883
FXUS63 KTOP 181844
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
144 PM CDT Wed Sep 18 2024

.KEY MESSAGES...

- A few isolated thunderstorms will be possible across the area
today and tomorrow with hail and wind associated with the most
intense storms.

- Above normal temperatures through Friday with Thursday likely the
warmest day with heat indices around 100 degrees over northeastern
into east central areas.

- Welcome and more widespread rain chances come into Saturday and
Sunday periods. Could see up to 2-3 inches in some areas with best
chances north I-70.

&&

.DISCUSSION...
Issued at 311 AM CDT Wed Sep 18 2024

Currently, at the 07Z hour, the upper air pattern across the CONUS
shows an area of upper low pressure over the southeastern states
working into the Carolinas. A broad trough with a pair of upper lows
is situated over the western CONUS with the eastern flank upper low
over the northern Rockies and associated negatively tilted trough
working over the High Plains region. The local forecast area will
remain just to the southeast of the best forcing for ascent with
this feature which has implications for the isolated to scattered
nature of any storms today and Thursday. Low level moisture is still
of good quality from south to north with dewpoints well into the 60s
from northern Texas into the Dakotas.

For today, a gradual eastward progression of overnight convection
will work into north central Kansas areas with weak isentropic
ascent along the 310K surface through this morning before weakening
into midday. Expectation is for non-severe showers and storms to
work into north-central KS areas with only light rainfall amounts
expected for this round. Could see a few isolated showers and storms
form again over western areas into this evening but not expecting
widespread coverage due to weaker instability over the region due to
lapse rates generally not as steep into the area as the upper low
over and associated trough lift north of the region along with best
shear and mid-level speed max. By late this afternoon the EML in
place may weaken in some areas with updrafts allowed to grow into
storms. Could still see the risk of hail and strong downdraft winds
over north central areas mostly.

On Thursday, the instability axis is allowed to advance east with
better quality theta-e advection due to the overnight LLJ set up
across the area. Deeper mixing into the day allows for high
temperatures to reach the middle 90s with increasing dewpoints
working into the region with persistent southerly flow before
veering into the evening. This setup looks to increase the overall
instability across the forecast area. Still not seeing much in the
way of forcing for ascent or strong low level convergence. Expecting
isolated to scattered storms - if they form - once again. The
environmental setup would favor more potential for downburst type
storms into Thursday evening if they do end up forming. Could also
see some hail potential if a given storm can remain persistently
strong with a generally tall updraft. Overall, shear profiles
suggest storms may not be highly organized again once they are
allowed to form with sufficient weakening of the EML.

Perhaps the most anticipated part of the forecast may come into the
late Saturday and Sunday periods when the second upper level low and
trough finally emerges from the central Rockies. Persistent forcing
along with moist theta-e advection into the area along with low to
mid level convergence could allow for some heavy rainfall totals
over a 24 to 48 hour period. Forecast anomalies suggest PWAT amounts
to exceed the 90th percentile. Could see some areas record 2-3
inches or possibly more generally north of I-70. Considering the
area is currently in abnormally dry to moderate drought conditions,
this looks to be welcome news. Temperatures fall back to around
normal after this second trough and upper low work through the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 141 PM CDT Wed Sep 18 2024

VFR conditions will persist through the TAF at all sites.
Southerly wind will remain gusty this afternoon and into the
early evening hours before falling below 20 mph around sunset.
BLs should remain fairly mixed overnight with winds sustaining
around 8-10 mph. Some showers may move over the terminals
overnight and into the morning of Thursday, but these should
remain fairly isolated in nature. Due to this, did not mention
in TAF.

&&

.CLIMATE...
Issued at 632 PM CDT Tue Sep 17 2024

Record high temperature data for September 19:

           Record maximum temperature   Forecast maximum temperature
Topeka           99, set in 2022                    96
Concordia       101, set in 2022                    92

&&

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

&&

$$

DISCUSSION...Drake
AVIATION...Griesemer
CLIMATE...Poage