980
FXUS64 KMEG 261544
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
1044 AM CDT Thu Sep 26 2024

...New UPDATE...

.UPDATE...
Issued at 1044 AM CDT Thu Sep 26 2024

Helene is currently accelerating north in the Gulf of Mexico and
will make landfall this evening in the Apalachee Bay as a major
hurricane. Impacts are expected to extend into W TN starting
tonight. The biggest change in the forecast is an increase in
winds within the HREF and NBM. Although we have to look at 75th
percentile and up, there is a large enough signal for winds in
excess of 25 mph to warrant a wind advisory for Friday to around
midnight Saturday throughout the MS River delta and our northern
tier of counties. Additionally, a persistent signal for wind gusts
exists at or above 40 mph across much of the aforementioned
region. In summary, expect a wind advisory to be issued for
Friday with the afternoon forecast package.

JAB

&&

.SYNOPSIS...
Issued at 317 AM CDT Thu Sep 26 2024

Showers from Helene will begin across the Mid-South tonight. A Flood
Watch will go into effect tonight at 7 PM and persist until 7 AM
Saturday morning for West Tennessee, the Missouri Bootheel, most of
eastern Arkansas, and a portion of north Mississippi. Rain chances
will begin to decrease Saturday and slowly phase out by Monday. Dry
and cool conditions return Tuesday.

&&

.DISCUSSION...
(Today through Wednesday)
Issued at 317 AM CDT Thu Sep 26 2024

A low pressure system is currently parked along the KY/IN/IL borders
at this hour. Hurricane Helene will make landfall this evening
along the Panhandle of Florida. The large and quick moving system
will then track northwest towards the Mid-South. Due to the size
of the system, outer rain bands will begin to approach the area
around sunset tonight. A Flood Watch will go into effect tonight
at 7 PM and persist until 7 AM Saturday morning for West
Tennessee, the Missouri Bootheel, most of eastern Arkansas, and a
portion of north Mississippi. For these areas, generally 3-4" of
rain is expected between tonight and Saturday morning. The bulk of
this rainfall will occur on Friday. Guidance has been trending to
show an axis of heavy rainfall from Blytheville, Arkansas to
Martin, Tennessee with 4-6" expected. This axis of heavy rainfall
could shift, so monitor the forecast closely.

The short lived tropical rain is due to Helene`s interaction with
the cutoff low. A Fujiwara effect seems likely with these two
systems, which will bring some additional gusty winds across West
Tennessee, the Missouri Bootheel, and northeast Arkansas. There is
roughly a 40-60% chance of wind gusts 40 mph or higher on Friday for
Memphis and northward. Helene will eventually phase with the
upper low and lift towards the Ohio Valley and leave light to
moderate showers on Saturday. A few light/drizzle showers are
possible on Sunday as the system pulls away from the region.

A pattern change will arrive Monday evening as a dry cold front
approaches from the northwest. This front will quickly cross the
region and allow high pressure to settle in. Dry and cool conditions
will prevail from Tuesday morning through the remainder of the
forecast period. Drier air will reach the surface beginning Tuesday
evening with forecast dewpoints to drop into the 50s by Wednesday
morning.

DNM

&&

.AVIATION...
(12Z TAFS)
Issued at 640 AM CDT Thu Sep 26 2024

VFR conds expected today with an increasing pressure gradient
leading to gusty NNE winds this afternoon. Rain along with
associated lower cigs and vsbys will rotate into the region
tonight as moisture from Helene gets injected into the upper low
sitting over the Mid-South. IFR conds are likely later tonight
into Friday. Gusty winds will continue and strengthen later
tonight into Friday morning.

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Flood Watch from 7 PM CDT this evening through Saturday morning
     for ARZ009-018-026>028-035-036-048-049.

MO...Flood Watch from 7 PM CDT this evening through Saturday morning
     for MOZ113-115.

MS...Flood Watch from 7 PM CDT this evening through Saturday morning
     for MSZ001>009.

TN...Flood Watch from 7 PM CDT this evening through Saturday morning
     for TNZ001>004-019>022-048>055-088>092.

&&

$$

PUBLIC FORECAST...DNM
AVIATION...SJM