Tornado and Hail in Kansas, April 15, 2017

Area Forecast Discussion
National Weather Service Topeka KS
638 AM CDT Sat Apr 15 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 308 AM CDT Sat Apr 15 2017

A broad upper level trough across the central Rockies will move east
across the plains states this afternoon and Tonight. The upper
trough will slowly fill as it moves east across the plains.

Weak isentropic lift ahead of deeper moisture advection may cause
isolated shower or an elevated thunderstorms to develop around 12Z
and last into the mid morning hours across the western and central
counties of the CWA.

A surface cold front will push southeast into the northwest counties
of CWA late this afternoon. Surface convergence along the front and
ascent ahead of the broad upper level trough will cause showers and
thunderstorms to develop along and ahead of the surface cold front
late this afternoon and evening. The NAM models has the slowest
solution with the front just entering the northwest corner of the
CWA by 00Z SUN. The WRF solutions along the the RAP model forecast
the front to move into north central KS around 21Z and for
thunderstorms to develop along the front. The 850mb and surface
winds will veer to the southwest ahead of the front thus the 0-6KM
effective shear will only be 20 to 30 KTS. MLCAPE will be in the
1500-2500 J/KG range which will be sufficient for strong to severe
thunderstorms to develop. Most models show linear forcing along the
front, thus a line of thunderstorms should develop. The primary
hazard would be damaging wind gusts from a line of thunderstorms. If
there are any rotating updrafts within the line, then there may be
an isolated large hail threat. The low-level shear looks weak, so
I'm not expecting any tornado threat.

Before the storms begin it will be another windy day across the
area. The low-level jet at 900mb should be in the 50 to 55 KT range,
thus once we begin to mix deeper after sunrise we may see some wind
gusts 40 to 45 MPH. Expect sustained winds in the 20 to 30 MPH range
with some gusts over 40 MPH. The stronger 850mb winds will translate
east of the CWA during the afternoon hours, so winds should diminish
a bit ahead of the surface front. However, there may be some strong
to severe wind gusts within the line of thunderstorms that will move
across the CWA during the late afternoon and evening hours.

The line of stronger thunderstorms will be pushing southeast of the
CWA by Midnight. There may be some scattered post frontal showers
and isolated elevated thunderstorms through the early morning hours
of Sunday. The greatest QPF will be across east central KS where a
half inch up to 1 inch of rain may fall late this afternoon through
Tonight. The northwest counties may only see a few hundredths as the
line of storms will begin to form over the northwest counties after
21Z and then push to the southeast.

Highs Today will reach the mid 70s to around 80. Overnight lows will
be a bit cooler behind the surface front with lows in the 50s.

.LONG TERM...(Sunday through Friday)
Issued at 308 AM CDT Sat Apr 15 2017

Scattered showers and isolated thunder clear southeast with the
frontal boundary Easter Sunday morning. Latest suite of models slow
the boundary from west to east a tad further north into southern KS
during the day Sunday. Decent isentropic lift over the boundary may
generate scattered showers and thunderstorms north of the front into
east central KS during the afternoon. Areas generally south of
Interstate 70 will see the best chance for precipitation. Meanwhile,
sfc ridge north of the boundary will keep the majority of the CWA
dry with partly to mostly sunny skies. Highs are a few degrees
cooler, yet still pleasant in the lower 70s. Winds will be much
weaker from the east at around 10 mph. Broad troughing centered over
the northern plains Sunday night lifts the front northward,
increasing shower and thunderstorm coverage over the entire CWA.
Meager instability and shear will preclude any severe weather,
however persistent light to moderate rainfall may pose concerns,
especially over far east central areas.

Should see a break in the precip Monday with temps recovering into
the lower and middle 70s. The break is short lived however as zonal
flow carries additional disturbances our way throughout the week.
Guidance has been fairly consistent on Tuesdays system, especially
near the NE border. The GFS is the far south solution, however the
ECMWF and Canadian are beginning to trend a bit further south,
leading to somewhat higher confidence in measurable qpf in far
northern KS. The front slows near the Kansas and Nebraska border,
becoming a focus for additional shower and thunderstorm chances
Wednesday and Thursday. Enhanced consistency between guidance at
this time lead to higher pops mentioned Wednesday evening for the
entire CWA. As subsidence builds behind the wave, may see a
legitimate break in rainfall Thursday with highs in the upper 60s.
Beginning to see a better signal for an organized upper low that
deepens across the Colorado Rockies before lifting northeast through
the CWA Friday into the weekend. Position of the trough axis would
place northeast KS on the northeast periphery of the low. Little to
no instability lead to a mention of mainly showers and isolated
thunder with cool advection from the northeast dropping temps below
normal into next weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 633 AM CDT Sat Apr 15 2017

There may be a few showers or elevated thunderstorms around the
terminals through the mid morning hours. Southerly surface winds
will pick up to 20 KTS with some gusts of 30 to 35 KTS between 13Z
to 18Z, then winds will decrease through the afternoon hours. A
line of storms will pass across the terminals through the early to
mid evening hours. Unsure of the exact timing so kept VCTS through
the evening hours. After the front passes winds will switch to the
northwest at 8 to 10 KTS.

&&

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

SHORT TERM...Gargan
LONG TERM...Prieto
AVIATION...Gargan

Hazardous Weather Outlook
National Weather Service Topeka KS
541 AM CDT Sat Apr 15 2017

KSZ008>012-020>024-026-034>040-054>056-058-059-161045-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
541 AM CDT Sat Apr 15 2017

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

.DAY ONE...Today and Tonight.

Strong to severe thunderstorms are possible late this afternoon
and evening across the outlook area. The main hazards are large
hail, damaging wind gusts and locally heavy rainfall.

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

As a series of storm systems make their way across the state
through the week, locally heavy rainfall is possible and could
bring localized flooding and river flooding. Stay tuned for
updates.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

&&

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