Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
1130 PM CST Friday Feb 12 2016
updated for 06z aviation discussion below.
Previous discussion... /issued 958 PM CST Friday Feb 12 2016/
A cold night is still expected across the middle-south with lows in
the teens northeast to middle twenties south and southwest. No
changes were needed to the forecast this evening.
Previous discussion... /issued 552 PM CST Friday Feb 12 2016/
updated for 00z aviation discussion below.
Previous discussion... /issued 333 PM CST Friday Feb 12 2016/
At 3pm... 500 mb analysis places a closed low over eastern Canada with
a ridge over The Four Corners region north to Montana...resulting
in northwest flow over the midsouth. Surface analysis places a
weak low center to the northeast of the Great Lakes region with a
potent Arctic high centered over eastern Saskatchewan building to
the southeast into the northern plains.
The Arctic high will begin to build into the region tonight with
surface winds becoming northerly as the high migrates from the
northern plains to central Illinois by Saturday night. This
coupled with northwest flow aloft will bring cold and dry
conditions to the region for Saturday with Saturday morning lows
mostly in the 20s...with teens possible at the coolest locales.
Saturday highs will only warm to the upper 20s to lower
40s...nearly 20 degrees cooler than normal for middle February. Alas
the cold will be short lived as the weather pattern evolves. As
the high continues to migrate east surface winds will transition
to be out of the east southeast by Sunday morning.
Meanwhile...under more zonal flow aloft...a subtle midlevel
impulse across Iowa will transition east as an associated surface
front trails into the midsouth as precipitation ensues.
Precipitation is likely to begin from west to east across
northeast Arkansas and the Missouri bootheel on Sunday morning as
the surface boundary nears the region. Temperature profiles
suggest this precipitation will begin as primarily sleet in areas
along and north of a line from Harrisburg Arkansas to Parsons
Tennessee. Soundings are persistent with a warm nose around 850
hpa with winds at that level out of the southwest. Temperatures at
and near the surface will warm throughout the day on Sunday with
highs ranging from the middle 30s to lower 50s. This will aid a
transition to freezing rain and sleet in the aforementioned areas
until eventually all rain is likely by midnight on Sunday night.
Right now it appears light ice and sleet accumulations are
possible with less than a tenth of an inch of either possible. All
rain is expected to fall through the entirety of the event at
locations south of the Harrisburg Arkansas to Parsons Tennessee
line. The only region where soundings are conducive to any
snowfall is in the extreme northern counties of west Tennessee.
A low will develop along the surface boundary by Monday
afternoon which could enhance rainfall especially in areas south
of Interstate 40 with quantitative precipitation forecast values between 1 and 2 inches in such
locations. Moisture will gradually move east with the surface low
by early Tuesday which will bring an end to the rain. By late
Tuesday an upper low moves to the east of the region. Models are
not in agreement on the placement of this feature and thus left
probability of precipitation out of the region after Tuesday morning.
Surface high pressure and ridging aloft will bring some pleasant
conditions to the region by midweek. Temperatures in the 50s on
Tuesday and Wednesday will be well into the 60s for Thursday and
VFR and north/northeast winds to prevail around the southern
periphery of Arctic high pressure dropping from northern plains
into the Great Lakes and Ohio Valley. These winds will weaken
after 00z...under increasing middle/high clouds.