Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 230446

Area Forecast Discussion
National Weather Service Topeka KS
1146 PM CDT Tue May 22 2018

...Update to aviation forecast discussion...

.DISCUSSION...(Tonight through Wednesday evening)
Issued at 1121 PM CDT Tue May 22 2018

As of 18Z Tuesday afternoon a cutoff upper low continues to weaken
across the southwestern US. A remnant MCV from the overnight
convection in eastern NM is lifting northeastward across the high
Plains of CO and KS. Latest CAM guidance is consistent with
thunderstorm development across western KS this afternoon. Without
the presence of substantial deep layer shear, storm motion will
primarily be with the mean flow, which is largely meridional. As
a result expect shower and thunderstorm activity to remain west of
the CWA tonight. Transitioning into the overnight, the only
concern of note is the possibility for patchy, shallow ground fog
-- especially in valleys/low lying areas -- near dawn Wednesday
morning. Otherwise a quiet night is expected with lows in the mid

Upper level ridge will continue to amplify across the central
Plains throughout the day Wednesday as an upper trough digs into
the northeastern US. Lee cyclone across western NE will result in
modest low-level mass response across the CWA with dew points
reaching the mid to upper 60s tomorrow afternoon. This moist
boundary layer coupled with modest mid-level lapse rates will
yield 1000-2000 J/kg of MLCAPE across the area. NAM/GFS and CAM
solutions continue to generate isolated to scattered QPF across
the southeastern 1/3 of the CWA. This matches up well with the
area of deepest moisture and weakest inhibition. Little deep layer
shear should promote short-lived, pulse convection with the
primary hazards including gusty winds and brief heavy rain. A
nearly identical setup is expected Thursday afternoon, with short-
lived, pulse convection during peak heating of the day. By
Thursday night the remnant upper low across the southwestern US
will eject into the northern Plains as an open wave. ECMWF/GFS/NAM
solutions all suggest an MCS should traverse portions of the
central and northern Plains late Thursday night/Friday morning as
an associated weak surface trough traverses the area. For the
remainder of the holiday weekend, upper level ridge will amplify
across the central US. A continued moist boundary layer may result
in isolated thunderstorms during peak heating throughout the
weekend. That being said, confidence is low in thunderstorm
coverage, given the lack of synoptic scale forcing. In regards to
temperatures, well-above normal temperatures will continue
through the holiday weekend with highs in upper 80s to low 90s and
lows in the 60s.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1121 PM CDT Tue May 22 2018

VFR conditions are expected throughout the period. There may be
some patchy ground fog tonight but no visibility restrictions are




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