the main
concern being wind. Feel the best chance will be after 04z moving
west to east. Did include a wind gust 30g45kts for now, but we'll
have to see how the storms evolve. During the storms MVFR to IFR
are expected with brief period of LIFR possible. Storms are
expected to move across the area at a good clip and look to exit
to eastern Nebraska before 12z.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Flash Flood Watch until 7 AM CDT Monday for NEZ039>041-046>049-
     060>064-072>077-082>087.

KS...Flash Flood Watch until 7 AM CDT Monday for KSZ005>007-017>019.

&&

UPDATE...Billings Wright
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Billings Wright

Hazardous Weather Outlook...CORRECTED
National Weather Service Hastings NE
242 PM CDT Sun Aug 11 2019

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-
121200-
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-
242 PM CDT Sun Aug 11 2019

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

.DAY ONE...This Afternoon and Tonight.

A line of thunderstorms is expected to move through the area late
tonight. Some of these storms will likely be severe. The main
threats will be wind gusts to 70 MPH and heavy rainfall.

A Flash Flood Watch is in effect tonight for the entire outlook
area tonight. Please see the Flash Flood Watch message for
further information on the heavy rain and flooding potential.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

A few strong thunderstorms may redevelop Monday afternoon and
evening, and another round of strong to severe thunderstorms is
possible Tuesday night into Wednesday.

There is at least some chance for thunderstorms again Thursday
night, but details on coverage and strength remain uncertain.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight.

&&

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