Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 261544 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1044 AM CDT MON SEP 26 2016

.UPDATE...A large upper trough located across the midwest is pushing
a cold front across NW MS. An upper level low is also currently
located along the western FL panhandle. Moisture pooling ahead of the
front has resulted in PWATs around 1.5-2 inches across portions of
the Delta, however drier air rotating around the aforementioned upper
low is located across our eastern zones and into portions of AL. Area
radars have indicated some isolated shower activity across our far
NW counties/parishes this morning and this activity is expected to
remain scattered through the morning hours. Latest hi-res guidance
isn`t too excited about convection this afternoon as the best forcing
is located to our north. The best coverage for afternoon storms
actually appears to be in our SE closer to the upper level low.
However, isolated showers and storms can`t be ruled out area wide
this afternoon as the cold front pushes through. An isolated strong
storm can`t be ruled out with a few thousand Joules of SBCAPE across
the SE, however weak lapse rates combined with the best shear lagging
behind the front will limit any severe weather potential.

As for the forecast update, daytime highs were lowered in the Delta
where more extensive cloud cover was located along and behind the
front and raised temps in the SE based on persistence, efficient
mixing and warm boundary layer temps. Also adjusted PoPs to reflect
most recent radar trends and thinking. /TW/

&&

.AVIATION...A cold front dropping southeast through the region
during the course of today and tonight, will result in a mix of
MVFR/VFR flight categories at sites.  Degraded categories will be as
a result of low clouds and an occasional decrease in visibility from
convection on station.  Winds ahead of the front will be light and
variable.  However, behind the front, winds will become northerly
between 10-15 knots and gusting to around 20 knots at times. Winds
will remain northerly overnight, but they will subside a bit during
the evening hours. /19/

&&

.DISCUSSION... /issued 355 AM CDT MON SEP 26 2016/

SHORT TERM...

Today through Tuesday Night...

Latest satellite imagery showed a large upper trough moving into the
middle to upper Mississippi Valley region.  The was pushing a cold
front into the delta region from the northwest. Some flat upper
ridging was observed over the CWA. Models remain in agreement that
the front will push through most of the cwa and become stationary
across the southeast this evening. Upper ridging will shift to the
east as the upper trough pushes into the region. Hi-res guidance
shows isolated to scattered coverage of convection across the region
through this evening. Pwats will be from 1.5 to around 1.8 inches.
The best lift and jet dynamics will be well north of the region
through tonight. Midlevel lapse rates will be weak and the best
shear will be post frontal. This will limit severe storm potential
through this evening. As far as temps are concern expect the best
heating to be in the east and south where highs will be in the lower
to middle 90s, while lower 80s to around 90 will be elsewhere. As we
push into the evening hires and models shows the best coverage
across the east and southeast before diminishing after midnight.
Overnight temps will be a little cooler with lows from the upper 50s
north to the upper 60s south. As we move into Tuesday the upper
trough will expand southward over the region. This will be enough to
push the front south of the CWA by Tuesday evening. Models and hi-
res shows some isolated convection across the southeast for Tuesday
afternoon with pwats around 1.7 inches, which will diminish by
evening. Highs on Tuesday will be from the upper 70s northwest to
the middle 80s southeast. Cooler air will filter into the region for
Tuesday night with below temps. Lows will range from the lower 50s
to the lower 60s as some fall air finally arrives across the
region./17/

LONG TERM...

Wednesday through Sunday....

The ArkLaMiss will experience a more Fall-like weather pattern which
is more typical of late September/early October than what we`ve been
experiencing over the last few weeks. Long term models place an
upper level closed low south of the Great Lakes by mid week. This
system will continuously pull cool, dry continental air into the
region from Canada. Temperatures will rebound to the mid to upper 80s
on Wednesday after the passage of the first surface front. However, a
reinforcing cold front will move through the region early Thursday.
High temperatures Thursday through the weekend should only reach the low
80s with dewpoints mainly in the 50s. Dry air and clear skies at
night will lead to a significant diurnal curve throughout the
extended period. Lows will fall into the 50s for the first time since
May. Weak pressure gradient forcing will result in light winds
throughout the long term lessening the fire weather risk. Weak upper
ridging will begin to set up late in the weekend as the closed low
weakens and moves further east. /3/

AVIATION...There may be some fog/stratus development during the
early morning hours, particularly in rain areas. Stratus may be a
bigger concern in the GLH to GWO area this morning in association
with a frontal passage. Expect SHRA/TSRA development today ahead of
the front...which will provide brief periods of mvfr/ifr conditions.
/17/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       90  65  83  58 /  24  17   6   5
Meridian      96  66  85  57 /  31  32   7   5
Vicksburg     89  64  82  54 /  22  14   5   4
Hattiesburg   95  68  86  61 /  33  37  15  11
Natchez       88  64  83  57 /  26  18   8   6
Greenville    82  61  80  55 /  26  14   4   2
Greenwood     85  60  81  53 /  20  13   4   3

&&

.JAN Watches/Warnings/Advisories...
MS...None.
LA...None.
AR...None.
&&

$$

TW/19


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