Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 192025

Area Forecast Discussion
National Weather Service Saint Louis MO
325 PM CDT WED OCT 19 2016

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 324 PM CDT Wed Oct 19 2016


Focus tonight will be on convective trends. Believe the most focused
and widespread area on convection will continue to be near the quasi-
stationary 850-hPa warm front through the early overnight hours
tonight. Have therefore shifted highest PoPs and heaviest QPF axis
to the north more toward the I-44 corridor in MO. This convection
should remain elevated in nature with the sfc boundary across the
far southern CWA. With the elevated convection...large hail is the
primary threat. Further to the south across southeast Missouri and
far southwest Illinois...wind gusts in addition to large hail are
both threats as convection along/south of the sfc front will likely
be more surface based. Severe threat should wane by late evening as
instability...both elevated and sfc-based...begins to fade to the
southeast of the area.

Maintained locally heavy rainfall mention just shifted the axis a bit
further to the north tied to the highest PoPs. It has been dry this
month and FFG values are high so it will take quite a bit of rain
over a short period of time. Concern would be in training of
convection which certainly could occur due to the quasi-stationary
low-level baroclinic zone.

Temperatures will be cooler tonight compared to the last several
nights but still a bit above normal. Lows in the 50s for most areas
are expected.


Bulk of precipitation should have exited the CWA by Thursday morning
but have schc-chc PoPs for showers into early afternoon for far
southern and eastern sections of the CWA. Main story will be the
much more fall-like look and feel to the day on Thursday. High
temperatures are only expected to be in the low 60s across the area
due to lingering cloud cover and strong CAA at low
levels...certainly a big change from the upper 80s to low 90s of
just a couple of days ago.


.LONG TERM...  (Thursday Night through Next Wednesday)
Issued at 324 PM CDT Wed Oct 19 2016

Any lingering precip will have moved out of the area as surface low
moves east Thursday. Strong surface ridge builds eastward as low and
cold front move out shifting winds to the northwest. The northwest
flow as well as clearing behind the front will lead to cooler temps
Thurs night. Temps to remain slightly below normal through Sat
morning. There will be a slight warming trend as surface ridge
progress furthr to the east and shifts wind become southerly. a weak
cold front will move through the area Sun into Monday but this is
expected to bring no precip and cold temps should stay north of the
forecast area. The next chance of precip will be Wed as surface low
moves in from the western plains.



.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1235 PM CDT Wed Oct 19 2016

Main concern through the afternoon and evening hours will be on
elevated convection affecting the terminals. Believe most
widespread shower and thunderstorm will be roughly along the I-44
corridor affecting the St. Louis metro terminals. Visibilities may
dip down into the IFR category with stronger storms. Hail will
also be possible with these strongest storms. KCOU will be on
northern edge of more widespread activity with KUIN only seeing
isolated to scattered showers around the area. MVFR ceilings have
crept northward into the metro area already and believe they will
be here to stay until early Thursday morning. Northeast winds
will back to the northwest late tonight as a sfc low passes to the


Focus will be on showers and thunderstorms from this afternoon
through this evening. Highest chances of widespread activity
around the terminal appear to be very late this afternoon through
late evening. Any stronger thunderstorm will be capable of
producing IFR visibilities along with hail. MVFR ceilings are
expected to persist until early Thursday morning. Winds out of the
northeast this afternoon will back to the northwest later on
tonight after a sfc low passes to the south of the terminal.





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