627
FXUS63 KSGF 301714
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1214 PM CDT Tue Apr 30 2024

.KEY MESSAGES...

- Some flooding persists across the area from the several days
  of repeated heavy rain.

- Dense Fog Advisory until 9 AM for the eastern Ozarks.

- Thunderstorm chances (20-50%) move back into the area tonight
  into Wednesday morning, generally along and northwest of I-44.

- The unsettled weather pattern will persist into the weekend
  with additional thunderstorm chances...the potential of severe
  weather...and more flooding. Most widespread chances are
  Thursday and Thursday night (70-90%).

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 300 AM CDT Tue Apr 30 2024

Subtle upper-level ridging is filling in over the Plains states
ahead of an approaching longwave trough and associated jet
streak. A cold front at the surface--bringing lower 50 lows this
morning--is just to the south, but is forecast to continue to
dissipate as upper-level forcing lifts away from the area.
Indeed, while much of our area has very calm and variable
winds, observations in our western counties are already
exhibiting SE`ly flow ahead of the next approaching system
coming off the northern Rockies.


Dense Fog Advisory until 9 AM for the eastern Ozarks:

The light winds, clear skies, and saturated air along and behind
the cold front is producing fog within the eastern Ozarks.
GOES Nighttime Microphysics have shown this area of fog
increasing in coverage and density as the night has gone on.
West Plains has also been sitting below a quarter mile
visibility for the past hour. As such, have issued a Dense Fog
Advisory for the area until 9 AM when clear skies and surface
heating will mix out any leftover fog.


Some flooding persists across the area from recent heavy rain:

While many rivers are starting to decline, several rivers,
especially in west-central MO and east-central KS, are still in
moderate to major flood stage. The Little Osage River - Horton
point is the only river still in major and is expected to
decline to moderate this morning. Despite the declining trend,
impacts from the flooding are still ongoing within areas
outlined by our flood products. Continue to pay attention to
which areas are under warnings/advisories and as always, turn
around, don`t drown!


Thunderstorm chances return tonight into Wednesday night:

Unfortunately, more rain chances are on the horizon, especially
for the areas that have already received a lot of rain and are
in the moderate/major flooding stages. The longwave pattern
that`s setting up will exhibit a broad longwave trough axis over
the northern Rockies. Several shortwaves are forecast to revolve
around this axis, forcing multiple chances for
showers/thunderstorms for the week ahead.

The first shortwave is expected to traverse the northern Plains
this afternoon. Synoptic ascent associated with the wave will
force a surface low that will track across SD/MN. This will
initiate S`ly flow across our region once again as warm, moist
air streams northward into the surface low. This will warm high
temperatures into the lower 80s today with dewpoints in the
upper 50s.

Storms are expected to form NW of our area along an associated
cold front. Recent CAMs suggest an MCS to eventually develop and
dive SSE, feeding off a moist 40-60 kt S`ly LLJ. The remnants of
this MCS may reach into our NW counties after 9-11 PM tonight
(20-50% chance). With MUCAPE values forecast to be in the
500-750 J/kg range, and the MCS becoming displaced from upper-
level support, it should weaken as it enters our counties. HREF
paintballs suggest the heaviest precipitation will stay NW of
I-44, where the SPC has a Marginal (1/5; 5%) risk for an
isolated damaging wind gust up to 60 mph and/or hail up to
quarter size. Additionally, LPMMs only bring 0.25-0.5" of rain
for our SE KS counties and <0.1" for other areas NW of I-44.
However, springtime nocturnal MCSs are known to be silly little
guys and last longer than models anticipate, so it would not be
entirely unlikely for areas along and SE of I-44 to see remnant
scattered showers/thunderstorms after 1-3 AM (15-30% chance).
Nevertheless, increased cloud coverage from the MCS will keep
lows near 60F tonight.

Lingering stratiform rain/thunderstorms from the overnight MCS
may be continuing across parts of the area Wednesday morning
(15-40% chance). But generally, there will be lingering clouds
and continued S`ly warm, moist flow ahead of the next shortwave
trough to round the northern Rockies longwave. The southerly
flow will bring highs Wednesday into the lower to mid-80s,
especially for areas untouched by morning rainfall. The next
wave will then slowly enter the northern Plains Wednesday
afternoon. The chances for storms Wednesday looks near identical
to Tuesday, with storms firing over KS/NE, congealing into an
MCS, marching ESE into our CWA by the 9 PM to 3 AM timeframe,
then slowly dissipating. As with Tuesdays chances, the areas
most likely to be affected will be NW of I-44 (20-50% chance).
And once again, lows will be in the mid-60s due to remnant cloud
cover from the convection.

If any or both of these rounds of convection occur, additional
rainfall will bring further stress to our already saturated
rivers along the MO/KS border. This is something that will need
to be watched and monitored very closely. If CAMs continue to
show a heavier rain signal, another Flood Watch may be needed
for that area.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 300 AM CDT Tue Apr 30 2024

Unsettled weather pattern will persist into the weekend:

The slow-moving wave that will have initiated Wednesday`s round
of convection, will slowly traverse through NE/SD during the
day Thursday. Positive vorticity advection along the eastern
edge will orient the wave into a negative tilt and allow for the
surface cold front to fully make its way through our area
rather than stalling off to the west. This will bring widespread
rain chances across our entire forecast area Thursday into
Friday morning (70-90% chances). It will also cool Thursday`s
highs into the upper 70s and lows in the 50s.

While this wave of convection is expected to clear through our
CWA, it will be slow-moving. Additionally, with the surface low
and upper-level wave off to the north, mean flow will be largely
parallel to the front, bringing another round of slow-moving and
training thunderstorms across the area. The WPC has a Slight
(2/5) risk for excessive rainfall for much of our area. This
will once again bring a flooding threat to our area, especially
in already rain-stressed zones/rivers. ESATs point to 99.5th
percentile of low-level moisture surging through the area with
PWATs around 1.25" which would indeed support any thunderstorm
to be efficient rainfall producers.

Additionally, the SPC has areas west of Hwy 65 in a Marginal
(1/5; 5%) risk for severe weather as just enough MUCAPE and
shear should be present. However, with the upper-level wave and
surface low well to the north, only isolated marginally severe
weather is forecast at this time (mainly damaging wind gusts up
to 60 mph and hail up to quarter size).

Lingering stratiform rain may be present during the day Friday,
especially in the eastern Ozarks, as the system slowly exits the
region. After of which, 20-40% chances of showers/thunderstorms
stay persistent from Friday evening through Monday. The presence
of chances during every time period highlights the ensemble
uncertainty. The ensemble mean longwave pattern with a trough
over the west CONUS and broad SW`ly flow across our area
supports multiple rain chances, the uncertainty comes from
disagreement in the location and timing of shortwaves that
progress through the longwave pattern. This will become clearer
with time, but for now, the average synoptic pattern does indeed
support rain chances for much of the weekend period.

Highs into the weekend will be in the middle to upper 70s with
lows in the middle to upper 50s.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1209 PM CDT Tue Apr 30 2024

For the 18z TAFS, A few light showers were starting to pop up
over southeast KS in a narrow band of enhanced cumulus. Not
expecting much in the way enhancement with this scattered narrow
band of showers as it shifts east into the CWA. The main
activity will develop ahead of a surface front from south
central Kansas into northeast Kansas later in the afternoon with
this activity weakening and spreading into our CWA after 02-04z.
For now am going to continue with a prob30 group for convection.
Should see VFR conditions outside of any convection, with the
potential for MVFR conditions within the convection. Some gusty
southerly winds will continue during the afternoon up to 25 kts
at times, but should diminish this evening and eventually become
light and variable.

&&

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

&&

$$

SHORT TERM...Price
LONG TERM...Price
AVIATION...Lindenberg