Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 241357 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
857 AM CDT Sun Sep 24 2017

Updated for morning discussion.



Update through this evening:

Patchy morning fog is burning off with skies otherwise clear to
mostly clear across the region at mid-morning. An upper level low
over the region will continue to enhance instability today and
help ensure scattered puffy cumulus clouds form quickly during the
late morning to midday time frame. Despite some dry air above the
surface it looks like the influence of the upper level will be
enough to get isolated to scattered afternoon showers and
thunderstorms going with highest coverage (and most robust storms)
confined to areas south of I-20. Several storms yesterday produced
some wind damage reports yesterday afternoon east of I-55, mainly
due to downburst winds and microbursts. There seems to be some
potential of this happening again as the setup hasn`t changed a
great deal from this time yesterday. For now we will advertise a
marginal threat of damaging winds in the HWO/graphics for areas
south of I-20 but will closely monitor the situation going into
the afternoon. Otherwise, anticipate high temperatures to
generally top out a degree or two cooler today across the region
owing to the slight cooling influence of the upper level low
overhead. /BB/

Prior discussion below:

Today and tonight...

A similar weather pattern will exist today that was in place
Saturday. An upper low will continue to sit across the ArkLaMiss
region. This is situated between ridging further north across the
Ohio Valley to the Mid-Atlantic region and a large upper trough that
is covering about half of the western part of the country. This low
will once again help spark showers and thunderstorms this afternoon
in a warm and moist airmass that is in place. As was the case
yesterday, vertical totals will be in the 26-27C range with also
good mid level lapse rates. Given this, I cannot rule out some
strong to isolated severe storms. With this being more isolated in
nature, will refrain from including into any graphics or HWO.
Temperatures today should reach into the upper 80s and perhaps some
lower 90s. The greatest coverage of storms looks to be in the
southern part of the forecast area this afternoon into early evening
before dissipating. Another mild night is in store, but overnight
lows look to be a little cooler in some spots than has previously
been the case. /28/

Monday and Tuesday...

A closed off mid/upper low will retrograde across the region
early in the week, then shift/redevelop southeastward. Isolated to
scattered convection will remain possible each afternoon, with
the highest rain chances farther south in the area where somewhat
deeper moisture will exist along with weak forcing along a coastal
baroclinic zone. As the airmass remains stagnant, temperatures
will remain above normal, but dewpoints are anticipated to be low
enough to preclude notable heat stress issues.

Wednesday through the rest of the week...

As the upper low shifts southeast and farther away from the area,
daily rain chances will diminish. However, a longwave upper
trough will begin to eat away at the upper ridging across the
southeast, allowing a cold front to slip across the region late in
the week. At this point, it appears the airmass will be too dry
for precip along the front. However, a drier and more seasonable
airmass is anticipated, with dewpoints into the 50s by Friday or
Saturday and high temps falling by around 5-10 degrees. /DL/


12Z TAF discussion:
VFR conditions are prevailing early this morning and expect this
to continue through much of the day. Another round of afternoon
and early evening showers and storms will be possible today,
especially for locations along and south of I-20. Since coverage
should be rather isolated and confidence in affecting a TAF site
is low at this time, have left it out of the forecast for sites
other than KHBG/KMEI(where I put in VCTS for these). Any storms
could bring brief MVFR vis restrictions. VFR conditions should
resume after any storms through the remainder of the evening. /28/


Jackson       90  68  88  67 /  24  11  19   6
Meridian      90  67  88  68 /  22  11  18   6
Vicksburg     90  68  88  67 /  24  11  18   5
Hattiesburg   88  67  86  66 /  45  22  44  11
Natchez       90  68  88  67 /  29  13  24   8
Greenville    92  67  89  66 /  20   9  18   4
Greenwood     91  68  88  69 /  18   9  18   5





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