Hail and Damaging Winds in Nebraska, May 10 to 11, 2018

Area Forecast Discussion
National Weather Service Hastings NE
636 PM CDT Thu May 10 2018

.SHORT TERM...(This evening through Friday)
Issued at 253 PM CDT Thu May 10 2018

Aloft: A broad low-amplitude shortwave ridge was over the Plns
per WV imagery...RAP analyses and aircraft data. A shortwave trof
extended from a low over WA down thru NV back to Srn CA. This trof
will move NE and weaken as it moves into the ridge while crossing
the Plns tomorrow. Meanwhile...the low will cut-off and sink into
NV.

Surface: The cool front that sagged into Neb this AM has settled
along the KS state line but then curved NW into the Neb Panhandle.
High pres was over Lk Winnipeg and low pres was continuing to
strengthen over SE CO. The largely stationary front will rotate
cyclonically tonight as the low ejects to near HLC by 12Z/Fri.
Most of the CWA will be on the cool side of the front tomorrow as
the low slowly inches to BIE. by 00Z the front should be
completely out of the CWA (just S and E).

Rest of this afternoon: M/sunny and warm. Temps will peak 4-5 PM.

SVR watch #79 is in effect immediately W of the CWA.

Tonight: Quite a variety of model solutions on what happens.
Confidence is low. We just have to wait and see. Tstms will
develop to the W and congeal into a squall line. The uncertainty
lies in how much of the CWA is affected as it moves E or NE.
Maintained highest pops N of I-80...but there could be other
tstms between I-80 and the KS state line. Some models suggest
bowing segments are likely. Still looking at a late eve/overnight
event.

Linear convective mode favors damaging wind as the primary
threat...though some hail can't be ruled out.

Please see SWODY1 and SWOMCD's for more details.

Fri: Quiet and dry for most or all of the CWA. Expect a lot of
low stratus will develop on the cool side of the front in the wake
of the overnight MCS. The MCS will probably lay down an outflow
boundary that will merge with/reinforce the front.

Tstm formation is highly questionable along the front late Fri
afternoon. The SPC outlook is conditional on if tstms develop at
all. The frontal inversion will result in a significant cap. There
could be no tstm development at all or they could occur just SE
or S of the CWA. However..."if" any tstms develop they have a high
probability of being severe.

.LONG TERM...(Friday night through Thursday)
Issued at 253 PM CDT Thu May 10 2018

Aloft: Split flow will be established over N America by Fri night
with a cut-off low over the Wrn USA. That will maintain largely
anticyclonic SW flow over the Cntrl Plns thru at least Tue. The
low will eventually weaken to a remnant vort max. Meanwhile...some
low- amplitude subtle vort maxima will probably move across the
CWA in the SW flow. Predictability goes down significantly from
Tue on due to noise associated with convectively-generated vort
maxima.

Surface: The front referenced above will remain quasi-stationary
from SW-NE across KS thru Mon. Thereafter...frontolysis is fcst.
NW flow in the Nrn branch of the split flow aloft will probably
send a cool front thru here Thu.

Temps: Much cooler than normal Sat as substantial stratus will
probably be trapped underneath the frontal inversion. This could
linger into Sun too. Right now we are fcstg temps to return to
normal Sun...but believe odds favor temps remaining below normal.
Temps are fcst to return to above normal Mon-Thu. Stratus could
still linger into Mon as well for parts of the CWA.

Precip: As mentioned above...tstm Fri eve could be few and far
between. Sat-Sun finally withdrew thunder from the fcst and
replaced it with a mention of drzl. There will be too much stratus
around... and while there will be elevated CAPE...there shouldn't
be anything to release it. The low-lvl jet will be directed into
MO or far SW KS.

Sun night thru Thu there could be some very spotty tstm activity
here and there...but predictability is too low to provide any
details. There will be no large-scale forcing. Therefore...Most
locations will be dry.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 633 PM CDT Thu May 10 2018

Thunderstorms to the west should move into the terminal areas a
few hours into the period. After the thunderstorms move through,
there will be some stratus that moves into the area and during the
day expect MVFR conditions.

&&

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

SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...JCB

Hazardous Weather Outlook...UPDATED
National Weather Service Hastings NE
310 PM CDT Thu May 10 2018

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-
111200-
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-
310 PM CDT Thu May 10 2018

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

.DAY ONE...This Afternoon and Tonight.

Severe thunderstorms are possible between 9 PM and 3AM...
primarily over south central Nebraska. The main threat will be
damaging winds...but some hail up to the size of ping pong balls
can't be ruled out.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

There is a slight chance for an isolated thunderstorm or two
Friday evening...mainly south of Highway 6 down into north central
Kansas. While the chance of storms is low...should any storms
actually form they could be severe with hail up to the size of
golf balls the primary threat. Damaging wind near 60 mph will also
be possible.

Sunday night through Wednesday there is a slight chance for some
spotty thunderstorm activity here and there. While strong or
severe storms cannot be ruled out...at this time there are no
identifiable organized threats.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is likely late this evening. Spotters...please
relay reports of wind damage and hail to the National Weather
Service.

&&

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

Kelley