787
FXUS63 KSGF 010607
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
107 AM CDT Wed May 1 2024

.KEY MESSAGES...

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

- Additional heavy rain potential tonight into Wednesday morning
  has prompted a flood watch for our western two tiers of
  counties in the CWA.

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

&&

.MESOSCALE...
Issued at 725 PM CDT Tue Apr 30 2024

A surface boundary, more of a dry line, is currently located
across central Kansas into northwestern Missouri early this
evening. Thunderstorms have developed on this boundary. The
surface boundary will sag southeast this evening and tonight
across northeastern Kansas and northwestern Missouri but will
remain north and west of the. Instability is highest across
central Kansas and weakens to the east.

The storms across central Kansas has formed into a line segment
and a cold pool appears to have developed. Based on MUCAPE
values of 2000-3000 J/kg this line of storms should follow the
forward propagating corfidi vectors which will start to move
more southeast if not south with time this evening. The
instability gradient will also set up across eastern Kansas to
the south into Oklahoma which the storms will also likely
follow. The northern or more eastern edge of this line may clip
extreme southeastern Kansas and far southwestern Missouri,
generally along and west of I-49 late this evening into tonight.
Gusty winds will be possible, generally up to 50 mph but
localized damaging winds gusts up to 60 mph may be possible.
Some small hail may also be be possible, but with the linear
nature of the storms and the better instability to the west,
winds will be the main risk.

Further north across northeastern Kansas and northwestern
Missouri more discrete storms have developed. This activity
will continue to move east. If a cold pool can develop a line of
storms could develop, but based on the current radar trends
coverage may be more limited. Later this evening storm motions
will start to be more southeast to south across Missouri and the
activity may move into the area. Instability will be weaker but
some uncapped MUCAPE will remain in place. Therefore some
scattered storms will be possible generally north of I-44 late
this evening into tonight, again coverage may be more limited
and overall this activity should be subsevere but a few strong
storms with gusty winds and small hail will be possible but
should weaken overnight.

The 0-3km shear vectors become more west to east overnight. It`s
possible that convection could develop behind the main line of
storms currently over central Kansas and train across portions
of extreme southeastern Kansas and far southwestern Missouri.
This could lead to a localized flooding risk, especially as
these locations received heavy rainfall over the weekend. Will
continue the Flood Watch for counties along and west of the
I-49 corridor from 9PM this evening to 9AM Wednesday morning.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 212 PM CDT Tue Apr 30 2024

Synoptic overview and current conditions: Upper level analysis
and water vapor imagery show a shortwave shifting east out of MT
and WY into the Dakotas and Nebraska. Surface analysis shows has
a low over central SD with a cold front trailing into central KS
and dew points rising into the low to mid 60s over eastern KS.
Temperatures have shot up into the upper 70s to low 80s. Surface
based CAPES were in the 3000-4000 J/KG range further west over
central KS ahead of the front and diminish to 1000-2000 j/kg
over our western CWA. A few showers have developed in a narrow
band over extreme southeast Kansas with some mid level warm
advection and in the area of increasing instability, but these
have struggled to intensify outside of a better forcing
mechanism.

Tonight: Convection should begin to develop over the next few
hours along the frontal boundary with a decent chance of
becoming severe with all modes of severe weather possible. The
severe chances should remain west of our CWA during the
afternoon. During the evening, the front and storms will drift
eastward into the area, but should also begin to decay with
lessening instability and upper level support as the main upper
shortwave quickly lifts northeast into the upper Mississippi
valley. Some stronger storms may be possible initially over our
far western CWA as they begin to push into the area with
marginally severe hail up to quarter size and wind gust
potential up to 60 mph. The decaying convection will also
produce some heavy rainfall in areas which remain in some pretty
substantial river flooding and ground saturation. With expectant
rainfall totals of a quarter inch up to an inch tonight in these
areas, we have opted to go with a flood watch from mid evening
into mid morning Wednesday.

Additional convection potential on Wednesday along any residual
boundaries from tonight thunderstorms. The main severe risk on
Wednesday will remain to our west, but any redevelopment of
storms will have the ability for some heavy rain.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 212 PM CDT Tue Apr 30 2024

An upper level trough will set up over the northern and central
Rockies starting Wednesday night with a southwesterly flow aloft
setting up over our CWA. A surface front over the plains is
expected to slowly push eastward into the area, but will be slow
to move through as it will be more oriented parallel to the
upper level flow. Showers and thunderstorms with heavy rain
will begin to push into the area again Wednesday night with the
best chances(70-90%) occurring Thursday into Thursday night.
While the severe risk looks marginal at this time, the
additional heavy rain will likely lead to more flooding over
parts of the area...especially over our northwest CWA and we`ll
likely need additional flood watches.

The initial front should stall out over northern Arkansas on
Friday, but will return to the north Friday night as additional
shortwave energy moves into the area. This will bring additional
shower and thunderstorm chances to the area over the weekend and
the unsettled pattern looks to continue with nearly daily
chances of thunderstorms into the middle of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1252 AM CDT Wed May 1 2024

A few showers and thunderstorms were moving through JLN and
approaching SGF however they are weakening and confidence is not
high that they will reach BBG. A brief period of gusty winds
will occur with variable winds likely through 12z. South winds
will then dominate through the rest of the period. There is a
low chance for a shower or storm this afternoon at the sites
however confidence is too low to include at this time.



&&

.HYDROLOGY...
Issued at 212 PM CDT Tue Apr 30 2024

Current warnings/flooding:

Western Osage River Basin, affecting Vernon and St. Clair counties
in MO:
-Little Osage River near Horton
-Marmaton River near Nevada
-Osage River at Taberville

Gasconade Basin, affecting Phelps and Pulaski counties in MO:
-Big Piney River near Fort Leonard Wood
-Gasconade River near Jerome

White River Basin, affecting Shannon County in MO:
-Current River near Powder Mill



Crests and stages at the time of writing:

-Marmaton River near Nevada: crested at 28.70 feet at 0215Z (9:15pm
Monday night) in moderate flood stage. Currently at 28 feet, in
moderate flood stage and decreasing.

-Little Osage River near Horton crested at 52.9 feet at 1000Z
(5:00am Monday morning)in major flood stage. Currently at 49 feet,
in moderate flood stage and decreasing.

-Osage River near Taberville, currently 31 feet in the minor flood
stage, yet to crest. Projected to crest at 34.7 feet at 0600Z on
Thursday (1:00am local) in moderate flood stage.

-Big Piney River near Fort Leonard Wood - East Gate is nearing
cresting, currently 16 feet in moderate flood stage.

-Gasconade River near Jerome yet to crest, at 13 feet and
approaching action stage. Projected to crest around 16.6 feet at 12Z
Wednesday (7:00am local) in minor flood stage.

-Current River near Powder Mill crested at 15.10 feet at 0600Z
(1:00am local) in  minor flood stage. Currently at 8.5 feet,
approaching action phase (8ft).


Discussion:

The Osage Basin has been hardest hit by an abundance of rainfall
since Thursday, with some areas (especially Bourbon County in
Kansas) receiving 6-12" of rain over the course of 4 days.
Widespread flooding of roads has been reported near the
Bourbon/Vernon county border, which should be receding as the
Marmaton and Little Osage drain downstream into the greater Osage
River. Most flood stage level rivers have either crested or are
approaching cresting, with the exception of the Osage at Taberville.
However, current forecasts do not include the expected precipitation
beyond 24 hours. An additional 1-2" inches of rain is expected
in this basin through Friday evening, and the "bullseye"
corridor of heaviest rainfall will likely be in the same places
that experienced the training precipitation over the weekend.
The bulk of this precipitation will occur on Thursday, and as
future river forecasts change in collaboration with RFCs, most
rivers could return to some level of flood stage.

The 95th percentile (maximum) future rainfall over the next 72 hours
could result in a return to moderate flood stage for most of the
western Osage Basin, while the best estimate for future rainfall
over the next 72 hours brings most of these areas only into minor
flood stage, according to RFC ensemble hydrographs. Elsewhere,
ensemble hydrographs using best guess QPF indicate the risk of
reaching flood stages is very low due rain accumulations below an
inch expected through the end of the week. The Current River in
Shannon County is the likely exception to this, simply because it
drains slowly regardless of low QPF amounts.

It`s difficult to give an exact probability of flood stages at this
point, because many of our readings are already in flood stage and
HEFS takes that into account when calculating 10-day flood stage
probabilities, which skews any station that`s been in flood stage
over the last day or so. However, it`s safe to say that areas that
received excessive rainfall over the weekend, in addition to the
more reactive tributaries, will be at risk of flooding with this
next round of rain. If rainfall verifies at the high end or above
current weather model guidance, additional impactful river flooding
in the Osage Basin should be expected. Additionally, if areal extent
of rainfall begins to trend further southeast, flooding concerns
will expand beyond the Osage River Basin.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
KS...Flood Watch until 9 AM CDT this morning for KSZ073-097-101.
MO...Flood Watch until 9 AM CDT this morning for MOZ066-077-088-093-
     101.

&&

$$

MESOSCALE...Wise
SHORT TERM...Lindenberg
LONG TERM...Lindenberg
AVIATION...Burchfield
HYDROLOGY...Camden