754
FXUS64 KMEG 260442
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
1142 PM CDT Wed Sep 25 2024

...New AVIATION...

.UPDATE...
Issued at 853 PM CDT Wed Sep 25 2024

Water Vapor Satellite trends this evening place an upper-level
low located over southern Illinois. Earlier isolated showers and
thunderstorms over southeast Missouri have dissipated over the
past couple of hours with the loss of daytime instability. Current
forecast remains on track for the remainder of the night with cool
and dry weather expected.

CJC

&&

.SYNOPSIS...
Issued at 140 PM CDT Wed Sep 25 2024

A cold front has passed through the region throughout the past day
and has brought our highs into the upper 70s and low 80s. Tomorrow
will see similar conditions before the remnants of Helene bring
rain and wind on Friday. Rainfall amounts could be up to 3 to 4
inches, especially with northern extent in Tennessee and Arkansas.
Lower accumulation of half inch to 1 inch is expected in northern
Mississippi. On Friday, highs will be in around 70, gradually
increasing into the mid 70s Saturday and Sunday.

&&

.DISCUSSION...
(This evening through next Tuesday)
Issued at 140 PM CDT Wed Sep 25 2024

Weather is expected to continue to be active across the
southeastern CONUS through the rest of the week. A large upper
level trough is currently swinging through the Midsouth and will
become progressively cutoff through tonight, eventually coming to
a standstill over our region. At the same time, this trough will
help steer what is now Hurricane Helene into the FL Panhandle
tomorrow evening. Helene is expected to quickly move inland and
pivot northwestward towards our region on Friday, bringing rain
and gusty winds.

Impacts from Helene are likely to be mainly from rainfall given
high soil moisture left behind by Francine a couple weeks ago. At
the moment, 2-3" are generally expected across the region by
Saturday evening, with some locally higher amounts possible with
northern extent. These factors could potentially aggravate rivers
and streams through the weekend. Have opted to hold off on a
flood watch but it is anticipated once more consistency in
rainfall totals are seen in future guidance. Winds could also
provide some concern as recent HRRR/HREF runs have pointed towards
an increase in winds along the northern periphery of the merging
surface lows across NW TN and NE AR. However, high- end short
range ensemble guidance progs winds at 20-25 mph and does not
offer enough coverage to warrant any advisories at this time. It
should be noted that, with high soil moisture, trees might be
more susceptible to being uprooted without meeting advisory
criteria.

As with any cutoff low, model variance is high earlier on in the
forecast cycle than usual. This is only compounded by the
interactions that will take place between Helene`s remnants and
the cutoff upper low. Current medium/long range ensembles display
this uncertainty in the position of the upper low. Some guidance
brings it out into the Atlantic by Sunday with others bringing it
north and keeping it over the CONUS. However, there is decent
confidence with respect to a new shortwave eventually dragging
the cutoff low east in to the Atlantic by next Tuesday with an
associated cold-frontal passage. Any specific timing or impacts
are too far out to be discerned with any accuracy at this time.

&&

.AVIATION...
(06Z TAFS)
Issued at 1142 PM CDT Wed Sep 25 2024

Winds will be primary aviation weather impact through 00Z/27, as
the surface pressure gradient begins to tighten in advance of
Hurricane Helene. Rain will begin to spread into the Midsouth late
Thursday evening, aided by a deepening upper level low over
eastern AR. IFR appears a good bet toward 12Z Friday.

PWB

&&

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

$$

PUBLIC FORECAST...JAB
AVIATION...PWB