501
FXUS63 KTOP 030536
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1236 AM CDT Wed Jul 3 2024

.KEY MESSAGES...

- Heat Advisory continues until 8pm.

- Severe thunderstorms look to develop by late this afternoon with
damaging winds and heavy rainfall as the primary threats. Flood
Watch has been issued for parts of northeast and east central KS.

- Additional rounds of thunderstorms, potentially severe, are
possible Wednesday night and again on Independence Day.

&&

.DISCUSSION...
Issued at 254 PM CDT Tue Jul 2 2024

Cold front has entered our north central KS counties with the
inverted sfc trough bisecting the CWA as of 19Z. Broad cyclonic flow
now encompasses much of the northern Rockies and Plains with
southwesterly flow over the area. Mid to high clouds cover much of
the western half of the forecast area with showers having developed
along the sfc trough axis as well as near and just behind the front
itself. Outside of this, hot and muggy conditions will continue
through the afternoon with heat indices between 105-110.

Both SPC mesoanalysis and our 18Z RAOB indicate substantial MLCIN
remaining early this afternoon, though further mixing and heating
should help to erode the cap with chances for more robust convection
increasing toward 4-5pm when MLCAPE increases to around 3000 J/kg
with shear around 30-40 kt. An inverted-V profile and DCAPE up to
1000-1400 J/kg should support a damaging wind threat. If a strong
enough updraft were to develop initially, perhaps some hail would be
possible, but high freezing levels lead to lower confidence in this
threat. Confidence in the tornado threat has also lowered, given
that the front is moving east a little faster, which is helping to
place that risk further northeast into MO and IA.

What may be the bigger concern, in addition to some damaging winds,
is potential for heavy rain and flooding. Storm motions parallel to
the boundary would likely result in storm mode becoming messy
quickly with interactions between individual storms. Pwat values are
already approaching 2" in far northeast KS and that 2 to 2.2"
moisture axis is progged to drop back south and set up near the
frontal boundary when the stronger convection develops. While
ensemble means aren`t showing much potential for widespread high
rain amounts, a closer look at individual CAMs shows the potential
for isolated locations receiving between 1-3" of rain, which seems
reasonable for thunderstorms given the moisture in the column.
Additionally, these heavier amounts look to occur over areas that
have recently had heavy rain and flooding issues. The 6-hr flash
flood guidance of 2-3" and 1-hr guidance between 1-2" lends to some
concern that efficient rain-producing thunderstorms could lead to
flash flooding. So have issued a Flood Watch for portions of
northeast and east central KS from 5pm this afternoon through 7am
Wednesday.

There could be some lingering, weakening storms in southern portions
of the area Wednesday morning. The sfc front looks to be south of
the area by this time, but could lift back north as a warm front
Wednesday into Thursday. An embedded perturbation in the flow aloft
should kick off another round of convection late Wednesday into
early Thursday with winds and heavy rain again being the main
concerns. Confidence in the forecast for the 4th of July holiday on
Thursday still isn`t overly high as it will depend on where sfc
boundaries end up after the overnight/morning convection. At this
time though, there are some hints that perhaps the upper trough and
associated sfc front are trending a bit further east. If this holds,
that could mean less of a severe risk particularly for western parts
of the area, but everyone should still keep an eye on the forecast
as details change in the coming days. Eastern KS could still see
damaging winds and heavy rain with storms that remain as long as the
front is still in the area.

Once the holiday passes, the more notable upper trough looks to be
passing northeast of the area to give us a bit of a break from the
active weather Friday into Saturday. Longer-range guidance has
another system bringing another rain chance Sunday into Monday, but
probabilities are on the lower side with lower confidence at this
time.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1232 AM CDT Wed Jul 3 2024

Expecting conditions to stay VFR, however, some models show MVFR
cigs/visibilities developing into the early morning hours of
Wednesday. Will monitor and amend TAFs if necessary. The next
impact will be a batch of rain with embedded thunderstorms
possible (30-50% chance) at terminals by midday Wednesday. Have
included VCSH with this update. Chances decrease after 00Z
Thursday.

&&

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

&&

$$

DISCUSSION...Picha
AVIATION...Teefey