Severe Thunderstorm Warning 62, NWS Topeka, KS

Area Forecast Discussion
National Weather Service Topeka KS
602 AM CDT Sat May 18 2019

...AVIATION UPDATE...

.SHORT TERM...(Today and tonight)
Issued at 359 AM CDT Sat May 18 2019

08Z water vapor imagery showed an upper low over southwest WY with a
couple shortwaves rotating around the upper low. At the surface,
area of low pressure had moved into central NEB with a trailing cold
front extending through southwestern KS. A linear MCS was slowly
moving east across the forecast area.

For today there is some uncertainty in how storms will evolve with
mixed signals from the convective allowing models. The RAP suggests
higher CIN values across eastern KS this morning implying the storms
would weaken. However think a 65KT low level jet continuing to
advect moisture into the line of showers and storms may allow the
convection to persist through the morning and into east central KS.
Obviously this could impact the severity of storms later today with
clouds and precip limiting daytime heating. In fact the forecast
highs are only in the mid 70s. Think storms will redevelop today as
models show a lead vort max lifting across eastern KS late this
morning or early in the afternoon. The severe risk later today seems
highly conditional on whether there can be enough heating to
destabilize the environment. While deep layer shear of 40KT could be
good enough for organized storms, forecast hodographs show a complex
wind field with inflections in the hodograph. This would favor more
storm interactions rather than discrete supercell storms. So in
general think showers and thunderstorms will be around for a good
portion of the day with some risk for large hail and damaging winds.
It is just unclear whether it will be more junky convection with
pulse storms or a more organized risk. Based on recent trends, am
leaning more towards the later.

For tonight, models show any instability having been spent. But
there should still be forcing for showers and storms as the main
shortwave trough rotates over the region. Concerns then become more
about flooding. Considered the need for a flash flood watch. But
with the uncertainty in how convection develops through the day,
it's difficult to have much confidence in where the higher QPF
amounts may occur. Also flash flood guidance is close to normal for
this time of year so the region may be able to withstand This
initial precip. It would be the second or third wave of heavy
rainfall that will lead to problems and the day shift can reevaluate
this potential. Lows tonight are expected to fall into the 50s as
the frontal boundary moves through and a northwest wind brings
cooler air in behind the front.

.LONG TERM...(Sunday through Friday)
Issued at 359 AM CDT Sat May 18 2019

The main takeaways from the extended period are as followed:

* An active weather pattern will continue into next week, resulting
  in additional thunderstorm activity and heavy rainfall.

* Severe thunderstorms are possible late Monday afternoon into
  Monday night.

* Confidence continues to increase for a significant flooding event
  Monday night through Tuesday morning.

Sunday through Sunday night...

A brief dry period is expected Sunday afternoon through Sunday night
as the second in a series of midlevel shortwave troughs ejects
northeast of the forecast area. Any lingering shower/storms will
quickly exit the area shortly after sunrise. Weak CAA across the
forecast area will limit temperatures to the low/mid 60s Sunday
afternoon.

Monday and Tuesday...

00Z model solutions continue to align with the evolution of the
third midlevel shortwave trough and the attendant surface
boundaries. A midlevel shortwave ridge axis will traverse the
forecast area Monday morning into the afternoon, ahead of the
aforementioned trough. This should keep conditions dry through much
of the day Monday. A sharp warm front is progged to straddle the KS/
OK border through much of the morning and early afternoon hours.
Given the slower progression of the midlevel shortwave trough,
large scale ascent within the warm sector is minimal, which should
keep convection isolated through much of the daylight hours. As
the shortwave trough ejects across the Plains, near/after sunset
Monday evening, additional development and upscale growth into an
MCS is likely. The warm front will likely lift northward as the
attendant surface low progresses northward, ushering in rich Gulf
moisture into the CWA.-- characterized by PWAT values exceeding
1.5 inches. The aforementioned MCS will likely move northeastward
along the warm front into portions of east-central and southeast
KS. WAA aided convection is also expected north of the warm front
Monday night/Tuesday. In regards to severe weather, the primary
hazards look to be damaging winds and large hail. Any established
cold-pools will have the potential to produce damaging winds.
Modest lapse rates combined with an impressive shear profile could
foster a large hail threat.

The biggest concern remains with very heavy rainfall resulting in
widespread flooding. Deterministic and ensemble guidance continue to
suggest widespread rainfall amounts of 3 to 6 inches, with locally
higher amounts likely, through Tuesday morning. As a result,
confidence has further increased for a significant flooding event
Monday evening through Tuesday morning. Very saturated soils
remain in place across the forecast area -- several Kansas State
Mesonet sites across northeast KS depict saturation values
exceeding 85 percent from the surface through a 50 cm depth. This
will result in little in the way of infiltration into the soil and
mostly runoff, greatly increasing the potential for flash-
flooding, possibly significant. Moreover, additional rises on
rivers and lakes may result in a longer duration flood event.
Please continue to check back through the weekend for forecast
updates as this has the potential to be a significant flood event
across much of the forecast area.

Wednesday through Friday...

Additional shower and thunderstorm activity is possible Wednesday
night into next week. Model solutions diverge with the strength
of the midlevel ridge across the southeastern US and the resultant
flow pattern through the central US. As a result, forecast
confidence beyond Tuesday is low at this time. That being said,
any additional rainfall will only worsen flooding concerns through
the remainder of the week. Temperatures are likely to remain
near-normal with highs in the 70s to near 80 and lows in the 50s
and 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 602 AM CDT Sat May 18 2019

There is a lot of uncertainty in how convection evolves through
the day. Think a brief time of MVFR CIGS could move in but much of
the afternoon should be VFR with widespread TSRA in the afternoon
and evening as upper level energy moves over the area. Models show
some potential for MVFR CIGS to move in behind the synoptic front
late tonight.

&&

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

SHORT TERM...Wolters
LONG TERM...Baerg
AVIATION...Wolters

Hazardous Weather Outlook
National Weather Service Topeka KS
1012 AM CDT Sat May 18 2019

KSZ008>012-020>024-026-034>040-054>056-058-059-191515-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
1012 AM CDT Sat May 18 2019

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

.DAY ONE...Today and Tonight.

Thunderstorms are expected to increase in coverage from south to
north through the day and more thunderstorms are likely across the
entire area tonight. Some of these storms may be severe with
large hail and damaging winds. A tornado or two is also possible
along and southeast of Interstate 35. Locally heavy rainfall is
also possible which could result in flash flooding.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Severe thunderstorms are possible Monday night into Tuesday.
Heavy rainfall is likely in these periods which will increase the
flash flooding potential. River flooding may also possible result
Monday night into the middle and later portions of the week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may 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
1041 AM CDT Sat May 18 2019

KSZ059-181615-
Anderson-
1041 AM CDT Sat May 18 2019

...SIGNIFICANT WEATHER ADVISORY FOR ANDERSON COUNTY UNTIL 1115 AM
CDT...

At 1041 AM CDT, Doppler radar was tracking a strong thunderstorm near
Iola, moving north at 40 mph.

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

Locations impacted include...
Garnett, Colony, Westphalia, Kincaid and Lone Elm.

A Tornado Watch remains in effect until 500 PM CDT for east central
Kansas.

LAT...LON 3826 9552 3826 9551 3829 9551 3829 9506
      3826 9506 3826 9507 3804 9508 3804 9552
TIME...MOT...LOC 1541Z 197DEG 36KT 3796 9539

BD

Special Weather Statement
National Weather Service Topeka KS
1052 AM CDT Sat May 18 2019

KSZ035-037-181615-
Dickinson-Morris-
1052 AM CDT Sat May 18 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN DICKINSON AND MORRIS
COUNTIES UNTIL 1115 AM CDT...

At 1052 AM CDT, Doppler radar was tracking a strong thunderstorm near
Burdick, moving northeast at 20 mph.

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

Locations impacted include...
Herington, White City, Wilsey, Parkerville, Latimer, Council Grove
Lake and Burdick.

LAT...LON 3861 9693 3861 9702 3887 9692 3887 9686
      3872 9647 3852 9673 3852 9693
TIME...MOT...LOC 1552Z 212DEG 18KT 3855 9690

BD