FXUS64 KMEG 171027
Area Forecast Discussion
National Weather Service Memphis TN
427 AM CST Sun Dec 17 2017
Rain is finally falling across the Midsouth and plenty more is on
the way over the upcoming work week. The latest 7 day QPF graphic
from the WPC shows in excess of 6 inches of rain over a swath of
the Midsouth encompassing East central Arkansas and much of North
Mississippi. Rainfall totals over this period taper off to the
North and West but all of the Midsouth is likely to see multiple
inches of rain. Guidance continues to trend less favorably for
any freezing or frozen precipitation.
The back edge of the ongoing rainfall is already approaching East
Arkansas and will likely shift across most of the Midsouth before
noon today. PW is in excess of 1 inch resulting in locally heavy
rain. Upstream over central Arkansas...many locations are
reporting rainfall rates between one third and one half of an inch
per hour. Rain may not last very long, but totals may approach an
We will remain under a very progressive pattern over the next week.
The current trough that was previously a cutoff low over West
Mexico will deamplify and quickly move off to the Northeast...but
another very similar trough will approach the midsouth Midweek.
This system continues to look more robust in model runs. Severe
thunderstorms do not look likely...but we will need to monitor the
threat for localized flooding. Will hold off on including a
flooding threat in the HWO since the rain is expected to fall over
several days but it may need to be addressed in upcoming forecast
Friday into next weekend, the third round of rainfall will
approach the Midsouth. A full latitude trough will shift out of
the Plains Friday night into early Saturday. Rain looks likely
ahead of an accompanying surface cold front. Once again, rain
could be heavy at times...and dependent on how much rain falls
before this system arrives, flooding could become a concern.
Temperatures today through the upcoming work week will be above
normal...warmest Monday and Tuesday when highs will be in the
middle to upper 60s. Much colder air is expected to arrive next
weekend behind a strong cold front. As is typical here in the
Midsouth...moisture should exit before the colder air moves in.
Highs next Saturday are expected to be in the 40s.
Rain showers continue to spread east across AR this evening and
will affect pretty much all of the Mid-South overnight and Sunday
morning. VFR conditions will prevail through 12z in most areas
with ceilings quickly lowering as the column moistens from the top
down. IFR conditions are expected in many areas for a few hours
Sunday morning with slowly improving conditions through the
afternoon hours. That said, ceilings are likely to remain near or
below 2500 ft. Winds will be generally from the south and
southeast at under 8 kts.
FXUS64 KOHX 171131
Area Forecast Discussion
National Weather Service Nashville TN
531 AM CST Sun Dec 17 2017
FOR 12Z AVIATION DISCUSSION.
Several things going on at forecast time, but we'll start with this
system that is quickly closing in on Middle Tennessee. Latest radar
trends show that rains are moving in much earlier than any model is
suggesting. For this reason, I have added in definite PoPs west of
I-65 prior to 6 am. Rains will continue to spread across the rest
of the mid-state through the morning hours and everybody should see
some rain from this system. That said, it really shouldn't be all
that much. Totals will likely range from a tenth of an inch for our
counties nearest the KY state line to a half inch for counties along
the AL state line. This afternoon, rains will taper off from west
to east and while the heaviest rains will end rather quickly, we
could be dealing with some lingering drizzle through the night and
into the Monday morning commute. Nothing of any significance on the
whole but there will likely be some reduced visibilities across the
area. We'll dry out during the day Monday, but I don't expect much
sun, so I'm going to back off on forecast highs Monday afternoon
just a bit.
The second system of this forecast will begin moving into Middle TN
Tuesday morning, spread across the mid-state through the day and
provide us with good rain chances and rainfall totals through
Wednesday morning. While the higher totals are expected to be south
of I-40, models are still a little out of agreement regarding the
path of the surface low. The Euro would suggest a more northerly
trajectory and higher rain totals versus the GFS. The NAM kinda
falls in the middle of the other two. So, I'll carry higher PoPs
for the southern half of the area, but there could be a fairly
significant gradient from north to south as to who sees rain and
Wednesday night and Thursday should be dry, but our third system of
the week (which models have been persistently portraying) should
move in Friday and bring us rains through Saturday morning. Storm
total rainfall should be as much, if not more, than the Tuesday
system. This system should be fairly dynamic. Colder air is being
progged to fill in behind the precipitation and while I'm nowhere
near ready to talk winter precip, I can tell you, only one long
range model is suggesting any frozen stuff. For now, I'll just
carry a small PoP on the backside of the Friday/Friday night
system and leave it all liquid.
The last recorded rainfall at Nashville airport was back on December
5th. While today's rainfall isn't going to go far to relieve us from
this latest snap of dry weather, we will make up for it through the
rest of this week.
12Z TAF DISCUSSION.
BNA/MQY/CKV/CSV...A shortwave approaching Middle Tennessee from
the southwest is just now beginning to spread light rain into the
region. Expect the showers to grow heavier during the next few
hours, with ceilings gradually lowering to MVFR later this morning
and afternoon. Even though the showers will exit the mid state
during the afternoon, drizzle and fog will develop by evening,
with ceiling & visibility concerns lasting through the night, and
LIFR conditions setting up at CSV after 00Z.
FXUS64 KMRX 171122
Area Forecast Discussion
National Weather Service Morristown TN
622 AM EST Sun Dec 17 2017
Showers are moving in from the west and bring with them low
ceilings and possibly reduced visibilities. The further northeast
the showers go the more scattered they will become leading to
better flight categories. Certainty on exact timing of when
RA/VCSH will end is somewhat low right now. Places that get rain
today have a good chance at seeing BR/FG overnight as well.