744
FXUS63 KTOP 201032
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
532 AM CDT Fri Sep 20 2024

.KEY MESSAGES...

- Marginal risk (level 1 out of 5) possible overnight Friday due to
possible nocturnal storms forming along the nose of the LLJ. Wind
and hail may be possible with the most intense storms that do form.

- Most every location across the area should see a very good chance
of seeing meaningful rainfall through Saturday and Sunday night
periods. North of I-70 still looking to see some of the higher
amounts of around 2 inches or possibly greater in some spots.

- Back to an early fall pattern returning to a generally dry
conditions with temperatures in the 70s for highs and 50s for the
lows into next week.

&&

.DISCUSSION...
Issued at 333 AM CDT Fri Sep 20 2024

The evolution of the upper air pattern continues to remain on track
for a wet weekend ahead - which is more than welcome by most
standards due to the dry conditions in place. The upper low over the
northern Plains has lifted into south central Canada leaving the
weak front over eastern Kansas left to stall out. This boundary will
begin to return north as a warm front through the day today (Friday)
as the next upper low over southern California begins to lift into
the central Rockies and eventually through the central Plains. The
southern Plains ridge is flattening and the ridge axis is shifting
to the southeast.

Today should be one of the last warm days before temperatures begin
to head to a more fall-like and near-normal pattern for next week.
Clouds begin to build late day into this evening as the southwestern
CONUS upper low begins lifting northeast. A lead shortwave is
forecast to emerge from the central Rockies into the overnight
period Friday. A moderately strong LLJ also becomes active with the
nose and convergence zone generally into north central and
northeastern Kansas before veering overnight. With the warm moist
advection resulting, a few storms could form which may pose a wind
and hail risk overnight.

Then, heading into Saturday - especially by Saturday evening into
Sunday - the parent upper low more fully arrives on the scene. There
remains generally good agreement amongst guidance that a modified
surface ridge from the north will be sliding into the central Plains
as this storm system builds with increasing DCVA into northern and
northeastern Kansas areas. Deep saturated profiles with PWATs
nearing 2 inches along with strong midlevel frontogenetical responses
and convergent moisture transport should come together to provide a
good chance for nearly all spots across the area to see meaningful
precipitation over a 24-36 hr period. Still focusing on some of the
heavier amounts generally along and north of I-70 with up to 2
inches and locally higher amounts possible. All other areas could
see at least an inch of much needed rainfall. Flash flooding
concerns remain low for now due to the nature of the event duration
and very dry antecedent conditions in place with rivers and creeks
being low.

Into next week, after this system fully exits the area into Monday,
expect much cooler conditions to help conditions feel more fall-
like. Right now, a northwest flow pattern looks to keep the area
void of any major storm systems and thus have kept a drying trend in
place for the balance of the forecast period generally from Monday
through the work week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 520 AM CDT Fri Sep 20 2024

Keeping VFR conditions for now. There are some indications there
may be ground fog around sunrise this morning mainly at KTOP as
low level dewpoint depressions are minimal but the wind may be
just strong enough to prevent MIFG from forming. Too much
uncertainty for the last 6hrs of the period where it may be
possible that isolated to scattered showers and storms could
form so have opted to hint at saturated mid levels with BKN100.

&&

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

&&

$$

DISCUSSION...Drake
AVIATION...Drake