Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 161025
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
525 AM CDT Mon May 16 2022

...Update to aviation forecast discussion...

.DISCUSSION...
Issued at 300 AM CDT Mon May 16 2022

- There may be a chance for strong to severe thunderstorms
on Tuesday, with the better chance along the NE border.

- Another chance for thunderstorms Thursday into Friday.

- Cooler temperatures expected by the end of the week into next
weekend with highs in the upper 60s to lower 70s.

Early this morning the upper trough that brought the severe
thunderstorms to the forecast area Sunday morning has phased with a
northern stream H5 trough across east central Canada and extended
southward east of the MS River Valley. A low amplitude upper level
ridge was noted across the central Rockies. A broader upper level
trough was located off the Pacific northwest coastline. The surface
cold front has pushed southward into north TX.

The upper level trough across the Great Lakes and MS River Valley
will shift east as the low amplitude ridge across the Rockies moves
east across the southern high Plains. The H5 ridge will deamplify,
as the mid and upper level flow across the Plains will become
more zonal. Highs Today will reach the upper 70s to lower 80s as
winds gradually become southerly through the afternoon hours. A
surface ridge of high pressure over the eastern portions of the central
Plains will shift east into the mid MS River Valley as a lee
surface trough deepens across the central and southern high
Plains.

Tonight: The southerly low level flow will increase with a LLJ of 30
to 40 KTS developing after midnight. This will transport richer
moisture northward into the central Plains. The resulting isentropic
lift will cause showers and a few elevated thunderstorms to develop
during the early morning hours of Tuesday. Overnight lows will only
drop into the upper 50s to lower 60s.

Tuesday through Tuesday night: During the morning hours the
isentropic lift aided by a mid level perturbation embedded in the
zonal flow will provide a chance for showers and elevated
thunderstorms. Some of the elevated thunderstorms may produce larger
hail during the morning hours of Tuesday as MUCAPE increases between
1000-2000 J/KG and effective shear will be over 30 KTS. During the
late morning hours the stronger isentropic lift will shift northeast
into NE/northwest MO/southwest IA. We should see a break during
the early and mid afternoon hours.

Most CAMs and some of the deterministic models do not show much
convection developing across the CWA during the afternoon hours
given the lack of any notable boundaries for surface convergence or
lift. The Nam nest does develop a few supercell thunderstorm
southeast of ICT in the warm sector. There is an embedded
perturbation in the zonal flow that may provide ascent for some
isolated storms to form in the warm sector. The dryline will be
located well west of the CWA across western KS. If deep moist
convection can develop within the warm sector Tuesday afternoon
and evening, then any discrete storm will have ample instability
(MUCAPES>2500 J/KG) and good low-level vertical wind shear
(curved low- level hodographs) for supercell thunderstorms, which
would be capable of producing large hail, damaging wind gusts, and
a possible tornado. However, I have low confidence of a
thunderstorms developing without some form of lift with an
associated surface boundary.

The higher based supercells that will develop Tuesday afternoon
across western KS along the dry line will likely converge into line
segments and lift northeast across the western and northern counties
of the CWA during the late evening hours of Tuesday and early
morning hours of Wednesday. The convergence will be enhanced by
surface cold front which will push southeast across the state during
the overnight hours. Any line segment of thunderstorms may be strong
to marginally severe but these storms should weaken into the early
morning hours of Wednesday. The surface front will pass southeast of
the CWA by 12Z WED bringing an end to the chances for showers and
thunderstorms.

Wednesday through Thursday night: An upper level trough moving
onshore across the Pacific northwest will dig east-southeast across
the central Rockies into northern Plains and central high Plains by
00Z FRI. The weak front on Wednesday will stall out across
northern OK where frontolysis will occur Wednesday night. A
deepening lee trough across the central and southern high Plains
will cause the southerly low-level flow to increase transporting
richer moisture northward. The isentropic lift early Thursday
morning looks weaker and may not provide enough lift for elevated
thunderstorms. On Thursday eastern KS will be in the warm sector.
The surface dryline will shift east into central KS by Thursday
afternoon and there may be enough surface convergence for discrete
storms to develop. The environment looks to be favorable for
supercell thunderstorms. These storms may move northeast into the
western counties of the CWA during the evening hours. As the H5
trough moves east into the central Plains, the ascent ahead of the
H5 trough along with surface convergence along a cold front
moving southeast into northwest IA, eastern NE and northwest KS
will cause a line of thunderstorms to back build southwest into
the northeast counties of the CWA overnight Thursday. Some of
these storms may be severe but the ECMWF solution shows the front
outrunning the line of storms which may weaken the line of
thunderstorms as the warm moist inflow gets undercut.

The 00Z GFS solution is slower digging the H5 trough moving
onshore across the Pacific northwest, southeast into the central
Plains. The GFS solution shows the better chances for
thunderstorms on Friday along a surface cold front. The back
building squall line looks to develop northeast to southwest
across the CWA during the afternoon hours of Friday.

Both the ECMWF and GFS show cooler temperatures for next weekend
with highs in the upper 60s to lower 70s but dry conditions, as the
upper flow becomes northwesterly on the west side of an applying
trough across the eastern US.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 523 AM CDT Mon May 16 2022

Expect VFR conditons at all terminals for the next 24 hours. Light
and variable winds will become southeast at 5 to 10 KTS this
evening. Early Tuesday morning a few elevated thunderstorms may
start to develop towards 12Z TUE.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

DISCUSSION...Gargan
AVIATION...Gargan


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