Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 060614

Area Forecast Discussion
National Weather Service Jackson MS
1214 AM CST Tue Dec 6 2016

Updated for 06Z aviation discussion


06Z TAF discussion:
Coverage of showers will decrease across the area overnight, but a
low stratus deck will persist into the day Tuesday. LIFR and IFR
conditions are already prevalent across the region and will stick
around into Tuesday before a gradual improvement to MVFR at some
terminals by afternoon or evening. Areas of lower visibility will
also be possible overnight into Tuesday morning, but low ceilings are
expected to be the main driver of reduced flight categories. /DL/


Showers and some thunderstorms are moving across the CWA this
evening. Rain is tapering off in some places, but feel that as the
upper trough swings across later tonight, additional rain may occur
and have kept high POPs going across the region. Confidence in severe
potential continues to wane as the evening has progressed. The upper
trough and low have been slower to swing through the region than
earlier models indicated. Also, influx of moist air has remained to
our south, closer to the coast. Hi-res model guidance indicates that
perhaps some lower 60s dewpoints might make it into the far, far
southern part of the CWA after 06Z but most of it remains to our
east. Instability also looks limited this far north as well. That
being said, perhaps a thunderstorm may be able to be strong in that
area later tonight, but confidence in that is not high at this
juncture. Hi-res reflectivity guidance also is lacking in robust
storms in the location where the better moisture may be located later
tonight. All this being said, have removed the limited severe risk
for the remainder of the night from the graphics and HWO. Heavy rain
may continue in some spots, but with the lack of stronger
convection, rainfall rates won`t be as high and thus have backed off
on the heavy rain/flooding limited threat. /28/

Prior discussion below:

Tonight through Tuesday: An upper low with an associated surface low
is centered over southwest Louisiana this afternoon. Widespread
showers and isolated thunderstorms are occuring out ahead of this
system as the low tracks Northeast towards the area. This low will
track from southwest Louisiana up along the Natchez Trace Corridor
this evening through the overnight hours. As the low tracks north
this evening into the overnight hours, there will be a window of
opportunity for severe mainly south of the natchez trace corridor.
With 70kts of deep layer shear and around 400 j/kg of surface based
cape, there will continue to be a risk for severe, with the primary
concern for damaging winds. With the strong shear tornadoes cannot be
ruled out. With all of the rainfall the past couple of days there is
at least a limited potential of flash flooding. Will keep the limited
chance for severe and flooding going in the HWO, but will trim the
severe area.

The low will move northeast of the area Tuesday morning with a few
light showers possible in the northeast, ending by lunchtime. Cold
air advection will keep temperatures cool on Tuesday with high
temperatures generally in the 50s.

Tuesday night through Sunday night: Much colder temperatures still
look in store later in the week. A cold front will drop into the
Highway 82 corridor and stall Tuesday evening as our winds aloft back
to the southwest in response to a deepening trough over the western
CONUS. A few models try to develop light precipitation along the
stalled front Wednesday but, model consensus is dry. The deepening
upper level trough will send a second cold front into our CWA
Wednesday evening that will push south of our area before noon
Thursday. The ECMWF generates some qpf with this front but lack of
moisture return and convergence along the front will limit
precipitation development as model consensus is mostly dry. However,
have accounted for the ECMWF and gone above guidance pops to carry
mention of rain.

The main effect of this cold front will be to usher in much colder
and drier air. Highs will be held in the 40s at most locations
Thursday with a breezy north wind. The center of the cold airmass, a
1040mb high will become centered over the central plains by Friday
morning. This will bring us the coldest temperatures so far this
season with morning lows in the low to mid 20s. Normal lows run in
the upper 30s. The large surface high will shift east across our CWA
Friday becoming centered over the southern Appalachians by Saturday
morning. Some lows Saturday morning could dip into the upper teens
over North Central Mississippi.

The surface high will continue shifting east Saturday resulting in
return flow back across our region. Zonal flow aloft Saturday will
back slightly Sunday ahead of an approaching more subtle shortwave.
The GFS and ECMWF are is good agreement that rain chances will return
to the northwest half of our area Sunday ahead of a weak surface low
that will develop in response to the shortwave. /22/


Jackson       50  56  41  60 /  43  11   5  10
Meridian      54  57  42  60 /  70  12   3   9
Vicksburg     49  56  40  59 /  41   9   6  14
Hattiesburg   56  61  44  65 /  41   7   2   4
Natchez       50  57  44  62 /  32   6   5  10
Greenville    46  55  40  53 /  79  11   7  14
Greenwood     48  54  38  55 /  80  17   7  12





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