449
FXUS63 KTOP 160537
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1237 AM CDT Fri Aug 16 2024

.KEY MESSAGES...

- Another round of thunderstorms are possible (20 to 50 percent
  chance) Friday afternoon and evening.

- Quiet weather and cooler temperatures expected this weekend
  and into early next week.

&&

.DISCUSSION...
Issued at 250 PM CDT Thu Aug 15 2024

20Z water vapor imagery showed a nearly zonal pattern across
the central parts of the country with an upper wave moving into
northern MN and another upper wave over OR. Surface obs had a
low pressure system over northwestern MN with a cold front
stretching south along the MO river and into central KS.

For the late afternoon and evening time frame, there remains a lot
of available energy for thunderstorm development across easter KS.
The 19Z SPC mesoanalysis showed MLCAPE values of 2500 to 3000 J/kg
with bulk shear between 35KT and 40KT. But models prog the better
dynamics to pass just north of the area with forecast soundings
holding onto some convective inhibition. Think the chances for
convection are small and the latest CAM runs still don`t generate
storms over the forecast area. Have left some small POPs in the
forecast for the outside chance a storm develops. But think as the
boundary layer cools this evening and energy to the north continues
east, this risk for convection will progressively decrease to only 5
or 10 percent by 10 o`clock. With weak high pressure building into
the area overnight and skies clearing out, the setup for ground fog
looks good. Have added a mention of fog in low lying areas for now,
but if moisture doesn`t scour out the fog could be a little more
widespread.

Friday the models have a shortwave diving down the back side of the
upper ridge. This energy is progged to affect central KS around mid
day with most guidance showing a signal for precip moving southeast
through the afternoon. It is not out of the question some of these
storms could be severe with reasonable bulk shear and mid level
lapse rates around 7.5C/km. The NAM is struggling with instability
parameters from convective feedback in the model and the GFS shunts
the best instability and moisture just southwest of the forecast
area with weak ridging over northeast KS. So will need to reevaluate
the severe potential overnight.

For the rest of the forecast period, models re-amplify the upper
ridge over the central Rockies with high pressure over the Upper
Midwest ridging into northeast KS. There is some variability in the
strength of the surface ridging, and given the amplitude of the
upper ridge and a little skeptical of the ECMWF and it`s cooler
surface temps. But overall a quieter period of weather is
anticipated. There could be a shortwave or two round the ridge and
potentially create some precip chances. Did not see any reason to
deviate from the NBM which has some 20 to 30 percent chances early
next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1237 AM CDT Fri Aug 16 2024

Clear skies and light winds overnight favors shallow fog development,
especially in the river valley at KTOP and KMHK. After any fog
burns off shortly after sunrise, VFR conditions prevail. A
complex of showers and storms moves towards terminals during
the afternoon. Location of this band of precipitation is
uncertain with best chances for TS near KMHK.


&&

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

&&

$$

DISCUSSION...Wolters
AVIATION...Flanagan