318
FXUS63 KSGF 101937
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
237 PM CDT Wed Jul 10 2024

.KEY MESSAGES...

- 20% chance of isolated showers and thunderstorms Thursday and
  Friday.

- Heat indicies climb into the 96-107 degree range from Sunday
  through next Tuesday.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 225 PM CDT Wed Jul 10 2024

Synoptic Scale Pattern and Current Conditions:

Water vapor imagery indicates that the remnants of Beryl continue to
quickly shift northeast through the eastern Great Lakes. On the
western flank of the Beryl remnants, a short wave trough is dropping
south across the Upper Mississippi Valley. An associated surface
trough is making its way south through the Corn Belt and will arrive
in northern Missouri by early this evening.

We have seen scattered fair weather cumulus clouds develop this
afternoon across the Missouri Ozarks and southeastern Kansas. The
cumulus clouds are slightly deeper across the eastern Ozarks where
MLCAPE values of 500-1000 J/kg reside with little in the way of a
capping inversion.

Temperatures this afternoon have been slightly below average with
most areas in the lower to middle 80s. Areas along the I-49 corridor
are pushing the 90 degree mark as a 850 mb thermal ridge embarks on
this region.

Late this Afternoon and this Evening:

A few high resolution models break out weak convection across the
eastern Ozarks in that weakly unstable and uncapped airmass.
However, the presence of mid-level dry air and a subsidence
inversion should tend to tamp down most, if not all activity. We
have therefore kept PoPs in the 5-10% range. Otherwise, scattered
deeper convection will develop across northern Missouri along and
ahead of that advancing surface trough.

Late Tonight and Thursday Morning:

That surface trough will continue to advance south and end up
somewhere near the I-70 corridor by 12Z. Short term ensembles
continue to indicate that isolated showers and thunderstorms may
make it (10-20% chance) as far south as the Highway 54 corridor by
12Z.

A secondary area to watch will be eastern Kansas as a weak low-level
jet veers into the area. If isentropic upglide is able to initiate
convection in the I-70 region down into the Flint Hills, some of
that activity could make it (10-20% chance) into the I-49 corridor
around sunrise.

The main potential hazards with either of these scenarios will be
occasional cloud to ground lightning.

We do expect patchy shallow fog to develop across south-central
Missouri late tonight due to light winds and little in the way of
cloud cover. Fog will especially be favored over lakes and rivers as
well as in valleys.

Lows tonight will be quite variable across the area with the eastern
Ozarks falling into the lower and middle 60s. A few of our coolest
valleys will likely dip into the upper 50s. In contrast, areas along
the I-49 corridor will fall into the upper 60s to around 70 degrees.

Thursday Afternoon:

That surface trough will wash out with a few convective outflow
boundaries possibly seeping into the Ozarks from overnight and early
morning thunderstorm activity. Meanwhile, a weakly cyclonic flow
aloft will be present over the area with a weak thermal trough
from 700 mb to 500 mb.

As temperatures warm into the upper 80s and lower 90s, MLCAPE values
of 1500-2500 J/kg are forecast to develop over much of the area with
little in the way of inhibition. This will result in at least
isolated thunderstorm activity during the afternoon and early
evening hours. We have gone with 20% PoPs over most areas to cover
this scenario, however PoPs may need to be raised as confidence
increases in both timing and location.

Where storms are able to develop, our experimental Ozarks Pulse
Severe Thunderstorm Index (OPSTI) is indicating low to locally
moderate potential for downbursts and perhaps hail up to the size of
quarters. We will get a better feel for any low-end severe potential
with 12Z sounding data.
&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 225 PM CDT Wed Jul 10 2024

Friday:

An upper level trough over the western U.S. will slowly begin to
build east into the Plains. This will mark the beginning of a slow
warming trend as we head into the weekend and early next week. NBM
data is strongly clustered around high temperatures in the upper 80s
and lower 90s over most areas. Areas along the I-49 corridor will
warm into the lower 90s with perhaps a few readings in the middle
90s.

We do again expect the potential for isolated afternoon pop-up
storms mainly east of the I-49 corridor. Mid-level temperatures may
be too warm for storms west of I-49. Once again, the OPSTI indicates
some low to locally moderate potential for downbursts and hail up to
the size of quarters with storms that develop.

Saturday:

Global ensembles show strong consensus that the upper level ridge
over the western U.S. will continue to expand east. There are some
ensemble members that hint at an MCS developing across the Corn Belt
late Friday night as a short wave trough tracks southeast across the
Upper Mississippi Valley. If this MCS were to develop, it would tend
to track south through portions of eastern Missouri Saturday
morning. This is a low probability scenario, but one to watch for.

Otherwise, the timing of that short wave trough will determine the
potential for afternoon pop-up showers and storms. An earlier
passing of the trough axis will lead to height rises in the
afternoon and no thunderstorm potential. A slower passage will
result in at least isolated storms. At this point, we are in the
middle of the road with PoPs around 10%.

Temperatures will continue their ascension on Saturday with most
areas warming into the lower or middle 90s.

Sunday through Tuesday:

The upper level ridge will continue to expand east with afternoon
temperatures warming well into the 90s over most areas. NBM
probabilities give areas along and west of the I-49 corridor 30-40%
chances for reaching 100 degrees on Monday and Tuesday.

While we have loaded NBM deterministic temperatures through the
extended period, it should be noted that bias correction within the
NBM is pushing its numbers closer to the 75th percentile of
statistical data. Thus, fine-tuning of temperatures may be needed as
we get closer to early next week.

Regardless, it`s going to be hot and rather humid with dew points
remaining in the middle 60s to lower 70s. This will result in
afternoon heat indices ranging from 96-107 degrees. Heat headlines
will likely be needed at some point.

Thunderstorm potential for the period looks very low (less than 15%)
as large scale subsidence keeps thunderstorm development at bay. One
low probability scenario we will have to watch is the track of a
tropical upper tropospheric trough (TUTT). This feature is currently
moving onshore over eastern Mexico. This TUTT will slowly track
north and will eventually encounter that western U.S. ridge early
next week. If this TUTT can get far enough north and east, it could
result in an increase in thunderstorm chances by Tuesday.

Wednesday:

Ensemble clusters depict an upper level trough diving southeast
through the northern Plains and Great Lakes. This trough will likely
support a cold front diving south into at least northern Missouri.
Roughly 60% of ensemble members depict this front making it as far
south as southern Missouri while 40% of the ensembles hang the front
up across northern or central Missouri.

A farther south frontal scenario will result in cooler temperatures
as well as some thunderstorm potential for next Wednesday. We
currently have 20-30% PoPs going for the area. These numbers will
likely need to be increased if the front does indeed make it this
far south.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1155 AM CDT Wed Jul 10 2024

VFR conditions will prevail through Thursday morning with a few
fair weather cumulus clouds. There is a 20% chance for MVFR
visibilities at KBBG late tonight and early Thursday morning
owing to light fog. Given the low probabilities, we have opted
not to include this scenario in the KBBG TAF.

Surface winds will remain light and variable.

&&

.CLIMATE...
Issued at 225 PM CDT Wed Jul 10 2024

Record High Minimum Temperatures:

July 15:
KSGF: 79/1954

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
KS...None.
MO...None.

&&

$$

SHORT TERM...Schaumann
LONG TERM...Schaumann
AVIATION...Schaumann
CLIMATE...Schaumann