Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 270230

Area Forecast Discussion
National Weather Service Jackson MS
930 PM CDT Sun Mar 26 2017

Updated for evening discussion.


Latest surface analysis shows a low over SW Oklahoma with decent
convective coverage in the warm sector and along the dryline. A
closed mid- and upper-level low was centered over W Kansas with an
associated trough extending through the Southern Plains. Surface
ridging along the East Coast has allowed southerly flow to
continue across the CWA ahead of the advancing system out of the
Southern Plains which has helped to keep warm temperatures and
upper 50s to low 60s dewpoints across the region. For the
remainder of the overnight, latest hi-res CAM guidance is in
agreement on weakening and eventually dissipating the organized
convection emanating from the Southern Plains as it moves into an
area of capping and less instability/forcing. This will limit any
convection concerns across the area tonight and into early
tomorrow morning, however an isolated shower or rumble of thunder
cannot be entirely ruled out across the Delta. Some of the hi-res
guidance has been more aggressive in shower/isolated storm
development after sunrise tomorrow morning as a remnant outflow
boundary interacts with increasing moisture and instability,
however given the capping issues confidence is not very high on
more than isolated coverage at the moment. Patchy fog will also be
possible overnight and into tomorrow morning mainly in the
southeast where the best moisture return and calmer winds will be.
Coverage and visiblities are not expected to be great enough to
warrant mention in the HWO at the moment, but will let the next
shift monitor any trends. Otherwise, temperatures will stay on the
mild side area wide with southerly flow and increasing cloud
cover through the period. See the prior discussion below for
information regarding Monday`s severe weather potential. /TW/

Prior discussion below:

Tonight and Monday: WV imagery this afternoon showing impressive
cold core system moving into the central Plains with warm
advection ascent taking shape over TX/OK. Meanwhile in our neck of
the woods, much of the cloud cover from this morning has mixed
away as dewpoints have fallen into the 50s. Better dewpoints are
poised over southern sections to advance northward over the area
again tonight. As this occurs, fog and low clouds will spread in
from the south mainly after midnight.

The HRRR is indicating that currently developing MCS over OK will
grow eastward overnight into AR, but diminish toward sunrise over
eastern AR as it moves into a more capped environment. Some concern
exists for its outflow to help force new convection over northern MS
in the morning, but models soundings continue to show impressive
capping that does not look to weaken until the afternoon. A less
impressive cap will exist over the northeast and it is in this area
that convection may initiate by afternoon. While a damaging wind
threat will exist with the storms, environmental parameters suggest
that large hail will be the primary threat. Cells look to be
scattered in nature during the afternoon and early evening until the
surface cold front moves in later in the evening. South of I20, the
cap strength looks to remain strong enough to only allow for
isolated convection, but severe potential will exist with these
storms as well. The convection will diminish toward late evening
with the loss of daytime heating./26/

Monday night through the week...As the system that should bring
us some potential severe weather departs to the northeast Monday
night, it will leave a cold front draped across the north central
portions of the ArkLaMiss region. Some light showers may linger
along or near this front Monday night but the remainder of the
region will begin to dry out. Upper ridging will move overhead for
Tuesday, but as daytime heating occurs, additional showers/storms
may develop around this stalled front.

The upper ridge will push east through Tuesday night and into
Wednesday but will still have some hold on our area Wednesday. This
will keep conditions warm but mostly dry. The aforementioned stalled
front will move north as a warm front during the day on Wednesday,
which could ignite some warm advection showers across my far
northern counties(or develop completely north of my CWA). Our next
weather system will continue to develop out to our west. By
Wednesday evening, a 998mb surface low will be located across the
Rolling Plains of Texas as the upper trough/closed low will be
located slightly further north across the Texas Panhandle. A dryline
feature will be across the eastern Pineywoods of Texas with storms
along/ahead of this feature in western Louisiana. Across our area, a
rather moist and unstable airmass will be in place with dewpoints in
the lower to mid 60s and temperatures having reached the lower to
mid 80s during the afternoon. During the evening hours, as the
surface low tracks to the north and east and the upper trough starts
to swing east, this line of storms should enter my western
counties/parishes and continue to track east overnight. Our
atmosphere will be rather unstable with steep lapse rates (Vertical
Totals of 28-31C and 7-8C/km mid level lapse rates) and greater deep
layer shear than we saw in previous events (40-45kts 0-6km shear)
and helicities are depicted as being 200-400 m2/s2. All of this
suggests that all hazards will be possible. Conditions look just as
good on Thursday, especially if the overnight line doesn`t work over
the atmosphere. Looks like there could be several rounds of weather
with this event from Wednesday night through Thursday. In addition,
with PW values around 1.5-1.7 inches, there could be some locally
heavy rainfall which perhaps could lead to some isolated flooding
instances given recent rainy conditions. Will continue with the
slight risk as highlighted by the previous shift, but expect that
this will be increased as the event gets closer and more details are
ironed out.

As the system pulls off to the northeast by Thursday evening/night,
rain will move out of the area and upper ridging will again move in
for the early part of the weekend. Springlike temperatures will
continue through the period with highs in the 70s and 80s and lows
in the 50s and 60s. /28/


00Z TAF discussion: Very few clouds were noted satl imagery at
2330Z and VFR conds were observed at all TAF sites. VFR conds wl
prevail this evening but MVFR vsby wl be psbl HBG-MEI by 06Z and
lower to IFR by 11Z. MVFR cigs are expected to develop at most
sites by 09Z lowering to IFR by 11Z before improving after 15Z
Mon. TSRA activity wl come in vcty of GLH by 15z and elsewhere Mon
aftn. /22/


Jackson       64  83  63  81 /   2  39  37  29
Meridian      62  82  63  81 /   2  42  35  30
Vicksburg     64  83  64  81 /   1  37  35  28
Hattiesburg   64  82  64  82 /   9  34  21  27
Natchez       65  82  66  82 /   2  37  26  27
Greenville    63  79  59  76 /   6  42  36  19
Greenwood     63  81  61  77 /   5  55  58  25





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