River Flood Warning 17, NWS Topeka, KS

Area Forecast Discussion
National Weather Service Topeka KS
648 PM CDT Thu Jun 18 2020

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday)
Issued at 158 PM CDT Thu Jun 18 2020

Surface map at 18z shows low pressure centered across southwest
Kansas with a stationary front extending northeast toward Grand
Island Neb. MLCAPE near the boundary is now around 2000 with
little CIN remaining. Effective shear is forecast to gradually
rise toward 20-25kts by evening. The atmosphere appears to
support a risk for wind or marginal hail with max instability
this evening. Water vapor also shows a subtle wave across the TX
panhandle while the mid to upper level ridge axis remains over
eastern KS.

Tonight...most likely scenario appears to be one where diurnally
driven storms impact northern KS this evening with a some risk for
severe wind/marginal hail then additional storms should develop
later tonight along the 925-850mb front. High PWATS and weak
steering flow aloft combined with 30-35kt LLJ will aid in the
heavy rain threat. Location of greatest coverage of storms after
midnight is uncertain but trends are suggesting along a Council
Grove to Lawrence southward later tonight where training could set
up after 9z.

Recent model signals appear to suggest that the weak wave now
across TX panhandle will drift NE and could contribute to forcing
during the day on Friday so there could be a prolonged period of
rainfall/convection mainly along/south of I-70 at least into
midday across the area. Heavy rains would be a threat if this
scenario occurs. At this point the HRRR and ARW WRF along with the
NAM80 all show some version of this scenario. Have raised precip
chcs into midday based on this potential. As mentioned given the
high PWATS and weak steering combined with some risk for training
it appears that local areas could see in excess of 2 inches.

Given the dry conditions and rainfall deficits over
the past month will not issue a flood watch but as mentioned given
the set up it appears there's the potential for amounts in excess
of 2 inches in spots late tonight through Friday morning.

.LONG TERM...(Friday night through Thursday)
Issued at 158 PM CDT Thu Jun 18 2020

The mesoscale situation on Friday night is low confidence and
dependent on how the convection evolves on Friday. The wave now
across NV is forecast to emerge into the Plains Friday night so
would expect some response with convection across eastern CO into
western KS Friday night but there's uncertainty how far east any
organized complex would get or if it would move more ESE into the
re-developing 850 jet so for now will keep the high chc/low likely
pops but confidence in coverage Fri night is low at this point.

The wave will move across the state on Saturday with a sfc low
forecast to drift east across the area into the afternoon. Timing
of this wave will be critical to determining how widespread
additional storms may be by afternoon with the NAM and GFS both
showing veering winds at 850mb by 00Z so for now it still appears
that there could be some risk for severe weather mainly across the
northeast half of the area on Saturday afternoon as the mid level
speed max moves across the area. Believe or not there may be a quiet
night on Sat night/early Sunday morning as the wave departs and
weak ridging moves in. However any break will be short as another
wave will approach on Sunday afternoon and wind fields will
respond with WAA in the low levels re-developing while mid level
WNW flow increases. This may set the stage for a more widespread
convective complex/severe event on Sunday evening or Sun night
with a forward propagating complex moving SE across some part of
central KS.

The flow aloft will become more northwesterly with another wave
fcst to drop into the region later Monday so there could be
another bout of storms and severe wx sometime late Monday into
Monday night but timing/location remain to be determined. At some
point drier more stable air may move into the area and provide at
least a short break from the storms by the middle of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 648 PM CDT Thu Jun 18 2020

Convection has started in north central KS and may impact KMHK
within the next few hours. Model trends continue to develop more
widespread TSRA mainly after 09z at KTOP/KFOE with low confidence
remaining in overall convective coverage and evolution through the
day Friday. Have kept general VCTS at this point until confidence
increases. Next issuance may be able to better pinpoint rain
chances through the day Friday.

&&

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

SHORT TERM...Omitt
LONG TERM...Omitt
AVIATION...Flanagan

Hazardous Weather Outlook...UPDATED
National Weather Service Topeka KS
327 PM CDT Thu Jun 18 2020

KSZ008>012-020>024-026-034>040-054>056-058-059-192030-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
327 PM CDT Thu Jun 18 2020

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

.DAY ONE...This Afternoon and tonight.

Thunderstorms are expected to develop late this afternoon and
early this evening in central and northern Kansas. Some of these
storms may initially be severe in the late afternoon and evening,
with damaging wind gusts and locally heavy rainfall the primary
hazards.

Additional storms will develop after midnight along and south of
Interstate 70. Those storms will be capable of producing heavy
rains.

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

Thunderstorm chances continue each day through the weekend, and
likely into early next week, as several systems move over the
state.

Repeated rounds of rain will bring locally heavy rainfall
to some locations, but flooding chances will be highly dependent
on if an area gets multiple rounds of rain. Generally one to
three inches of rain are forecast, but higher amounts will occur.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

&&

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