Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 190146

Area Forecast Discussion
National Weather Service Jackson MS
846 PM CDT Sun Aug 18 2019

Updated for evening discussion.



As of 02z, a few scattered showers and storms continue to hang on
across portions of the area. The overall trend, however, has been
for gradual weakening and eventual dissipation with the loss of
daytime heating and waning instability. Overnight low temperatures
are expected to drop into the low to mid 70s with partly cloudy
skies. Minor changes were made to PoPs to account for ongoing
radar trends, otherwise no additional changes to the forecast were
needed. /TW/

Prior discussion below:

Tonight and tomorrow...

Showers and storms are moving east across the region this afternoon.
These are providing some brief relief from the heat, though once
they pass and the sun returns, heat indices are returning to around
95-100 degrees. This activity will continue to push east through the
afternoon and all activity should diminish this evening. With
moisture back in full force across the region, overnight lows will
be on the muggier side with readings in the lower to mid 70s.

A little bit of a weakness on the eastern part of the subtropical
ridge(which is centered across Texas) will combine with the return
of 70s dewpoints to bring a better chance for convection Monday.
This will also make outlooking any heat stress issues tricky. The
best potential for this looks to be in the west/north and will
continue to mention heat indices near 105 in these locations in a
limited risk. Further south, coverage of storms will be greater.
There is potential to see a little better microburst risk tomorrow
as lapse rates should be better than today. Will hold off on any
outlook for this at this time. /28/

Tuesday through next weekend (Saturday):

Deep subtropical ridge will situate over the over the Desert
Southwest, central Plains & the eastern periphery will build into
the ArkLaTex & our region. This perturbed & persistent moisture feed
of nearly 2 inch PWs & isentropic ascent will remain as a shortwave
trough & potentially closed upper low will sit just to our east.
This will combine with north-northeasterly flow aloft to keep high
moisture & rain & storm chances around the region through the long
term period. This period of higher chances of storms from lingering
shortwave trough axis just to the east-southeast over the northern
Gulf & Florida Panhandle. Due to continued isentropic ascent &
moisture transport, we should be able to maintain some scattered to
even higher storm rain chances southeast of the Natchez Trace
corridor. Due to this, expect temperatures to be held down but still
near normals. Further to the northwest, global consensus has 595DM
mid-level ridge & thermal warmth building a little stronger into the
northwest Delta & northern portions of the region. This increasing
subsidence could dry us out aloft slightly & bring a little less
coverage of storms. A longwave trough will swing through the Great
Lakes & Canada, bringing another front & low-level convergence &
higher coverage of storms down into the Mid-South & Mid-Mississippi
Valley around Thursday into the weekend. Global models, including
the Euro, continue to depict a weak tropical wave & surface
trough/reflection over the northwest Gulf of Mexico by the end of
the week. Even though the guidance is not really bullish with it,
this could be something to watch, especially with higher plume of
tropical moisture & heavy rainfall potential into next weekend.

Rain & storms chances have trended upward from the past few days, so
this could limit overall heat & higher humidity across the region.
Regardless, with highs near or slightly above normal in the low to
mid 90s & dewpoints in the mid 70s, we should be able to maintain
heat stress potential. Higher rain chances Tuesday & Wednesday,
mainly along & southeast of the Natchez Trace corridor, should limit
heat stress, while areas to the north should be able to reach near
or slightly above 105 degrees. Due to the trend upward in rain
chances, decided to only continue a "Limited" area for heat in the
HWO/graphics but to adjust the wording. At the current rate, an
"Elevated" & heat advisory area & an increase in area for the
"Limited" would be possible, if coverage was lighter. If we do reach
these values near or above 105 degrees, it`ll likely be prior,
possibly mid-morning to just afternoon, to the convection, which
could start a little early with the higher moisture. Lastly, there
remains favorable juxtaposition of perturbed flow, lapse
rates/vertical totals & microburst composite parameters for some
organized wet microburst potential & gusty winds. There might be
some organized convective potential on Wednesday from any complex
off in the Ozarks. The newer NAM & somewhat the GFS depict this
scenario off to the north-northeast by Wednesday evening, so
something to keep an eye on. This potential will likely have to be
assessed daily. /DC/


00Z TAF discussion: Isolated showers and thunderstorms will
continue into the early evening then dissipate. Where these occur,
brief periods of IFR ceilings and visibilities will be
encountered. Otherwise, mostly VFR conditions will persist
overnight into Monday morning. Isolated MVFR ceilings and
visibilities will be seen around sunrise with VFR conditions
returning by mid morning. Scattered showers and thunderstorms will
develop once again by late morning and continue through the end
of the period./GG/


Jackson       74  93  74  94 /  12  46   8  43
Meridian      73  94  73  95 /  12  36  14  55
Vicksburg     75  94  75  95 /  28  40  10  36
Hattiesburg   73  92  73  93 /  19  69  17  70
Natchez       74  92  74  92 /  26  66  13  49
Greenville    75  94  75  95 /  30  31   5  21
Greenwood     75  93  75  95 /  30  32  11  27





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