412
FXUS63 KTOP 151045
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
545 AM CDT Wed May 15 2024

.KEY MESSAGES...

- Scattered thunderstorms are expected through tonight.

- An isolated storm or two could become strong enough for some
  hail and strong wind gusts.

- Temperatures warm up this weekend with a typical spring
  forecast for precipitation chances just about every day.

&&

.DISCUSSION...
Issued at 258 AM CDT Wed May 15 2024

07Z water vapor imagery showed a shortwave trough over WY and
northwest CO with showers that developed off the high plains
weakening as the move east across the state into some weaker
flow. Surface obs showed low pressure over the southern high
plains with an inverted trough extending through northwest KS
and into central SD. Moisture return has been muted thanks to a
weak meso high over western parts of the forecast area. There
hasn`t been much fog formation so far across eastern KS and with
cirrus spreading in from the west, conditions for fog early
this morning look to become less favorable.

The overall weakening trend with the precipitation to the west is
expected to persist through the morning since the better dynamics
for vertical motion remain to the west. The CAMs do show some
isolated shower activity persisting or redeveloping late in the
morning. This may be a result of some insolation along with a weak
MCV passing overhead. But models show the better instability
remaining south and west of the forecast area through the afternoon.
Bulk shear does look a little better than it did 24 hours ago, but
MUCAPE values around 1000 J/kg may be optimistic if cloud cover
hangs around for much of the day. SPC`s outlook bringing the slight
risk up into southern Lyon county is more for what may develop in
western OK and move into southeast KS then what could form up here.
Think the better POPs are going to be overnight as the low amplitude
shortwave lifts along the KS/NEB state line. And given the marginal
instability coupled with 0-6km shear of 40KT to 45KT, there could be
an isolated intense storm with some hail or gusty winds.

A weak boundary is progged to set up across east central KS through
the day Thursday. There looks to be decent moisture along and
southeast of the boundary such that any weak disturbance lifting
along it within the southwest flow could spark additional showers
and storms. Models would suggest forcing would be subtle so the
forecast only shows chance POPs persisting over east central KS.
Bulk shear appears to be weaker even though models develop MUCAPE
upwards of 1500 J/kg suggestive of more pulse type storms if they
form. By Friday, most guidance has the upper trough axis shifting
east of the forecast area. The GFS however wants to lift a closed
low through the Ozarks and has much more QPF than other solutions. A
look at the 12Z cluster analysis shows the GFS doesn`t have much
support from the other ensemble members and the GFS cluster only has
about a 25 percent chance of occurring. Because of this have kept
POPs similar to what the previous forecast had through the day
Friday. Am not ready to go dry as the ECMWF would have it, but
think the NBM may have to much of an influence from the GFS.

A break from the precip chances is expected Saturday. But the
overall pattern for Sunday through Tuesday of southwest flow aloft
and the potential low amplitude perturbations makes it difficult to
argue against the low POPs provided by the NBM. There seems to be
some signal for more organized forcing Sunday night and again Monday
night. This is when the forecast has relatively higher POPs, but
they remain in the chance category. A lack of consensus among the
ensembles with the GFS appearing to be in one camp and the ECMWF
another, tends to lower confidence in the forecast beyond Saturday.
So have kept the blend in tact.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 545 AM CDT Wed May 15 2024

Area of -RA continues to shrink as it moves east. CAMs show
isolated to scattered showers possible through the day. Skill in
timing and location is not that great without a focus, so will
continue with VCSH and adjust as things become more obvious.
Think that VFR conditions should prevail for much of the day
once the MVFR BR dissipates at TOP and FOE. There is a better
signal for some MVFR CIGS moving in late in the period.

&&

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

&&

$$

DISCUSSION...Wolters
AVIATION...Wolters