Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 211502 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1002 AM CDT Thu Sep 21 2017

.UPDATE...
Updated for morning discussion.

&&

.DISCUSSION...
Latest satellite imagery and rap analysis showed the region under
an upper ridge which extended through the Lower Mississippi
Valley as well as under a shear axis over the southern areas which
extended from an upper trough over the eastern seaboard. Midlevel
temps on area soundings in JAN and LIX was near -10c at 500 mb
for some good instability for this afternoon. Latest Cam guidance
shows isolated storms for this afternoon with midlevel lapse rates
at 6-7c over the south half of the forecast area. So a few storms
could be on the strong side with some gusty winds. So with this
in mind put in isolated pops for the whole forecast area. Left
afternoon highs in the lower 90s./17/

Prior discussion below:

Today and Tonight...Warm and humid conditions will continue across
the forecast area today as high pressure at the surface strengthens
a bit from the northeast into the region.  Aloft, the forecast area
will be fixed between high pressure wedging southwest from the Mid-
Mississippi River Valley through the Mid-South region, and increased
troughing from the East Coast, southwest into the Deep South.  This
combination will result in northeast flow aloft across the forecast
area.

Patchy fog will erode across the area after sunrise this morning and
heating ensues.  Highs this afternoon under mostly sunny skies will
warm up to around 90.  With dew points remaining in the low and
middle 70s, afternoon heat indices will hover around the century
mark across much of the area.

Isolated to scattered showers and storms will again be possible
during the afternoon hours, primarily across the Golden Triangle
area and southern portions of the CWA.  Given the before mentioned
northeast flow aloft over the area, movement with much of today`s
convection will likewise have a northeast to southwest movement.
While severe storms aren`t expected today, an isolated storm or two
could become capable of producing wind gusts up around 40 mph,
mainly across southern portions of the CWA where mid-level lapse are
a tad bit steeper than elsewhere.  Like convective trends the past
few days, this activity will quickly dissipate after sunset this
evening.

Despite some lingering clouds from afternoon convection, skies will
be mostly clear overnight.  Some slightly drier air will begin to
gradually filter into the region from the east during this time.
With some patchy fog again possible early Friday morning, especially
in locales where rain is observed today and skies clear tonight,
lows will range from the upper 60s to lower 70s. /19/

Friday through Wednesday...Little change will occur to our weather
pattern through the period. Upper level ridging will take hold of
the region through the weekend into early next week. This will
keep our summer-like pattern in place despite the fact that fall
officially arrives on Friday. Highs through the period should
remain in the upper 80s/lower 90s. Overnight lows will also remain
mild for this time of year in the upper 60s and lower 70s. Rain
chances will exist through the weekend, especially for the southern
half of my forecast area. This upper ridge will be strong enough
to block the eastward motion of an upper trough and cold front to
our west. As the upper ridge breaks down by mid-week next week,
this will allow the trough to trek eastward, and allowing the
front to drop through the area. /28/

&&

.AVIATION...
12Z TAF discussion:
Some patchy fog is plaguing a few TAF sites across the area this
morning, with visibilities bouncing from VFR to IFR status at
times. Visibilities will quickly rebound to VFR categories after
sunrise as this patchy fog gradually erodes when heating ensues.
Some isolated to scattered convection will again be possible this
afternoon, mainly across the Golden Triangle area and locales
south of the Interstate 20 corridor. This could again result in a
brief bout of degraded flight categories at sites where convection
is observed. Winds today across the area will be around 5 knots,
becoming northeasterly during the course of the day. /19/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       92  70  90  70 /  15   8  32   8
Meridian      93  69  90  69 /  15  10  35   9
Vicksburg     92  70  91  70 /  16   6  27   9
Hattiesburg   91  69  90  69 /  21  14  35  16
Natchez       90  71  90  70 /  24  10  27  16
Greenville    93  70  92  70 /  15   4  12   4
Greenwood     92  70  90  70 /  15   4  13   4

&&

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

&&


$$

17



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