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fxus64 kjan 161040 
afdjan

Area forecast discussion
National Weather Service Jackson MS
440 am CST Sat Dec 16 2017

Discussion...

Today through tonight:

A chilly polar airmass is entrenched over the arklamiss region as
of early this morning with temperatures falling well into the 20s
over most of the forecast area. This airmass will be slow to
modify this morning, but the slow moving cut-off low crossing
northern Mexico will eject quickly eastward toward our region as
a major upstream trough digs southward through the western Continental U.S..
the rapid approach of the low will cause rapid mass northward
transport of anomalously moist air for mid December (precipitable
water > 1.5 inches, ~3 sds) into the area. Expect showers and
perhaps a few elevated thunderstorms to develop rapidly and move
into western portions of the area prior to daybreak Sunday, but
not expecting too many run-off problems given the antecedent
drought conditions and progressive nature of initial activity.
This could be a different story looking down the Road. Otherwise,
expect a much milder Saturday night for most of the arklamiss
given the modifying airmass and increasing cloud cover. /Ec/

Sunday through the work week...

Confidence is increasing in a dynamic, wet pattern unfolding from
Sunday through next weekend as models come into better agreement.

Rain will continue to spread into the region on Sunday as a
deamplifying upper level shortwave trough embedded in SW flow
progresses over the area. Significant lift and Bountiful moisture,
by the way of pwats of 1.5"-1.8", will result in heavy rainfall at
times. However, as mentioned previously, both the progressive
nature of this system and recent dry conditions will help lessen
the flash flood threat. Even though the best instability will
remain offshore over the northern Gulf, sufficient bulk shear
magnitudes in the ranges of 45-50kts between 0-3km and 50-60kts
between 0-6km indicate that there could be some strong storms
mainly in the Pinebelt region on Sunday.

The upper level SW flow regime will remain intact through early
week while flow from the south in the mid to low levels will
continue to supply the region with ample moisture from the Gulf.
This will result in rain chances sticking around through Monday
and Tuesday. A deep cutoff low will begin to cross the Southern
Plains as the week progresses, approaching the lower MS valley
region by Wednesday. A very moist atmosphere will exist ahead of
this system as it brings some significant height falls to the
region. There are still some differences spatially and temporally
between the GFS and Euro, but our best chance for organized storms
during the week will exist as the aforementioned disturbance
traverses the region Tuesday night through Wednesday.

The sun may finally make an appearance later in the afternoon on
Wednesday or early Thursday as dry air finally filters into the
region behind this disturbance and some weak ridging builds into
the upper levels. However, this quiet period will be short lived
as rain chances begin to increase once again as the upper level
pattern transitions back to a SW flow regime in response to a deep
trough splitting off from the mean flow and diving towards the SW
US/Mexican border. /Jpm3/

&&

Aviation...
06z taf discussion:
VFR conditions will prevail through Saturday evening. Expect
lowering ceilings and increasing rain showers chances toward daybreak
Sunday in the glh/gwo/Jan/hks area. /Ec/

&&

Preliminary point temps/pops...
Jackson 60 44 66 55 / 2 45 84 34
Meridian 57 42 63 54 / 2 10 82 41
Vicksburg 60 44 66 52 / 2 79 83 20
Hattiesburg 57 43 70 60 / 2 11 83 45
Natchez 59 46 69 57 / 4 74 84 37
Greenville 59 43 62 48 / 1 90 79 15
Greenwood 60 41 62 48 / 1 76 84 18

&&

Jan watches/warnings/advisories...
MS...none.
La...none.

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