Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 281949

Area Forecast Discussion
National Weather Service Saint Louis MO
249 PM CDT SUN AUG 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 248 PM CDT Sun Aug 28 2016

Storms fired up a bit earlier today along an area of moisture
convergence. Storms continue to develop back to the southwest of
original activity over central and northeast Missouri, mainly due to
outflow boundaries. Will see isolated/scattered activity through the
evening hours before diminishing. With slow movement and PWs near 2
inches, storms that do develop will drop quite a bit of rain in a
short amount of time.  Otherwise, another mild night in store with
lows in the mid 60s to low 70s.


.LONG TERM...  (Monday through Next Sunday)
Issued at 248 PM CDT Sun Aug 28 2016

The synoptic pattern at the start of the long term period will
feature generally weak flow aloft across much of the CONUS as mean
ridging prevails.  However, a strong trough/associated PV anomaly
will dig into the Northwest early this week while another PV anomaly
dives out of central Canada, each acting to knock down the ridge
over the region by the middle of next week.

Scattered mainly diurnally driven convection will persist into the
day on Monday.  Still not much synoptically to focus the convection,
so will continue with generally broad-brushed 20-40 pops, with the
highest coverage expected across north-central MO where capping will
be slightly weaker given greater displacement from the upper-level
ridge.  Given temperatures overachieving the past couple of days,
will continue to go above most guidance for highs Monday.

Convective coverage may increase a bit Tuesday into Wednesday as a
cold front approaches from the north.  This front will be double-
barreled, with a wind shift/weak convergence to focus convection on
Tuesday mainly across northern MO/western IL and another wind shift
and actual airmass change late Wednesday as Canadian high pressure
builds into the region.  The Wednesday front will also have some
upper-level support as a weak PV anomaly passes through and knocks
down the ridge. Given a surface focus and the upper-level forcing
for ascent, went ahead and upped pops on Wednesday.

Behind Wednesday`s front, a pleasant airmass will push into east-
central MO and western IL.  Some guidance is advertising widespread
mid/upper 70s Thursday into Friday.  However, given overachieving
temperatures as of late and the cool bias noticed in guidance with
the last fropa, will keep temps in the upper 70s/low 80s.

Conditions will slowly warm through the weekend as surface ridging
shifts east of the region and southerly flow commences.  However,
the region should continue to remain mostly dry as isentropic ascent
ahead of the next system should remain focused just to the west of
the region.



.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 113 PM CDT Sun Aug 28 2016

Once again with isolated/scattered storms firing up over region.
As of 18z, most of activity closer to KUIN, so added tempo group
from 18z to 19z. Otherwise, kept VCTS mention at all other sites
through the afternoon hours, diminishing after 01z Monday. Light
southeast to south winds to become light and variable tonight,
then pick back up a bit from the east to southeast Monday morning.

Once again with isolated/scattered storms firing up over region.
As of 18z, activity well northwest of KSTL, so kept VCTS mention
from 21z Sunday to 01z Monday. Light southeast winds to become
light and variable tonight, then pick back up a bit from the east
by 15z Monday.





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