Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 190017 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
717 PM CDT Fri Aug 18 2017

.UPDATE...
Updated for evening discussion.

&&

.DISCUSSION...

Early evening update:

Most of the convection has died off as anticipated. However,
isolated to scattered showers and storms have been initiating over
the past hours along an axis running northwest from Jackson MS to
Dermot Arkansas. Extending notion of the underlying weak
baroclinic zone further northwest has it interacting with a more
robust cluster of storms dropping east/southeast out of the
Ozarks. Went ahead and rose pops to 20 to 30 percent range for
many areas in the northwest quad of the CWA because this scenario
holds some potential for increasing coverage (especially in the
far northwest Arklamiss Delta) as we go through the evening (and
maybe even into late tonight). We will do another update in a bit
to refine thinking. /BB/

Prior discussion below:

Tonight through Saturday:

Afternoon thunderstorms will continue to develop from now into the
late evening hours; generally focused along Hwy 49 and to the south.
A few of these storms may be strong due to decent low level lapse
rates. After sunset, storms will gradually dissipate and a quiet
evening will be in store.

Saturday`s main concern is a heat risk for areas west of I-55, heat
index values can top between 106-109 degrees in the Delta if
convection holds off. Thus, we are going to issue out a heat
advisory for the early to late afternoon time frame. Diurnally
driven thunderstorms are still possible, but mainly in the southern
region. /12/

Saturday Night through Friday:

A TUTT low will continue to drift westward across the northern
Gulf of Mexico through the later half of the weekend and into
early next week, with a low- to mid-level ridge of high pressure
anchored over the southeastern CONUS. This pattern will keep a
hot and humid airmass in place across our forecast area through
the middle of next week. An axis of somewhat drier air will edge
into northeastern portions of Mississippi, so POPs have been
limited there. Better chances for afternoon thunderstorms will
exist mainly through southern and central Mississippi and
northeast Louisiana. Heat stress will continue to be a possibility
Sunday through Wednesday as temperatures in the low 90s and dew
points in the mid to upper 70s result in peak heat index values
near 105 degrees. The Heat Advisory is scheduled to run through
Sunday for areas mainly west of Interstate 55.

A developing low pressure system over the Great Lakes region on
Wednesday will quickly sweep eastward and push a cold front into
our region. There will be a chance for showers and thunderstorms
across the ArkLaMiss as the cold front pushes south Wednesday into
Thursday. This should also bring an end to any heat concerns as
drier air and slightly cooler temperatures move in. For the time
being, it does not appear that any tropical weather will threaten
our region, but the tropics are expected to remain active through
the week ahead.

For aspiring astronomers, there was some extra detail given to
Monday`s daytime forecast elements. Some early morning shower
activity will be possible, but the current expectation is for
morning clouds to scatter out and lift by around eclipse time.
As daytime heating occurs, a scattered to broken cloud deck could
develop across the area, but better chances for showers or
thunderstorms should increase later in the afternoon. /NF/

&&

.AVIATION...
00Z TAF discussion:

There will still be a few more isolated showers and thunderstorms
around the region for the next handful of hours, but at this
point the prospect of a direct impact at any area TAF sites
through this evening is pretty low. There is a small chance some
storms coming in from the NW late tonight might impact GLH/GWO
around daybreak but chances of that occurrence deemed too low at
this juncture to include in the official TAFs. Otherwise, expect a
few patches of MVFR mist between 6 and 8 am but conditions should
be mainly VFR otherwise. Isolated to scattered showers and
thunderstorms should again pop up starting toward midday tomorrow,
but most of the activity will probably be concentrated south of
Interstate Twenty tomorrow. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       75  94  75  93 /  25  23   8  32
Meridian      74  93  74  93 /  11  20   6  23
Vicksburg     75  95  74  94 /  14  24  21  35
Hattiesburg   74  94  74  94 /  15  26   9  35
Natchez       74  94  74  92 /  11  42  15  40
Greenville    75  95  75  92 /  28  20  21  26
Greenwood     75  92  74  93 /  13  20  21  23

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Heat Advisory from 11 AM Saturday to 7 PM CDT Sunday for MSZ018-
     019-025-034>036-040>043-047>049-053>055-059>063.

LA...Heat Advisory from 11 AM Saturday to 7 PM CDT Sunday for
     LAZ007>009-015-016-023>026.

AR...Heat Advisory from 11 AM Saturday to 7 PM CDT Sunday for ARZ074-
     075.


&&


$$

NF/12/BB


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