Scientific Forecaster Discussion
fxus63 ktop 211739
Area forecast discussion
National Weather Service Topeka Kansas
1239 PM CDT Mon Oct 21 2019
..update to aviation forecast discussion...
Short term...(today and tonight)
issued at 422 am CDT Mon Oct 21 2019
Sfc cold front has now passed entirely east of the cwa, which
extends out of low pressure centered over SD/NE/IA. This stacked low
will continue to deepen and move northeast into Minnesota today, resulting
in a strong pressure gradient across much of the plains. This
gradient will be slightly stronger to our north in NE/IA, but
forecast soundings show mixing heights around 850mb for most of our
area with potential for wind gusts up to 35mph across the County Warning Area. North
central and portions of east central Kansas have 850mb winds pushing 45-
50 kts, which could translate to gusts around 45mph mixing to the
surface. Otherwise, sustained 25-30mph winds are likely. As such,
have issued a Wind Advisory for these areas starting at 14z lasting
until 00z this evening. Cold air advection as a result of these winds will keep
temperatures cooler than the last few days with highs in the mid to
upper 50s for most places, up to the low 60s in east central Kansas.
Winds should subside this evening, particularly after sunset when
mixing decreases. Mostly clear skies will allow temperatures to fall
to the mid 30s to low 40s overnight.
Long term...(tuesday through sunday)
issued at 422 am CDT Mon Oct 21 2019
While not as strong as Monday, the pressure gradient throughout the
atmospheric profile remains tight as the strong upper low lifts
northward into the Canadian provinces. Therefore, opted to increase
wind speeds for Tuesday afternoon between 10 and 20 mph sustained
with gusts up to 30 mph throughout the County Warning Area. Meanwhile temperatures
hover below normal with the sustained cold air advection Tuesday
before a sfc trough develops into the Central Plains on Wednesday.
This will allow winds to back towards the southwest and become gusty
by Wed. Afternoon as warmer h85 temps up to 12c mix downward towards
the sfc, resulting in highs reaching the upper 60s for most of the
County Warning Area. This should be the warmest day of the extended period before a
strong cold front takes over the region Thursday Onward, dropping
highs into the 50s for highs and overnight lows near or just above
the freezing mark. Timing of the front pairing with available
moisture associated with the upper shortwave trough aligns the
optimal precip chances towards far southern Kansas into Oklahoma.
Latest guidance has much of the qpf centered near and south of
Interstate 70 corridor throughout the day Thursday where sfc temps
remain in the 50s so only rain chances were added with this system.
Models differ greatly after Thursday as the European model (ecmwf) tries to cutoff
the upper low across nm before lifting it over the Central Plains
this weekend. Meanwhile the GFS maintains an open upper trough and
dry forecast throughout the weekend. Have added a slight rain chance
to Saturday afternoon but otherwise temps return to near normal
values in the middle 60s.
Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1233 PM CDT Mon Oct 21 2019
The broken stratus at 4000 to 5000 feet will continue through he
afternoon hours. This may help to keep northwest winds to remain
under 25 kts with gusts under 40 kts the remainder of this
afternoon. The winds will gradually diminish through the evening
hours. However, northwest winds above 1000 feet will continue to
be in the 40 to 45 knots range through the early morning hours of
Tuesday. Therefore, all terminals may experience low-level wind
shear from 3z Tuesday through 13z Tuesday.
Wind Advisory until 7 PM CDT this evening for ksz008-009-020>022-