Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 281746 AAB

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1246 PM CDT Sat Mar 28 2020

Updated for 18Z aviation discussion


18Z TAF discussion:
Varying ceilings height across the region will continue to result
in a mix of VFR/MVFR flight categories at TAF sites through the
afternoon. Gusty southerly winds will also exist at sites through
the afternoon, especially across the Delta region where winds
could gust around 35 knots at times while sustained between 17-22
knots. Clouds, along with showers and storms, associated with a
cold front moving into and through the area from this evening
though early Sunday morning, will further result in a degradation
of both ceilings and visibilities to MVFR/IFR status. Categories
will gradually improve through Sunday morning in the wake of the
front, with winds becoming more west and northwest in the process.


Warm and humid conditions will persist yet again across the forecast
area today as highs top out in the 80s under partly cloudy to mostly
sunny skies.  Most of the day will be rain-free.  However, high
pressure over the region will weaken enough to allow a cold front to
approach far western portions of the forecast area, resulting in an
increase in showers and storms over areas mainly west of the
Mississippi River during the late afternoon hours.

Some severe storms remain possible late this afternoon into this
evening as the front approaches and later moves into the area
tonight. Damaging winds of 60-70 mph, quarter size hail, and
tornadoes will be possible, especially over the northwest Delta
region where the better combination of forcing, instability, and
wind shear exists. There, a "Slight Risk" for severe storms resides
from late this afternoon into this evening.  Across much of the rest
of the CWA, a "Marginal Risk" for isolated severe storms exists from
late this afternoon through this evening.  Damaging wind gusts and
hail up to the size of quarters are possible, and a tornado cannot
be ruled out.

In addition, the tightening pressure gradient over the region due to
the approaching system, will cause breezy southerly winds over the
CWA today.  This will especially be the case of the Delta, where
sustained south winds between 15-20 mph and gusts up to 30 mph are
possible.  Elsewhere, sustained winds will be between 10-15 mph,
with gusts between 20-25 mph possible.

Overall, the current forecast is in good shape.  Adjustments were
made to the hourly elements of the forecast to better fit ongoing
trends.  Otherwise, no major changes will be made to the forecast on
this morning`s update. /19/

Prior discussion below:

An upper low will move from the eastern plains into the Great
Lakes this afternoon into Sunday. The tail end of the system will
drag a cold front across the area this afternoon through tonight.
Hi-res models and CAM guidance suggest that strong deep layer
shear and instability will be sufficient for severe storms across
the northern portions of the delta, later this afternoon into the
evening hours. Hi-Res reflectivity indicates bowing segment`s with
severe winds being the primary threat during this period, but
with decent lapse rates and deep layer shear, hail to the size of
quarters are also possible. As the front continues to trek east
across the area the instability/shear begins to weaken, but
isolated severe storms continue to look possible. SPC has
introduced a slight risk for portions of the delta and continued
the marginal risk for areas generally along and north of the
Natchez Trace. Like previously mentioned, the main risk looks like
it will be wind and hail, but a tornado cannot be ruled out. The
winds will become gusty out ahead of the boundary Saturday
afternoon with gusts from 25-30 mph, mainly for areas west of
I-55. High temperatures will be above normal once again, in the
mid/upper 80s.

As the front progresses east overnight, the precipitation will
diminish with only a few showers possible early Sunday morning in
the southeast. Lows tonight will range from the mid 50s across the
Delta to the mid/upper 60s in the Pine Belt region.

Tomorrow through Friday...
Forecast high temperatures cool back down into the 70s on Sunday
for most of the area behind the storm system as a narrow ridge of
high pressure builds back into the region for the latter half of
the weekend. A wave moving out of the southern Plains later on
Monday/Tuesday morning will bring the next chance for showers and
thunderstorms to the region. Models are inconsistent with how this
plays out in timing and northern extent of the brief warm sector.
Easterly flow associated with the ridging tempers much warm air
and moisture advection out ahead of the system, limiting much of
the activity Sun night/Monday. However, any activity will also
work to provide some limit to the available instability at least
early. Timing of the low moving into the lower MS Valley overnight
Mon night/Tuesday morning is a bit inconsistent, but will likely
be in the early half of Tuesday more than later. Concern for LLJ
and deepening shear profile may result in enough to counter the
other limitations and at least set up for a slight threat for
severe weather, particularly in the ArkLaMiss region of the Delta.

Behind this system, the forecast dries out again and temperatures
move closer to seasonal normals. As a matter of fact, after
Wednesday, the NBM numbers get a little static in the maxTs given
a little more modulation in the mid level temps. Have made some
small adjustments, warming the temps slightly at the end of the
week over guidance for now.


Jackson       88  63  78  58 /   9  76   8  19
Meridian      88  65  80  58 /   3  53  16  14
Vicksburg     87  60  76  59 /  19  71   5  21
Hattiesburg   88  68  80  62 /   5  52  17  13
Natchez       86  62  78  59 /  18  67   8  22
Greenville    84  56  72  56 /  40  77   3  24
Greenwood     86  58  73  57 /  15  85   4  23





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