Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 291124
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
624 AM CDT THU SEP 29 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 245 AM CDT Thu Sep 29 2016

Main upper jet over the continent was from the Pacific Northwest
into eastern Canada per water vapor imagery with blocking regime
over much of the CONUS with upper ridge over the High Plains between
the lows off the coast of British Columbia and over the Ohio Valley.
Surface ridge axis was just east of the upper ridge axis with bits
of stratus in eastern Kansas identified on recent satellite fog
enhancement product and nearby surface obs.

Little change in synoptic situation expected through tonight. North-
northeast low level flow keeps lower level temp fields fairly steady
for highs again around 70 anticipated. May see some stratus in the
mid morning to early afternoon as mixing increases but mainly clear
skies should dominate. Low temps tonight again should be close to
persistence in the mid to upper 40s.

.LONG TERM...(Friday through Wednesday)
Issued at 245 AM CDT Thu Sep 29 2016

Upper low over the Ohio Valley stays nearly stationary Thursday
night into early Saturday, even retrograding back westward a bit
for this time frame. This keeps northerly flow over our area and
cooler daytime temperatures in the middle 70s, with lows in the
40s to 50s. As the warmer temps advect back over the state
Saturday night, EC spits out some light qpf as the LLJ moves
through, while the GFS remains dry and have a dry forecast at
this time considering much saturating needed for precip. Warm
advection brings temperatures back up for Sunday into Monday as
southerly flow returns and highs rise back into the 70s/80s.

Western counties could see some slight chances for rain by the
early hours of Tuesday, but better chances come as upper trof
approaches and associated surface front passes through Tuesday
through the day and into the evening hours. Still model
differences in the system, with the EC swinging a negatively
tilted trof over Kansas early Wednesday, while the GFS splits the
energy into a northern and southern component and swings across an
open wave. Neither solution has much instability to work with,
although both bring across stronger dynamics with their respective
waves. GFS ensemble spreads still vary considerably and will not
delve into specifics this far out given uncertainties. Dropped
highs back into the 70s with clouds and precip, with warmer lows
in 50s and 60s in southerly flow regime.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 624 AM CDT Thu Sep 29 2016

VFR conditions anticipated. Greatest threat of restrictions will
likely come at the end of this forecast when winds could be weak
enough for some BR to form, but this still looks unlikely.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...65
LONG TERM...67
AVIATION...65


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