Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 172310
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
510 PM CST Sat Feb 17 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday)
Issued at 343 PM CST Sat Feb 17 2018

Current satellite imagery shows a broad west to east zone of
subsidence trailing behind a baroclinic wave that as translated east
over the Ohio valley which brought light rain and some mixed
precipition very early this morning over extreme eastern areas of
Kansas into the Mid MS Valley region.  Mostly zonal flow aloft
remains over the central CONUS with downslope flow off the Rockies
into the forecast area.  This has resulted in some gusty winds this
afternoon over the area.

See Fire Weather discussion for details on the balance of the
afternoon and Sunday for fire related concerns.

High temps today have warmed nicely into the upper 50s across much
of the area aided by the effects of adiabatic heating.  A dry
atmosphere will remain in place over the next 24 hours with a
transition period taking place.  Overnight lows tonight only bottom
in the 30s.  Sunday, upper flow transitions to a more southwesterly
regime which will activate the lee trough.  Along with high pressure
sliding east and strengthening, return flow will be on the increase
along with a LLJ overnight into Sunday morning.  This should set the
stage for a well mixed day ahead which will likely result in high
temps in the 60s and pushing the upper 60s out over north central
areas.  Lows as a result of southerly flow into Sunday night remain
warm as well into 40s and low 50s over much of the area.

.LONG TERM...(Sunday night through Saturday)
Issued at 343 PM CST Sat Feb 17 2018

Beginning of the week looks to be active weather wise with a western
trough digging into the Desert Southwest by the evening on Sunday
and into Monday morning.  Southwest flow increases over the Plains
and soundings across the board hint that a strong and rather warm
EML will overspread the area. The GFS does hint as perhaps a period
where storms could become more surface based heading into the day
Monday over southern portions of the area.  SRH values are high
because of strong wind fields, but confidence in severe weather is
low at this time.  There may be more confidence for elevated storms
with weak instability early Monday morning.  Therefore, have kept
mention of thunderstorms in the forecast.  There has been a decent
amount of run to run inconsistency with the thinking on thunderstorm
potential and nature of how storms may evolve which seems worth
noting.

Bigger concern is as the western trough amplifies, it sharpens the
baroclinic zone at the surface and CAA develops by Monday night into
Tuesday morning.  With little in the way of ice introduction
expected at this time and time needed for the warm nose to erode,
low level CAA could present problems in the aspect of freezing rain
to enter the picture.  The timing of the cold air will be critical
of course but still could see flash freeze problems over areas with
previous liquid rain.  With current thinking on QPF amounts, do
expect ice accumulation amounts to less than 0.10 of an inch through
the period on Monday night into Tuesday.  Temps exhibit a high
gradient on Tuesday generally in the 20s north of I-70 and possibly
still upper 30s over portions of east central KS.  Lows fall back to
teens over much of the area as arctic air quickly rushes in with
sub zero wind chills.

From here, Wednesday and Thursday are dry and then again a chance
for a mixed precip system to work into the Friday and Saturday time
frame. Less certain on this at this point.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 506 PM CST Sat Feb 17 2018

Low level wind shear is expect late tonight with a strong low
level jet developing over central KS and spreading eastward. With
such a strong jet occasional gusts may make it down to the
surface overnight. The surface gusts may rapidly increase with the
onset of day time mixing a few hours after sunrise. Towards the
end of the period VFR/MVFR stratus moves towards the sites from
the south.

&&

.FIRE WEATHER...
Issued at 343 PM CST Sat Feb 17 2018

Concerns today remain for a few hours this afternoon
over southwestern portions of the area into Central and north
Central KS.  RH values will remain in the low 20s with spotty gusty
winds 25-30 mph but should drop off after sunset.  Thus we have
remained in very high fire danger today.

Sunday, Very high fire danger spreads across the entire area as
temperatures increase on the whole and winds become very strong with
sustained winds possibly around 25-30 mph and some gusts at times
approaching 40 mph.  With moisture return on the rise, have not gone
with Red Flag warning at this time.  However, if moisture proves to
be not as rich in quality as models prog and higher dewpoints stay
south then there may be a possibility Red Flag conditions could be
met over western areas.

&&

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

$$

SHORT TERM...Drake
LONG TERM...Drake
AVIATION...Sanders
FIRE WEATHER...Drake



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