Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 142102
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
302 PM CST Sun Jan 14 2018

.SHORT TERM...(This evening through Monday)
Issued at 300 PM CST Sun Jan 14 2018

This afternoon skies have cleared across much of the CWA. southwest
winds ahead of a weak surface trough across central KS has caused
some weak WAA with temperatures in snow free areas of central and
south central KS climbing into the mid 40s. Temperatures across the
southwest counties have warmed into the mid to upper 30s.

Tonight...an intense upper level trough across south central Canada
will dig southward into the upper midwest. A 95 KT H5 jet max was
digging south-southeast across the northern high plains into the
central plains, on the west side of the intense upper level trough
across south central Canada. As the H5 jet max shifts southeast
across the plains the right exit region of the jet will move
northwest to southeast across the CWA during the early morning
hours. Strong frontogenetical forcing will develop at 700mb from
central NE  this evening and expand southeast into south central and
southeast KS during the early morning hours. This will provide
additional ascent for a band of light to moderate snow to develop.
Due to the speed at which the H5 trough and associated jet max will
dig southeast across the midwest and central plains the light to
moderate snow band will move quickly southeast across the CWA during
the early morning hours of Monday.

Forecast sounding profiles show a warm nose of 2 to 4 degrees at
920mb which may cause the precip to fall as light rain in the mid
evening hours across the western counties of the CWA, and perhaps a
mix of precip across east central KS. Though wet-bulb cooling should
cause the warm nose to cool down to or below 1 deg C after the first
hour or two of light precip so that an all snow pattern develops.
The potential heavier band of snow will develop along the I-70
corridor and move southward across southeast KS from 6Z through 10Z.
At this time it looks like around 1 inch of snow will fall along the
I-70 corridor with up to 2 inches across the extreme southern
counties of the CWA. There could even be some 3 inch snow reports
across south of a Chapman, to Ottawa line. However, some of the
higher resolution grid models show less snow accumulations with near
an inch along I-70 and up to 1.5 inches in our southern counties.
Most of the snow will fall between 6Z and 9Z. North of I-70 expect
less than an inch of snowfall. Therefore, I have issued a winter
weather advisory along the I-70 corridor southward across the
southern counties of the CWA from 5Z MON through 15Z MON.

Strong low-level CAA was pushing an arctic front southward into
northern NE this afternoon. This front will move southward across
the CWA after midnight and bring in a much colder airmass. In fact,
some of the most treacherous road conditions may be when the snow
ends and the arctic air arrives between 8Z and 15Z, since any snow
that melts on treated roadways may freeze once temperatures drop
through the teens late Tonight and early Monday morning.

Monday, any lingering light snow in the southeast counties will end
during the mid morning hours. Skies will clear from west to east
across the CWA during the afternoon hours. However the strong CAA
will only allow highs to struggle into the mid to upper teens. Areas
along the NE border may not reach 10 degrees for highs. northwest
winds of 15 to 20 MPH with higher gusts will cause wind chill values
to be in the single digits below zero.

.LONG TERM...(Monday night through Sunday)
Issued at 300 PM CST Sun Jan 14 2018

The strong Arctic high pressure center will continue to build into
the region producing wind chills Monday night and Tuesday morning
down into the -15 to -24F range area wide. Consensus with
surrounding offices is to go ahead and issue a wind chill advisory
for the entire area for Monday night through midday Tuesday. Given
modest but new snow pack feel that lows should fall to 0 to -5F
across the entire area despite the northwest winds of 5 to 10 mph.

The high center will settle across the area Tuesday night into
Weds so another cold night appears in store with lows approaching
zero again before a substantial warm up begins on Weds and
persists into late next week. Highs by Friday and Saturday could
be approaching or exceeding 50. The longwave pattern by late next
week into next weekend suggests the potential for a storm system
to move across the region with rain or snow possible by Sunday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1148 AM CST Sun Jan 14 2018

Expect VFR conditions through mid evening. A band of light to
possibly moderate snow at times will move southward across the
terminals after 3Z MON. At this time I placed in 3SM visibilities
in light snow from 4Z to 9Z at KTOP and KFOE and from 3Z to 8Z at
KMHK. An arctic front will move southward across the terminals
after 9Z switching winds to the north-northwest and these winds
will increase to 12 to 15 KTS with gusts of 20 to 25KTS through
the morning hours of Monday.


&&

.TOP WATCHES/WARNINGS/ADVISORIES...

Winter Weather Advisory from 11 PM this evening to 9 AM CST
Monday for KSZ021>023-026-034>040-054>056-058-059.

Wind Chill Advisory from 6 PM Monday to noon CST Tuesday for
KSZ008>012-020>024-026-034>040-054>056-058-059.

&&

$$

SHORT TERM...Gargan
LONG TERM...Omitt
AVIATION...Gargan


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