Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Memphis Tennessee
552 PM CST Sat Feb 28 2015
updated for 00z aviation discussion below.
Previous discussion... /issued 357 PM CST Sat Feb 28 2015/
Discussion...water vapor satellite/WSR-88D VAD wind profiles
indicate a shortwave trough moving across portions of the middle
Mississippi Valley this afternoon. Meanwhile...across the middle
south...mainly precipitation free weather is occurring across much
of the area. Temperatures as of 3 PM CST range widely from the
upper 20s across northeast Arkansas...40s along the I-40 corridor
and 50s across northeast Mississippi. Wintry precipitation
potential tonight and Sunday night across northern sections of the
middle south...shower and thunderstorm chances for Tuesday and
Tuesday night...and another round of wintry precipitation
Wednesday into Wednesday night across much of the forecast area.
Short term...(tonight through monday)...short term models
indicate a potential for a subtle but weak shortwave trough
embedded within southwest flow aloft will move across portions of
the middle and lower Mississippi valleys later tonight. This
shortwave trough combined with some isentropic lift may produce
light rain where temperatures are above freezing and light
freezing rain across northern sections of the middle
south...especially across Lawrence and Randolph counties where
temperatures may not warm up above freezing as precipitation
starts. Based on the latest short term trends decided to issue a
Freezing Rain Advisory for these areas between 10 PM CST and 8 am
CST. Evening shift will continue to monitor trends and
adjust/expand headlines if deemed necessary.
A weak cold front is expected to drop into the middle south on
Sunday. This should help to focus better precipitation chances
across the middle south on Sunday...as temperatures cool late Sunday
night towards Monday morning. There is a potential for some of
this precipitation to change over to freezing rain near the
Long term...(tuesday night through saturday)...models indicate
this surface boundary is expected to move back north as a warm
front later on Monday into Monday night. This will bring a return
of warmer air with highs on Tuesday reaching the 60s to perhaps
approaching 70 degrees across north Mississippi. Showers and
thunderstorms along with heavy rainfall is possible Tuesday into
Tuesday night but confidence in strong to severe thunderstorms is
low based on overall low instability expected.
GFS/European model (ecmwf) long term models indicate another Arctic cold front will
arrive across the middle south later Tuesday night into Wednesday and
bringing a potential for wintry precipitation in the form of
freezing rain...sleet...and snow across much of the middle south. Its
still too early to assess exact precipitation types and amounts.
Nonetheless...this wintry precipitation event will continue to be
monitored for the potential of winter weather headlines for the
middle of next week. Stay tuned...
Main short term concern is fzrapl potential near jbr through 04z
or so. 2345z knqa showed numerous light returns over northern
Arkansas... moving northeast. Temperatures and any light precipitation type at jbr
will be tricky...given that there is an inverted pressure trough
south of jbr...with subfreezing temperatures locked into the north.
Otherwise...VFR will prevail this evening at the midsouth terminals.
IFR potential will increase overnight...as precipitation aloft moistens
the low level thermal inversion.
Arkansas...Winter Weather Advisory from 10 PM this evening to 8 am CST
Sunday for Lawrence-Randolph.