Severe Thunderstorm Warning 197, NWS Hastings, NE

Area Forecast Discussion
National Weather Service Hastings NE
211 PM CDT Wed Aug 9 2017

.SHORT TERM...(This evening through Thursday)
Issued at 202 PM CDT Wed Aug 9 2017

A cold front is currently located just to the northwest of the
CWA. This front is expected to be the focus of thunderstorm
development over the following few hours. The HRRR has been very
consistent developing a line of storms and moving it southeastward
across the area through the early evening. I expect that this
line will gradually weaken later in the evening as instability
wanes a bit. Speaking of instability, RAP soundings show
1500-2000J of sfc-based CAPE. Coupled with around 25 kts of 0-6km
bulk shear, storms will be supportive of marginally severe hail
and up to 60 mph wind gusts...especially if storms develop into a
well-defined line.

Thunderstorms should clear out of the area by around midnight at
the latest. After that, we are looking at a decent potential for
fog development into Thursday morning. There is some question on
how well we will clear out, but the HRRR and SREF are both hinting
at lower visibilities, so I've continued the forecast of patchy
fog across the area.

Later Thursday afternoon, another cluster of thunderstorms is
expected to develop over the High Plains, mainly affecting the
southwestern half of the CWA into the evening and overnight. A
strengthening upper level jet will lead to higher bulk shear
values than today...on the order of 40 to 50 kts. With a corridor
of 2000J of MUCAPE present according to the NAM, strong to severe
storms are a threat once again.

.LONG TERM...(Thursday night through Wednesday)
Issued at 202 PM CDT Wed Aug 9 2017

Thunderstorm chances will gradually diminish Thursday night into
Friday morning, before returning from the west Friday night as a
compact wave moves through the area.

The model blend has PoPs lingering across the entire area through
the day on Saturday as additional thunderstorms will likely develop
on remnant boundaries. That said, I think that there will be
significant dry time after the overnight convection moves out of the
area, but it is hard to pinpoint timing enough to have any 6-hour
dry periods.

Off and on rain and thunderstorm chances continue Sunday and Monday
as the main trough and enhanced upper level jet continue to impact
the area. These features will gradually move east of the area Monday
night into Tuesday. While we don't have a completely dry forecast
for these time periods, I think that it will mark a transition to a
somewhat drier pattern through the middle of next week.

Thanks to northwesterly flow aloft, temperatures will continue to
be below normal. In fact, high temperatures are expected to stay
out of the 90s for the entirety of the forecast period. Look for
this to change as we move into increasingly zonal flow by the
latter half of next week.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Thursday)
Issued at 1209 PM CDT Wed Aug 9 2017

Main impacts for this TAF period will be thunderstorms tonight and
fog overnight.

Thunderstorms are expected to develop later this afternoon along a
cold front stretching roughly from LBF to ODX. These storms will
push southeastward into the late afternoon and evening, most
likely impacting GRI and EAR between 22Z and 02Z.

After these storms clear out of the area, models are indicating a
decent potential for fog development. For now, I've only taken
visibility down to 4SM, as the HRRR doesn't really drop
visibilities much lower than that. That said, the SREF does have
40-50% probabilities of visibilities less than 3 miles, so this
will need to be re-evaluated again this evening.

&&

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

SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Mangels

Hazardous Weather Outlook
National Weather Service Hastings NE
233 PM CDT Wed Aug 9 2017

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-
101200-
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-
233 PM CDT Wed Aug 9 2017

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

.DAY ONE...This Afternoon and Tonight.

A cluster of thunderstorms is expected to move across the area
late this afternoon through the evening. Some of these storms
could be strong to severe with hail near the size of quarters, 60
MPH wind gusts and locally heavy rainfall. The best chance for
severe weather will occur northwest of a line from Stockton,
Kansas to Geneva, Nebraska from 4PM to 8PM.

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

Between Thursday and Tuesday, there are several chances for
thunderstorms within the outlook area. At this time, it appears
that the best chances for thunderstorms will occur Thursday and
again Friday night through Saturday.

There is a risk for a few strong to severe storms Thursday
afternoon and evening, mainly south of a line from Elwood to
Hebron. Threats include hail to the size of ping pong balls, wind
gusts up to 60 MPH and locally heavy rain.

There may be potential for a few more strong to severe
storms through the weekend, but details remain uncertain at this
point.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed between 4PM and 8PM this evening.

&&

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

Mangels

Special Weather Statement
National Weather Service Hastings NE
324 PM CDT WED AUG 9 2017

NEZ060-072-092115-
Dawson NE-Gosper NE-
324 PM CDT WED AUG 9 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL GOSPER AND
SOUTHWESTERN DAWSON COUNTIES UNTIL 415 PM CDT...

At 324 PM CDT, Doppler radar was tracking a strong thunderstorm 7
miles northwest of Eustis, or 20 miles west of Lexington, moving
southeast at 15 mph.

Penny size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Farnam.

LAT...LON 4090 10022 4079 9987 4053 9990 4053 9998
      4070 9998 4070 10022
TIME...MOT...LOC 2024Z 300DEG 13KT 4075 10013

Mangels

Special Weather Statement
National Weather Service Hastings NE
421 PM CDT WED AUG 9 2017

NEZ046-061-092200-
Buffalo NE-Sherman NE-
421 PM CDT WED AUG 9 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN BUFFALO AND SOUTHERN
SHERMAN COUNTIES UNTIL 500 PM CDT...

At 421 PM CDT, Doppler radar was tracking a strong thunderstorm over
Litchfield, or 28 miles north of Kearney, moving southeast at 20 mph.

Penny size hail and wind gusts of 50 to 55 mph will be possible with
this storm.

Locations impacted include...
Ravenna, Pleasanton, Litchfield, Hazard and Poole.

LAT...LON 4106 9875 4105 9875 4104 9872 4103 9872
      4080 9900 4104 9927 4105 9921 4115 9921
      4123 9910
TIME...MOT...LOC 2121Z 305DEG 16KT 4112 9914

Mangels