000
FXUS63 KTOP 250856
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
356 AM CDT Thu Apr 25 2024

.KEY MESSAGES...

- Widespread showers and thunderstorms this morning shift
  towards far eastern Kansas by the afternoon. A few may be
  marginally severe with damaging wind gusts and hail to quarter
  size.

- Next round of thunderstorms is late this evening into Friday morning
  with the potential for a few severe storms capable of
  producing large hail and damaging wind gusts.

- Severe weather threat increases over eastern Kansas Friday
  late afternoon - evening. Highest chances are north of
  Interstate 70 with all hazards being possible with any storm
  that develops.

- Saturday afternoon - evening is the most likely period for
  more widespread severe storms across the CWA. All hazards are
  expected into the evening.

- Final round of severe storms is on Sunday afternoon - evening
  towards far eastern Kansas.


&&

.DISCUSSION...
Issued at 347 AM CDT Thu Apr 25 2024

Increasing mid level moisture as an embedded upper trough rounds the
weak ridge in the panhandles region, entering the area later this
morning. Isentropic lift is steadily increasing as the warm front
currently stretched across central OK is progged to lift
northward today. Current radar and short term guidance is in
line with this reasoning for convection to become more
widespread aft 12Z as elevated CAPE values increase from
500-1500 J/KG over portions of central and northeast Kansas.
Effective bulk shear from 35-45 kts is supportive of embedded
stronger updrafts capable of producing hail to quarter size and
damaging wind gusts. This activity persists into mid afternoon,
migrating into far east central areas by late afternoon. As low
level moisture increases, indicative of dewpoints in the upper
50s, cloud cover sticks around through the evening as
southeasterly winds increase from 15 to 25 mph, gusting to 35
mph. The rain and cloud cover limits highs today to the lower
and middle 60s.

Isolated convection is forecast to develop off the dryline over
western KS/South central NE this evening. 00Z runs of the Fv3,
WRF models, and the HRRR are maintaining this convection into
north central Kansas aft 00Z, aided by a 50 kt LLJ. In addition,
sustained WAA within the moist sector for the remaining CWA
will likely spark additional scattered showers and storms early
Friday morning. While storms should be elevated, large hail and
isolated damaging wind gusts cannot be ruled out given MUCAPE
values around 2000 J/KG.

On Friday, the upper trough becomes negatively tilted as it digs
northeast into southeast NE by 00Z Saturday. Dryline/Pac Cold
front approaches eastern KS by late afternoon, accompanied by
moderate instability upstream near 2500 J/KG as sfc capping
layer gradually erodes per forecast soundings in the late
afternoon. Main factor for storm initation is position of the
upper level low over NE and depth of height falls further south
into KS. CAMs remain consistent in isolated convection
developing by early evening near the KS/NE border, however its
important not to rule out the possibility for an isolated storm
to form as far south as I-70. Given the strong low level wind
profile amid an uncapped unstable environment, any storm that
forms will be supercellular in nature, capable of producing very
large hail, damaging wind gusts, and a few tornadoes through
early evening. On a smaller side note, the tightening pressure
gradient likely signals advisory level winds in the afternoon.
South wind speeds are from 20 to 30 mph with gusts up to 50 mph.

The most concerning round of severe weather may occur on
Saturday as the dryline/front retreats westward, orienting
southwest to northeast from south central KS to far northeast
Kansas. The next negatively tilted upper trough enters the CO
Rockies by mid afternoon. Forecast soundings exhibit a decent
capping inversion through the afternoon period, before eroding
completely by 21Z as SFC cape builds over 3000 J/KG. Low level
winds back to the south at this time as SRH climbs above 200
m2/s2. While uncertainty remains on exact location of storms
initiating, consistency amongst available guidance lends to
increasing concern for higher end supercells to form within the
region, capable of producing very large hail, damaging winds,
and a few strong tornadoes. Convection is anticipated to expand
in coverage, perhaps merging into a line later in the evening
towards eastern/southeast Kansas as the trough axis ejects into
western KS. In addition to the very large hail and damaging wind
gusts, the tornado threat may extend into the late evening.

There may be some lingering convection south of the CWA Sunday
morning. Latest guidance indicates a slowing in progression of the
upper trough axis, still residing from central NE to central KS by
mid afternoon. While recovery time is highly questionable with any
morning convection, we could still see SFC cape values rise to near
2000 J/KG while effective bulk shear is favorable for
rotating updrafts at around 45 kts. Better chances for
additional severe weather is over far eastern KS (east of
highway 75) in the late afternoon. Any activity that develops
will quickly push east into Missouri by the evening bringing an
end to this extended period of active severe weather.

Westerly flow aloft returns next week, allowing additional weaker
shortwave troughs to potentially bring shower and storm chances
Monday evening into Wednesday. Ensembles are highly variable in
timing and location this far out with modest low precip chances
inserted attm. Temperatures remain seasonable in the low 80s
for highs and overnight lows in the 50s.


&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1229 AM CDT Thu Apr 25 2024

VFR to start TAF period as scattered SHRA gradually becomes
more widespread as moisture increases from the south. Cigs are
expected to quickly fall to IFR as scattered TSRA develops from
11Z-14Z, moving southeast through early afternoon. A few short
term models try to lift cloud bases to MVFR in the late
afternoon, however with the continued warm and moist advection,
I am leaning towards IFR stratus remaining through the remainder
of the period. There may also be additional showers that
develop aft 00Z.

&&

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

&&

$$

DISCUSSION...Prieto
AVIATION...Prieto