PAH Disco hinting at an excess of a foot where banding sets up-
National Weather Service Paducah KY
238 PM CST Sun Feb 14 2021
.SHORT TERM...(Tonight through Monday night)
Issued at 238 PM CST Sun Feb 14 2021
A major winter storm is taking aim on the area. The first round of
snow will be tonight in a zone of increasing low/mid trop
frontogenetical forcing positioned out ahead of the main upper trof,
that by 12z Monday should be over the central and southern Plains.
We may see an initial 1-3" of snow tonight (give or take). We have
incorporated the HREF closely with a consensus of deterministic
guidance for tonight and Monday (see below). We will be close to
Wind Chill Advisory conditions again tonight across portions of
southeast MO and southwest IL. We have addressed the bitter cold in
our current Winter Storm Warning that remains as is from 6 PM
Tonight through 6 AM Tuesday.
Monday, the main energy within the mid level trof comes up over top
of the region in the afternoon and evening. This will be the round
of greatest significance (snow rates, accumulations, impacts). The
overall trend seems a bit faster, so the lull is not expected to
last real long.
WPC banding probabilities increase notably with the main wave, with
some inference of instability and prominent snowfall rates. The HRRR
depicts this possibility as well. So for now we have storm total
accumulations 6 to 12". Given above average snow to liquid ratios
and this added concern, 12" may not be high enough should some of
these indicators pan out. But for now, we have headed the right
direction in our opinion.
The snow will taper off Monday evening and should be all but
completely over across southwest IN and the KY Pennyrile region
In terms of messaging, the bitter cold remains a real concern with
this system, as does the potential for blowing snow with NNE winds
10 to 15 mph gusts to 20 mph or even slightly higher. Stay tuned for
updates and adjustments to snow amounts (if needed).
.LONG TERM...(Tuesday through Sunday)
Issued at 238 PM CST Sun Feb 14 2021
The main focus later this week continues to be another potential
winter storm Wednesday into Thursday. This system is still four days
away, so many details remain to be ironed out. The 500 mb pattern
actually appears more complex than it did yesterday, mainly because
a northern stream 500 mb shortwave has entered the picture. This
northern stream shortwave will move down into the northern Plains
mid-week. There is some potential for this shortwave to shunt our
moist southern stream shortwave further south. This is reflected in
a majority of the model qpf fields, which show the heavy qpf
suppressed more to the south of the Ohio Valley than they did
yesterday. There is also less of a warm air intrusion, which results
in less mixing of wintry precip.
In a nutshell, the 12z models are still split into two camps. The
European solutions have trended even farther to the southeast,
taking the surface low northeast from the central Gulf Coast to
Georgia. The gfs ensemble mean is also further southeast, taking the
surface low across Alabama Thursday. The gfs consensus basically
places our region in the sweet spot for heavy snow, with heavy qpf
shown by the gfs ensemble mean over the Ohio Valley and se Missouri.
An elevated warm nose in the gfs guidance would result in mixing
with sleet or freezing rain se of the Ohio River.
Until the models resolve the influence of the northern stream
shortwave, the forecast will remain in flux. A forecast trend toward
drier and colder conditions is possible if the northern stream
becomes more dominant. The models at face value today do continue to
suggest the likelihood of a winter storm Wednesday into Thursday.
Otherwise, the main story on Tuesday into Wednesday will be the
continued bitterly cold wind chills.
Following the late week winter storm system, high pressure will pass
overhead on Friday. In the wake of the high, southwest winds are
expected to bring above freezing temps this weekend following the
extended winter blast. The ecmwf and gfs mos highs in the 50s at pah
Sunday look a little unrealistic given the snowcover, so the
forecast will be for highs in the 40s. Model ensemble means have
been in good agreement on a nearly zonal flow aloft this weekend.