Area Forecast Discussion
Issued by NWS Jackson, MS

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000
FXUS64 KJAN 142339
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
539 PM CST Thu Dec 14 2017

.UPDATE...
Updated for 00Z aviation discussion

&&

.AVIATION...
00Z TAF discussion:
VFR conditions are expected for the next 24 hours. Winds will
remain out of the north around 5 kts and no aviation concerns
expected. /28/

&&

.DISCUSSION...
Tonight and Friday:

Continued cooler than normal and dry through the short term.
Afternoon surface analysis had a weak cold front drifting into the
central portions of the CWA. This cold front was losing its
momentum as it has become nearly parallel to the upper level
winds. The cold front is still expected to push southeast of our
area this evening as a surface high centered over the Central
Plains this afternoon shifts east through Friday. This will result
in shallow cool air beneath mid level flow that will back a
little further to the southwest tonight. Satellite imagery showed
mid and high level clouds streaming across the southern half of
our CWA this afternoon. Models suggest our CWA will remain in the
favorable quad of a jet streak that will strengthen to >150kts by
Friday morning. Although no precipitation is expected in our CWA
the cloud cover will continue through Friday and limit insolation.
This will hold afternoon highs in the 50s again. Friday morning
lows will be cooler than normal as well with lows in the 30s
areawide. /22/

Friday night through Wednesday:

As we go into the weekend, expect a chaotic upper pattern as a
longwave polar trough will be moving through the Great Lakes while
two distinct closed shortwaves will be diving into the Great Basin
to over western Mexico. This will only help slowly increase
moisture & clouds as we go into the weekend. By Friday night, the
mid-level ridge axis will be slowly moving towards the area while
PWs will only be around a quarter of an inch or so. The surface
ridge axis will be centered off along the Atlantic seaboard. This
will help south-southwesterly return flow to slowly develop &
moisture will only be slowly moving in by that timeframe. Thus
expect a cold and chilly night (~5-10 degrees below normal) near
freezing to just below in the northeast. As the the shortwave
trough swings into southern Texas on Saturday, the ridge axis will
move directly over the area and expect near normal highs warming
into mid-upper 50s. As isentropic lift slowly increases, mid-high
clouds will increase in coverage.

By late weekend on Sunday, expect the ridge axis to shift east &
southerly return flow to bring back in better moisture into the
area. This will help a cold front with decent low-mid level wind
flow to propagate through the area. PWs will increase to around an
inch and a half to inch and three quarters. Right now it looks as
though most destabilization will remain off to our south & the
surface low development looks to move through most of the central
portions of the area. With around 30-40kts 0-3km bulk shear, can`t
rule out a couple stronger storms in the south but overall
organized convection is not expected. This looks to bring enough
moisture & moisture transport into the area to bring some
potential for some heavy downpours, possibly upwards of an inch or
so. This will help make some of a dent in rainfall deficits
across the area.

Expect this shortwave trough to swing through by Sunday night.
However, this persistent southwest flow pattern will continue
through most of next week. This will help moisture & rain chances
to linger through the work week. The main difference looks to be
around mid- late week as the Euro is less phased, which keeps the
rainfall chances lingering through the period. This airmass will
also keep clouds & cooler temperatures but with increasing thermal
profiles, can`t rule out temperatures reaching the mid-upper 60s
or so (~8-10 degrees above normal). Went slightly cooler for highs
around early portions of the week but due to increasing warm air
advection, still could warm efficiently. Also lows seemed too cool
as there is significant spread in the ensembles/guidance on
phasing of the trough & timing of the cold front moving through.
Due to that, trimmed lows around 3 degrees or so towards the MOS
ensemble means but would not be surprised for this to slowly
increase due to moisture, rain & clouds around. By Wednesday, if
the pattern is less phased (which this package was leaning towards
with the Euro), we could have some showers mainly along & south
of I-20 on Wednesday. /DC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       34  51  31  58 /   0   3   0   2
Meridian      34  50  30  56 /   0   3   0   2
Vicksburg     34  52  31  59 /   0   3   0   2
Hattiesburg   37  54  31  57 /   4   6   0   2
Natchez       34  51  31  59 /   2   4   0   4
Greenville    32  50  31  57 /   0   2   0   1
Greenwood     31  50  31  57 /   0   2   0   1

&&

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

&&


$$

28



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