Area Forecast Discussion
Issued by NWS Jackson, MS

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806
FXUS64 KJAN 260548 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1248 AM CDT Sun Mar 26 2017

.UPDATE...
Updated for 06Z aviation discussion

&&

.AVIATION...
06Z TAF discussion:

Expect lots of low clouds and patchy fog around tonight with
widespread MVFR to IFR flight cats around daybreak and lasting
through 10 am. Some tempo LIFR flight cats will also be possible
around the region as well at daybreak due to same concerns. A few
showers will be found tonight into tomorrow morning at
GTR/CBM/HKS/JAN/PIB/HBG/NMM/MEI, but most areas will remain dry.
The risk of an isolated shower or stray storm will linger much of
tomorrow in far eastern MS but generally anticipate that by late
morning and through the afternoon tomorrow will feature VFR
conditions and south to southwest winds blowing up to 10 mph at
times. /BB/

&&

.DISCUSSION...
Things are beginning to quiet down following an active morning and
afternoon across much of the area. Latest surface analysis shows a
cold front centered along the MS river and slowly moving east.
Meanwhile, a closed mid- and upper-level low was centered over
central MO with the an associated trough axis oriented through the
lower MS river valley. After this morning`s squall line moved
through the atmosphere was able to destabilize enough ahead of
the approaching cold front to support additional thunderstorms
mainly north of I-20. Enough shear was juxtaposed with a tongue of
diurnally enhanced instability for isolated supercell structures
to be realized with an attendant hail and wind threat through the
late afternoon hours. However, this activity has quickly weakened
following sunset and a loss of diurnal heating. As of 2z, a few
scattered showers and thunderstorms remain oriented SW to NE from
TVR to CBM.

For the remainder of the overnight period, expect
this scattered shower and storm activity to continue to move east
with the main focus for a shower or two becoming more oriented
across the SE portions of the CWA. Any lingering lightning should
dissipate quickly as convection continues on a downward trend. Our
attention now turns to the potential for fog development across a
good portion of the CWA. Latest hi-res guidance is fairly
aggressive with low visibilities, especially across the SE,
however confidence is not as high right now given that 1) there`s
lingering cloud cover, 2) winds could stay just high enough to
limit widespread dense fog, and 3) exact location of the cold
front. Given these uncertainties will hold off on mentioning fog
in the HWO for now and will keep patchy dense fog wording in the
SE with regular patchy fog elsewhere ahead of the front and will
let the next shift monitor the trends for future updates. In terms
of min temps, went a degree or two cooler in the NW for areas
that have the best chance of cooling behind the front and kept
temps more mild everywhere else. /TW/

Prior discussion below:

Tonight and Sunday: Visible satellite imagery this afternoon showing
cold core low spinning about over the northern Ozarks. Meanwhile,
down in our neck of the woods, the majority of this morning`s
convection has moved to the east and southeast, but other storms
have developed lately over north and west central sections of MS.
These storms are developing in a confluent area of mid 60s
dewpoints that have combine with heating to produce CAPEs around
1000 j/kg. Some of these have had robust updrafts and have produce
some hail.

The HRRR is showing these storms maintaining themselves for the rest
of the afternoon with the possibility of a few more severe storms.
Also, the convective area over the southeast looks to spread out to
the northeast before moving into AL this evening. and only a few
light showers left by midnight. With low level moisture hanging
around overnight, fog looks like a good bet after midnight as skies
clear.

Surface winds never drastically change directions, thus southerly
flow Sunday will begin quickly reloading the moisture levels in the
lower levels ahead of a storms system slated for Monday. Low to mid
60s dewpoints look to overspread the area by 12Z Monday./26/

Monday through Friday: A generally active weather pattern will
remain in place through the remainder of the forecast period
thanks to a progressive upper level pattern. The next system of
interest is still on track for Monday, as a mid level shortwave
and surface low track across the Mid South. Moderate instability
is expected across our area, along with decent height falls
occurring with the passage of the wave. Given the timing of the
system (peak heating/instability) and anticipated steep lapse
rates, a respectable severe weather threat will exist with
somewhat greater potential farther north in the area closer to the
better forcing. The currently advertised slight/marginal risk
areas may need to be tweaked upward in later forecasts for some
portions of the area.

The surface baroclinic zone associated with Monday`s system will
stall just north/northwest of the CWA, keeping most or all of the
forecast area in a warm/moist environment into the middle portion
of next week. This will keep lower end chances for less organized
showers/storms around Tuesday into Wednesday even as shortwave
upper ridging passes across the area. The next system of interest
is still on track to arrive around the Thursday time frame. Some
model inconsistencies exist with respect to the nature of this
system (slower moving cut off upper low vs more progressive upper
wave). Nevertheless, the soupy airmass will remain in place ahead
of this system, and another increase in rain/thunderstorm chances
appears to be a good bet. Stronger deep layer shear will accompany
this system, and there are indications that steep lapse rates
will once again be possible. Particularly once we begin to see
better model consistency, there is a good chance that severe
potential will need to be added to HWO and graphics products for
this period of the forecast. There is a better chance of an actual
frontal passage with the late week system, suggesting a break in
the rain is possible by next weekend. /DL/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       63  82  63  80 /   9  58  43  33
Meridian      63  81  62  80 /   8  37  37  35
Vicksburg     63  82  64  81 /   7  58  38  33
Hattiesburg   64  82  63  82 /   8  28  19  32
Natchez       64  82  65  81 /   7  47  28  30
Greenville    63  78  60  77 /  15  61  43  19
Greenwood     62  80  62  78 /  12  63  56  28

&&

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

&&

$$

BB/TW/26/DL



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