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Area forecast discussion
National Weather Service Topeka Kansas
1140 am CST Thu Nov 21 2019

..update to aviation forecast discussion...

Short term...(today and tonight)
issued at 346 am CST Thu Nov 21 2019

A surface cold front was moving southeast across east central Kansas
this morning. A line of showers and scattered thunderstorms extended
from Lawrence southwest through Emporia at 220 am and will move
southeast into western MO, as the surface cold front shifts
southeast of the County Warning Area by 12z. The upper level trough that lifted
northeast across Kansas early this morning will shift northeast across
Iowa and MO today and into the Great Lakes states tonight. A
surface ridge of high pressure will build southward across eastern
Kansas this afternoon, so north-northwest winds may diminish a bit
this afternoon. A more amplified closed low, centered across
southeast California will shift east across the southwestern US today.
Highs across the southeast counties will probably occur this
morning with temperatures slowly falling through the day into the
40s. Highs elsewhere will be in the lower to mid 40s.

Tonight, the upper low across the southwestern US will shift east
into the central and southern High Plains by 12z Friday. Ahead of
the closed upper low, mid level DCVA will cause stronger ascent
across western Kansas and a 50 knots mid level jet Max will move
northeast across the Texas Panhandle. The large scale ascent will cause
light snow to develop across western KS, which will slowly spread
east into north central Kansas towards sunrise. At the same time low-
level cold air advection will be advecting drier air southward across the cwa, so
the low-levels may take a while to saturate enough for measurable
light snow, may be just flurries at first. Lows will drop into
mid to upper 20s.

Long term...(friday through wednesday)
issued at 346 am CST Thu Nov 21 2019

Friday through Friday night, the upper low will fill as it moves
east across the State of Kansas. The best chance for light snow during
the morning hours will be across the western counties of the County Warning Area
where there may be a dusting up to a half inch of snow. Since
temperatures will be slowly warming up to freezing by the mid
morning hours, there could be some slick spots on area roadways
Friday morning west of a Washington, to Manhattan to Council Grove
line. The remainder of the County Warning Area may see very light snow or flurries
but as temperatures warm into the mid 30s during the late morning
hours, the light snow may mix with rain and change over to light
rain during the afternoon hours. Friday night the upper low will
continue to fill as it shifts east across eastern Kansas into western MO
by 12z Sat. The light rain may mix with and change back to snow
during the evening hours of Friday as temperatures fall back into
the upper 20s. Any snow accumulation's Friday night will only be a
dusting of snow at best across the County Warning Area and the snow will end from
west to east across the County Warning Area during the late evening hours of
Friday into the early morning hours of Saturday.

Saturday through Sunday night, the upper trough will amplify across
the eastern US and this will keep the Central Plains in northwest
flow at mid and upper levels of the atmosphere. Expect dry
conditions and temperatures will slowly warm into the upper 40s to
lower 50s on Saturday, and with southerly winds, highs will warm
on Sunday into the mid to upper 50s. An upper level trough across
western Canada will dig southeast across the central rockies late
Sunday night.

Monday through Tuesday night, the upper level trough will amplify
across the Central Plains as it digs southeast, and then will
lift northeast across the Great Lakes states. Stronger low-level
cold air advection will cause a cold front to push southward across the County Warning Area on
Monday. There may be a few rain showers Monday afternoon ahead of
the upper trough. As the depth of the cold air increases and
vertical temperature profiles cool below freezing, the light rain
may change over to light snow showers Monday night into Tuesday
morning before the low-levels warm enough for the the light snow
to change back to light rain during the mid morning hours of
Tuesday. The upper trough will amplify as it shifts east across
the Ohio River valley and the precip should end Tuesday evening.
Monday will continue to be mild with highs in the mid to upper
50s. Highs on Tuesday will only reach the mid 40s to lower 50s.

Wednesday through Thursday (thanksgiving), a amplified upper level
trough will dig southeast from the Pacific northwest across the
western US by 00z Friday. The European model (ecmwf) model solution shows an 500 mb trough
embedded in the subtropical jet across northern Mexico getting
kicked north-northeast into the southern and Central Plains. The
combination of isentropic lift as deeper moisture returns
northward and ascent ahead of the 500 mb trough will cause scattered
showers and perhaps a few thunderstorms to develop Thursday
morning and continue through the day. The stronger warm air advection via the
European model (ecmwf) model run, forecasts highs on Thursday in the mid 50s to
around 60 with a better chance for rain.

The GFS has a similar solution to the European model (ecmwf) for Thursday
but there is not a southern stream 500 mb trough that lifts north-
northeast across the southern and Central Plains and the better
moisture return and isentropic lift remains across eastern OK and
AR, so the County Warning Area would remain dry. The GFS model would keep skies
mostly cloudy with highs in the upper 40s to lower 50s.

&&

Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1136 am CST Thu Nov 21 2019

For the 18z tafs, no significant aviation hazards expected after
ceilings lift to VFR by late afternoon into early this evening. Winds
continue to decrease and have opted to leave out mention of any
snow that may be possible late in the period due to low confidence
in timing. Dry air near the surface may delay any precipitation
until the afternoon tomorrow which would be after the forecast
period.

&&

Top watches/warnings/advisories...
none.
&&

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