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000
FXUS63 KTOP 171136 AAA
AFDTOP

Area Forecast Discussion...UPDATED
National Weather Service Topeka KS
636 AM CDT Wed Apr 17 2024

.KEY MESSAGES...

- Severe storms will be possible late this evening into Thursday
  morning. Large hail will be the primary hazard.

- Below normal temperatures are expected late this week into the
  weekend. Frost and freeze conditions will be possible Sunday
  morning around sunrise.

&&

.DISCUSSION...
Issued at 405 AM CDT Wed Apr 17 2024

Early this morning an upper level trough was lifting northeast
across the upper Midwest. A second upper level trough was digging
southeast across central Canada into the Great Basin.

A surface cold front has become stationary across southeast OK and
west central TX. South of the front, rich moisture with surface
dewpoints in the mid to upper 60s were noted across southern
and east central TX.

Today:

The upper trough across the upper Midwest will lift northeast into
the northern Great Lakes. The positive tilt H5 trough across
southern Canada and the Great Basin will translate east across
the central Rockies into the northern Plains. The stationary
front across southeast OK will begin to lift northwest across
central OK by late afternoon. A lee surface trough will deepen
across eastern CO and extend southward into the southern high
Plains. Surface winds will become southeast across the CWA and
will gradually increase in speed to 10 to 20 MPH by late
afternoon.

Tonight through Thursday:

The positive tilt upper trough will move into the upper Midwest and
central Plains through the night. The surface warm front will move
northward into east central KS and central MO by 6Z. A few of
the CAMs show isolated storms developing along the warm front
across southeast KS. A few of these storms may reach the
southeast counties of the CWA during the late evening hours.
Forecast soundings show these storm will be elevated with near
1000 J/KG of MUCAPE, so some quarter size or large hail may be
possible given the effective shear around 42 KTS.

Through the early morning hours of Thursday, low-level CAA across
the northern Plains and upper Midwest will cause a surface cold
front to move southeast across NE into northeast KS by 12Z THU.
The more intense DCVA, ahead of the H5 trough, will spread
across IA and northern MO. A line of thunderstorms will develop
along the front in western IA and northwest MO and begin to
build southwest into the CWA after 7Z. The 4km NAM and Fv3 Cams
show a line of scattered storms developing southwest across the
northeast counties, southwest to ABI. The NAM shows the
potential for a broken line of elevated rotating supercell
thunderstorms given MUCAPES of 2500 J/KG and effective shear of
46KTS. This environment would be conducive for hail to the size
of 2 inches or greater. However, the HRRR, RAP and versions of
the ARW keep the back building line of storms just east of the
CWA across MO along the surface front. If these CAMs verify, we will
not see much in the way of large hail across the CWA. However,
the environment from the HRRR mode shows about 2100 J/KG of
MUCAPE and effective shear of 30KTS, so the environment would be
conducive to large hail if a storm happened to develop along or
just northwest of the surface front. The potential line of
scattered severe storms will move southeast across the CWA
through the early and  mid morning hours of Thursday. So, stay
tuned to this potential large hail threat late Tonight through
the morning hours of Thursday.

There may be some lingering showers into the early afternoon
hours of Thursday, but skies will clear from northwest to
southeast as the upper trough moves east into the upper MS
River Valley. Winds behind the front will also be gusty but
should remain below advisory levels. Highs will be cooler
behind the front with upper 50s to lower 60s. The Southeast
counties may reach the upper 60s by late morning but
temperatures will slowly fall through the 60s during the
afternoon.

Thursday night through Saturday night:

The northeast H5 trough will amplify and the resulting CAA will
cause an area of high pressure from central Canada to build
southeast across the Plains Friday into Saturday. Expect much
colder weather with highs only reaching into the 50s to around
60 degrees both Friday and Saturday. Overnight Saturday into
Sunday morning, lows will drop into the mid to upper 30s across
the CWA with some sub freezing temperatures across the northern
counties of the CWA. There may be frost developing along and
north of I-70 by sunrise on Sunday morning. Frost and freeze
headlines may be needed late Saturday night into Sunday morning.

Sunday through Wednesday:

The upper flow will become zonal across the Plains resulting in
a lee trough deepening across the High Plains on Monday. Warm
advection combined with perturbations embedded within the zonal
flow will provide low chances for showers and thunderstorms
Monday through Wednesday. Highs will be a bit warmer on Sunday
after a cold morning start, look for highs to reach the lower to
mid 60s Sunday afternoon. Highs will warm into the lower to mid
70s Monday through Wednesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 630 AM CDT Wed Apr 17 2024

Expect VFR conditions for the next 20 to 22 hours. There may be
some BKN MVFR stratus over the terminals after 11Z THU. There
may also be scattered storms after 10Z but the uncertainty in
timing and coverage precludes me from placing in the 12Z TAFs.
West-northwest winds will be 11 to 15 KTS through the morning
hours with gusts of 18 to 23 KTS. The winds will diminish this
afternoon and back more to the southwest by late afternoon. A
strong southerly low-level jet of 40 to 45 KTS will develop
after Midnight and cause low-level wind shear at the terminal by
8Z to 9Z .

&&

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

&&

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

&&

$$

DISCUSSION...Gargan
AVIATION...Gargan