Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 231820 AAC

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
120 PM CDT Mon Apr 23 2018

Updated for 18Z aviation discussion


18Z TAF discussion:
VFR conditions now prevail at most sites across the area, with a
BKN/OVC deck just above MVFR thresholds, though MVFR conditions
remain at some sites in between. General improvement is expected
to continue through this afternoon, but ceilings will again
decrease later tonight, with MVFR and IFR conditions returning to
most sites and lasting well into Tuesday morning. Isolated to
scattered -SHRA are possible late this afternoon into this evening,
mainly at GLH and GWO. /DL/


Morning satellite imagery depicts a vertically stacked storm
system near the Missouri bootheel. Though the associated cold
front has already passed our region, continuing convergent low
level flow is resulting in the persistence of low level clouds
across much of the area. There were considerable breaks in the
cloud cover across the Pine Belt earlier this morning, but since
clouds have increased in that area as well. Strong upper level
forcing with the mid/upper low is also resulting in light showers
across the Midsouth. As the low continues to pivot slowly toward
the TN Valley, we`ll likely see some of these showers reach areas
mainly north of I-20 into the afternoon, but remaining mostly
isolated to scattered in nature. Given the lingering clouds and
the prospect for showers through the afternoon, we nudged daytime
highs down slightly across much of the area with this morning`s
update. No other major changes are needed at this time. /DL/

Prior discussion below:

Today and Tonight: Expect a cooler, dreary and cloudy afternoon
today. As a cold core upper level low (per GOES-16 water vapor
imagery) spins over the mid-South, expect cold air advection and
wrap around moisture to remain locked in the area through the
afternoon. Due to mid-level ridging over the mid-Atlantic states
and Atlantic seaboard, expect this upper low to remain mostly
parked over the region through the afternoon-evening and only very
slowly drift to the east. This will help keep widespread low
stratus and some light rain/showers and drizzle through the
region. High temperatures will be much cooler, some 5-10 degrees
below normal. Expect the light rain chances to slowly increase as
wrap around moisture (PWs close to an inch) swings southeast
around through mid-afternoon. This could bring some isolated to
scattered light rain showers at least along and north of I-20
through the evening.

As this upper trough axis slowly drifts east through the mid-South
and Tennessee and northern Alabama, expect the wrap around moisture
to only slowly pull off to the east. This will help low stratus to
linger and light rain chances to slowly pull east-northeast through
the night, especially after midnight. Due to this, expect
temperatures to stay up near normal in the low-mid 50s areawide.
There could be some patchy fog through the region, especially if the
light rain/drizzle can linger well into the night. However, with
widespread clouds, thinking it will be patchy at most and most areas
may struggle to radiate enough, unless some low stratus builds down
into some more widespread fog. /DC/

Tuesday through Sunday: Building mid level longwave ridge over the
Intermountain West and troughiness over the eastern two-thirds will
set the stage for an unsettled regime over the forecast area through
much of the period.

Departing system over the TN valley Tuesday will keep light rain
chances in the northeast early, with improving conditions by evening
as shortwave ridging moves into the area. The fair weather will be
brief, though, as the next shortwave approaches by Wednesday
afternoon. The precipitation with this system looks to be mainly
in the form of showers initially as the lack of any low level
return flow or instability aloft reduces the deep convective

As the core of the system drops through the forecast area during max
heating Thursday, deeper convective potential will exist with
vertical totals in the mid 20s and CAPEs nearing 1000 J/kg. Would
not be surprised to see a few strong storms as deep layer shear
increases to near 50 knots. Though this system will rapidly push
east during the evening, the next system will impact the area
Friday with a similar convective potential as the system core
passes nearby.

The longwave ridge will move out of the Rockies and into the Plains
by Saturday. This will bring an end to the succession of systems up
to this point and provide generally dry and warmer conditions
through the end of the period./26/


Jackson       54  72  53  74 /   8  17   9   1
Meridian      53  71  53  75 /   4  12  13   2
Vicksburg     55  73  53  75 /  12  15   7   1
Hattiesburg   55  74  54  76 /   1   6  10   2
Natchez       55  74  54  75 /  10   6   7   1
Greenville    54  71  53  71 /  34  20   9   1
Greenwood     53  70  53  71 /  32  33  12   1




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