Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 162026

Area Forecast Discussion
National Weather Service Topeka KS
326 PM CDT Fri Mar 16 2018

.SHORT TERM...(This evening through Saturday)
Issued at 255 PM CDT Fri Mar 16 2018

Short-term forecast for this bulk of the afternoon still hints that
there is a very minimal chance and short window of opportunity for a
strong storm to develop and still can`t rule out a brief tornado
based on the environmental vorticity available (generally just to
the southeast of the LWC vicinity). Some storms have been developing
just southeast of the LWC area within an a region of higher mixing
ratios and higher theta-e air. Meager MLCAPE values lie within the
axis of instability on the order of a few hundred J/kg and are
resulting in previous convective rolls developing into an area of
agitated cu field per GOES-16 mesoscale sector 1-minute resolution
data.  This narrow area is being squeezed and shunted to the
southeast fairly quickly as the afternoon progresses with the
advancing upper cold core low and surface frontal boundaries with
the triple point now near the Topeka area. WSR-88D still shows some
areas of showers over northeastern KS just to the north of I-70 into
the KTOP area with very light returns. Therefore, even with plenty
of low level SRH with values on the order of 200-300 m2/s2, it would
appear not enough moisture and instability exits for too much in the
way of development.  Based on forecast soundings and also GOES-16 WV
imagery, it appears too much of an EML may have remained in place
points west of the current areas seeing isolated storm development.
In short, the window on storms for the forecast area does have a
very small window left in extreme eastern areas, but that appears to
be rapidly closing.

Rest of the forecast for tonight and Saturday will remain dry after
this evening with any chances of wrap around showers with the cold
core feature coming to an end as the mid level closed low passes
over the area and begins to fill as it moves east being pushed along
by another sharp ridging feature building into the area during the
day Saturday.  Winds continue to veer to the south over the
afternoon in areas impacted by fire weather concerns.  Due to strong
winds and dry conditions with fuels still mostly cured, have left
Red Flag warning in place until this evening.  It is possible it may
be canceled early, but again changing winds through the 01Z time
frame will be the main concern for fire crews should any fires
develop.  Winds change to a northwesterly direction into the
overnight period.

Overnight lows reach the low 30s out over northcentral areas and
remain near 40 near east central KS.  Winds slowly calm back down
Saturday with another gradient of temps remaining from near 60 over
central KS to around 50 over extreme northeastern KS.

.LONG TERM...(Saturday night through Friday)
Issued at 255 PM CDT Fri Mar 16 2018

On Sunday a midlevel shortwave trough will dig across the Four
Corner region. As the trough progresses eastward it becomes
negatively tilted and closes off. On Sunday evening the deepening
low is forecasted to eject out of the Rockies. Upper-level
diffluence and left exit region divergence as well as differential
positive vorticity advection spreads eastward Sunday night and
provides large scale lift across northeast KS. The GFS tracks the
midlevel low near and along the OK/KS state line with the ECMWF
south of that. There will be substantial poleward mass flux on
Sunday that results in PWATs reaching upwards of 0.75" and the
900-700 mb moisture transport focusing over eastern KS. This
appreciable low-level moisture beneath steep midlevel lapse rates
will yield some instability. Surface-based convection is more
likely across portions of central KS, which is where the dry line
will be present during peak diurnal heating. The zone of buoyancy
east of the surface cyclone could provide enough instability for
some storms to maintain strength into Sunday evening. The
northward and eastward extend of this surface-based convection
will be dictated by the positioning of the warm front and deeper
low-level moisture. As of now some models depict the front
reaching portions of eastern KS therefore the risk for a strong to
severe storm is non-zero. Given the amount of forcing storm mode
is highly uncertain as well as the track of the midlevel low. The
widespread precipitation supported by the large scale forcing
appears to linger into Monday. Cooler temperatures advect into the
area behind the departing system that could be cold enough to
support a rain snow mix Monday night and Tuesday morning.
Northwest flow aloft continues into Thursday with ridging ahead of
the next trough by Friday. Generally highs will be in the 50s and
lows in the 30s.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1245 PM CDT Fri Mar 16 2018

For the 18Z TAFs, MVFR conditions will be transitioning to mostly
VFR in the next 2 to 4 hours after a small window for for showers
and perhaps a thunderstorm works over the area. A low pressure
system slowly transitions over the area through the evening, so
winds will remain gusty at times and begin to veer progressively
this afternoon and overnight before eventually becoming
northwesterly by early morning time frame. Expect a few hours of
gusty winds once again as winds do become northwesterly with
additional wrap around clouds that could bring categories back to
MVFR for a period near the end of the forecast.


Red Flag Warning until 8 PM CDT this evening for KSZ034>038-



LONG TERM...Sanders
AVIATION...Drake is the U.S. government's official web portal to all federal, state and local government web resources and services.