977
FXUS63 KTOP 291651
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1151 AM CDT Wed May 29 2024

.KEY MESSAGES...

- A few showers and thunderstorm (20% or less chance) may occur
  across the western and southern counties of the forecast area
  areas this afternoon.


- Thursday night through Saturday morning, widespread rain and
  thunderstorms will be possible (60 to 80 percent chance).
  Rainfall totals are forecast to be in the 1 to 2 range. Some
  rivers may see minor flooding.

- Chances for showers and storms will continue through the
  weekend and into the middle of next week. The weekend will
  not be a total wash out but we may see a 30 to 50 percent
  chance for showers and storms daily.

&&

.DISCUSSION...
Issued at 321 AM CDT Wed May 29 2024

Early this morning a broad upper trough was centered across the
eastern Great Lakes States, with a upper trough axis extending
southward across the mid Atlantic States. An upper level trough
was moving onshore across the Pacific northwest. A perturbation
embedded within the southern stream of the upper jet was
moving east across OK and east central TX. A second
perturbation was located across northwest Mexico.

At the surface a lee trough extended from eastern CO, south across
the southern high Plains. A stationary front extended from
southeast TX, northwest into the South Plains of west TX, where
it formed a triple point with the surface dryline along the
TX/NM border. Richer moisture at 850mb, was being advect
northwest into the western TX PNHDL/eastern NM, then north into
eastern CO.


Today and Tonight:

The Pacific Northwest H5 trough will move east across MT and WY
while weak near zonal flow will continue across KS. The
Southeast 850mb winds will veer more to the south-southwest
across OK and western KS, allowing for some richer moisture to
shift east towards the western counties of the CWA. A broad
surface ridge across the southern Great Lakes will expand
southwest into the lower OH River Valley with drier air parcels
rounding the ridge axis across MO and far eastern KS. The WRF
and FV3 cams show enough ascent from the richer moisture
advection into central KS and perhaps ascent ahead of a weak
perturbation, may allow a few showers and thunderstorms to
develop across central and north central KS. Some of these
storms may move southeast across the western and southern
counties of the CWA. The CAMs vary in the amount of instability
that develops. Most show only 400-800 J/KG of MLCAPE this
afternoon. The NAM12 has the high bias of 1200 J/KG of MLCAPE.
The effective shear will only reach 20 to 25 KTS. So, storms
that develop should not be severe, though some of the pulse type
storms may produce gusty winds and small hail. Any showers and
storms that develop this afternoon should dissipate after
sunset. Highs Today will reach the upper 70s to lower 80s.

Most of Tonight will remain dry, with showers ans storms developing
in west central KS as a more amplified perturbation moves northeast
out of NM into southwest KS early Thursday morning.

Thursday through Wednesday:

The first perturbation over southwest KS will fill as it shifts
northeast into northeast KS/southeast NE. The combination of
weak ascent along with isentropic lift ahead of deeper moisture
advection northward across KS will cause scattered showers and
storms to move east across the CWA after 12Z THU. We may see a
break in the rainfall during the late morning and afternoon
hours. A more amplified perturbation will move east out of CO
into western KS by 00Z FRI. Widespread showers and thunderstorms
will develop across western KS Thursday afternoon and spread
east across the CWA Friday night. The stronger H5 trough will be
moving across the norther Plains. The westerly H5 flow across
KS will only be 15 to 25 KTS. The lack of vertical windshear
will prevent any organized severe thunderstorms from developing.
The perturbation across KS will begin to amplify as if shifts
east into MO Friday evening. At this time, much of the CWA will
see 1 to 2 inches of QPF Thursday night through Friday.

During the Weekend and into Monday, there will continue to be
chances for showers and thunderstorms, with weak zonal flow
across KS and embedded perturbations moving east across the
region. The more amplified H5 trough across the northern Plains
will lift northeast into the Great Lakes and New England. Highs
will be in the lower tom mid 80s.

Tuesday through Wednesday morning, a more amplified upper level
trough will move east across the Plains. The H5 flow in the
base of the H5 trough will increase to 30 to 50 KTS, so the
effective shear confined with instability may provide the CWA
with a better chance for strong to severe thunderstorms Tuesday
afternoon into Tuesday night ahead of a cold front. The GFS and
ECMWF are in fair agreement with the timing of the upper trough
moving across the central Plains. These longer range model
solutions could change over time.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1151 AM CDT Wed May 29 2024

There may be a diurnally driven shower or two this afternoon,
but activity is expected to remain isolated with probabilities
of impacting a terminal around 10 percent. Chances for TS will
increasing through Thursday. At this time, CAMs keep the
activity west of MHK through 18Z. So will keep a dry forecast.
There could be some stratus advect in from the south. But this
is not a consensus among the models and probabilities for CIGs
below 3 KFT only ramp up after 12Z. Will let later shifts
reevaluate the potential for low clouds.

&&

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

&&

$$

DISCUSSION...Gargan
AVIATION...Wolters