Flash Flooding and Hail in Kansas, August 15 to 18, 2019

Area Forecast Discussion
National Weather Service Topeka KS
250 PM CDT Thu Aug 15 2019

.SHORT TERM...(This evening through Friday night)
Issued at 250 PM CDT Thu Aug 15 2019

Convective trends and intensities are the main challenges. Mesoscale-
convective system continues to impact northern portions of the area
in seasonally-strong west-northwest flow aloft with continued 850 mb
southwest winds around 20 knots keeping some higher theta-e air
ingest in place. Outflow boundary from this convection was bisecting
the CWA from west to east with well-mixed and moisture-rich boundary
layer air pushing north-northwest into it. Latest analysis indicates
at least modest ML CIN persists but strong convergence was leading
to some 19Z cumulus development in central Kansas with ML CAPE near
3500 J/kg.

Short-range guidance continues to struggle with ongoing
precipitation most solutions point to some redevelopment in the next
several hours. Hard to get too precise with location and timing but
expect at least isolated convection to develop by 00Z near the
boundary and push east to southeast into the evening. The developing
nocturnal low-level jet will increase already strong shear for a
environment very supportive of supercells into the evening, with
their persistence at least partially moderated by the orientation of
the boundary, with continues to alter with time. All modes of severe
weather will be possible into at least 03Z with a slowly-
destabilizing boundary layer likely leading to decreasing potential
overnight. The decreasing trend will also be aided by a shortwave
trough pushing east into the upper Mississippi Valley, bringing a
reinforcing boundary into northern Kansas.

The eventual location of this boundary will be a key player in
thunderstorm activity for Friday afternoon and evening. Most
guidance brings it through at least I-70 but it may reside over the
southern counties in the late afternoon and early evening. There is
some potential for an increasing capping inversion to build in over
the boundary layer and may keep daytime development in check, and
this could be under a deck of lower stratus, further curtailing
convection and resulting in lower confidence in high temperatures.
The greater threat will likely come as the low-level jet returns
in the evening and overnight for elevated WAA-induced development.
With potential training of storms over this boundary over precip
falling today/tonight, there is some concern for excessive
rainfall amounts.

.LONG TERM...(Saturday through Thursday)
Issued at 250 PM CDT Thu Aug 15 2019

Evolution of the weather on Saturday will depend on linger
convection and outflow/front from Friday night, and speed of the
shortwave trof progged to move through the state.  Generally zonal
flow across the state does little to shift warm front north or
south, leaving a focus for convection across the northern part of
the state. GFS solutions would pose a higher threat for strong
storms given available instability as wave moves over eastern Kansas
in the afternoon/evening hours, advecting moist unstable air into
the warm sector then developing convection. Will keep chance PoPs
for lingering morning convection, followed by the uncertainty of the
location of redevelopment in the afternoon/evening.  Highs rise to
the low 90s, possibly a few degrees cooler north of the warm front
near the NE border.

Broader large scale upper trof moves across southern Canada and the
northern plains late Saturday night, giving the upper ridge a chance
to nose northward into the Central Plains Sunday into Monday. Highs
rise back into the 90s with upper 90s in central parts of the state,
and heat indices possibly back into the 100-110 range Sunday
through Tuesday afternoons.

May start to get some influence from cooler air pushing southward
behind the upper low over the Great Lakes for Wednesday, and another
chance for rain as it does so, bringing forecast highs back down to
the upper 80s to near 90 for mid/late week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1243 PM CDT Thu Aug 15 2019

Thunderstorm chances inhabit much of the first half of this
forecast, though confidence on specific windows when they will
impact the terminals is not high. Have kept at VCTS in the next
few hours for TOP and FOE near the developing line to the north.
Storms are expected to redevelop along associated outflow
boundaries in the 22Z-02Z window though where the updrafts form is
in question based on trends over coming several hours. Lingering
moisture behind a reinforcing front may result in a MVFR ceiling
late in the forecast.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...65
LONG TERM...67
AVIATION...65

Hazardous Weather Outlook
National Weather Service Topeka KS
311 PM CDT Thu Aug 15 2019

KSZ008>012-020>024-026-034>040-054>056-058-059-162015-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
311 PM CDT Thu Aug 15 2019

This hazardous weather outlook is for east central...north
central and northeast Kansas.

.DAY ONE...This Afternoon and tonight.

Thunderstorm chances increase across the entire area as the late
afternoon and evening progress, but thunderstorm chances
gradually end overnight. Some of the storms this afternoon and
this evening may be severe with large to very large hail,
damaging winds, and a few tornadoes. Locally heavy rainfall is
also possible.

Flooding on the Big Blue River near Blue Rapids continues.

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

Additional rounds of thunderstorms with locally heavy rainfall
are possible Friday night through Sunday morning. Severe weather
can't be ruled out with these storms with the most likely hazards
being large hail, damaging winds, and heavy rainfall that could
lead to localized flash flooding concerns.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed through the late evening hours.

&&

More detailed information can be accessed at...
http://www.weather.gov/top/sitrep

Special Weather Statement
National Weather Service Topeka KS
1039 AM CDT Thu Aug 15 2019

KSZ008-020-151615-
Republic-Cloud-
1039 AM CDT Thu Aug 15 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN REPUBLIC AND
NORTHWESTERN CLOUD COUNTIES UNTIL 1115 AM CDT...

At 1039 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 3 miles west of Davenport to near Esbon.
Movement was east at 45 mph.

Winds in excess of 40 mph will be possible with these storms.

Locations impacted include...
Belleville, Scandia, Courtland, Norway, Republic and Munden.

LAT...LON 4000 9739 3957 9792 3958 9793 4000 9793
TIME...MOT...LOC 1539Z 279DEG 38KT 4033 9788 3981 9844

Skow

Special Weather Statement
National Weather Service Topeka KS
1225 PM CDT Thu Aug 15 2019

KSZ010-011-151800-
Nemaha-Marshall-
1225 PM CDT Thu Aug 15 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN NEMAHA AND
NORTHEASTERN MARSHALL COUNTIES UNTIL 100 PM CDT...

At 1224 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 5 miles north of Summerfield to near Beattie.
Movement was east at 45 mph.

Winds in excess of 40 mph will be possible with these storms.

Locations impacted include...
Seneca, Centralia, Axtell, Beattie, Bern, Summerfield, Oneida and
Baileyville.

LAT...LON 3969 9606 3985 9656 4000 9649 4000 9583
TIME...MOT...LOC 1724Z 290DEG 41KT 4007 9631 3985 9647

Skow

Special Weather Statement
National Weather Service Topeka KS
1246 PM CDT Thu Aug 15 2019

KSZ011-012-024-151815-
Brown-Jackson-Nemaha-
1246 PM CDT Thu Aug 15 2019

...SIGNIFICANT WEATHER ADVISORY FOR NEMAHA...NORTHERN JACKSON AND
WESTERN BROWN COUNTIES UNTIL 115 PM CDT...

At 1245 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 3 miles northwest of Bern to 3 miles northwest
of Centralia. Movement was east at 40 mph.

Pea size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Hiawatha, Sabetha, Seneca, Centralia, Wetmore, Fairview, Morrill,
Bern, Netawaka, Goff, Reserve, Powhattan, Oneida, Hamlin, Kickapoo
Reservation and Woodlawn.

LAT...LON 3959 9571 3974 9622 4000 9609 4000 9541
TIME...MOT...LOC 1745Z 272DEG 36KT 4000 9601 3978 9616

Skow

Special Weather Statement
National Weather Service Topeka KS
110 PM CDT Thu Aug 15 2019

KSZ011-012-024-151845-
Brown-Jackson-Nemaha-
110 PM CDT Thu Aug 15 2019

...SIGNIFICANT WEATHER ADVISORY FOR EASTERN NEMAHA...NORTHEASTERN
JACKSON AND BROWN COUNTIES UNTIL 145 PM CDT...

At 109 PM CDT, automated weather stations and doppler radar reported
strong thunderstorms along a line extending from near Reserve to
near Wetmore. Movement was east at 50 mph.

Pea size hail and wind gusts up to 50 mph will be possible with these
storms. A 48 mph wind gust was reported near Bern.

Locations impacted include...
Hiawatha, Sabetha, Horton, Wetmore, Everest, Fairview, Robinson,
Morrill, Whiting, Netawaka, Goff, Reserve, Powhattan, Hamlin, Willis,
Kickapoo Reservation and Woodlawn.

LAT...LON 3965 9534 3965 9556 3957 9556 3957 9557
      3953 9557 3968 9601 4000 9580 4000 9534
TIME...MOT...LOC 1809Z 286DEG 42KT 3999 9559 3965 9585

Skow

Special Weather Statement
National Weather Service Topeka KS
305 PM CDT Thu Aug 15 2019

KSZ010-011-152030-
Nemaha-Marshall-
305 PM CDT Thu Aug 15 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN NEMAHA AND NORTHEASTERN
MARSHALL COUNTIES UNTIL 330 PM CDT...

At 304 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 4 miles southeast of Pawnee City to 5 miles
southeast of Summerfield. Movement was southeast at 35 mph.

Wind gusts up to 50 mph, nickel sized hail and heavy rainfall will
be possible with these storms.

Locations impacted include...
Sabetha, Seneca, Axtell, Bern, Summerfield, Oneida and Baileyville.

LAT...LON 3999 9580 3985 9579 3972 9623 4000 9643
      4000 9582
TIME...MOT...LOC 2004Z 319DEG 30KT 4007 9609 3995 9627