Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 121000
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
400 AM CST FRI FEB 12 2016
.SHORT TERM: (Through Late This Afternoon)
Issued at 400 AM CST Fri Feb 12 2016
Ongoing snow event will be winding down at the beginning of the
period this morning. What is currently on the radar will move esewd
and exit the CWA between 12z and 15z. Overall, believe storm totals
for this event will be generally around 1 inch with some spots
receiving up to 1.5 inches.
For the rest of today, expect clouds to be slow to move out of the
area. With the sfc fnt pushing swd today as the ridge builds into
the area, expect a brief warming period this morning for srn
portions of the CWA. Warming elsewhere will be hampered by clouds
with little temp rise thru the day. Have trended aob the coolest
guidance for today with continued CAA.
.LONG TERM: (Tonight through Thursday)
Issued at 400 AM CST Fri Feb 12 2016
The longwave TROF that has dominated eastern North America for the
past several days is expected to continue thru about the middle of
next week before we start to see a definitive pattern shift, whereby
the western North America RIDGE translates eastward. In the
meantime, NW flow aloft will continue with a series of disturbances
continuing to roll thru the area.
A very cold day is expected on Saturday with an Arctic high pressure
bearing down. Wind chills Saturday morning for many areas will be
between 5 and 10 below zero, with near advisory criteria in northern
MO and central IL. Max temps are only anticipated to be in the
After the ongoing clipper exits early this morning, the next system
is expected to affect our region later in the weekend. It seems the
onset timing for these systems in this very fast flow cannot be fast
enough, and so an initial decent first guess can be ascertained with
the fastest model, which is the EC and GEM. Both of these models
bring in pcpn with the strong WAA on the front-end of the system by
nightfall Saturday into parts of northeast and central MO, and so
have added in low PoPs Saturday afternoon for these areas. At this
point, it looks like the pcpn associated with this system will track
eastward but also develop southward on Saturday night and for a time
on Sunday before heading east, and result in likely chances across
our region at some point. It doesn`t seem to be as much a question
of if, but how much. But as it stands now, and with the very fast
flow, bets are on pcpn amounts to be on the light side once again.
The pcpn type will predominantly snow. As it stands now, snow
accums up to 2" will be possible thru Sunday afternoon.
Right on the heels of this system will be another one that will take
place Sunday night and Monday, but as it stands now, looks to be
further south. The best pcpn chances remain over southeast MO and
southern IL, with pcpn types initially being snow and transitioning
to rain on Monday as warmer air continues to build in. Snow accums
will again be on the light side. Track confidence is rather low
here given how far offshore the system is now.
Yet another clipper may take one final advantage of the leftover
cold air on Tuesday to result in additional accumulating snow.
Confidence with this system is quite low, but enough to place a
small mentionable PoP. Temps will be very dependent on track.
Otherwise, look for a mainly dry forecast from Wednesday on, with
steadily rising temps with well above normal temps possible for next
.AVIATION: (For the 06z TAFs through 06z Friday Night)
Issued at 1149 PM CST Thu Feb 11 2016
Snow will continue to move quickly across the area during the
overnight hours reducing visibilities to MVFR or possibly IFR at
times. The snow will move into the St. Louis area terminals in the
next hour and out by 09-11Z. The snow will also move out of KUIN
and KCOU by 06-08Z. Snow accumulations of up to 1 inch are
possible. Then MVFR ceilings are expected to persist through the
morning hours before drier air moves in and allows VFR conditions
Specifics for KSTL: An area of snow is expected to move into the
terminal between 06-07Z and move out by 10Z. Any snow
accumulations are expected to be less than an inch. Then MVFR
ceilings are expected to persist through the morning hours before
drier air moves in and allows VFR conditions to develop.