462
FXUS63 KTOP 240508
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1108 PM CST Mon Dec 23 2024

.KEY MESSAGES...

- Mild temperatures should persist through the weekend.

- There are off an on chances for light rain through Saturday,
  the better chances looking to be Thursday night.

&&

.DISCUSSION...
Issued at 209 PM CST Mon Dec 23 2024

A series of shortwaves from the Upper Midwest to off the
Pacific Northwest coast were noted in the 20Z water vapor
imagery. At the surface, obs showed a weak frontal boundary or
trough axis across east central KS extending northeast from an
area of low pressure over west TX.

The main change to the previous forecast has been to limit precip
chances for tonight and Tuesday to the far southern counties. 12Z
guidance had trended south with the better moisture as the forcing
from a passing shortwave impacts the southern plains more. The weak
boundary over east central KS is progged to slip a little further
south through the evening with models showing little or no moisture
advection over the boundary. So have trended POPs lower and think
prospects for drizzle are slim to none. There is a concern for some
dense fog to develop north of the forecast area. However models keep
some mid and high clouds over the forecast area through the night
inhibiting radiational cooling. The HREF has probabilities for dense
fog over parts of north central KS between 20 and 40 percent. With
the expectation of clouds holding on, will only have some patchy fog
along the NEB state line where clouds may thin some.

The better chance for rain looks to be late in the day Thursday and
Thursday night as an upper wave with a negative tilt lifts across
eastern KS. The NBM and forecast maintain some chance POPs with this
wave as moisture quality remains a question. Also the 12Z ECMWF is
taking the wave further south which could keep better precip chances
south. But something to keep an eye on will be the warm air
advection pattern that develops Wednesday night and into Thursday.
Isentropic surfaces show increasing lift and if there is enough
moisture to go with the lift there may be some drizzle form. The
good news is with the warm air advection, temps should be to warm
for any freezing precip.

Models show potential shortwave energy passing through the plains
for Friday and Saturday. However the more amplified wave Thursday
night may tend to take the bulk of the moisture with it. QPF progs
are split between a dry GFS and a more amplified and wet ECMWF.
Ensemble data shows increasing spread and lower predictability so
have stayed with the blend which keeps a slight chance POP across
eastern parts of the forecast area through Saturday. Again temps
look to remain relatively warm and ensembles show the potential for
measurable snow to be near zero.

Northwest flow sets up for Sunday and Monday with a break from the
shortwave activity. However the 12Z ECMWF is wanting to bring a
shortwave through the central plains about 24 hours quicker.
Confidence in the ECMWF is low given it`s variability in timing, so
the forecast remains dry through the end of the forecast.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1108 PM CST Mon Dec 23 2024

Monitoring the stratus oozing south of out Nebraska and Iowa
which will likely impact terminals in the 12-14z timeframe.
Current obs are largely MVFR, but cigs could fall to IFR as this
stratus moves in. How long these low cigs hold on through the
day remains a bit uncertain with some guidance mixing out clouds
by midday with others keeping them through the period. Went
with a middle ground and scattered out clouds this afternoon.
Think stratus builds back in Tuesday evening with fog, even some
dense fog, possible near the end of the period and beyond.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Wolters
AVIATION...Flanagan