Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 141707

Area Forecast Discussion
National Weather Service Topeka KS
1207 PM CDT Mon May 14 2018

Issued at 1207 PM CDT Mon May 14 2018

A complex severe weather threat exists for this afternoon and
evening across portions of northeast and east central Kansas with
hail and wind the main threat.

An elevated line of convection rolled across portions of north
central and northeastern Kansas this morning and gradually waned
as the morning wore on. This line appears to have been tied to
weak ribbon of H800 theta-e advection, but most 06/12Z guidance
failed to resolve this convection. This early round of convection
will likely reinforce and shunt southward the synoptic stationary
front bifurcating NE Kansas from NE to SW. By midday, surface
observations and radar data depicted the outflow boundary/front
along a line from Brown to Morris counties and pushing to the SE.

Shallow warm sector convection has begun festering over the SE
portions of the CWA and this trend is expected to continue given
the lack of CINH in the forecast RAP soundings. The focus for
renewed, deeper convection will be along the frontal boundary over
the next few hours with warm sector MLCAPE values of 2000-3000
J/kg. However, the lack of strong convergence and weak CINH,
combined with only marginal deep shear and backed mid-level winds,
will result in a complex initial storm mode with a mixture of
discrete and multi-cell clusters possible at first, growing
upscale into line segments. Low-level southerly inflow winds are
progged to be weak with speeds of only 5 to 10 kts, but there is
enough SRH in the lower profiles of the atmosphere to warrant a
non-zero tornado risk, especially near the surface boundary.


.SHORT TERM...(Today and tonight)
Issued at 320 AM CDT Mon May 14 2018

Unsettled pattern remains over the central plains states overnight
as elongated surface front continues to bisect the forecast area
under southwesterly flow aloft. Initial wave of convection has
lifted into Nebraska at this hour, leaving behind outflow boundaries
and mesoscale convective vortices.  As a result, forecast is
heavily impacted by small scale features that synoptic models dont
resolve well, and CAMs give variations on how the day pans out.  Am
leaning toward NAM/HRRR solutions which may have some initial
residual showers or an isolated storm, but the bulk of rain chances
come later this afternoon as instability builds along the surface
boundary and redevelops storms mid afternoon through the evening and
overnight hours. Once again plenty of instability to work with,
steep mid level lapse rates, and slightly better directional shear -
making wind and large hail once again the primary hazards. Clouds
and outflow also having an impact on high temperatures and have gone
a little cooler across north central Kansas in the middle 70s with
middle to upper 80s along the I70 corridor and southward.  May also
get some locally heavy rainfall with these storms, particularly
across east central Kansas.

.LONG TERM...(Tuesday through Sunday)
Issued at 320 AM CDT Mon May 14 2018

There may be a few lingering showers and thunderstorms Tuesday
morning from the overnight convection, however most of it should be
confined to southern Kansas. By Tuesday morning the frontal boundary
is progged to be positioned over northern Oklahoma. Weak embedded
waves within the westerly flow aloft may spark a few showers and
thunderstorms in the afternoon and evening hours. However with the
optimal low level convergence to our south, it is more likely for
northeast Kansas to remain dry. On Wednesday, the latest NAM, GFS,
and ECMWF solutions are coming in better agreement with an organized
shortwave trough coming off the CO Rockies. Southerly flow lifting
over the frontal boundary develops scattered showers and
thunderstorms Wednesday afternoon and evening. At this time, best
chances appear south of Interstate 70. Weak unidirectional shear
profiles suggest multicellular storm modes and a low threat for
severe weather. Both the GFS and ECMWF are coming into better
agreement on a weak mid level ridge traversing over the central
plains Thursday, providing a brief break in rain chances. For those
areas needing rainfall, the next major system to impact the area
Saturday and Sunday is looking more promising in terms of widespread
precip. A strong cold front also passes through the CWA, cooling
temps from the 80s, back towards normal values in the middle 70s on


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 605 AM CDT Mon May 14 2018

Forecast is primarily impacted by onset of convection and lower
cigs/visby such storms could bring. Not high enough confidence in
timing and placement for a tempo group just yet, but will keep a
late afternoon wind shift with some sct lower clouds with it and
vicinity thunder. Guidance coming out with some low cigs (AOB 003)
and will need to watch for this as data comes in today.




LONG TERM...Prieto
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