FXUS64 KMEG 280510
Area Forecast Discussion
National Weather Service Memphis TN
1210 AM CDT Fri Apr 28 2017
Updated for the 06Z Aviation Discussion
.PREV DISCUSSION... /issued 931 PM CDT Thu Apr 27 2017/
Quiet evening across the Mid-South as weak high pressure and
light winds prevail. A few mid and high clouds will scrape the
northern counties overnight as a weak disturbance passes by to
the northwest. Forecast on track. Stay weather aware for the
PREV DISCUSSION... /issued 346 PM CDT Thu Apr 27 2017/
A potentially busy weekend is shaping up for the Mid-South. Not
much is going on at the present in the post-frontal airmass but
things will change over the next 24+ hours as a warm front lifts
north across the CWA. Temperature are currently in the 60s across
the Mid-South and may top out around 70 degrees this afternoon.
Fair weather is anticipated tonight but moisture will surge north
after sunrise tomorrow as the warm front lifts across the area,
rapidly increasing dewpoints mid/upper 60s.
Abundant instability is forecast across the area tomorrow, but a
stout cap will be in place most of the day. However, by early
evening, the combination of surface heating and large scale ascent
will help erode the cap, allowing storms do develop along the
warm front. The big forecast question is how far north is the warm
front by the time convection initiates. There is still some model
uncertainly, but it appears likely to set up well north of I-40,
placing much of the CWA in the capped warm sector. Rain chances
will remain rather low along and south of I-40 outside of a few
warm advection showers beneath the capping inversion.
Along and north of the warm front, strong to severe storms are
likely. These storms will move northeast away from the boundary,
with additional cells spawning back on the front. Heavy rainfall
amounts will be possible with these storms with average totals
between 1-3 inches (especially north of Jonesboro-Dyersburg
line), with localized higher amounts. The Flash Flood Watch is in
good shape for now so no changes are necessary. Steep lapse rates
and large MUCAPE will support a potential for very large hail.
There is also a potential for damaging winds and a low tornado
threat. These storms are expected to weaken toward sunrise as the
low- level jet weakens. All of that said, there is a possibility
of the warm front lifting a bit farther north and keeping the
severe weather threat more confined to the Ohio River Valley.
We`ll have to wait and see on that.
Much of Saturday may turn on dry as capping persist across much of
the CWA. The thunderstorm potential will again be highest north of
I-40 and any storms that develop will have a favorable environment
for intensification. The greater threat for severe weather will be
late Saturday night and Sunday as the primary shortwave trough
lifts northeast across the Ozarks. The cap will erode as this wave
approaches and we`ll see more focused forcing along and ahead of
a surface cold front. Strong shear/instability will support a
threat for all modes of severe weather. Convection on Friday night
could throw out outflow boundaries or modulate the environment,
so there are still a few unknowns about thunderstorm mode.
However, thunderstorms are likely, with some becoming severe.
Again, heavy rainfall will be a threat across the area as this
system slowly moves east.
Rainfall will come to an end Sunday night with cooler and drier
air settling over the area for the early part of next week. Expect
generally benign weather Monday and Tuesday, but rain chances
return by midweek.
06Z TAF cycle
VFR conditions will continue during the overnight hours and for
much of Friday morning. Lower clouds will move into the region by
late Friday morning into Friday afternoon producing IFR ceilings.
By Friday evening, there will be some periods of VFR ceilings.
Thunderstorms will move into mainly northern sections of the
forecast area by Friday evening. Winds will be mainly from the
southeast at 5 to 10 knots overnight increasing to 10 to 15 knots
with higher gusts by Friday afternoon.
AR...Flash Flood Watch from Friday evening through Sunday evening for
MO...Flash Flood Watch from Friday evening through Sunday evening for
TN...Flash Flood Watch from Friday evening through Sunday evening for