Hail in Kansas, May 18, 2017

Area Forecast Discussion
National Weather Service Hastings NE
309 PM CDT Thu May 18 2017

...Big Concern Now thru Sat AM is Potential for Another 1-3" of
Rain otherwise Temps Remain Cooler than Normal thru Mid Next
Week...

.SHORT TERM...(This evening through Friday)
Issued at 309 PM CDT Thu May 18 2017

Aloft: GOES WV imagery showed a sizable low centered over UT/CO
at 19Z. There were two vort maxima dumbbelling around the low. The
first was over CO and it will lift N and NW into WY tonight. The
second was over NV/UT and it will swing into NM tonight and then
lift into Wrn KS Fri eve.

Surface: A cool front extended from Ern Canada WSW thru the
GtLakes across KS to low pres over the TX Panhandle. This front
will pivot cyclonically tonight as a weak low ejects into KS. The
front should remain just SE of the CWA. This front will then
remain quasi- stationary across KS tomorrow with the main low
lingering near the TX Panhandle. Meanwhile...chilly high pres will
migrate across Srn Canada...with an axis expanding down into the
Cntrl Plns by late tomorrow.

Late this afternoon: Please follow meso discussions and outlooks
from SPC...and any possible watch/warning products from this
office.

Very little has changed from prvs thinking. The main svr wx show
will be S-SE of the CWA...with some of these storms and storm
clusters migrating N into the CWA. A very cool air mass remains
even over our N-cntrl KS counties where low clouds have retarded
daytime heating. As these storms lift N they will become
increasingly elevated...mitigating the damaging wind and tornado
threat. There will be enough elevated instability (MUCAPE up to
1500 J/kg) to support svr hail over Rooks/Osborne/Mitchell/Jewell
Counties.

Over S-cntrl Neb...believe we're looking at general tstms with
limited potential for sub-svr hail (< 1").

Tonight: Cldy. We should see a large swath of rain lift from S-N
across the CWA along with embedded tstms. We remain very concerned
about hvy rain as the soil remains saturated over the SE 2/3 of
the CWA. Most of the rain should be out of the CWA by daybreak
Fri.

QPF: Model consensus and SREF as well as the NCAR CAM ensemble
suggest that a swath of 1-2" of rain will fall over part of the
CWA tonight. Flash flood guidance suggests 2" in 6 hrs will be
enough to initiate flash flooding.

Fri: Cldy and unseasonably chilly with blustery NE winds gusting
25- 35 mph at times. Really cut the mention of shwrs in the AM and
removed thunder altogether. We'll be in the wake of overnight
tstms and deep moisture will be gone. The mention of AM shwrs over
S-cntrl Neb is probably overdone. Expect patchy drzl.

As the second vort max approaches...expected more tstms to
develop in the afternoon over Wrn/Cntrl KS. These storms will lift
N into the CWA once again...but with even less instability than
today. So the drzl should transition to shwrs with most tstm
activity limited to N-cntrl KS...although a couple rumbles can't
be ruled out over S-cntrl Neb S of Hwy 6.

Again...more swaths of locally R+ are possible...especially as a
deformation zone develops/matures with the vort max lifting across
the region.

Was tempted to extend the flash flood watch back to daybreak Sat
...but will hold off and let later shifts extend if necessary.

.LONG TERM...(Friday night through Thursday)
Issued at 309 PM CDT Thu May 18 2017

The upr low referenced above will lift across the Cntrl Plns Sat
with the upr trof remaining overhead. The mean longwave trof that
has been over the W will transition over the Plns in the wake of
this low with NW flow finally becoming established by Tue as the
trof nudges E...but some guidance suggests that might not occur
til Wed. Substantial diff's develop Thu in the last 2 runs of the
EC and the CMC/GFS. The EC runs have a ridge moving over the Plns
with a potent low over Alberta/Sask while the GFS/CMC and the GFS
ens mean maintain NW flow. The 00Z EC ens mean supports this
scenario.

As far as shorter wavelengths...models are in good agreement that
a shortwave trof will swing thru Mon-Tue...possible bringing a
few shwrs and non-svr tstms.

Temps: Sat will still be unseasonably cool. Temps will return
close to normal Sun thru Wed but will still be a little below
normal.

Frost: Sun AM has the potential for a bit of frost over the usual
cold spots in Dawson/Valley/Greeley countries...possibly more.
Bias corrected guidance suggests we may not be cold enough with
fcst temps.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday)
Issued at 1234 PM CDT Thu May 18 2017

Significant Wx: Predominantly IFR CIGs. A period of +TSRA likely
this eve.

This Afternoon: Teetering on MVFR v IFR CIGs...but low-end MVFR
should prevail. NE winds roughly 13-23 kts. Gusty at times.
Confidence: High

Tonight: CIGs decay to IFR with a period of +TSRA. There is a low
prob for GS (small hail). VSBYs should begin to lower in light
fog after TSRAs end. ENE winds 15-25 kts except possibly
erratic near TSRAs. Confidence: High

Fri thru 18Z: IFR CIGs/VSBYs with patchy -DZ developing.
Confidence: High

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Flash Flood Watch from 6 PM CDT this evening through late Friday
     night for NEZ048-049-062>064-073>077-083>087.

KS...Flash Flood Watch from 6 PM CDT this evening through late Friday
     night for KSZ005>007-017>019.

&&

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

Hazardous Weather Outlook...UPDATED
National Weather Service Hastings NE
322 PM CDT Thu May 18 2017

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-
192030-
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-
322 PM CDT Thu May 18 2017

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

.DAY ONE...This Afternoon and Tonight.

Some area creeks and river remain high after recent heavy
rainfall. Flood warnings remain in effect for Clear Creek in Polk
County...and the Republican River over Webster County and extreme
southwestern Nuckolls County. Please see the Flood Warnings and
Statements for more information.

Scattered thunderstorms will move into the area from south to
north beginning around 5 pm. Some storms could be severe until
roughly midnight, mainly over north central Kansas. The primary
threat will be large hail up to the size of golf balls. There is a
lesser risk of damaging wind gusts near 60 mph and a tornado over
extreme southern Rooks...Osborne and Mitchell Counties.

Further north between the Kansas state line and Highway 6...there
is a very slim chance a storm or two could produce hail near the
size of quarters.

Given the wet soil conditions, heavy rain accompanying any
thunderstorms may lead to flash flooding or low land flooding
in localized areas, and a Flash Flood Watch is in effect. Please
refer to the latest Flash Flood Watch message for additional
information.

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

A few thunderstorms will be possible late Friday afternoon...
mainly over north central Kansas. No strong or severe storms are
expected.

More rain is likely Friday afternoon and night...possibly lasting
into Saturday. A Flash Flood Watch remains in effect through
late Friday evening. Please refer to the latest Flash Flood Watch
message for additional information.

A few thunderstorms will be possible again Monday afternoon and
evening. These are not expected to be severe.

.SPOTTER INFORMATION STATEMENT...

Spotter activation might be needed late this afternoon and evening
over north central Kansas.

&&

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

Kelley