Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
844 PM CST sun Dec 8 2013
Discussion...02 surface analysis places a weak quasi-stationary
boundary/surface low near the Louisiana/Mississippi/Alabama Gulf
Coast this evening. Meanwhile...a ridge of high pressure is
located across portions of the middle Mississippi Valley into
portions of the middle south. Temperatures as of 8 PM CST range from
the middle 30s to around 40 degrees across west Tennessee near the
Tennessee River and portions of northeast Mississippi and upper
20s to lower 30s along and west of the Mississippi River.
Knqa/kgwx WSR-88D radar trends indicate light rain showers across
northeast Mississippi in association with a middle level shortwave
trough and an upper level jet streak moving across the region.
Latest RUC short term model seems to be handling current trends
the best with respect to precipitation. Will make adjustments to
limit and lower precipitation chances overnight to extreme
As of 8 PM CST...visibilities are currently ranging from 4sm to
p6sm. Light winds have kept low level moisture lifted as a low
stratus layer thus far. Will continue to monitor short term trends
for the possible development of fog/freezing fog and any headlines
if it becomes necessary.
Will also make minor adjustments to temperatures and all other
elements as needed to account for latest trends.
Updated grids will be available shortly.
Previous discussion... /issued 536 PM CST sun Dec 8 2013/
Previous discussion... /issued 320 PM CST sun Dec 8 2013/
A sharp temperature gradient is occurring across the midsouth
this evening. Locations south and east of a Memphis to Jackson
Tennessee line are reporting temperatures in the middle 30s to lower
40s. North and west of this line temperatures range from 28-32
degrees. Temperatures also remain near freezing farther south in
the Delta such as Marianna...Tunica and Clarksdale. Patchy dense
freezing fog has formed along this gradient between the Arctic air
and the warmer air. West
Memphis...Millington...Blytheville...Dyersburg and Union City are
reporting visibilities from a quarter mile to three quarters of a
mile. Thus far no icing has occurred as a result of the fog but a
little worried that this may change once the sun GOES down. Will
let evening shift monitor for any potential advisories.
Meanwhile...rain continues to push northward into north
Mississippi where locations are above freezing. This is due to a
surface low developing along a stationary front near the Gulf Coast.
Models indicate the northern extent of the precipitation could
reach into locations this evening that are sitting just above or
at freezing currently. As temperatures drop this evening this
could change rain over to freezing rain...but confidence is low
thus again will let evening shift monitor for any potential
advisories. Will just mention a slight chance or chance of
freezing rain in the forecast as best chances of precipitation
will occur across northeast Mississippi where locations will
remain above freezing.
Another surface low will develop along the stationary front located
along the Gulf Coast by Monday evening. This will bring another
round of precipitation that will skirt northeast Mississippi.
However by Monday evening...northwest winds will have pushed
Arctic air further south and east thus precipitation could fall in
the form of freezing rain if precipitation makes it as far north
as northeast Mississippi. Stay tuned.
In addition...a shortwave will swing across southern Missouri and
western Kentucky Monday night. This could bring a brief shot of light
snow across portions of northeast Arkansas...the Missouri bootheel
and northwest Tennessee. Any accumulations that would occur would
be less than an inch.
By Tuesday...Arctic high pressure settles over the midsouth.
Expect dry conditions with highs ranging from the lower 30s to
lower 40s. A reinforcing shot of Arctic air will move into the
area on Wednesday into Wednesday night. Lows Wednesday night will
range from the middle teens to the middle 20s.
By Thursday night...the high will shift east turning winds around to
the south. The next low pressure system will move into the area on
Friday and will bring chances for precipitation to the midsouth
over the next weekend. How quickly the Arctic air departs will
depend on possibly precipitation type for portions of next
weekend. The 12z European model (ecmwf) is colder than the 12z GFS. For now have
tried to go with an in between solution which would have
temperatures near normal and would keep precipitation in the form
00z taf cycle
Visible has improved to MVFR levels at all sites but ceilings remain IFR.
Feel like those ceilings will continue most of the night possibly even
lowering to LIFR levels for brief periods of time. Included tempo
1-200 foot ceilings along with 1sm br at tup mkl and mem for brief
periods this evening/tonight. Some marginal improvement to ceilings is
expected by sunrise...but not above IFR levels until after
sunrise. Guidance wants to continue to lift ceilings through the day
even to VFR levels...based on experience...feel like clouds will
linger longer than guidance suggests...but will bring levels to
5kft during the afternoon for all locations except tup. May
Rain at tup will be light...with little to no precipitation
elsewhere. Winds generally light overnight...light from the north
Preliminary point temps/pops...
mem 28 39 27 38 / 40 10 20 10
mkl 29 38 24 37 / 50 10 20 10
jbr 24 31 24 32 / 10 10 20 10
tup 36 43 33 42 / 80 30 60 10