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 191708
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1208 PM CDT Wed Apr 19 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 408 AM CDT Wed Apr 19 2017

The sfc fnt remains just N/NW of the CWA this morning. Ongoing
convection along this fnt across nwrn MO will continue to move newd
thru sunrise. Can not rule out some isod/sct TSRA across nrn
portions of the CWA, but activity is expected to be short lived as
it moves out of the region.

The remainder of today is expected to be dry. However, some mdl
guidance wud suggest a chance of TSRA across ern counties early this
afternoon. This is most prevalent in CAMs and believe this is a
result of strong heating and a lack of a convective scheme. That
said, while have kept dry PoPs going for now, they are not zero due
to the GFS suggesting the s/w from ongoing convection lurking in
that region.

Otherwise today, expect rather deep mixing today, to around 800 mb.
This shud result in temps into the mid 80s across much of the CWA.
Would not be completely surprised if the area saw temps slightly
warmer, but convective debris and afternoon CU field shud hinder
heating somewhat.

For tonight, focus will be on precip chances. TSRA shud form along
the cdfnt from wrn IA to ern KS late this afternoon into the
evening. The focus of this convection shud split somewhat with one
area further north closer to the sfc low with better upper level
forcing, then another further south with the better instability.
There shud be a relative minimum between these areas, which is what
wud otherwise affect the nwrn to wrn portions of the CWA. As the LLJ
increases thru the night, expect some of this area to fill in with
redevelopment and propagation. Given the time of day and somewhat
limited CAPE and possibly capped, expect severe threat to be
limited.

Tilly

.LONG TERM...  (Thursday through Tuesday)
Issued at 408 AM CDT Wed Apr 19 2017

As cold front slowly sinks south and east across forecast area, will
see increasing chances of showers and storms on Thursday. Models
continue to show decent CAPES, low level moisture and shear along
and south of I70, so strong to severe storms not out of question for
the afternoon hours on Thursday.

As front sinks south of forecast area Thursday night, rain chances
to taper off most locations, but will see lingering showers along
and south of I-70 due to front becoming stalled just south of
Missouri/Arkansas border.

By Friday, extended models in pretty good agreement with upper level
short wave over Central Plains sliding east, dragging surface low
along stalled boundary just south of forecast area. So will see
increasing chances of overrunning showers across region Friday
through Saturday. With front south of forecast area, it will be a
rather chilly rain with highs by Saturday only in the mid to upper
50s.

Surface ridge to build in beginning late Saturday night, so will see
dry and moderating temperatures for the remainder of the forecast
period. Temperatures to warm back up into the mid to upper 60s on
Sunday, then into the upper 60s to mid 70s Monday and Tuesday.

Byrd

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1139 AM CDT Wed Apr 19 2017

Just scattered diurnal cumulus clouds along with high level
clouds this afternoon. A cold front will drop southeastward
through the taf sites late tonight and Thursday. Showers and
thunderstorms may move into UIN and COU late tonight or early
Thursday morning, then into the St Louis metro area by late
morning. Prevailing cloud ceiling may drop into the MVFR catagory
by 12Z Thursday in UIN and COU and by 15Z Thursday in the St
Louis metro area. South-southwesterly surface wind will veer
around to a northwesterly direction after fropa in UIN and COU
Thursday morning and in the St Louis metro area Thursday
afternoon.

SPECIFICS FOR KSTL: Just scattered to broken diurnal cumulus
clouds along with high level clouds this afternoon. A cold front
will drop southeastward through the STL area by late Thursday
morning. Showers and thunderstorms may move into the STL area
by late morning as well. Prevailing cloud ceiling may drop into
the MVFR catagory by 15Z Thursday. South-southwesterly surface
wind will veer around to a northwesterly direction after fropa
Thursday afternoon.

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.