Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 231800 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
100 PM CDT Mon Oct 23 2017

.UPDATE...
Updated for 18Z aviation discussion

&&

.AVIATION...
18Z TAF discussion:
Stratus is slowly filtering out of the region as low pressure &
front slowly lift off to the north-northeast into the western
Appalachians & Great Lakes. Any lingering MVFR stratus at GTR,
CBM, NMM & MEI should lift out over the next hour & VFR conditions
are expected areawide elsewhere. Expect these gusty 15-20kt west-
northwest winds to slowly subside through the day by around
23/21-22Z & become more westerly & much lighter after 24/00Z.
Another cold front will move in tonight, helping a strong pressure
gradient & gusty winds to filter in the wake. Expect the dry cold
front, other than a few passing high clouds, to move into
northwest TAF sites (GLH & GWO) late this evening around 24/00Z,
near central TAF sites (JAN, HKS, GTR, CBM, MEI & NMM) around
24/06Z & southern TAF sites (PIB & HBG) around 24/12Z. This will
help winds shift to the northwest & become quite gusty. Sustained
winds could reach 12-15kts with gusts upwards of 15-20kts by
around 24/13-15Z at most TAF sites. Higher gusts are possible,
especially at GLH & GWO, where they could gusts upwards of 25kts
or higher. /DC/


&&

.DISCUSSION...
Water vapor imagery this morning shows the distinct closed upper
low amplifying over the mid-South with much drier air filtering
in the wake. There is some potential vorticity advection & wrap
around moisture helping some lower stratus to move across central
& eastern areas, mainly along & east of the I-55 corridor. This
will gradually filter east as nearly a half to three quarters inch
PWs continue to propagate to the east-northeast as the closed
upper low becomes phased on the eastern fringe of the developing
trough over the northern Plains. For today, as the surface low
ejects northeast, expect a lingering pressure gradient between the
surface low & strong surface high over Texas. As low clouds move
east, we could still be gusty through the day but gradually moving
to the east throughout the early-mid afternoon & becoming
lighter pressure gradient lightens. All wrap around moisture &
any really light rain will remain off to our northeast as it`s too
dry for much, if any of this to make it to the ground. Much
cooler boundary layer temperatures (850 & 925mb around 9 deg C)
will only support high temperatures today closer to normals,
mainly in the low 70s to slightly cooler in the east. As the
trough absorbs the closed upper low & deepens, expect a strong dry
cold front to drive down through the Plains & into the ArkLaTex
by this evening & into our area tonight. This will help bring
gusty winds in our Delta late tonight. /DC/

Prior discussion below:

Today through Tonight:

A cool quiet weather pattern will be the general rule for this
period. Latest RAP analysis and satellite imagery show the upper
closed low tracking east across the Lower Mississippi Valley.
Wrap-around clouds were pushing across the region from the
northwest. A strong cold front was pushing east of the forecast
area.

For today the wrap-around stratus will clear across the ArkLaMiss
from the west by the afternoon. The upper closed low will open up
and pivot across the region and track to the northeast across the
Ohio Valley by this evening. Under northwest winds highs will
range from the upper 60s to the middle 70s. Another upper trough
will surge down toward the region as another strong cold front
approaches the region. Winds will be breezy from the northwest as
high pressure builds in from the northwest.

For tonight the approaching front will quickly push into the region
and will exit prior to dawn on Tuesday. The upper trough will build
across the region overnight with a deep upper low center over the
Middle Mississippi Valley. It will be a cool night with lows from
the middle 40s to the lower 50s. /17/

Tuesday:

Following the dry cold front Tuesday, expect sunny skies and
strong mixing up to H700 to support northwest surface winds in
the 20 to 25 mph range with gusts to over 30 mph primarily in the
ArkLaMiss Delta region. Due to the low afternoon relative
humidity, will continue to highlight the limited fire weather
danger threat, and will a separate mention of the wind threat in
the HWO.

Tuesday night through Thursday night:

As we go through mid to late week, a cooler northwest flow
pattern will keep the weather dry with temperatures averaging
below climatic normal, something that has been rare so far this
fall season (e.g., only one day below normal at JAN since Sep
13th). Would not rule out some frost potential early Wednesday
morning over some of the normally colder locations of north
central MS, but expect temperatures to remain well above freezing
for the most part.

Friday through the weekend:

The forecast for the next significant cold front is quite
uncertain with global models suggesting that slight timing
differences will have big impacts on rain chances and timing of
colder air. The GFS has been faster and drier with the front,
pushing it through and well east of the area by Friday night,
while the ECMWF has been slower to push the front through
resulting in greater rain chances and slightly less cold air over
the forecast area. Have generally kept the forecast closer to the
more conservative model blend guidance temps/POPs for now, but the
first legitimate freeze threat is looking more probable for at
least northern portions of the area by Saturday night. /EC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       72  48  69  41 /   0   0   0   0
Meridian      69  48  69  41 /   3   0   0   0
Vicksburg     73  47  70  41 /   0   0   0   0
Hattiesburg   70  49  69  42 /   0   0   0   0
Natchez       72  49  69  42 /   0   0   0   0
Greenville    73  48  68  40 /   0   0   0   0
Greenwood     72  46  68  39 /   3   0   0   0

&&

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

&&


$$

DC



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