Area Forecast Discussion
Issued by NWS St. Louis, MO

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509
FXUS63 KLSX 240730
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
230 AM CDT TUE MAY 24 2016

.SYNOPSIS...
Issued at 227 AM CDT Tue May 24 2016

Forecast challenge remains convective trends for the next few days
as the boundary layer becomes increasingly unstable and the large
scale upper air pattern becomes more southwesterly, allowing steep
mid level lapse rates to overspread the region. Weak shortwaves
ejecting from the main trof across the southwest CONUS will interact
with this unstable atmosphere to produce several rounds of
thunderstorms across the Midwest each day. Strong instability will
combine with adequate shear to keep a threat of severe thunderstorms
in the forecast every day.

Unfortunately, there really isn`t any surface feature to latch onto
to help determine convective coverage or location and therefore the
details of the forecast will hinge upon mesoscale features such as
outflow boundaries, subtle convergent zones and/or the remnants of
thunderstorms further west (including MCVs) in the short term (today
through Wednesday) and shortwave locations in the longer term.

CVKING

&&

.SHORT TERM... (Through Tonight)
Issued at 227 AM CDT Tue May 24 2016

MCV located across the eastern Ozarks/southeast Missouri has
been slowly marching east overnight and has had a few showers
associated with it. A handful of the convection allowing models
develop some thunderstorm activity with this feature toward sunrise,
while others do not. Of more importance is the convective complex
developing across north central Kansas at this time. Model guidance
is struggling on the details of how this feature evolves/moves
today. Some models advance it south-southeast into southwest
Missouri this morning essentially keeping the CWA dry, while others
march it east along I-70 into east central Missouri by this
afternoon/evening. Given the elevated nature of the convection and
its ties to the low level jet and location of the best instability
across the central/southern Plains I would suspect that this
activity will initially propogate toward southwest Missouri this
morning, but the residual outflow will help to initiate additional
convection further northeast along and south of I-70 this afternoon
as the atmosphere diurnally destabilizes. Some of these storms could
become strong/severe with large hail and damaging wind gusts being
the primary threats.

The diurnal activity should weaken with sunset and move east of
the area during the early evening. Next round of thunderstorms
should develop overnight as the low level jet intensifies and
another shortwave ripples across the region. This activity will be
centered further northwest though (thinking along and north of
I-70 in Missouri). These storms will have the potential of
producing large hail.

CVKING

.LONG TERM... (Wednesday through Monday)
Issued at 227 AM CDT Tue May 24 2016

Convective trends become harder to pin down as much of it will
again depend on what occurs each night. At this point it appears
that the morning convection on Wednesday will move east and the
atmosphere may destablize enough for another round of
thunderstorms during the afternoon/evening, though more
isolated/scattered due to the weak ridging in the wake of the
overnight/early morning shortwave.

Pattern remains active through the weekend and into next week, with
chances of thunderstorms each day and temperatures remaining warm
with highs in the 80s each day.

CVKING

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1140 PM CDT Mon May 23 2016

MCV just southwest of forecast area continues to slowly track to
the east northeast. Starting to see some scattered showers
redevelop south of taf sites. So will keep vicinity showers in for
KCOU from 08z to 15z Tuesday. Showers to move into metro area by
daybreak, but hard to pin down coverage, so kept vicinity shower
mention from 11z to 18z Tuesday. Since KUIN will remain well north
of MCV, not confident they will get much so for now just have vicinity
showers from 16z to 20z Tuesday. Otherwise, VFR outside of
activity with south winds persisting.

Specifics for KSTL:
MCV just southwest of forecast area continues to slowly track to
the east northeast. Starting to see some scattered showers redevelop
south and southwest of metro area. So could still see showers move
into metro area by daybreak, but hard to pin down coverage, so
kept vicinity shower mention from 11z to 18z Tuesday. Otherwise,
VFR outside of activity with south winds persisting. Better
chances of rain will be after 09z Wednesday, so added vcsh
mention.

Byrd

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     83  68  84  71 /  40  50  60  40
Quincy          81  67  82  68 /  20  60  60  50
Columbia        80  66  83  69 /  50  60  60  40
Jefferson City  82  67  84  70 /  50  50  60  30
Salem           82  66  83  70 /  20  40  50  40
Farmington      81  65  83  70 /  50  40  60  20

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



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