Scientific Forecaster Discussion
fxus64 kmeg 250441
Area forecast discussion
National Weather Service Memphis Tennessee
1141 PM CDT Tue Apr 24 2018
updated for 06z aviation discussion.
Previous discussion... /issued 637 PM CDT Tue Apr 24 2018/
Updated to maintain isolated showers into the evening across the
eastern half of the mid south.
Isolated showers will continue across eastern sections early this
evening in response to the upper level low pressure to our east.
This activity should dissipate later this evening with skies
gradually clearing from west to east overnight. Patchy fog will
likely redevelop late tonight into early Wednesday morning.
Updates have been sent.
Previous discussion... /issued 258 PM CDT Tue Apr 24 2018/
The first in a series of three upper lows was about to exit to
the east of the midsouth this evening, with isolated showers or
sprinkles in the interim.
The next upstream system will drop from the northern rockies into
the Central Plains by Wednesday morning. 12z model runs continue
the trend of deepening and slowing the southward movement of this
cut-off low, with the impact for the midsouth being delayed onset
of showers to late Wednesday and Wednesday night. NAM depicts
MUCAPE around 800 j/kg over northeast MS Thursday morning, under
strongly diffluent flow aloft. The marginal instability will likely
be rooted in an elevated layer, which would limit the chances of
severe storms. Thursday morning's upper low will make a quick exit
to the east, with at least partial sunshine prevailing over the
midsouth Thursday afternoon.
The last in a series of upper level lows will arrive Friday. GFS
joined the European model (ecmwf) in closing this feature off, depicting a southern
lobe phased with a open northern branch trof. This morning's European model (ecmwf)
model was quite a bit drier than the GFS or NAM, primarily a
result of the ecmwf's more southerly track near the Gulf Coast.
In any case, not a significant rain event for Friday. Should the
more northerly GFS and NAM solutions pan out, rain should be out
of the midsouth by Friday evening.
Sunny and dry conditions will prevail for the weekend, under low
amplitude ridging aloft. Weekend warmup should not see temps too
much above normal, given weak low level winds and nearly saturated
Return flow will increase early to middle next week, ahead of a
longwave trof setting up over the western U.S. A low level instability
axis will likely build north through the plains, perhaps setting
the stage for the first springtime severe weather event. Closer
to home, breezy, mainly dry and warm conditions should prevail
across the midsouth for the early to middle part of next week.
VFR conditions to start with potential MVFR vsby near sunrise at
mkl and tup. Next system will usher in VFR midlevel cigs with a
gradual lowering to IFR/MVFR during the latter half of the cycle.
Light to moderate rainfall is expected as well. Light northwest
thru north winds may back more westerly before swinging north
again. Speeds of up to 5 kts overnight will increase to 7-11kts.