Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 241609

Area Forecast Discussion
National Weather Service Jackson MS
1109 AM CDT Tue Apr 24 2018

Updated for morning discussion.


Clouds continue to hold on across much of the region this morning
on the back side of closed upper low now over nrn TN/srn KY,
keeping temps from warming on a typical diurnal curve. Areas along
the MS River seeing less cloud cover, and are running several
degrees warmer than the rest of central MS. That said, ongoing
fcst seems to be reasonably on track, so will not be making any
changes attm.

Prior discussion below:

Today and Tonight: Expect another cool, dreary and cloudy
afternoon, similar to yesterday, but clouds gradually departing
through the mid-late afternoon. As a mid-level ridge builds up the
Atlantic seaboard, the cold core upper low will continue to
slowly propagate east across Tennessee and into the Appalachians.
This will continue lead to cold air advection and continued
isentropic ascent on the back side of the upper low. Expect
continued widespread low stratus and low-mid level cloud deck
across most of the area, especially along and east of the
Mississippi River and across the I-20 corridor and into the
eastern Pine Belt. There is very light rain this morning moving
east across central Mississippi. Expect continued light rain
showers & drizzle to slowly propagate east and into east-northeast
Mississippi (especially the Golden Triangle) through the
afternoon. At most it will be very light due to limited moisture
and only kept slight chances of rain through the afternoon. Due to
widespread clouds and light rain/drizzle, lowered highs toward
raw guidance. Highs temperatures will still be below normal (~5-10
degrees, especially in north-northeast) & may struggle to reach
the upper 60s, while elsewhere could reach the low-mid 70s.

As the cold core upper low moves into the Appalachians and mid-
Atlantic tonight, expect increasing isentropic subsidence and
clearing of the clouds especially by mid-late evening. As mid-level
and surface ridging build in the wake, expect dry and chilly night
in store, near normals in the low-mid 50s. Due to light winds,
efficient radiational cooling, high residual boundary layer moisture
& falling ~2-4 degrees below crossover temperatures, we should be
able to radiate enough for low stratus and fog overnight. Hi-res
guidance is hitting at this idea pretty hard. Added patchy fog to
the weather grids areawide but wouldn`t be surprised that this could
lead to some more areas or dense fog. With a pretty good environment
for fog, decided to introduce a "Limited" for patchy dense fog in
the HWO/graphics. /DC/

Wednesday through Monday: Northwesterly mid level flow pattern
will bring a couple of relatively weak storm systems across the
region during the first half of the forecast period. The first
will arrive by late afternoon Wednesday. Though deep moisture will
be lacking over the area, strong warm advection will be
sufficient to squeeze out rainfall totals near an inch by Thursday
afternoon. Since overall instability will be limited, MAUL
availability in the strong warm advection regime and the
proximity of the cold core aloft should be adequate for thunder

Weak/brief shortwave ridging will ensue Thursday night ahead of the
next fast moving system set to arrive mainly Friday afternoon.
Slightly better low level moisture with dewpoints in the lower 60s
will support CAPEs near 1000 J/kg during maximum heating. This along
with better lapse rates will support deep convective possibilities
again for Friday afternoon. With the loss of heating, the
precipitation will diminish rather rapidly during the evening.

For Saturday through the end of the period, mid level ridge moving
out of the Plains into the mid MS valley will bring drier and warmer
conditions back into the region./26/


12Z TAF discussion:
Ceilings continue to be the main concern this morning as
widespread low stratus remains locked into the area. There are
some scattered MVFR ceilings through the region. Expect this to
continue, with a couple sites briefly lowering or currently at
IFR. There could also be some scattered lower visibilities at
times but ceilings have been the main restriction this morning.
Expect these ceilings to slowly lift after 24/15-16Z or so, with
VFR conditions possible at most sites between 24/21Z-25/00Z.
Expect west-northwest winds around 7-10kts and weakening by the
evening. Some lower MVFR/IFR ceilings and/or visibilities are
possible tomorrow morning around 25/09-10Z, with some possibly
lowering towards LIFR restrictions due to patchy dense fog &/or
low stratus. /DC/


Jackson       72  53  76  56 /  10   0  10  60
Meridian      71  53  77  56 /  20   0   0  40
Vicksburg     74  53  77  56 /  10   0  10  70
Hattiesburg   76  54  78  57 /   0   0   0  30
Natchez       76  54  78  57 /   0   0  10  50
Greenville    72  54  74  54 /  10   0  20  80
Greenwood     68  52  74  53 /  10  10  10  70





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