Had to do a double look. First time I have ever seen this but it appears NWS in Memphis did a copy and paste of Little Rocks AFD. Interesting to say the least. I guess in a nut shell it says "we dont know what the hell this thing is going to do".
Area Forecast Discussion
National Weather Service Memphis TN
Issued by National Weather Service Little Rock AR
618 PM CST Mon Feb 8 2021
.SHORT TERM...
.PREV DISCUSSION... /issued Issued by National Weather Service Little Rock AR/
DISCUSSION...
A broad trough exists across much of the CONUS this afternoon. A
shortwave trough is embedded within the flow over the Central Plains
and this will bring a chance for rain to the area overnight.
Temperatures have struggled to reach forecast highs today north of
the slowly retreating warm front but clouds have cleared for most
areas south of Interstate 40. The aforementioned shortwave trough is
already producing some light showers over southeast MO and this will
begin to affect northeast AR and the Bootheel in the next few
hours.
Rain will spread south and east overnight but QPF looks to remain
very light at less than 1/10 inch. The good news is temperatures
will remain above freezing for most of the CWA but some locations
from Paragould to Tiptonville may be just cold enough for some
patchy, light freezing rain. Again, with marginal temperatures and
very light QPF, we`re not anticipating much in the way of impacts.
It will certainly be something to watch. As the shortwave trough
moves east tomorrow, the quasi-stationary front will waffle back to
the south. With weakening lift, we do anticipate a lull in the light
rain activity much of the day tomorrow. Highs tomorrow are forecast
to range from the mid 30s in the northwest to the mid 60s in the
southeast. Needless to say, the bust-potential in this forecast is
high, depending on where the front ends up.
Isentropic ascent will begin to increase Tuesday night and Wednesday
ahead of the next shortwave trough. This will maintain rain chances
and widespread cloud cover over the top of the shallow arctic dome.
Rainfall amounts are expected to be a bit higher and we may again
see a period of light freezing rain in the northwest. There is a
greater potential for accumulations early Wednesday morning so we`ll
be keeping an eye on it very closely. However, the main concern
exists Wednesday night and Thursday morning.
The cold air will begin to deepen slightly Wednesday night as the
leading edge of the cold dome slides farther south. In addition,
warm advection around 850 mb will result in a prominent warm nose,
perhaps as warm as 6-8C. This will promote full melting of any
falling dendrites in a classic freezing rain sounding. Surface
temperatures will fall into the mid 20s to lower 30s along and north
of I-40 where accumulating ice will pose a potentially significant
hazard. As noted in collaboration with WPC, isentropic ascent will
be quite strong but wind barbs not being orthogonal to the pressure
countours results in weaker lift and reduced precipitation
intensity. This could enhance accumulations where as heavier precip
would result in more runoff.
Some sleet could mix in farther north where the cold air will be
deeper but precipitation types look to be predominiantly rain and
freezing rain (depending on surface temps). Using the 25th-75th
percentiles for accumulations, 1/10 to 1/4 inch of ice looks
reasonable in northeast AR, the Bootheel, and northwest TN. A worst
case scenario (i.e. 90th percentile) is 1/4 to 1/2 inch of ice along
and north of I-40. These accumulations would be very significant and
would result in widespread power outages and travel problems.
At this time, the primary concern is the lack of confidence in where
the freezing line will set up. As stated, right now Interstate 40
seems to be a good first guess. If this slips a bit farther south,
heavier ice amounts are possible. We`re not issuing a 5th period
Winter Storm Watch, but this may be needed tonight or tomorrow at
the latest should the trends hold.
This system finally moves east Thursday night, but that`s when the
really cold air is expected to finally make an arrival. Model
trends are converging on much colder air this weekend into early
next week. NBM high temperatures are in the 20s and 30s across most
of the area this weekend with overnight lows in the single digits in
some areas. We did keep overnight temperatures just a bit warmer
than this guidance given model performance over the past week or two
but it sure looks like the cold air is finally going to arrive. A
brief system may bring some additional rain/snow to the area this
weekend, but it doesn`t look like much at this time. We will be
dealing with some very low wind chill readings this weekend as well,
so make sure you get the coats out.
