278
FXUS64 KMEG 121205
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
605 AM CST Wed Feb 12 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 545 AM CST Wed Feb 12 2025

 - Multiple rounds of rainfall this week into the weekend will
   bring a range of 3-7 inches of rain, with highest amounts south
   of I-40.

 - A few strong to severe thunderstorms are possible across
   portions of North Mississippi and West Tennessee on Saturday
   as an area of low pressure moves across the Lower Mississippi
   Valley.

 - Much below temperatures are favored next week. Long range
   models are hinting at the potential for some winter precip
   toward the end of next week.

&&

.DISCUSSION...
(Today through Tuesday)
Issued at 229 AM CST Wed Feb 12 2025

The rain shield across north Mississippi is oriented along a
nearly stationary front this morning. As we get into the mid
morning and afternoon hours, a warm front from the Gulf Coast will
lift north and eventually interact with this boundary. As these
two fronts meet during peak diurnal heating hours, weak synoptic
lift will favor a few thunderstorms across north Mississippi. In
addition, PWATs just under 1.5 inches (above the 97.5th
percentile for this time of year) will support very efficient
rainfall rates. This rainfall efficiency combined with the
orientation of the frontal boundary may create a training storm
situation across northeast Mississippi this afternoon. The
difficulty in this afternoon`s forecast will be pinning down
exactly how far north the warm front is able to make it before
colliding with the stationary front. The frontal tug-of-war will
make or break the axis of heavy rainfall (2-3 inches) in our CWA
today; it may stay just to the south or creep up to our
southeastern zones. Will be something to monitor in the near term.

The main story, rainfall-wise, will be Saturday`s system. A deep
Colorado Low and its associated cold front will sweep through the
Lower Mississippi River Valley on Saturday afternoon. This isn`t a
particularly fast-moving system to begin with, and it may actually
slow down as it approaches the Mid-South, which only adds to the
heavy rainfall threat. PWATs are once again looking to be around
1.5 inches, supporting updrafts with extremely efficient
downpours, especially across west Tennessee. Expect the bulk of
the heavy precip to fall between mid morning and late evening on
Saturday, though it will pretty much be a washout for most of the
day. Due to the speed and orientation of the warm conveyor belt
with this system, storm total QPF amounts for Saturday/Sunday
morning alone range from 2-4 inches, with locally higher amounts
up to 5 inches across West Tennessee. The ground will already be
pretty saturated from yesterday and today`s rain, further
compounding into a flash and riverine flooding threat. Stay tuned
for later forecast periods as a Flood Watch will most likely be
hoisted for Saturday.

Another layer to Saturday`s system is the potential for severe
weather. Comparing the surface low`s track via ensemble MSLP, the
three main global models are actually in pretty good agreement
that the center of the surface low will track through the Missouri
Bootheel. This will essentially bisect the CWA with the severe
weather threat in the warm sector, which is about the southeastern
half of the CWA. Right now, it`s looking like the mode of severe
weather will be a messy clump of convection across the ArkLaMiss
region that eventually congeals into a QLCS after it crosses the
Mississippi River. Digging into the parameter space, this is a
very well-sheared system with plenty of kinematics to go around.
Bulk shear upwards of 70 kts may actually be too strong for the
initial formation of the line early in the day on Saturday. As
the QLCS marches eastward toward Middle TN and northern AL, the
ingredients should start to come into better balance to support
more organized severe weather. This will most likely be after 4PM
Saturday and could certainly impact our eastern zones. Given the
linear mode of storms, damaging winds will be the primary threat.
The magnitude of the tornado threat will depend on the discrete
cell formation ahead of the front, but a well-sheared environment
at all levels certainly supports embedded circulations within the
line as well.

Sadly, our break from active weather will be very short-lived next
week. A 1030 mb surface high is slated to sit right over the Mid-
MS River Valley on Monday morning, which will bring dry and
downright chilly conditions for a few days. Monday morning`s wind
chills are sub-20 degrees areawide due to the brisk northeasterly
wind associated with the surface high. CPC`s temperature outlook
also favors a 70-80% chance of below normal temperatures for the
next 6-10 days (Monday-Friday). For context, "normal" lows in mid
February are just above freezing and normal highs are in the mid
50s. The next system in this active period actually looks like a
bit of a hybrid between a Colorado Low and a Gulf Low on Thursday.
It may end up being more of a one-two punch situation where a
relatively dry cold front sweeps through the region on Wednesday
and primes the column for cold air throughout the vertical
profile. Then Thursday, a Gulf Low follows shortly thereafter,
taking advantage of the preceding cold airmass. Amounts are highly
uncertain at this point but it does look like the setup favors at
least some winter precip mid to late next week.

CAD

&&

.AVIATION...
(12Z TAFS)
Issued at 545 AM CST Wed Feb 12 2025

A low pressure system will ride northeast along a stalled frontal
boundary over north Mississippi this morning. Simultaneously, a
vigorous shortwave will pivot into the region from the west.
SHRAs will overspread all sites by late morning and persist
through late afternoon and could linger into the late evening
hours. The best chance of TSRA will be south of the area, but
could affect TUP this evening.

Winds will be initially be easterly and turn around the south and
west this afternoon in response to the surface low. Winds will
then shift to the north as the front slides east this evening.

AC3

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

$$

PUBLIC FORECAST...CAD
AVIATION...AC3