Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 211040

Area Forecast Discussion
National Weather Service Topeka KS
540 AM CDT Mon Sep 21 2020

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 303 AM CDT Mon Sep 21 2020

The central part of the CONUS remains under a mid-level ridge,
placed between Tropical Storm Beta off the TX coast and a trough in
the Northern Plains and southern Canada. With no notable changes in
air mass, this leaves similar conditions to what we`ve seen the last
several days with highs in the upper 70s to low 80s and lows in the
mid to upper 50s. The pressure gradient becomes more relaxed
compared to the past weekend, so while north central KS will still
be a bit breezy, we`ll be less windy overall. Could see temps being
a few degrees cooler than currently forecast since 850mb temps in OK
are cooler and that air gets advected north with continued southerly
flow; however 850mb flow weakens slightly into the daytime hours so
this should only be a minor impact.

.LONG TERM...(Tuesday through Sunday)
Issued at 303 AM CDT Mon Sep 21 2020

TS Beta continues to move inland with moisture looking to reach
southeast KS by Tuesday morning. While the bulk of the precip is
most likely to stay south and east of our area into MO as the upper
low tracks northeast, can`t entirely rule out a few showers clipping
parts of east central KS Tuesday evening into early Wednesday. A
building ridge in the southwestern US then impacts our weather for
the latter part of the work week. In the meantime, a weak frontal
boundary drops south from the Northern Plains Wednesday into early
Thursday but washes out over NE, so is not expected to have an
impact on temp changes or precip chances. WAA does increase Thursday
and Friday as the ridge builds in, however, so highs warm to the mid
to upper 80s with lows in the upper 50s to low 60s.

For next weekend, the ECMWF/GFS/Canadian models all depict a cold
front associated with another upper trough translating across the
High Plains. There are a few timing differences that will need to be
worked out in the coming days and precip chances are still uncertain
this far out as well. The GFS suggests the bulk of the rain may not
develop until after the front has passed the area, while the ECMWF
fails to generate any precip over our area likely due to weak sfc
convergence with better upper lift to our north. As a result, only
have low end chance PoPs Saturday into Sunday for now. High temps
cool back down to the 70s area-wide by Sunday.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 538 AM CDT Mon Sep 21 2020

Winds start light from the south before increasing late this
morning and remaining at 10-15 kts through the afternoon. They
diminish this evening and slightly turn to the SSE. VFR conditions




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