Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KLSX 192135
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
435 PM CDT Sat May 19 2018

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 312 PM CDT Sat May 19 2018

Ongoing convection is expected to continue east and may produce
marginally severe hail and/or winds. Behind this area of
convection, airmass has been able to rebound already with 3000
J/kg of MUCAPE already over far SW MO.

The time line is subject to change, but believe ongoing
convection over srn KS/nrn OK will continue ENE along the wrmfnt.
These storms shud reach wrn portions of the CWA around 9 to 10 pm
and will potentially be severe with a hail and wind threat. Expect
more development further north into KS that shud also track into
nrn portions of the CWA. These storms may also be severe either
given the amount of elevated CAPE that shud be available. These
clusters of storms shud quickly move thru the CWA overnight.

The convection this evening increases uncertainty for how things
will evolve late tonight into Sun morning. However, latest
guidance suggests yet another round of storms entering wrn
portions of the CWA around sunrise Sun. The 18z NAM suggests that
the morning convection may be a repeat of today, which is
possible. Unfortunately, with the numerous sfc boundaries that may
be present, confidence is somewhat low and have kept PoPs on the
somewhat low side with questions in timing. With the weak sfc low
traveling across the nrn portions of the CWA, still believe storms
are likely across the nrn half of the CWA during the afternoon and
into the evening. However, going forecast for the morning hours
may be too low. Given the amount of CAPE as well as deep layer
shear available thru the day Sun, any of these storms may be
severe.

Tilly

.LONG TERM...  (Sunday through Friday)
Issued at 406 AM CDT Sat May 19 2018

Will continue to see the potential for a few strong to possibly
severe storms on Sunday and Sunday evening.  Both the GFS and NAM
are showing that a stationary front will lie across the CWA, most
likely to the north of I-70 during the day on Sunday. The
atmosphere will likely become very unstable during the day across
much of the CWA with MLCAPES between 1500-3000 J/kg and deep layer
shear between 25-40kts. Thunderstorms may develop along the
aforementioned front, or a weak cold front that will move
southeast across the area during the area late in the afternoon
and the evening. The main limiting factors with this event will be
lack of mid-level ascent and some capping seen on the forecast
soundings. The main threat from any strong storms will be large
hail and damaging winds.

The front will move south of the CWA on Sunday night into Monday
limiting shower and thunderstorm chances to southeast Missouri and
southwest Illinois.  This front will remain south of the area
through midweek keeping rain chances over southeast Missouri.  Rain
chances will increase across the CWA by late in the week as an upper
trough moves across the Midwest.

Temperatures are still expected to stay above normal through next
week as 850mb temperatures stay in the middle to upper teens Celsius
and the GEFS mean temperatures are 5-10F above normal.

Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 101 PM CDT Sat May 19 2018

Storms across south central MO will move east with the nrn flank
of the line likely impacting KSUS/KCPS. These storms may have some
stronger gusts, but shud be below severe limits.

Otherwise expect another round of storms this evening into the
overnight hours.

SPECIFICS FOR KSTL: Line of showers expected to impact the
terminal around 20z, but shud remain sub-severe. Another round of
storms is possible late this evening which may be severe with
damaging winds as the primary threat.

Tilly

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     69  89  67  84 /  40  40  50  20
Quincy          62  81  61  77 /  70  60  50  10
Columbia        64  84  62  79 /  60  30  40  10
Jefferson City  65  86  63  81 /  60  30  40  10
Salem           67  88  65  84 /  40  40  50  30
Farmington      66  87  63  83 /  30  40  40  30

&&

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

$$

WFO LSX


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.