Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 160434

1134 PM CDT Mon Sep 15 2014


.SHORT TERM...(This Evening through Tuesday)
Issued at 314 PM CDT MON SEP 15 2014

Clouds and some light drizzle are moving slowly southeast across the
forecast area today, associated with a cold front dropping southward
across the Central Plains.  Temperatures under incoming high
pressure generally near 60 with dewpoints in the lower 40s.

Do expect skies to clear later this afternoon and leave light winds
and mostly clear skies for the overnight hours. Think however that
airmass coming in will be dry enough to not warrant widespread fog,
although could certainly see another morning of fog near water
bodies like this past weekend.  Cooler lows tonight in the 40s rise
to highs in the upper 60s to low 70s for Tuesday under mostly sunny

.LONG TERM...(Tuesday Night through Monday)
Issued at 314 PM CDT MON SEP 15 2014

Moderate upper northwest flow to dominate the middle week periods.
Weak lee surface cyclogenesis near the northern High Plains and
exiting high pressure will lead to mid level isentropic lift and
frontogenesis over the Central Plains Tuesday night into early
Thursday. Models have been very consistent with precipitation
breaking out in mainly the overnight periods when nocturnal
increases in lower level parcel trajectories occur. Tuesday night
currently looks to be the more active and threatening period with a
weak upper wave`s passage and elevated CAPE values of 1000 to near
3000 J/kg though moisture fluxes and shear are not very strong in
still modest flow and lapse rates are not extreme. At this point
expect a few storms could briefly approach severe hail production.
Have left PoPs in chance range but some locations could see a
few rounds of storms as motion vectors change little with some
potential for locally heavy rain. Upper ridge builds east into the
Plains Thursday and should end chances for a third night of precip
potential Thursday night. 850-925MB temperature gradient overhead and
when timing of precip waning in the daytime hours leads to a lower
confidence high temperature forecast for Wednesday and Thursday.

The drier conditions extend into most of Friday, but timing of the
next upper trough and cold front`s progression east is fairly
consistent in the Friday night to Saturday night periods. There
are some suggestions of the old tropical system maintaining some
continuity this far northeast, but a fairly deep moisture profile
should be in place in any event. Friday temps should reach well
into the 80s and fall back into mainly the 70s for Sunday and
Monday as secondary Canadian high pressure builds in behind the


.AVIATION...(For the 06Z TAFs through 06Z Tuesday Night)
Issued at 1134 PM CDT MON SEP 15 2014

Conditions continue to point to possible ground fog developing
around sunrise. Concerns are the moisture is very shallow and there
could be just enough mixing of dry air to prevent fog. But with
forecast soundings shows a narrow window where the boundary layer
decouples combined with moisture from the KS river, think there is
a good enough chance to keep the tempo for ground fog. TOP tends
to go down hard if it forms so continued with IFR VSBY at TOP,
with MVFR VSBY possible at MHK and FOE. Otherwise the forecast
should be VFR. Looks like any elevated storms would hold off until
late in the period or after 06Z. However think clouds will be on
the increase early in the evening and later shifts will need to
monitor whether a cloud deck moves in below 3 KFT.





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