Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 211812 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1212 PM CST Tue Feb 21 2017

Updated for 18Z aviation discussion


18Z TAF discussion:
Numerous to widespread showers/VCSH are ongoing near most TAF
sites this afternoon. These showers will linger through today
before decreasing from west to east after 22/06Z. In addition,
low ceilings, some MVFR/IFR conditions, are going to linger
throughout the afternoon. There could be some increase in ceilings
this afternoon before widespread IFR low ceilings and
visibilities, with some patchy dense fog, are possible at most TAF
sites tonight, mainly after 22/06Z or so. Expect these conditions
to linger through early tomorrow morning before lifting around
22/15Z. Winds will be from the south-southwest today around
5-10mph before becoming light and variable tonight and more
north-northeast tomorrow. /DC/


Upper low is evident in water vapor imagery, situated over western
Louisiana. Out ahead of this system, the rain shield that has been
shifting off to the east and is mainly over eastern Mississippi
into Alabama. Expect these best rain chances to move off to the
east this morning. However, expect light drizzle to linger
through the early afternoon areawide before more showers may pop
up underneath the cold core as the upper low moves into northeast
Louisiana, west and southern Mississippi. We should warm some but
due to lingering cloud cover and cooling over 5+ deg C at 925mb,
per 12Z KJAN sounding, so we should only top out in the mid-upper
60s. Due to increasing lapse rates over the southwest, could not
rule out an isolated thunderstorm. However, shear will be very
light so not expecting any inclement weather. Expect this upper
low to shift southeast tonight with rain chances lessening as we
go into the evening. Will have to monitor for fog chances tonight
due to us drying out and recent rainfall but that will be
addressed later today.

Adjusted POPs/weather to adjust the trend in timing to move out
the heaviest rain in the east. Slightly adjusted highs and sky
cover. Rest of the forecast is out. /DC/

Prior discussion below:

Today through tonight,

An upper low in the process of closing off is centered roughly over
the ArkLaTex region early this morning and is pushing slowly east.
The leading edge of the rain shield has moved into western Alabama
and widespread light to moderate rain covers the forecast area.
While the bulk of the initial rain shield will continue to move east
of the area this morning, expect showers to regenerate later today
as the system cold core has more influence. Some thunder will be a
possibility given colder mid/upper level temperatures and increased
instability, but not expecting intense deep convection.

Otherwise, temperatures will be cooler today than in recent days
largely because of the clouds/rain. Rain chances will diminish
tonight as the closed low shifts southeast of the area. While
explicit guidance is not bullish with fog development tonight, the
moist boundary layer and wet ground will be supportive should winds
decrease enough and skies clear, so will need to monitor for fog
potential. /EC/

Wednesday through Monday night:

A anomalous warm pattern will be the general rule for the remainder
of the work week. This will be followed by a cooler pattern for the
weekend as temps dip toward normal levels. A warming trend will come
back to the region for early next week. Looking at some low end
chances of rain for mid week as well this weekend into Monday night.

On Wednesday the closed upper low will be tracking Southeast of the
ArkLaMiss into the eastern gulf. There will be some wrap around
isolated showers on Wednesday. Shortwave ridging will provide some
dry weather for Wednesday night into Thursday night. A weak upper
trough will track across the Central and Southern Plains on
Friday. It will push a cold front through the region on Friday
night. Precipitable water will be around one inch which will be
just enough to support isolated convective chances with limited
instability for Friday night. The airmass in the wake of the front
will push our temperatures a little closer to normal for this
time with precipitable water less than 0.50 inch. Cool high
pressure will build across the region on Saturday from the
Southern Plains. Gulf return flow will come back across the region
by Sunday night. Precipitable water will approach one inch as we
develop some isolated showers in the Delta region on Sunday
night. Low end rainfall chances will spread across the region on
Monday into Monday night. Gulf inflow will bring another anomalous
warming trend to the region for early next week.

Looking ahead, southwest flow aloft will keep an unsettled
weather pattern across the region through the remainder of next
week. /17/


Jackson       53  73  53  80 /  23  20   5   2
Meridian      55  74  53  80 /  40  23   7   2
Vicksburg     54  74  52  81 /  22  19   4   1
Hattiesburg   53  75  54  80 /  23  22   5   2
Natchez       55  72  53  80 /  26  19   4   2
Greenville    55  73  54  77 /  20  14   4   2
Greenwood     55  75  53  79 /  28  19   5   2





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