Nice write up from the KC office tonight.
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
558 PM CST Wed Feb 3 2021
.Discussion...
Issued at 227 PM CST WED FEB 3 2021
Key messages:
- A cold front will move through the area tomorrow morning, dropping
temperatures and bringing a brief period of wintry weather.
- Another front will move through Friday night/Saturday morning with
arctic air settling into the region by Sunday morning.
- Accumulating snow is looking more likely for Saturday
afternoon/evening.
Detailed discussion...
Water vapor imagery shows the next upper-level shortwave trough
moving through the Great Basin and northern Rockies this afternoon.
This wave will move into the Plains late tonight into early Thursday
morning and help push a strong cold front southeastward through the
area. A well mixed boundary layer overnight will keep temperatures
relatively mild overnight. With the timing of the front moving
through in the morning, temperatures are expected to fall throughout
the day. Ascent ahead of the front and upper wave should lead to
areas of drizzle or light rain. Temperatures then quickly cool
off behind the front, at the surface and aloft, and that will lead
to period of snow during the later part of the morning into the
afternoon. For now, it`s looking like a 2-4 hour block when snow
looks most likely behind the front as the whole system quickly
tracks east.
Models warm the region back up into the lower 40s for Friday as
winds shift to the west. This may be a bit overdone, especially if
there`s a little snow cover from Thursday`s system. The NAM, being
weaker with the Thursday system, is the warmest for Friday and
likely an outlier. A secondary cold front moves through Friday night
with winds switching to the north and colder air spilling south into
the area. The NAM is also weaker with this surge of colder air and
that has a pronounced effect with the next system that comes in
Saturday afternoon and evening. The NAM never really moves the front
through Friday night and then develops a stronger surface low in
response the next upper shortwave. This results in Saturday
temperatures warming into the 40s ahead of the shortwave. The GFS
and the Canadian, and to a lesser extent, the ECMWF are all cooler
and as a result produce more snow for Saturday afternoon and
evening. Our forecast is closer to the colder ECMWF/Canadian/GFS
blend and that leads to more snow in our forecast. Feel that with
the area likely to be under broad cyclonic flow aloft, a colder
solution is preferred. With that said, have increased PoPs to
likely for Saturday and increased snow ratios to the 15-18 range.
The colder solution and higher snow ratios result in several
inches of snow for the area with this system.
Arctic air then settles into the region and by Sunday morning, lows
could be in the minus single digits in our north and single digits
above zero elsewhere. Broad troughing over northern North America
will result in nearly zonal flow aloft for the first half of next
week. Models show several embedded shortwaves moving through the
fast upper flow aloft resulting in several periods of small chances
for wintry weather. Also, once we go below freezing Friday
evening/night, it doesn`t look like we`ll see above freezing
temperatures through at least the middle of next week and likely
through next weekend.
