Area Forecast Discussion
Issued by NWS Topeka, KS

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532
FXUS63 KTOP 231728
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1228 PM CDT Wed May 23 2018

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 344 AM CDT Wed May 23 2018

Midlevel low pressure continues to spin over the Great Basin and is
forecasted to lift northeastward today. Any associated vorticity
maximums rotating around the base of the trough and lifting out over
the plains have and should remain west of the area. A few convective
complexes have developed in eastern NM and there is a very slight
chance any resulting MCVs or waves could lift northeastward
towards eastern KS. Therefore the environment today should lack
synoptic scale forcing. Day time heating is expected to be the a
mechanism for convective development across the area this
afternoon. Also, weak isentropic lift spreads northward out of OK
late this morning, which could support elevated convection within
the 700 mb moisture on the western periphery of the high over the
mid MS valley. With the lack of inhibition by early afternoon
additional storms could develop with a focus in east central and
southeast KS. Most of the CAMs support these storm chances, but
confidence in the extent of the coverage is low at this point.
There is an overall lack of deep layer shear to allow for long-
lived updrafts, but the MLCAPE could reach 2000 J/kg. If realized
this could support small hail and perhaps localized gusty winds
when the cells collapse to the surface. The convection should
dissipate in the early evening with the loss of surface heating.
High temperatures today are forecasted to reach the mid to upper
80s although depending on the storm and associated cloud debris
coverage the temperatures could be slightly cooler than expected
at some locations. With no major change in the surface pattern
wind speeds go light and variable tonight. Patchy fog may be
possible late tonight especially in low lying areas that receive
rain today, but the better chances are in MO closer to the surface
high. There are some signs that some isentropic lift could
develop late tonight over portions of central KS/NE, and
convection could be possible especially close to sunrise.

.LONG TERM...(Thursday through Tuesday)
Issued at 344 AM CDT Wed May 23 2018

On Thursday and Thursday night the upper level trough will move
across the northern Plains and into southern Ontario Canada. The
southern extent of the trough will extend south across the central
Plains. Once again on Thursday afternoon and unstable airmass is
expected to be in place with little convective inhibition in a weakly
sheared environment amidst steepening lapse rates. Isolated to
scattered pulse type convection is expected to develop during the
afternoon and evening hours with locally heavy rainfall and gusty
winds as the main hazards. Overnight Thursday models continue to
hint at MCS development across Nebraska and northern Kansas with the
complex traversing east southeast across the cwa into Friday
morning. Good moisture transport initially across western Kansas
into central Nebraska is forecast to veer and across eastern Kansas
Thursday night should help to sustain the MCS as it tracks east
southeast and builds into the lower to mid level rich theta-e air,
therefore will continue with higher chances of precipitation.
Later Friday afternoon and evening additional storms are possible
along residual boundaries left over from the morning convection
and near a weakly defined surface boundary across south central
Nebraska into north central Kansas. Steep lapse rates are expected
to be in place and northwesterly flow aloft will enhance the
shear along the boundaries within an unstable air mass. A few
strong to severe storms are possible with damaging wind gusts and
large hail the main hazards.

For the Memorial Day weekend an upper level ridge will build across
the Plains as an upper level trough/low remains across the western
states. A moist airmass will continue to remain in place resulting
in some isolated thunderstorms possibly forming during the afternoon
and evening hours. On Tuesday some energy looks to move out of the
base of the trough and into north central Kansas increasing the
chances for showers and thunderstorms. Temperatures will continue to
remain around 10 to 15 degrees above normal for late May with highs
in the upper 80s to mid 90s and lows in the 60s to around 70.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1226 PM CDT Wed May 23 2018

VFR conditions are expected through the period with isolated
thunderstorms this afternoon. Did mention VCTS for MHK for mid-
afternoon given the ongoing convection to the SSE along a N-S
boundary, but given the weak and transient nature of the storms,
did not mention in the TOP/FOE TAFs. Winds will remain from the
south at 5 to 15 kts.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...53
AVIATION...Skow



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