Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 120836
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
336 AM CDT Tue Mar 12 2024

.KEY MESSAGES...

- Another warm day with some high cloud cover this afternoon.
Elevated fire conditions will be present in central Kansas.
- 20% chance for storms this evening in far east-central Kansas.
Best chances should stay off to our east.
- Another round of storms, some likely becoming severe, will be
possible Wednesday afternoon and evening.
- Rain chances linger around the area Thursday, mostly in northern
Kansas.
- Cool air filters in Friday and into the weekend with highs topping
out in the 50s and 60s.

&&

.DISCUSSION...
Issued at 334 AM CDT Tue Mar 12 2024

Mid-level water vapor imagery this morning shows shortwave troughing
over the central Rockies that has continued to stream in upper-level
moisture into the central Plains. A surface lee cyclone has deepened
in western Kansas with a tight pressure gradient laid out to its
east across eastern Kansas. With BLs staying well-mixing this
morning, temperatures have been able to stay in the upper 50s area-
wide! Expect temperatures to drop a few degrees further by sunrise,
bottoming out in the upper 40s and low 50s.

By this afternoon, the surface low will continue to advect east
towards north-central Kansas, keeping windy conditions across the
area, especially south of I-70. Warm and dry 850mb air will advect
in behind the surface low from the southwest this afternoon, and
with efficient BL mixing today, expect upper 70 degree high temps
and low relative humidities across central and east-central Kansas.
This could again pose the risk for very high fire danger in central
Kansas this afternoon as this dry air moves east, see the Fire
Weather Discussion for further details. The remainder of the area
will see winds shifting to the west as the surface low bisects the
area, keeping temperatures in the low to mid 70s north of I-70. As
the surface low and dry line approaches far eastern Kansas, richer
moisture will pose the risk for an isolated storm to develop.
Instabilities across our area remain weak (~500 J/kg) since better
moisture will remain further east, but if surface convergence can
help parcels overcome afternoon capping between 21-00z, a quick
storm could develop east of I-35. Confidence in this solution is
fading as CAMs are continuing to agree that by the time forcing
reaches sufficient moisture, the small and compact upper low will be
east of the area, suppressing most convection that tries to develop.
Have maintained small PoPs (20%) for the outside chance that an
isolated storm can develop, but best chances will remain to our east.

If you are saddened by minimal storm chances this afternoon and
evening, you will not need to wait long before chances area-wide
will increase for rain and storms (some becoming severe). By
Wednesday, a stalled boundary south and east of our area will begin
to lift north as a warm front as another surface low deepens over
the lee of the Rockies. Moisture advection will increase throughout
the afternoon area-wide with upper 50 degree dewpoints overspreading
eastern Kansas. This paired with diurnal heating and WAA, afternoon
instabilities will quickly increase, with MLCAPE values ranging from
1500-2500 J/kg along the warm front. As the upper-level shortwave
moves further east, 0-6km shear will increase to 30-40 knots across
northeast Kansas, sufficient for supercell production. Storm
initiation will likely begin to occur after 21z (4PM) and along and
north of I-70. Initially, storms in eastern Kansas further from the
triple point in north-central Kansas will need to overcome residual
capping, but once this can be overcome, storms will should quickly
develop and move north/northeast into the late afternoon and evening
hours. Steep ML lapse rates (>8C) advecting in ahead of the upper-
level wave will create a large hail risk for storms that do develop.
At this time, hail larger than 2 inches in diameter will be possible
in storms that can maintain a strong and persistent mesocyclone. A
tornado threat will also be present as forecast soundings depict
southeasterly surface winds and strong southwesterly flow aloft,
indicating looping hodographs along and south of the warm front. Low-
level SRH values will be impressive, and continue to increase into
the evening hours as the LLJ strengthens. If a storm can develop in
the late afternoon hours along or just south of the warm front, all
modes of severe weather will be possible. Once storms cross the warm
front, they will likely become elevated, only posing a large hail
risk. All this said, ingredients for severe weather are beginning to
take shape across the area, but certain mesoscale details are still
up in the air. Details will change a bit over the next 24-36 hours,
so please stay tuned for further updates on the severe weather
potential Wednesday afternoon and evening.

Overnight Wednesday and into the day Thursday, the compact upper low
will lift north into central and eastern Nebraska as the longwave
trough over the western CONUS begins to advect further east towards
the Rockies. Precipitation chances will persist for areas in
northern Kansas as the surface low lingers in eastern Nebraska.
Guidance continues to keep the main QPF axis north of the area
throughout the day Thursday, but cannot rule out rain chances for
far north Kansas as this system moves east Thursday into Friday.
Isentropic ascent along a stalled boundary set up over Missouri
could increase rain and storm chances for far eastern Kansas
Thursday afternoon, but the GFS and Euro do not seem to get on board
with this and push majority of QPF into Missouri.

Dry and cooler air moves in behind the system by Friday and the
weekend with highs topping out in the 50s and 60s. Moisture
advection will be limited over this time frame, so any waves that
pass overhead will likely pass dry.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1217 AM CDT Tue Mar 12 2024

VFR TAFs will be expected through the period at all sites with
winds and LLWS being the main concerns. A strong low-level jet
will be present this morning until around 8-9 AM Tuesday and
will create LLWS within the lowest 2000 feet. Surface winds will
remain out of the south around 10 knots until increasing with
gusts for a few hours in the afternoon Tuesday. Winds will shift
to the west and weaken by sunset Tuesday with mostly clear
skies.

&&

.FIRE WEATHER...
Issued at 336 AM CST Sun Mar 10 2024

By this afternoon, a surface low will move east into northeast
Kansas, and increase dangerous fire behavior across central Kansas.
A dryline moving across central Kansas (around 2-6 PM) and deep
mixing of dry and warm air to the surface will drop RH values in
central and east-central Kansas between 20-30%. Winds today will
remain strong, initially out of the south around 20 mph, with gusts
upwards of 35 mph. Winds will then shift to the southwest and then
to the west following the dryline passage (between 2-6 PM),
sustained between 15-20 mph and gusts to 30. The sudden change in RH
values and wind shift could pose a significant risk in any fires
that are on the ground. Fires could quickly get out of control and
exhibit erratic behavior. RH values recover above 40% after 8 PM
this evening in central KS. Outdoor burning is not recommended in
central and east-central Kansas (generally south of I-70) this
afternoon.

&&

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

&&

$$

DISCUSSION...Griesemer
AVIATION...Griesemer
FIRE WEATHER...Griesemer


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