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ms discuss


Office: JAN

FXUS64 KJAN 131645 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1045 AM CST Wed Dec 13 2017

.UPDATE...
Updated for morning discussion.

&&

.DISCUSSION...
The synoptic pattern continues to consist of large scale trough
over the east coast while our area continues to be under northwest
flow aloft while westerly flow will begin to build into the
region. In addition, a shortwave trough & associated surface
low/attendant cold front will begin to shift winds more from the
west-southwesterly in the lower levels & at the surface. This
pattern is very similar to earlier this week where dewpoints were
low, moisture was anomalously low & winds helped us mix
efficiently. Due to this, continued to go towards mixing with
warmer guidance, which puts us in the low-mid 60s or so today. In
addition to this, as the cold front swings into the Great Lakes,
the pressure gradient will tighten across the area & help winds to
become gusty across most of the area. Winds will be strongest in
the 15-25mph range, especially in the Delta. Winds should remain
below wind advisory criteria in the Delta, so left out of the
HWO/graphics.

Fire danger continues to look to be the main issue today as we
should efficiently mix out & warm into the low 60s. With PWs are
only around a quarter of an inch or so & dewpoints just above the
surface are in the low teens, wouldn't be surprised to see mixing
a little more on the aggressive side into the upper 20s dewpoints.
Therefore, we should be able to reach near or just into critical
levels. Expanded the limited area for fire danger down, mainly
along & northwest of the Natchez Trace Corridor, other than some
expanding into eastern Mississippi. Also expanded the elevated
fire danger area into the ArkLaMiss Delta in the HWO/graphics. We
could reach right on the cusp of critical levels (humidities down
near 25% and gusty winds just around or above the surface around
15mph). For now, with it being the Delta, not a long time
exceeding & a small area, decided to not issue a red flag
warning. But this will have to be continue to be evaluated. /DC/

Prior discussion below:

Today and tonight:

The ArkLaMiss will start today out with chilly temperatures in the
upper 20s under clear skies. As a surface low tracks southeastward
over the Western Great Lakes today, a tight pressure gradient will
form over the ArkLaMiss. Winds will increase out of the southwest
going into this afternoon. Sustained wind speeds of 10-15 mph will
be common with gusts, particularly in the Delta, up to 20-25 mph
possible. This dry air mass in place over the region will continue
to foster an overachievement of afternoon mixing and aide in
maximizing afternoon temps. Temperatures will warm, for the most
part, into the 60s across the area today with higher values in the
west and values closer to 60 in east.

This dry air mass continues to foster the need to be fire aware
today. With gusty winds and low humidity values, the fire danger
threats remain in the HWO. A limited fire danger threat will be in
place over areas north and west of the Natchez Trace and an
elevated threat over our very far northwestern tier of counties
where winds will be greatest and relative humidity values bottom
out near 25% this afternoon.

Wind speeds will relax this evening and temperatures will fall
quickly into the 40s after sunset. Temps will then gradually
slip in to the mid 30s across the area. /10/

Thursday through Tuesday:

The pattern will change from a highly amplified to a more
progressive split flow pattern across the conus which will be more
influenced by pacific airmasses during the period. A dry cold front
will come through the region on Thursday before we get a weekend
front that will bring some rain for Saturday night into Sunday night
with better moisture return, while a second short wave will bring
some light rain for Monday night in this progressive pattern. For
Sunday there will be just enough limited instability for some
isolated embedded thunderstorms across the south half during the
day. For early next week the Euro model was a little faster with the
second short wave then the GFS. So opted to go with the faster
solution of the Euro in this pattern.  The GFS and Euro along with
its ensembles continue to show better qpf coverage.

As far as temperatures are concern daily highs will be in the 50s
and 60s. Nightly lows will be in the 20s and 30s before warming to
mainly the 40s over the weekend then 30s and 40s for Monday and
Tuesday./17/

&&

.AVIATION...
12Z TAF discussion:
VFR conditions expected to prevail at all sites throughout the
period. Southwesterly winds will increase going into this
afternoon and may become gusty at times. Sustained winds of 10-15
kts are expected at most sites with gusts up to 20-25 kts possible.
Winds will relax this evening. /10/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       62  36  61  34 /   0   0   1   3
Meridian      60  35  60  34 /   0   0   1   3
Vicksburg     66  35  59  33 /   0   0   1   3
Hattiesburg   60  35  62  38 /   0   0   1   7
Natchez       66  36  61  35 /   0   0   1   4
Greenville    64  35  53  30 /   0   0   1   3
Greenwood     65  34  54  30 /   0   0   1   3

&&

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

&&


$$

DC