491
FXUS63 KTOP 162318
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
618 PM CDT Fri May 16 2025

.KEY MESSAGES...

- Warm and dry today and Saturday.

- Rain chances increase Sunday morning north of a warm front before
severe storm chances increase by the afternoon and evening. All
modes of severe weather will be possible with storms Sunday. See
discussion for further details.

- Cold front pushes through the area Monday afternoon and
  evening with additional chances for severe weather across
  eastern Kansas.

- Cooler and cloudy conditions build in Tuesday into Thursday.

&&

.DISCUSSION...
Issued at 300 PM CDT Fri May 16 2025

19Z water vapor imagery this afternoon shows a cutoff low over the
Great lakes region, a 50-70kt sub-tropical jet extending from Baja
California to the Ohio River Valley, and associated convection that
has begun to develop in central Missouri. Across eastern Kansas, a
surface trough has shifted southeast of the area, ushering in gusty
northwesterly winds. This should help to keep temperatures from
warming much higher than the low to mid 80s this afternoon. For the
remainder of the afternoon, pressure gradients should remain tight
into this evening with an 850 mb jet streak pushing into southeast
Nebraska. This will help to keep very gusty winds across the area,
especially across north-central and far northeast Kansas with
occasional gusts to 35-40 mph. Winds should subside just after
sunset as the boundary layer decouples. By Saturday, the northern
upper low will push east, ushering in surface ridging to the central
Plains. Pleasant conditions will be expected Saturday as low
humidity, light northerly winds and temperatures topping out in the
upper 70s and low 80s build in for the afternoon.

Changes begin to build into the area Saturday evening as the 850 mb
ridge axis slides east of Kansas and begins to push moisture back
north. By Sunday morning, our next upper low begins to dig south
into the central Rockies and in response, will quickly deepen a
surface cyclone across eastern Colorado. Cyclogenesis will continue
through the morning Sunday as a warm front will slowly lift north
out of northern Oklahoma and into southern Kansas. With a 30-40 knot
LLJ overriding this frontal boundary across eastern Kansas,
precipitation north of the boundary will likely increase Sunday
morning. Morning precipitation chances should just be light to
moderate rain shower activity, but a few rumbles of thunder cannot
be ruled out as elevated instability increase into the later morning
hours. The main timeframe of discussion comes later in the afternoon
Sunday as the warm front begins to slow its northward march,
stalling somewhere along the I-70 corridor in eastern Kansas as a
dryline begins to push into south-central Kansas with the surface
low ejecting out across central Kansas. South of the warm front in
the warm sector of the cyclone, MLCAPE of 2500-3500 J/kg, 0-6km bulk
shear of 40-50 knots and very steep ML lapse rates will become
realized pointing to very strong to severe storm potential across
central and eastern Kansas. Parcels that are able to overcome any
environmental capping along the dryline in south-central Kansas or
along the warm front would be expected to quickly strengthen, posing
risks for very large hail (2+ inch) damaging winds (60-70 mph) and a
few tornadoes, some possibly strong. That said...confidence is still
low to moderate for severe storms Sunday due to several inputs that
will likely play a role in who sees severe storms Sunday afternoon
and evening. The main uncertainty lies in where the surface features
set up Sunday morning and afternoon. CAMs are beginning to come in
with their first solutions as to where these boundaries might be,
but there still are differences in where the NAM, EURO and GFS want
to position these features. Currently, the GFS remains the most
bullish in how far north it pushes the warm front with most guidance
keeping the warm front along or south of I-70. Model trends have
also pushed the dry line a bit further west over the past few runs.
If the warm front remains shunted to our south for Sunday, our
severe risk will be a bit lower as most severe storms that do move
over northeast Kansas will remain elevated, only posing a large hail
risk. If the warm front and warm sector can move further north, that
opens the door for storms to become surface-based and pose the risk
for all modes of severe weather. Another uncertainty with Sunday
will be how much of an impact morning showers and cloud cover will
have on available instability. Not overly worried this will play too
much of a role in limiting severe storms as cooling aloft and
increasing surface moisture will keep CAPE values very large.
Lastly, some residual capping in the lower levels may limit overall
storm coverage if lift remains overly weak. Still, if a storm can
develop, remain surface-based, parameters suggest it quickly
becoming strong. Storm initiation for Sunday afternoon appears to be
around the 3-4 PM timeframe, mainly depending on when MLCIN becomes
weakest.

As storms move east Sunday evening and overnight into Monday some
downstream evolution may become realized as the LLJ increases across
southeastern Kansas. This could create some localized flooding
concerns, especially if storms train over the same areas. That said,
most of Kansas should be storm-free by 06z Monday. By Monday
afternoon another round of severe weather will be possible as the
main upper low begins to occlude in central Nebraska. A fair amount
of uncertainty remains with Monday`s severe storms chances as Sunday
will likely impact where surface moisture remains for Monday.
Overall set up for storms Monday will be along frontal boundary
extending from the surface low in Nebraska. A dryline may also
become a forcing mechanism Monday afternoon in evening across
central Kansas that could kick off storms. Given severe parameters
of 40-50 knots of 0-6km shear, a good axis of SBCAPE > 2000 J/kg and
steep ML lapse rates, all modes of severe weather will be possible
again. It seems that guidance keeps most appreciable surface
moisture across far eastern Kansas by Monday afternoon, so it seems
like this would be the main area of interest for the most widespread
storm coverage Monday afternoon and evening. Stay tuned to the
forecast in the coming 48 hours for additional details for Monday`s
storm threat.

Tuesday into the remainder of the week will see conditions
characterized by cooler air and mostly cloudy conditions, especially
Tues/Wed. Severe storm chances should stay south and east of the
area as well. Warmer and sunnier conditions should begin to return
to the area Thursday as the upper low finally moves east into the
Ohio Valley.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 617 PM CDT Fri May 16 2025

Gusty sfc winds will subside during the first few hours of the
00Z TAF period. Lighter winds are then expected through the
night and tomorrow with high pressure moving into the area. VFR
will also continue.

&&

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

&&

$$

DISCUSSION...Griesemer
AVIATION...Teefey