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082
FXUS63 KSGF 180830
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
330 AM CDT Wed Sep 18 2024

.KEY MESSAGES...

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- Generally dry and becoming unseasonably warm temperatures
  through the rest of the work week with the hottest day on
  Friday.

- Some low-end rain chances late in the week (10-30%)...with
  better chances over the weekend (30-60%)...and additional
  chances through the middle of next week (10-30%).
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&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
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Issued at 330 AM CDT Wed Sep 18 2024

Current water vapor imagery paired with RAP synoptic analysis
reveals an interesting pattern set up across the CONUS. Three
mid-level lows paired with occluded surface low pressure
systems are currently scattered across the CONUS. One is over
the Carolinas, and the other two are embedded within a longwave
trough over the western CONUS. The most potent mid- and upper-level
wave is situated over WY, forcing precipitation across the
Central and High Plains. Despite all this active weather across
the country, Missouri is placed in between the lows, where
upper-level ridging, surface high pressure, and subsequent fair
weather has taken hold.

Mostly clear skies tonight will bring lows down into the 60s
(middle 60s along the MO/KS border, upper 50s and lower 60s in
the eastern Ozarks). Paired with calm winds, light patchy fog is
possible tonight into tomorrow morning (10-30% chance).
However, with dewpoint depressions being slightly more spread
than yesterday, most of the fog should stay within river valleys
and low-lying areas.


+Generally dry and becoming unseasonably warm:

The mid- and upper-level lows will do some dancing through
Thursday, creating quite an unusual pattern. By Thursday
evening, one low will still be hovering over the Carolinas,
another will be along the US(North Dakota)/Canada border, and
the third will be over SoCal. The amplified nature of these
waves places the southern Plains--including our region--within
a building ridge. This will slowly increase temperatures through
Saturday. Wednesday will see highs in the middle to upper 80s
with some areas along the MO/KS border seeing values just at or
above 90 F. As the ridge builds, Thursday will be warmer with
highs in the upper 80s to middle 90s (warmer along the MO/KS
border).

Lows will also warm. Wednesday night will see lows in the upper
50s in the eastern Ozarks, to around 70 F along the MO/KS
border. Thursday night will be near record-breaking with lows in
the upper 60s to lower 70s. Joplin is forecast to be at 73 F
Thursday night. See the Climate section for more info.


+Some low-end rain chances late in the week (10-30%):

While the short-term pattern will stay mostly dry for most areas,
there are some low-end chances for remnant rain to impact areas
along the MO/KS border late Wednesday night into Thursday
morning, and again Thursday afternoon into the night. Chances
are currently low (10-30% chance) as the corridor of instability
and ample shear for forward-propagating thunderstorm complexes
will be quite narrow and just to our west. However, we`ve seen
cold-pool driven systems escape further east than modeled
several times before, so it`s worth mentioning.

The instability/shear corridor will shift eastward Thursday
evening with the 00Z HREF giving a 50-80% chance for a >500
J/kg and >30 kt CAPE/Shear combo to be situated just west of
Hwy 65. This could allow showers and thunderstorms to impact our
CWA Thursday afternoon into Friday morning (10-30% chance),
though confidence is still low since the initiating cold front
and associated upper-level support is expected to stay well
west of the area. Nonetheless, the SPC does have a Marginal (1
of 5) Risk clipping Bourbon County, KS for Thursday afternoon
into the night.
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&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
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Issued at 330 AM CDT Wed Sep 18 2024

+Unseasonably warm through the weekend. Hottest day Friday:

As the southwesternmost potent shortwave trough lifts into the
Four Corners region over the weekend, the mid-level ridge over
our area will amplify to anomalous levels. ECMWF ESATs depict
>99.5th percentile 500 mb heights inching into SW MO. This will
bring high temperatures Friday into the middle to upper 90s
(with upper 80s in the eastern Ozarks). These highs will be 3-5
degrees below record levels. According to our climatology, lower
to middle 90s is well above the 25th percentile for *checks
notes* the middle of September. Additionally, upper 60s
dewpoints will bring max Heat Index values to 100-103 F west of
Hwy 65. So it will feel hot, especially for September, even if
no Heat Advisory is issued. Lows Friday night will also be near
record-breaking in the upper 60s to middle 70s.

As the shortwave trough progresses eastward, temperatures will
cool slightly with highs Saturday in the middle 80s (lower 90s
in extreme SW MO and SE KS). Lows will be in the middle to upper
60s.

Sunday onward, temperatures will cool to near normal (lower to
middle 80s) with a signal for slightly below normal
temperatures into the middle of next week (middle 70s). However
as discussed next, ensemble spread becomes very high after
Sunday, so take the temperature forecast with a grain of salt as
the NBM spread is high and the mean naturally gravitates to
near-normal. Lows during this period will also decrease to the
50s and lower 60s.


+Better rain chances over the weekend (30-50%):

The potent shortwave will traverse through our region this
weekend, bringing better rain chances (20-40% Saturday; 30-60%
Sunday). However, there is still great uncertainty on how the
timing, location, and amounts of precipitation will pan out.
Cluster analysis are showing that the ensembles are having quite
a tough time figuring out how to deal with this unusual
pattern. Saturday onwards, differences in the clusters become
stark. For example, for Saturday, GEFS and GEPS dominated
clusters have the precipitation maximum either over IA, or
across S NE/N KS, while the Euro dominated cluster has a swath
of precipitation from IA down through E KS/W MO. These locations
are very different. It only gets more uncertain Sunday with one
cluster maximizing precipitation over IA/WI/MN, another over
IA/NE/N KS, and another portraying almost no precipitation (only
a band of light precip across central MO).

All that being said, a potent trough moving through with an
eventual cold front passage should bring showers and
thunderstorms to much of our CWA sometime and somewhere this
weekend. However, ensemble uncertainty in timing, location, and
amounts are keeping chances on the lower end for right now.
Check back for more up-to-date information in future forecasts.


+Additional chances through the middle of next week (10-30%):

Ensemble spread only becomes greater into next week. This is
creating 10-30% chances for rain everyday through Wednesday.
However, note that this is an artifact of widespread model
disagreement, so it`s likely that as models come into more
agreement, specific days and locations will begin to be picked
out for the higher rain chances.
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&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1240 AM CDT Wed Sep 18 2024

VFR conditions are expected to prevail for the entire TAF
period for SGF and JLN. Some patchy fog is possible at BBG
between 09-13Z (40% chance for visibility to drop below 4
miles). Otherwise, winds will be at 5-10 kts out of the SSE with
mostly clear skies, save for FEW high clouds and a ~6 kft
cumulus field between 18-01Z.

&&

.CLIMATE...
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Issued at 330 AM CDT Wed Sep 18 2024

Record High Temperatures (Joplin):

September 19:
98 (1954) Forecast: 94

September 20:
99 (1954)       Forecast: 96



Record Highest Minimum Temperatures (Springfield):

September 20:
74 (2018) Forecast: 70

September 21:
73 (1931)       Forecast: 70

September 22:
70 (2017) Forecast: 68



Record Lowest Precipitation for Month of September:

Springfield: 0.05" (1928)
September 2024 Thusfar: 0.04"

Joplin: 0.2" (2013)
September 2024 Thusfar: 0.00"
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&&

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

&&

$$

SHORT TERM...Price
LONG TERM...Price
AVIATION...Price
CLIMATE...Price