Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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
000
FXUS63 KLSX 241650
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1150 AM CDT Wed May 24 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 352 AM CDT Wed May 24 2017

Upper low continues to sink swd early this morning. As it does, the
pocket of mid clouds over central MO will continue to move esewd,
although, any precip associated with it will likely be
light/sprinkles.

Otherwise, expect much of the region to be dry thru about mid
morning as SHRA begin to develop. Expect these SHRA to continue to
develop thru the afternoon with isod TS also during the afternoon.
Uncertain exactly what coverage will be, but kept PoPs in high
chance range. These SHRA shud dissipate quickly with sunset, except
over the ern portions of the CWA where precip is more dynamically
forced.

As for temps, have trended twd cooler guidance for today expecting
most breaks in clouds to fill in. Also trended cooler for tonight as
well with the clouds breaking up as the ridge builds into the area.
Winds will be light tonight, especially across wrn portions of the
CWA. Have held off adding fog to the forecast with better conditions
west of the CWA. However, will need to monitor and may need to be
added with updates.

Tilly

.LONG TERM...  (Thursday through Tuesday)
Issued at 352 AM CDT Wed May 24 2017

Weak surface ridge will be over region on Thursday with dry and mild
weather in store for the forecast area. Highs will be in the low to
mid 70s.

By Thursday night, surface ridge to move off to the east as next
system moves in from the southern plains. Fairly zonal flow aloft,
frontal boundary associated with system to stall out along I-70
corridor for the last part of the work week and into the holiday
weekend. Will see increasing low level moisture towards daybreak on
Friday with showers and some storms on the increase. Late Friday
night, with sufficient instability and shear could see an MCS
develop and slide east along boundary moving into forecast area
Saturday/Saturday night with main threats being large hail, damaging
winds and isolated tornadoes. So SPC has placed areas along and
south of I-70 in a slight risk for Day 4.

By Sunday night, precipitation moves off to the south and east with
dry weather for Memorial Day. However, could see some wrap around
showers/isolated storms along and north of I-70 Monday afternoon and
evening. Could see more isolated/scattered showers on Tuesday, as
another spoke of energy aloft rotates around system anchored over
Great Lakes.

As for temperatures through the period, will see at or below normal
temps on Thursday, then warm up a bit above normal for the holiday
weekend despite the chances of precipitation. Then cool down to near
normal Sunday through Tuesday.

Byrd

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1055 AM CDT Wed May 24 2017

Scattered showers will develop this afternoon due to diurnal
heating coupled with an upper level low over central MO moving
southeastward through southeast MO. Broken diurnal cumulus cloud
field around 2000-3000 feet should gradually rise during the
afternoon hours. The showers should dissipate or shift east-
southeast of the taf sites this evening. The sky will clear out
from west to east as the surface low over the TN Valley region
shifts northeastward into the OH Valley region. The northwest
surface wind should diminish this evening as the surface ridge
over the Plains shifts eastward through MO late tonight and
Thursday morning.

SPECIFICS FOR KSTL: Scattered showers will develop this afternoon
due to diurnal heating coupled with an upper level low over
central MO moving southeastward through southeast MO. Broken
diurnal cumulus cloud field around 2000-3000 feet should gradually
rise during the afternoon hours. The showers should dissipate or
shift east-southeast of the STL area this evening. The sky will
clear out from west to east as the surface low over the TN Valley
region shifts northeastward into the OH Valley region. The
northwest surface wind should diminish this evening as the surface
ridge over the Plains shifts eastward through MO late tonight and
Thursday morning.

GKS

&&

.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.