Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 260601

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
101 AM CDT Sun May 26 2019

.SHORT TERM... (Through Late Monday Night)
Issued at 321 PM CDT Sat May 25 2019

CAMs are indicating another round of strong to severe storms
developing, especially over northern portions of forecast area
early this evening through the overnight hours along an old
outflow boundary. With 0-6km shear 40+ kts, ML CAPES around 3000
J/kg, SCP values over 10, expect scattered supercell development
with main threats being large hail and damaging winds. In the
meantime, as an upper level shortwave lifts out of a trof to our
west with decent moisture convergence on nose of LLJ, will see
another thunderstorm complex develop and track east, mainly along
and north of I-70 corridor, moving into the forecast area after
09z Sunday. This complex will gradually weaken as it tracks to the
east, laying out numerous boundaries. These boundaries will be
the focus of activity that could fire up during the afternoon
hours on Sunday.

Once again activity will then shift back to the north as upper ridge
builds back into region. So for Sunday night through Memorial Day,
the best chances of showers and storms will be across portions of
northeast MO and west central IL.

Lows tonight will be at least 10 degrees above normal, in the mid
60s to low 70s. Highs on Sunday will be a bit lower than today due
to cloud cover and precipitation, in the upper 70s to mid 80s. Lows
Sunday night will be in the mid to upper 60s. Then hot and humid
conditions expected on Memorial Day with highs in the 80s. Dry and
mild weather expected Monday night with lows between 65 and 70


.LONG TERM... (Tuesday through Next Saturday)
Issued at 321 PM CDT Sat May 25 2019

Unsettled weather will persist into the middle of next week. Models
are still indicating that the upper level ridge will break down once
again allowing a developing system over the Central Plains to slide
through region. However, the models are a bit slower with this
system as it deepens over the Central Plains and is slowly ejected
out towards the Great Lakes. Beginning Tuesday afternoon decent
instability, low level moisture and convergence increase over region
ahead of pre-frontal trof, so will see strong to severe storms
develop by late afternoon and through the overnight hours Tuesday
night. Another round of showers and storms are expected Wednesday
night through Thursday morning as main cold front slides through.

Beyond Thursday morning, dry and mild weather expected through
Friday before next system moves in for the first part of next

Temperatures will remain rather mild through the extended period.
Tuesday will be the warmest day with highs in the 80s, then a bit
cooler in the mid 70s to low 80s for the rest of the extended period.



.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1242 AM CDT Sun May 26 2019

The primary concern for the next 6-12 hours will be thunderstorms.
Storms will likely continue to affect northeast Missouri and west
central Illinois for much of the rest of the night. Additional
thunderstorm development could occur further south across central
and eastern Missouri into southwest Illinois toward 12Z this
morning. Current thinking is this convection further south will
not be as strong or concentrated as the current storms are over
northeast Missouri. Guidance then shows rain ending from west to
east from late morning through the early afternoon, and then quiet
weather for the evening. VFR flight conditions are expected
outside of thunderstorms.


Scattered thunderstorms may develop over east central Missouri
toward 12Z and continue in the vicinity until mid or late morning.
Quiet weather is expected thereafter. VFR flight conditions are
expected to prevail outside of any potential thunderstorms.



Saint Louis     68  89  70  88 /  10  20   5   5
Quincy          65  84  67  83 /  60  40  10  30
Columbia        66  86  67  84 /  20  20   5  20
Jefferson City  66  87  68  85 /   5  10   5  20
Salem           65  87  69  87 /  10  10   5   5
Farmington      65  87  67  86 /   5  10   5   5


MO...Flash Flood Watch until 9 AM CDT this morning for Knox MO-Lewis
     MO-Marion MO-Shelby MO.

IL...Flash Flood Watch until 9 AM CDT this morning for Adams IL-Brown



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