Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 231731 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1231 PM CDT Thu Mar 23 2017

.UPDATE...
Updated for 18Z aviation discussion

&&

.AVIATION...
18Z TAF discussion:
VFR conditons will prevail for the remainder of the afternoon and
early evening. MVFR ceilings will develop after 24/03Z and
continue through the end of the period. Southeasterly winds
around 10 knots this afternoon and evening will increase to around
15 knots after 24/06Z with gusts approaching 25 knots./26/

&&

.DISCUSSION...
Today and Tonight:

High pressure ridging at the surface and aloft will continue
today with mainly partly cloudy skies. Temperatures will climb
into the low/mid 80s for much of the area. Little will change
tonight with seasonably warm overnight lows in the low/mid
60s./15/

Friday into the middle of next week:

Friday night into Saturday look to be the start of an active
streak of weather that should at least extend through next week.
This period will be characterized by rather potent atmospheric
disturbances crossing the region every two to three days and
working with available moisture and instability to produce a good
deal of showers and storms. Most times when the regime across the
Lower Mississippi Valley gets as active as is anticipated,
forecasting details and timing of impacts resulting from specific
systems gets increasingly difficult due to inherent chaos from
mesoscale convective processes. That said, we will do our best.

The initial system we will be dealing with still looks to come
through Friday night into Saturday and the Storm Prediction
Center continues to advertise a Slight Risk of severe
thunderstorms through this period. During the day Friday
increasing moist southerly flow will support partly to mostly
cloudy skies but before nightfall any precipitation should be
mainly limited to isolated showers. These clouds will hold highs
shy of 80 degrees in a majority of locales. By the Friday
afternoon potent convection is expected to develop across the
ArklaTex as the meat of the disturbance and associated frontal
system move in. Late Friday evening into early morning Saturday a
squall line, previously formed to our west, should be moving
through western portions of the forecast area. The main severe
weather threats will be damaging winds and hail, but there will be
enough low level wind shear to not rule out a tornado or two.

Deep moisture return in advance of this anticipated squall line
will not be great, especially the further east you go, and this
environmental limitation should cause the squall line to slow down
or considerably weaken very late Friday night into Saturday
morning. But this will not be the end of the severe weather threat
since no front will be coming through to clean out instability and
the bulk of the disturbance will not pass through until Saturday
night. The most likely scenario is that additional showers and
storms (and perhaps another, different squall line) will develop
in the vicinity of our region by late morning to early afternoon
Saturday and reinvigorate the severe weather threat, especially
for central and eastern areas. High resolution models will better
handle the details of what will unfold, but the period of interest
will not come into the time domain of most of those models until
later today.

So by Saturday night a weak boundary dragging in the wake of the
frontal system exiting to our northeast could still be bringing at
least eastern sections of the forecast area thunderstorms in the
evening. Expect this boundary to basically stall near southeast MS
Saturday night and start returning back north on Sunday. A good
deal of clouds should be found around this boundary over that time
frame although any precipitation should be rather insignificant
with temperatures above normal.

Model consensus is increasing with regard to the next disturbance
coming down the pike on Monday. This disturbance should interact
with warmth and instability in place and the lingering baroclinic
zone to bring a good chance of more showers and storms (especially
over northern zones). Through collaboration with the Storm
Prediction Center it was decided to introduce another slight risk
of severe storms for these areas as the combination of modest wind
shear and at least moderate instability could yield potent
thunderstorm organization. At this point the main risks again look
to be hail and high winds.

My initial offered caveat implies heavily from this point forward,
but the gist of model consensus is that Tuesday and Wednesday
could be relatively dry (although the inherent uncertainty of the
chaotic forecast requires holding on to lower end rain chances).
Thereafter, another potent disturbance will arrive before the work
week is out, possibly as early as next Thursday. As will be the
case with the previous two disturbances, this one may again hold
the potential for severe weather. However, at this point we will
refrain from yet mentioning anything regarding this system in the
HWO. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       85  62  78  64 /   3   5  20  69
Meridian      82  60  77  61 /   6   5  10  33
Vicksburg     85  63  80  64 /   1   5  14  84
Hattiesburg   85  63  77  63 /   6   5  22  43
Natchez       85  64  80  66 /   1   5  14  77
Greenville    83  62  79  63 /   2   5  15  89
Greenwood     82  62  77  63 /   2   5  14  83

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.

&&


$$



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