Area Forecast Discussion
Issued by NWS Memphis, TN

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252
FXUS64 KMEG 301733 AAA
AFDMEG

Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
1233 PM CDT Thu Mar 30 2017

.UPDATE...
Updated for 18Z Aviation Forecast Discussion below.

&&

.PREV DISCUSSION... /issued 1148 AM CDT Thu Mar 30 2017/

UPDATE...

Well it`s been an interesting morning to say the least. We have
received many photos of wind damage from what was likely a wake
low that moved across west Tennessee and north Mississippi this
morning. Winds were measured near 60 MPH at Memphis International
and near 50 MPH at Tupelo Regional this morning.

In terms of the our current severe weather outlook, which has
been reduced by a factor of two over the past 12 hours, a slight
risk seems to be the best buffer at this point. Latest GOES
imagery shows a scattered low level Cu deck across much of the
area with high cirrus over much of northeast Mississippi. Latest
WSR-88D radar shows a line of showers firing up along the cold
front in eastern Arkansas at this hour, however no lightning has
been detected at this point. The moisture field remains largely
suitable for severe storms to develop this afternoon along and
possibly ahead of the surface cold front. Latest SPC mesoanalysis
yields about 1000 to 1500 J/kg of surface based CAPE along the
delta where dewpoints are in the low to mid 60s, with only 500
J/kg further east where dewpoints have mixed down into the 50s.

The real question is how much moisture recovery will occur over
northeast Mississippi and west Tennessee ahead of the front. If
sufficient moisture return occurs, organized surface-based storms
capable of producing large hail and damaging winds will be
possible. The NAM 3km continues to be the most bullish with a
simulated line of supercells possibly forming around 19Z and
pushing eastward through sundown. Conversely, The past few runs of
the HRRR consistently show very little activity and intensity as
the front moves across the area. The most likely scenario appears
to a broken line of showers and thunderstorms, with a few embedded
supercells in the short term, before congealing into a broken
line of multi cluster storms with possible instances of wind
damage this afternoon. All convection should push east of our area
after 8 PM.

Adjusted POPs and dewpoints. The rest of the forecast is on track.

AC3

PREV DISCUSSION... /issued 626 AM CDT Thu Mar 30 2017/

UPDATE...
Updated to include the 12z aviation discussion.

PREV DISCUSSION... /issued 311 AM CDT Thu Mar 30 2017/

DISCUSSION...

Ongoing showers and thunderstorms over Eastern Louisiana and
Central Mississippi has killed severe thunderstorm chances across
the Mid-South thus far. Although have seen strong 40-50 KT gusts
with showers over portions of the CWA thanks to the strong low
level jet that is occurring over the Mid-South at this time. The
jet is forecast to remain strong through the morning hours thus
the threat for strong winds will continue across the area. Best
chances for showers and isolated thunderstorms will occur over
Northeast Mississippi and portions of Eastern Arkansas through
sunrise.

Short term models are in pretty good agreement that redevelopment
of thunderstorms will occur along the cold front roughly around
1-2 PM CDT. The front will roughly be located along the
Mississippi River at that time. Storms should become severe
rather quickly as the atmosphere remains unstable especially
across areas of West Tennessee near the Tennessee River as these
locations have been affected by little shower and thunderstorm
activity. The storms will be capable of producing large hail,
damaging winds, and isolated tornadoes. The storms will
eventually evolve into a line of showers and thunderstorms by the
time the line moves into Northeast Mississippi. The line is
expected to move out of the Mid-South by 8 to 10 PM CDT ending the
threat for severe storms.

Quiet weather will occur across the region from Friday into
Saturday as an upper ridge begins to move over the area. The next
chance for showers and thunderstorms may begin to occur as early
as late Saturday Night as a warm front associated with the next
low pressure system begins to lift northward over the area. Models
diverge on timing of the system by Sunday as the GFS is much
faster bringing the the system into the region. Models also differ
on evolution as well. For now have the best chances for showers
and thunderstorms from Sunday Night into Monday. Depending on the
exact track of the SFC low, there could be some potential for
severe storms with this system as well. Stay tuned to the latest
forecasts for updates.

That system will quickly be followed by another cold front that
will move through the region on Wednesday and will bring
additional chances for showers and thunderstorms as well.

KRM

&&

.AVIATION...
18Z TAFs

Last several runs of the HRRR and RAP models show reduced TS
potential this afternoon. A broken line of SHRA likely along or
just east of the MS River, but marginal forecast confidence in TS
at MEM given the drier and less unstable boundary layer.

VFR to prevail this evening and overnight, with dry westerly
winds prevailing in the boundary layer.


PWB

&&

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

$$



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