Areal Flood Warning 13, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1243 PM CDT Mon May 6 2019

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 341 AM CDT Mon May 6 2019

Active period of weather expected starting later this afternoon and
tonight. Have issued a flash flood watch for central Missouri
where I expect 2-3"+ rainfall between tonight and Wednesday night
which could cause flash flooding.

The weather is relatively quiet early this morning as the surface
cold front remains across Iowa and southern Wisconsin. Some
showers and thunderstorms were moving into west central Missouri
in an area of weak low level forcing. This area will move across
central Missouri this morning, so will carry low PoPs for showers
and thunderstorms. Scattered showers and thunderstorms may
initiate along the front as it moves south into the area later
this morning and this afternoon. Better chance for storms will
occur tonight when MCS initiation is likely over eastern Kansas
and western Missouri. Strong convergence will occur along the
front with showers and thunderstorm developing ahead of the MCS as
it moves east into central Missouri late this evening, and
eastern Missouri and southwest Illinois overnight. There will be
some severe threat over parts of central and east central Missouri
given the available shear and instability with some risk for hail
and damaging winds. Of more concern is flash flooding given PWATS
around 1.5" and deep warm cloud layers seen on forecast
soundings.

Will continue likely PoPs across the central parts of the CWA
into Tuesday as the front will remain stalled across southern
Missouri and Illinois and the low level jet will continue to
intersect it throughout the day resulting in strong moisture
convergence along it. In addition, a couple of weak mid-level
impulses will move across Missouri and Illinois providing extra
lift for showers and thunderstorm development.

Britt

.LONG TERM...  (Tuesday Night through Sunday)
Issued at 341 AM CDT Mon May 6 2019

NAM/GFS still suggests that the front will start the day over
southern Missouri and Illinois on Wednesday. This front will
begin to move northward during the day in response to an upper
low over the southwest CONUS opening up and moving into the Great
Plains. There will continue to be chances for showers and
thunderstorms along the west-east oriented front Tuesday
night/Wednesday as there will notable moisture transport northward
ahead of aforementioned trough and significant moisture
convergence along the front. There will also be embedded shortwave
troughs in the southwesterly flow aloft that will add ascent that
will help aid in thunderstorm development along the front.
Combination of depicted instability and shear Tuesday night into
Wednesday suggests the continued potential for a few strong storms
over the area. The best potential for severe weather will
continue will be Wednesday night into Thursday when the upper
trough and attendant cold front will move across the area.

Once the front moves through the area on Thursday, then less active
weather is expected as we go into next weekend.  GEFS mean is
showing the upper flow staying zonal over Missouri and Illinois with
a surface high moving across the area on Friday into Saturday.

Temperatures will be above normal Wednesday and Thursday ahead of
the front, but the fall below behind the front over the weekend.

Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1225 PM CDT Mon May 6 2019

An area of showers and a few thunderstorms between KCOU and the
metro terminals is weakening and should be completely dissipated
within the next hour. Isolated showers and storms may develop
along a slow-moving cold front late this afternoon and evening so
have a VCTS group in at KUIN. Showers and storms should impact
KCOU after 0600 UTC tonight and may also impact the metro
terminals more toward daybreak. IFR visibilities are possible in
the heavier downpours. The front should make it south of KCOU and
KUIN overnight, but stall out near or just south of the metro
terminals. Behind the front, ceilings should lower to MVFR at KCOU
and IFR at KUIN for Tuesday morning.

SPECIFICS FOR KSTL:

Dry/VFR conditions are favored for this afternoon and much of
tonight. Will be watching showers and thunderstorms try to move in
from the west toward daybreak Tuesday but best chances are just
southwest of the terminal. Therefore, have a VCTS group in from
1100 to 1500 UTC for now. South/southwest winds should become
light/variable after midnight tonight through much of Tuesday as a
cold front approaches and then stalls out near or just south of
the terminal.

Gosselin

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flash Flood Watch from 7 PM CDT this evening through Thursday
     morning for Boone MO-Callaway MO-Cole MO-Moniteau MO-Osage
     MO.

IL...None.
&&

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
517 AM CDT Mon May 6 2019

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-071030-
Adams IL-Audrain MO-Bond IL-Boone MO-Brown IL-Calhoun IL-Callaway MO-
Clinton IL-Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-
Greene IL-Iron MO-Jefferson MO-Jersey IL-Knox MO-Lewis MO-Lincoln MO-
Macoupin IL-Madison IL-Madison MO-Marion IL-Marion MO-Moniteau MO-
Monroe IL-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-Pike IL-
Pike MO-Ralls MO-Randolph IL-Reynolds MO-Saint Charles MO-
Saint Clair IL-Saint Francois MO-Saint Louis City MO-Saint Louis MO-
Sainte Genevieve MO-Shelby MO-Warren MO-Washington IL-Washington MO-
517 AM CDT Mon May 6 2019

This Hazardous Weather Outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Today and tonight.

Major river flooding is expected or ongoing along the Mississippi
and Illinois Rivers, as well as the back water points of the Meramec
and Cuivre Rivers.

There is a chance of thunderstorms this afternoon and tonight. A few
of these storms over central Missouri tonight could become severe,
capable of producing large hail and damaging wind gusts. These
storms will also be capable of producing heavy rainfall that could
produce flash flooding. Refer to the flash flood watch for details.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Thunderstorms will be likely through Thursday. Heavy rainfall will be
likely over central Missouri where a flash flood watch remains in
effect through Wednesday night. In addition, severe weather will be
possible over the area again Wednesday into Thursday.

Major river flooding is expected to continue for much of the
upcoming week along the Mississippi and Illinois Rivers, as well as
the back water points of the Meramec and Cuivre Rivers.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be required later today and tonight.

Britt