Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 230235 AAB

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
935 PM CDT Thu Mar 22 2018

Updated for evening discussion.


A mostly clear and cool night is underway across the area.
However, high clouds are increasing across northern MS ahead of a
very weak upper disturbance. The 00z KJAN sounding revealed a
rather dry column top to bottom, with PW only around 1/2". High
res guidance suggests light showers may try to clip the Golden
Triangle toward daybreak, but Bufr soundings indicate the low
level dry layer will hold firm. Still, there will be an increase
in clouds overnight/early tomorrow morning across the NE portion
of the CWA. Even if some sprinkles were to reach the ground,
measurable rain is rather unlikely. Having said all of that, the
existing forecast was in good shape, and other than negligible
tweaks to temps/dewpoints/sky cover to account for current trends,
no changes will be made at this time. /DL/

Prior discussion below:

Tonight through the day Friday:

Quiet conditions are expected through the day tomorrow although
clouds will be on the gradual increase, especially north of the I-20
corridor. Aloft, the far western extent of a minor "clipper" wave
advancing toward the east CONUS trough axis will be inducing
isentropic upglide (ergo, clouds) upstream of our region where some
light precipitation will also exist. But, as mentioned, in our
neck of the woods all that should manifest is mid to high layer
clouds with conditions tending to moderate quickly as surface high
pressure transitions to the east. Through tonight the high is
close enough to keep winds light and variable over most of the
region, but by tomorrow low-level southerly flow will commence in
all areas by the afternoon. In fact, these surface southerly winds
could a bit gusty at times from midday through the afternoon
hours in portions of the Arklamiss Delta, although at this time
thinking is that gusts and speeds will remain low enough to
refrain from mentioning in the HWO/graphics. Temperatures will
continue to trend upward but scattered clouds will make forecasts
of minimum and maximum temps a little tricky, especially in
northern zones. /BB/

Friday night through next Wednesday:

Expect above normal and warm start to the weekend before heavy
rain potential ramps up by mid-late next week.

Overall they synoptic pattern on Saturday morning will consist of
trough departing off the eastern seaboard while mid-level ridging
will be building into the area from the west. This will support the
strong surface high, that has brought below normal low temperatures
into lower 30s and some frost, to build off the southern Atlantic
seaboard. In addition, a mid-level shortwave will be propagating
through the mid-Mississippi Valley, helping lead to surface low over
Missouri area and better southerly return flow and some gusty winds.
This boundary and moisture return look to be the best in the Highway
82 corridor, where some rain & storm chances can`t be ruled out on
Saturday. Some of that may extend a little closer to the I-20
corridor but overall should remain in our northern areas. This
pattern of rain and some storms will persist through the weekend,
with a stalled front lingering in the Highway 82 corridor to Golden
Triangle & east Mississippi, which will keep some light rain chances
around. Due to increasing warmth and moisture advection, we should
still top out in the mid-upper 70s to low 80s in the south under
cloudy skies. This will help temperatures remain well above normal
Saturday morning in the mid-upper 50s (~10 degrees above normal) and
in the low 60s (~12-15 degrees above normal). During this time,
couldn`t rule a stronger storm or so but overall limited forcing
should limit any more organized potential.

As the strong subtropical ridge builds over the southern Gulf of
Mexico & into the Carribean early next week, the mid-level ridge
axis will extend through the Appalachians and northeast. This will
support a continued warm and cloudy period with some light rain
and storm chances around. As the ridge axis builds to the east,
expect warmer and muggy conditions with cloudy skies and most rain
chances over the western portions of the area.

The pattern around the middle of next week will become more
amplified and consist of a deep mid- level trough digging into the
Desert Southwest and better influx of Pacific moisture into the
southern Plains and mid-Mississippi Valley. This will help a storm
system develop, which will be the main focus. As strong southwest
flow, upper divergence and increasing influx of moisture feeds
along a stalled surface boundary into and just northwest of our
region, heavy rain and a significant flash flooding potential
will be possible. This is somewhat similar to the February heavy
rain event just to our northwest, but with the subtropical ridge
centered over the southern Gulf, it is slightly different.
Uncertainties remain on how this pattern is going to iron out, but
a significant flooding threat will exist near the mid- late
portions of next week. Most of the heaviest axis will remain just
off to our northwest by Wednesday but newer 12Z Euro has sped up a
lead shortwave bringing the heaviest rain in just after the end
of the forecast period. In addition, due to increased warmth,
moisture and stronger southwest flow aloft, some severe threat
could be possible around mid-late next week. Main takeaway is to
keep a close eye on this pattern mid-late next week as small
synoptic differences could make a large differences on impacts
across the region. /DC/


00Z TAF discussion:
VFR conditions will prevail through the TAF period. During the
daytime hours Friday, southerly winds will gust to around 20 kt at
times, especially at sites in the ArkLaMiss Delta. /DL/


Jackson       45  77  57  80 /   0   1   2   7
Meridian      42  75  55  79 /   0   1   2   4
Vicksburg     47  78  59  80 /   0   1   4  10
Hattiesburg   42  75  55  81 /   0   1   1   4
Natchez       47  78  60  80 /   0   1   2   6
Greenville    49  74  58  75 /   0   1  13  24
Greenwood     48  73  58  75 /   6   1   6  26





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