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000
FXUS64 KJAN 200600
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
1200 AM CST Tue Nov 20 2018

.UPDATE...
Updated for 06Z aviation discussion

&&

.AVIATION...
06Z TAF discussion:
Limiting flight conditions will be experienced throughout the
region tonight and through some potions of tomorrow at a few sites
as a deck of low CIGs exist well behind a frontal boundary that
has already cleared the region to the SE. KGWO and KGLH will be
the first sites to clear as conditions will begin to improve over
the next few hours as drier air filters into the region. CIGs
will range from VFR at times to possibly LIFR at the remaining
sites through the night and well into the morning before the
arrival of the drier airmass. CIGs should return to VFR areawide
before 18Z. A few showers will be in the area near KPIB and KHBG
overnight and may help to reduce visbys over the next few hours.
Winds will be from the north through the period.

&&

.DISCUSSION...
As of 0330z, a surface cold front was analyzed over southeast
Mississippi. This front will continue to slide through the
remainder of the area overnight before clearing by morning.
Anafrontal showers, mist, and fog have been noted across portions
of the area early this evening but this activity will come to a
gradual end from west to east as drier air filters in from the
northwest. The back edge of the cloud shield will also clear the
area overnight with only a few lingering clouds across the I-59
corridor come sunrise. Only changes to the forecast were minor
tweaks to PoPs and temperatures, otherwise the rest of the
forecast remains on track. /TW/

Prior discussion below:

Tonight & Tuesday: The synoptic pattern will consist of the
shortwave energy diving down through the Plains & mid-Mississippi
Valley & shortwave trough/jet energy swinging into the lower
Plains & Mississippi Valley. Expect these two to phase overnight &
some weak cyclogenesis develop across the mid-Atlantic to off the
Atlantic seaboard. This will help drive the trough & cold front
through the area into the overnight hours tonight. As this cold
front moves through overnight, expect winds to become more
northwesterly with temperatures falling through the night. In
addition, low level & deep layer moisture will fall through the
night (i.e. PWs falling from just over an inch to around a quarter
to half an inch & dewpoints falling down into the upper 30s in
the north to mid-upper 40s in the Pine Belt). Lows will fall near
to slightly below normal across the northern half of the area in
the mid-upper 30s to slightly above normal (i.e. ~5 degrees or so)
across the southeast & Pine Belt. There could be some patchy fog
in spots but with lowering dewpoints & moisture & some
gradient/wind around, holding off putting in the weather grids for
now. In addition, due to winds holding around, going to hold off
putting any frost in there as well.

Expect a nice day on Tuesday as a strong surface ridge builds in
down through the southern Plains & ArkLaTex in the wake, with
continued drying & cooling thermal profiles. Expect clearing clouds
with light northerly winds. Highs will top out well below normal,
around 8-10 degrees or so, in the low-mid 50s in the north to near
60 degrees in the Highway 84 corridor. Any rain chances should
clear out before daybreak, across the southern half of the area. /DC/

Tomorrow night into early next week:

Expecting temperatures generally below normal through this period,
although this coming Saturday and Sunday may feature a brief
return to near to slightly above normal readings. This is
occurring as a -NAO teleconnection sets up in the vicinity of
Greenland and works to suppress the flow pattern over the Eastern
CONUS.

In this suppressed flow, a parade of disturbances in the atmospheric
upper levels will continue to transition through the Lower MS
Valley region. The first disturbance will move across Wednesday
night and focus clouds and light and cold rain showers in areas
south of I-20 as most of the significant precipitation with this
system remains offshore. A stronger and amplifying disturbance
will come in Friday, spurring cyclogenesis near the coast and
inducing widespread rain showers and embedded thunderstorms in our
area due to massive lift and moisture advection/convergence
aloft. This system bears watching, but at this point rainfall
(which could be locally heavy) will likely not last long enough to
produce more than an inch or two of rainfall in isolated spots.
In addition, wind energy and shear with this system will be
tremendous, but confidence is good that instability will be based
mainly above the surface and should be too meager to worry about
severe storms. Another potent upper level system is set to come
through around Sunday, but is trending toward looking too
moisture-starved to produce much in the way of significant
weather. We will keep our eye on the evolution in this scenario as
well, but confidence is good that quite chilly conditions will
build south for a time in the wake of this system.

As alluded to above, there are currently no big hazardous weather
concerns through the long term period. Temperatures should be
chilly enough Tuesday night to bring frost or a light freeze to
many locations along and north of the I-20 corridor, but at this
point in the season we are no longer doing agricultural frost or
freeze watches or warnings. A light freeze can also not be
totally ruled out Wednesday night along and north of the I-20
corridor.

As for Thanksgiving, right now we anticipate decent weather with
partly cloudy skies at worst and high temperatures ranging from
the upper 50s to lower 60s. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       40  56  33  56 /  30   1   0   1
Meridian      44  58  33  57 /  48   8   0   1
Vicksburg     39  57  34  55 /  22   1   0   1
Hattiesburg   48  60  36  60 /  76  19   0   1
Natchez       41  58  35  57 /  38   1   0   2
Greenville    37  54  32  53 /   6   1   0   1
Greenwood     38  55  31  54 /  12   1   0   1

&&

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

&&


$$

JPM3