Special Weather Statement, NWS Topeka, KS

Area Forecast Discussion
National Weather Service Topeka KS
1220 AM CDT Fri Jun 25 2021

...Update to aviation forecast discussion...

.DISCUSSION...
Issued at 359 PM CDT Thu Jun 24 2021

Main focus is the concern for severe weather potential late this
afternoon and evening, with several factors leading to plenty of
uncertainty in how tonight evolves, which will then affect the next
couple of days.

A 1004mb surface low is centered over south central KS with a warm
front extending into northeast KS while the cold front extends into
western KS and into southeast NE. We also have outflow boundaries
from this morning's convection, which had pushed south of the area
but is retreating north, and another boundary was noted on satellite
in southeast NE earlier today, likely associated with convection
that had decayed to the north of that area. Having multiple
boundaries hanging around the area leaves room for uncertainty on
which one storms will initiate on, and also is a cause for concern
because enough clearing has taken place for the atmosphere to become
quite unstable. The 19Z TOP sounding shows the boundary layer as
being warm and moist, but the atmosphere still capped. Most
deterministic and ensemble guidance has favored storms developing
first near the KS/NE border around 22-23Z where the synoptic
boundary looks to be situated, then moving southeast. There remains
some possibility storms could initiate a bit further south, but
there isn't much confidence in that scenario - in any case, areas
north of I-70 are favored at least for the beginning of the event.
Any storms that develop in this area during the late afternoon/early
evening would have potential to produce a tornado or two, given
backed winds at the surface resulting in a veered wind profile as
shown in forecast hodographs. This would be especially true for a
storm that develops along any boundaries in the area, with CAPE of
3000-5000 J/kg to work with. That being said, large hail and
damaging winds are still the bigger threats, with hail being up to
baseball size and wind gusts up to 70mph possible.

We will also need to monitor heavy rain with potential for flash
flooding late tonight, mainly after midnight. Storms are also
expected to develop in western KS associated with the cold front or
dryline, and any discrete cells initially should grow upscale as
boundaries interact with each other. There is a possibility storms
could be progressive enough tonight to not cause problems,
especially since we have been dry enough for most areas to take a
quick inch or two. However, Pwat values are already near the max
based on local sounding climatology and are expected to remain there
overnight into Friday. As a result, have issued a Flash Flood Watch
for parts of northeast and east central KS that would be at greatest
risk for receiving heavy rainfall tonight. This may need to be
expanded south and/or west to account for Friday's activity, but
given the uncertainty with how tonight evolves and what kind of soil
conditions will be present by morning, so have focused more on
tonight for the watch area for now.

Most activity should move out by sunrise, with a brief break in the
morning for most places. Another round of severe weather then
becomes possible during the afternoon and evening with the cold
front bisecting the area. Damaging wind, hail, and heavy rain will
be the main threats for this round, and the exact area will depend
on where exactly the boundary sets up. Some storms may continue into
Saturday as well, and there is still some variability between models
on how soon the front moves entirely out of the area. Although PoPs
are small heading into next week, troughing remains over the area to
at least keep some storm chances around. Otherwise, expect cooler
temperatures relative to what we've seen the last couple days, with
highs in the 80s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1219 AM CDT Fri Jun 25 2021

Multiple rounds of thunderstorms will continue across the area
throughout the period. The initial round of overnight storms seems
more likely to impact KMHK, while tomorrow afternoon's round of
storms seems more likely to impact KFOE/KTOP. Conditions should
remain VFR away from any thunderstorms. South winds and LLWS
continue tonight across KFOE and KTOP ahead of a cold front, with
winds remaining northerly at KMHK behind the front. LLWS will end
before sunrise as the strongest LLJ shifts to the east, with
surface winds not changing much throughout the day as the front
stalls.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Saturday morning for KSZ010>012-023-
024-026-038>040-055-056.

&&

DISCUSSION...Picha
AVIATION...Reese

Hazardous Weather Outlook
National Weather Service Topeka KS
403 PM CDT Thu Jun 24 2021

KSZ008>012-020>024-026-034>040-054>056-058-059-252115-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
403 PM CDT Thu Jun 24 2021

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

.DAY ONE...Tonight.

Heat index values of 100 to 105 degrees will continue this
afternoon, especially along and south of I-70.

Another round of severe thunderstorms is expected late this
afternoon into tonight. Large hail, damaging winds, heavy
rainfall, and a few tornadoes are all possible. A Flash Flood
Watch has been issued for parts of northeast and east central
Kansas tonight through Saturday morning.

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

More severe thunderstorms could develop Friday afternoon across
the area. Large hail, damaging wind, and heavy rainfall are the
main threats with this round. The Flash Flood Watch remains in
effect through Saturday morning. Please reference this product for
more information.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

&&

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

Special Weather Statement
National Weather Service Topeka KS
939 PM CDT Thu Jun 24 2021

KSZ024-026-039-250315-
Shawnee-Jefferson-Jackson-
939 PM CDT Thu Jun 24 2021

...SIGNIFICANT WEATHER ADVISORY FOR JEFFERSON...NORTHERN SHAWNEE AND
SOUTHEASTERN JACKSON COUNTIES UNTIL 1015 PM CDT...

At 939 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 6 miles southwest of Atchison to near Hoyt to 4
miles northeast of Silver Lake. Movement was east at 30 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
these storms.

Locations impacted include...
Valley Falls, Oskaloosa, McLouth, Meriden, Hoyt, Ozawkie,
Nortonville, Winchester, Mayetta, Denison and Perry Lake.

A Severe Thunderstorm Watch remains in effect until 300 AM CDT for
northeastern and east central Kansas.

LAT...LON 3913 9519 3912 9519 3909 9520 3914 9592
      3929 9583 3943 9557 3942 9557 3942 9518
      3913 9518
TIME...MOT...LOC 0239Z 265DEG 25KT 3949 9519 3923 9570 3916 9580

Gargan

Special Weather Statement
National Weather Service Topeka KS
1041 PM CDT Thu Jun 24 2021

KSZ011-012-250415-
Brown-Nemaha-
1041 PM CDT Thu Jun 24 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN NEMAHA AND
NORTHWESTERN BROWN COUNTIES UNTIL 1115 PM CDT...

At 1040 PM CDT, Doppler radar was tracking a strong thunderstorm near
Bern, moving east at 30 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Sabetha and Bern.

LAT...LON 3988 9571 3990 9610 4000 9611 4000 9570
TIME...MOT...LOC 0340Z 265DEG 24KT 3996 9601

Gargan

Special Weather Statement
National Weather Service Topeka KS
1048 PM CDT Thu Jun 24 2021

KSZ012-250415-
Brown-
1048 PM CDT Thu Jun 24 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL BROWN COUNTY UNTIL 1115
PM CDT...

At 1046 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 3 miles southeast of Highland to Powhattan.
Movement was southeast at 25 mph.

Half inch hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Hiawatha, Horton, Everest, Fairview, Robinson, Powhattan and Willis.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may
lead to localized flooding. A flash flood warning continues in
effect for northern Brown County until 100 AM CDT. Do not drive your
vehicle through flooded roadways.

&&

LAT...LON 3965 9534 3965 9555 3985 9577 3996 9534
TIME...MOT...LOC 0346Z 304DEG 20KT 3984 9520 3976 9564

Gargan

Special Weather Statement
National Weather Service Topeka KS
1131 PM CDT Thu Jun 24 2021

KSZ012-250500-
Brown-
1131 PM CDT Thu Jun 24 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN BROWN COUNTY UNTIL
MIDNIGHT CDT...

At 1130 PM CDT, Doppler radar was tracking a strong thunderstorm near
Hamlin, moving east at 35 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Hiawatha, Sabetha, Fairview, Robinson, Morrill, Reserve and Hamlin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. A flash flood warning is in effect until 1
AM CDT. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3980 9534 3984 9579 4000 9579 4000 9534
TIME...MOT...LOC 0430Z 274DEG 29KT 3990 9557

Gargan

Special Weather Statement
National Weather Service Topeka KS
1221 AM CDT Fri Jun 25 2021

KSZ035-250545-
Dickinson-
1221 AM CDT Fri Jun 25 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL DICKINSON COUNTY UNTIL
1245 AM CDT...

At 1220 AM CDT, Doppler radar was tracking a strong thunderstorm
over Abilene, moving east at 30 mph. A second strong thunderstorm
was over northeast Saline County, moving east at 30 MPH.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Abilene, Chapman, Solomon, Enterprise and Moonlight.

This includes Interstate 70 between mile markers 267 and 289.

LAT...LON 3901 9737 3904 9696 3880 9696 3882 9737
TIME...MOT...LOC 0520Z 269DEG 24KT 3892 9724

Gargan

Special Weather Statement
National Weather Service Topeka KS
1256 AM CDT Fri Jun 25 2021

KSZ012-250630-
Brown-
1256 AM CDT Fri Jun 25 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN BROWN COUNTY UNTIL
130 AM CDT...

At 1255 AM CDT, Doppler radar was tracking a strong thunderstorm 6
miles north of Robinson, moving east at 30 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Hiawatha and Robinson.

LAT...LON 3981 9534 3983 9556 4000 9556 4000 9534
TIME...MOT...LOC 0555Z 273DEG 28KT 3992 9541

Gargan