Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
1140 PM CST Wednesday Mar 4 2015
Updated for the 06z aviation discussion
Previous discussion... /issued 920 PM CST Wednesday Mar 4 2015/
winter storm ongoing at midevening. Precipitation has changed over to
snow over northeast Arkansas...through the MO bootheel into northwest
Tennessee. Near blizzard conditions were occuring over MO Delta...with
gusts near 30 miles per hour. Just north up the Delta into southeast MO...
Airport observation were reporting few if any gusts. Expect winds to
relax a bit over bootheel in the next hour or two. Further
east...with winds prevailing near 10kts over the Tennessee River
valley...have cancelled Wind Advisory there.
Current forecast on track...with expected reinforcing midevening
frontal surge approaching the i40 corridor. Concurrently... the
elevated warm layer will drop southeast into the early overnight...
with sleet transitioning to during the late overnight near the i40
corridor. Over north MS...elevated above freezing layer will be
sufficient to support a sleet/freezing rain mixture over north MS.
Previous discussion... /issued 537 PM CST Wednesday Mar 4 2015/
Major winter storm underway across the northern half of the middle
south and will overspread the remainder of the middle south this
A large and now phased positively tilted upper level trough
stretches from the upper Mississippi Valley southwestward into The
Four Corners region. An Arctic cold front has surged through the
entire middle south as of late this afternoon with much colder air
surging through the region. The freezing line now extends from
near Memphis Tennessee northeast to just north of Jackson
Tennessee. A large shield of moderate to heavy precipitation is
ongoing along and north of Interstate 40...with mainly a
transition to freezing rain...sleet...and even some snow where
temperatures are now below freezing.
Temperatures should be all below freezing areawide by midnight.
This should support winter precipitation types across the entire
middle south after midnight. Significant accumulations of snow and
sleet are anticipated along and north of the Interstate 40
corridor along with much of the Mississippi River Delta. As
precipitation transitions from sleet over to more snow...expect
the potential for near blizzard conditions to develop as winds
gust in excess of 40 miles per hour at times. This will result in
significantly reduced visibilities and significant blowing and
drifting of snow. In some locations...an upgrade to a Blizzard
Warning may be needed. These conditions are most likely across
northeast Arkansas into the Missouri bootheel...and portions of
west Tennessee. The evening shift will continue to monitor the
conditions and provide updates/upgrades as or if needed. Further
south to include southern west Tennessee near the Tennessee
River...east central Arkansas...and much of north Mississippi...a
more prolonged period of freezing rain should occur before
transitioning to sleet later tonight into Thursday morning. Ice
accumulations in these areas may reach one quarter of an inch.
This icing combined with strong winds may down a few trees and
power lines and result in at least sporadic power outages.
A Mississippi State University balloon launch team is currently
launching an experimental research balloon from near National Weather Service Memphis.
The sounding from this launch should be completed prior to 00z and
will provide a better understanding of the boundary layer and
depth of low level cold layer. This should help evening shift to
refine precipitation types if needed.
Snow will eventually diminish in coverage and intensity west of
the Mississippi River by middle morning Thursday and should end from
west to east by Thursday afternoon.
Dry and very cold conditions due to existing deep snow and ice
cover can be expected through the end of this week and should
result in a prolonged period of hazardous driving conditions
possibly into the first part of this weekend in some areas. As
skies clear Thursday night...temperatures should plunge to near
zero in northwest Tennessee...single digits southward into far
north Mississippi...and lower teens far southern portions of the
County Warning Area. Winds may also result in wind chill values
below zero areawide and a Wind Chill Advisory may be needed.
Temperatures should be held below guidance into the weekend as
snow and ice cover melts. With that stated...they should warm some
and be a rather pleasant reprieve from the recent winter weather.
Much warmer temperatures are expected next week along with more
rain chances. The good news hear...warmer!
06z taf cycle
Winter precipitation continues to fall over the northwest 2/3rds
of the forecast area. This area of precipitation will continue to
move slowly southeast overnight and Thursday morning with
precipitation ending during the afternoon hours. IFR/LIFR ceilings
will remain over the forecast area overnight and Thursday morning
with VFR conditions returning by Thursday afternoon. Winds will be
mainly from the north at 15 to 20 knots with higher gusts
overnight and Thursday morning. Winds will gradually diminish
Arkansas...Wind Advisory until 6 am CST Thursday for Clay-Craighead-
Winter Storm Warning until 9 am CST Thursday for Clay-Craighead-
Winter Storm Warning until noon CST Thursday for Crittenden-
cross-Lee AR-Mississippi-Phillips-Poinsett-St. Francis.
MO...Wind Advisory until 6 am CST Thursday for Dunklin-Pemiscot.
Winter Storm Warning until 9 am CST Thursday for Dunklin-
MS...Wind Advisory until 6 am CST Thursday for Coahoma-DeSoto-Panola-
Winter Storm Warning until noon CST Thursday for Alcorn-Benton
Winter Storm Warning until 3 PM CST Thursday for Calhoun-
Winter Storm Warning until 3 PM CST Thursday for Lafayette-
Tennessee...Wind Advisory until 6 am CST Thursday for Dyer-Lake-Lauderdale-
Winter Storm Warning until 9 am CST Thursday for Dyer-Gibson-
Winter Storm Warning until noon CST Thursday for Benton Tennessee-