Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 122319
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
619 PM CDT Tue Mar 12 2024

.KEY MESSAGES...

- Storm chances increase Wednesday with best chances (50-70%)
  along and north of Interstate 70. These storms could be
  severe and produce large hail, damaging winds, and even a
  tornado or two.

- Rain and storm chances continue on Thursday before conditions dry
  out for Friday. Severe chances are low (<5%).

- Cooler and drier air filters in Friday into early next week
  with highs in the 50s and 60s.

&&

.DISCUSSION...
Issued at 255 PM CDT Tue Mar 12 2024

A mid-level perturbation is working across the central CONUS this
afternoon with a surface low centered over central Kansas. Low-level
moisture is pooling along a frontal boundary across southeast Kansas
and will continue to shift east into Missouri this evening. The
overall track of the surface low has been slightly farther south
than was depicted by guidance even this morning, keeping the lower
dewpoints confined to south central Kansas. The degree of mixing has
also been limited to an extent given the passing high clouds, so
wind gusts have been more intermittent in nature. This leads to
lowering confidence in any fire weather impacts this afternoon. With
the moisture continuing to be shunted east through this evening, the
chances for any storms has also decreased; there is a 10-15% chance
a storm impacts far eastern portions of the CWA this evening, but
any convection would quickly progress east into Missouri.

Attention turns to the next trough that is currently making its way
onshore across the west coast. As this trough approaches the Plains,
a surface low develops over southeast Colorado and lifts northeast
across Kansas through the afternoon and evening on Wednesday. A
strengthening low-level wind field ahead of this low will lift
a warm front north through the day. Models differ on the
progression of this boundary, but consensus shows the front
entering the southern portions of the CWA by late morning and
advancing further to along or just north of Interstate 70 by
6-7pm. Dewpoints rising into the 50s coupled with steeping mid-
level lapse rates will lead to MUCAPE of 1000-2000 J/kg. The
degree of forcing and moisture quality to support thunderstorms
remain in question during the afternoon and early evening.
Forecast soundings show an eroding cap by mid afternoon, but
largely lack lift and moisture for convection. If deeper
moisture works in faster and lift is sufficient for a storm to
develop, the environment would support a strong to severe storm
with large hail and damaging winds being the main hazards,
although a tornado is also possible.

Better forcing and shear comes with the approach of the mid-level
wave and enhancement of the low-level jet after 6pm. CAMs are in
fairly good agreement in convection developing along and north of
the warm front at the nose of the LLJ in the 6-9pm timeframe.
Differences in the warm front`s position at this time lead to some
uncertainty in where storms will develop, but areas generally north
of the I-70 corridor have the greatest chances (50-70%) of seeing
storms. The environment supports supercellular structures with the
potential for large hail (potentially very large hail),
damaging winds, and even a tornado or two, especially along the
warm front, as the LLJ increases and hodographs become favorable
for more streamwise vorticity to be ingested. The LLJ should
shift convection north- northeast through the late evening.
Another perturbation passes through after midnight which could
spark some additional storms across east central Kansas, but
confidence in this scenario is low.

Precipitation chances continue through Thursday with the area
remaining in the warm sector through midday or so before a cold
front sweeps through. A few storms are possible (20-40%) through the
day before dry conditions return Thursday evening into Friday
morning. Cooler air returns Friday through the beginning of next
week with highs in the 50s and 60s.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 619 PM CDT Tue Mar 12 2024

Westerly winds will be light under 10kts then become southeast
after 11Z then increase to near 12kts by 19Z. A warm front will
lift northward in the afternoon to near or north of the
terminals. Isolated TSRA could develop at the end of the
forecast period or after it as short term models suggest. Will
leave out on this forecast as confidence is too low to include.
VFR conditions are expected to continue.

&&

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

&&

$$

DISCUSSION...Flanagan
AVIATION...53


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