Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 262330

Area Forecast Discussion
National Weather Service Topeka KS
630 PM CDT Sat May 26 2018

...Update to aviation forecast discussion...

.Discussion...(This evening through next Saturday)
Issued at 240 PM CDT Sat May 26 2018

Unseasonably warm temperatures will be the story for the
remainder of the holiday weekend, with the possibility of storms
this afternoon and again midweek.

Northeast Kansas was baking under a late May sun this afternoon
with highs toping out in the 90s to even near 100 along the KS/NE
border where a drier airmass promoted more efficient warming. Heat
indicies were about the same throughout the region with dewpoints
10+ degrees higher further south. A band of cumulus clouds has
developed across Brown and Nemaha counties in the last hour or so
along the gradient between these airmasses where weak surface
convergence was also noted. All 12Z HREF members and daytime runs
of the HRRR has indicated that convective initiation will take
place around 20-21Z in this region. With 2000 J/kg of MLCAPE but
weak vertical wind shear, robust but short-lived cell clusters are
anticipated along and east of a line from Marysville to Topeka
this afternoon and evening, ending by 01-03Z as they propagate
S/SW on the collective outflow boundary. With ample mixing today,
DCAPE values of 1500-1800 J/kg will promote efficient downward
momentum transport and downburst winds with any convective cell.
Thus, cannot rule out a severe wind gust with any thunderstorm
this afternoon. The threat for small hail will also exist given
the degree of instability.

High clouds spilling over the top of the approaching H300 ridge
are progged to move into NE Kansas this evening and tonight,
though all synoptic and short-range solutions are failing to
resolve these clouds. Thus have leveraged satellite imagery tends
to advect the cirrostratus shield in overnight. These clouds
linger throughout much of the day tomorrow and call into question
how high temperatures will climb in the afternoon. For now have
kept the going forecast for near record to record highs, but there
is some concern that high clouds may temper these readings by 2-4

The upper level ridge pushes east by Sunday night with SW flow
for Monday and Tuesday. The cutoff low over the SW U.S. migrates
northeastward for Monday into Tuesday, dragging a frontal boundary
slowly eastward over the High Plains and Mid-Missouri River
valley. This will serve as the focus for shower and thunderstorm
development midweek, though confidence in timing and placement of
these storms is on the low side. These storms may temper highs
somewhat, but looks for continued above average temperatures
throughout the seven day forecast.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 619 PM CDT Sat May 26 2018

VFR prevails at terminals. Despite the short term models showing
convection forming near terminals, current radar and satellite
trends suggest there is not enough focused lift or boundary to
warrant a mention for VCTS through 02Z.




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