Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 121749
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1149 AM CST Sun Nov 12 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 309 AM CST Sun Nov 12 2017

Early this morning an upper level trough axis extended from northern
WI, southwest across western MO. The upper trough will amplify as it
shifts east across the Great lakes states and lower MS river valley.
A weak surface front was located across the western CWA and will
move southeast across the entire CWA by 12Z. As the H5 trough
amplifies across the mid MS river valley Today, stronger isentropic
downglide should begin to clear the stratus from northwest to
southeast across the CWA during the afternoon hours. The RAP model
is the slowest with the clearing and shows the far eastern counties
not clearing out until sunset. The NAM and GFS models show most of
the area should clear out by 19Z. Highs Today will only reach the
lower 50s even with areas that do see insolation, since there will
be weak CAA.

Tonight, skies will be mostly clear. A surface ridge of high
pressure will move east across the CWA. Expect light winds with lows
reaching the lower to mid 30s. Cross-over temperatures will probably
be in the lower 30s Sunday afternoon and with overnight lows
dropping off into the lower 30s we may see patchy to areas of ground
fog developing through the early morning hours of Monday.

.LONG TERM...(Monday through Saturday)
Issued at 309 AM CST Sun Nov 12 2017

Will continue with fog for mainly eastern areas Monday morning
until mixing increases. The drying of the lower troposphere is
brief as south-southwest winds bring increasing moisture back to
the area with lower cloud returning by late afternoon. The warm
air in the mid-levels remains with isentropic upglide and
saturation occurring below Monday night into Tuesday. The lift
isn`t as impressive as was the case in the past 24 hours, so am
comfortable keeping a smaller PoP in place, but could see a
scenario where some drizzle reaches the ground at most locations.
Shortwave moving across the northern Plains brings a Pacific cold
front through Tuesday night for a better chance for measurable
rain. Models continue to vary on home much instability can be
generated as the moisture deepens and dynamic cooling occurs
aloft, but have kept some thunder at this point. This front stalls
over Oklahoma Wednesday as a stronger wave begins to impact the
Pacific Northwest. Although details become more uncertain, another
drizzle setup looks possible Thursday and Thursday night. Timing
of the front with this next fast-moving wave varies considerably,
but the deeper moisture should be to the east and keep convective
potential low. There is good agreement in strong wind fields with
this system and some wind and fire weather parameters of concern
could develop around Friday. Northwest flow and another modified
Pacific airmass keeps Saturday dry.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1145 AM CST Sun Nov 12 2017

Stratus deck continues to progress southward across the area. Cigs
will return to VFR near 19Z at MHK and between 20-21Z at the
Topeka terminals. Expect fog to develop after 07Z overnight, some
of which could be dense at times. Uncertainty arise with low
level stratus. Currently have a scattered LIFR deck at all
terminals, although future outlooks may have to increase sky
cover. If cigs do form, they look to persist through the end of
the period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Gargan
LONG TERM...65
AVIATION...Baerg



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