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Area Forecast Discussion (AFD)

Issued by St. Louis, MO (LSX)

                            
000
FXUS63 KLSX 260205
AFDLSX

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
905 PM CDT Tue Jun 25 2019

.UPDATE...
Issued at 859 PM CDT Tue Jun 25 2019

Thus far severe storms have remained just north of the LSX moving
across extreme northeast MO and southwest IA and now moving into
central IL. Outflow from the complex has moved into our northern
counties and has periodically generated some scattered short-lived
cells. Current thinking is the current bowing severe storm
entering Fulton County will remain to the north of the CWA as it 
moves east-southeast within western IL. Will still have to keep 
an eye on the outflow for storm development but in the short-term
there appears to be a low severe threat within the LSX CWA 
portion of the severe thunderstorm watch. Will also have to keep a
close eye on the elongated region of strong to severe storms in 
southwest IA that have formed in the wake of the previous 
activity. These appear to be elevated and have formed in response 
to lift via the south-southwest LLJ above the weak cold pool and 
to the north of the composite outflow boundary stretched across 
northern MO. The east-southeast motion would bring these close to
the northern CWA counties later this evening should they maintain
there current motion and intensity.

Glass

&&

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 245 PM CDT Tue Jun 25 2019

The threat of thunderstorms this evening continues to decrease as
the focus for development has shifted north into southern Iowa
where the cold front resides this afternoon. Majority of the short
term convective allowing models keep the CWA dry now, so have
decreased PoPs to chance and limited them to the northern tier of
counties in MO and IL. The guidance also shows a rapid decrease in
intensity after sunset and therefore the threat of severe weather
remains conditional and quite honestly, low for our northern CWA 
this evening. 

The upper level ridge begins to build north into the central
Plains on Wednesday but our CWA remains on the eastern periphery
and any MCV, or weak upper level disturbance floating across the
area during the afternoon could lead to a diurnal surge of
thunderstorm activity. About half of the guidance shows this
scenario with thunderstorms initiating during the afternoon across
the southeastern half of the CWA. Have maintained slight
chance/chance PoPs for this reason and expect later shifts to
refine based on upstream observations tonight.

CVKING

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 245 PM CDT Tue Jun 25 2019

The ridge will continue to build across the Plains and into the
upper Midwest through the weekend. Temperatures will slowly warm
into the 90s for afternoon highs. Have maintained a largely dry 
forecast for the end of the week and weekend, but the orientation 
of the ridge from roughly New Mexico to Minnesota does give me 
some pause. The classic "ring of fire" would suggest that at least 
our eastern CWA could be under the gun for any MCS or outflow that
drops south from northern Illinois this weekend. 

CVKING

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 638 PM CDT Tue Jun 25 2019

The main focus tonight is how far south/southeast showers and 
thunderstorms currently along the IA/MO border will move this
evening. The primary area of concern is across northeast MO and
west central IL including KUIN. I have added a VCTS at 02z and
this may not hit the threat high enough or early enough. I will be
monitoring the southward trend over the next few hours and may
need to add a greater thunder threat with gusty winds. Otherwise
VFR flight conditions are expected tonight into Wednesday morning.
There might be some isolated to scattered showers or storms across
central and eastern MO into southwest IL on Wednesday afternoon
but the threat is too low to mention at this time.

SPECIFICS FOR KSTL: 

Showers and thunderstorms are expected to remain well north of the
terminal tonight and remain across northeast MO and west central
IL. Therefore VFR flight conditions are expected tonight into 
Wednesday morning. There might be some isolated to scattered 
showers/storms across eastern MO on Wednesday afternoon but the 
threat is too low to mention at this time.

Glass

&&

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

$$

WFO LSX