Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 221033
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
533 AM CDT Sun Apr 22 2018

.UPDATE...
Updated for 12Z aviation discussion

&&

.AVIATION...
12Z TAF discussion:
MVFR ceilings have moved into the area along with showers. Some
IFR ceilings have also moved in. These lowered ceilings will
continue through the morning into the afternoon as a swath of rain
moves east and should affect all TAF sites. Additional showers and
some thunderstorms will be possible this afternoon ahead of the
cold front that will move through. Some storms could be severe
with gusty winds. The bulk of the rain should move out of the area
by 00Z. A brief return to VFR ceilings may be possible this
afternoon or early evening before a return to MVFR/IFR ceilings
tonight. Some lowered vis will also be possible, especially in the
heavier rain bands through the day. Today is not looking like a
good day to fly. /28/

&&

.DISCUSSION...
Today and tonight:

The main concern in the short term is the rain and storms today and
potential for severe storms. A swath of showers and embedded
thunderstorms are slowly making their way east overnight. This comes
as a large cutoff low spins across the Southern Plains. Through
today, this low will slowly move east. As this occurs, a surface low
will develop across portions of southeast Arkansas. Ahead of this
low, moisture will continue to move into the region. Showers and
storms will develop and move across the area through the day. The
greatest potential for any severe storms should be generally along
and east of the Mississippi River, but especially across portions of
east central Mississippi. This will be the case as some
destabilization could occur later this morning into the afternoon
hours especially along the actual cold front. Hi-res model guidance
shows less in the way of storms across northern portions of the
forecast area due to potentially being more stable from earlier
convection, but if there can be enough of a lull and/or breaks to
allow for some heating, there could be a severe storm along the
front. Thus, will leave this area in the marginal risk. The primary
risks with these storms today will be from damaging winds, but a
tornado cannot be completely ruled out, particularly across east
central Mississippi. Hail seems less likely of all the weather
hazards as lapse rates are not overly impressive. Will also keep the
mention of heavy rain and localized flooding, though this seems like
a lesser risk as well.

The rain and storms should mostly be out of the forecast area by
this evening, though some wraparound moisture may bring a few light
showers to the northeast/Golden Triangle this evening. The upper low
will be very slow to move out of the region, with it lingering
across the Mid-South as we head into Monday morning. /28/

Tomorrow (Monday) through next Saturday:

In the wake of the cold front moving through, expect west-
northwesterly cold air advection to keep lingering moisture and
widespread clouds locked in by the start of the work week. With the
center of the cold core upper low moving right over the mid-South,
expect these conditions to remain locked in throughout the day.
These widespread light rain and drizzle chances will keep most of
the area much cooler to start the work week, some areas around 10
degrees below average (mid-upper 60s in the north to low 70s in the
south). Expect the coolest temperatures Monday along and north of
the I-20 corridor & some areas could reach the top 5 coolest high
temperatures for Monday. If coverage and intensity of light rain
is more than anticipated, this setup could easily struggle to
reach these anticipated highs. In addition, lows will be slightly
warmer due lingering clouds. Expect ridging to slowly build along
the Atlantic seaboard Tuesday, keeping the cold core upper low
slow to depart the area. This will keep boundary layer moisture
and light rain and drizzle chances lingering into the Golden
Triangle by Tuesday, with highs slightly below normal.

As the upper low builds to the east, finally you can expect a brief
drying period as weak shortwave ridging builds in. However, this
will be only temporary and maybe not even last into mid-week
(Wednesday) as another trough & clipper dives down through the
Great Lakes. Model consensus continues to struggle with the
phasing of this trough and one also diving through the Plains. The
GFS is the most phased and faster to move rain chances in
Wednesday while the Euro/Canadian are less phased and more focused
on Thursday. Decided to lower PoPs Wednesday but kept lower end
light rain chances through Thursday. Timing consensus will be
ironed out in the coming days.

As the trough and rain chances depart, expect another brief dry
period around Friday morning. However, another clipper system
(trough) will be diving down again through the Great Lakes. This
will help another weak cold front and light rain chances to move
back in around late week-early weekend. Consensus of global models
continues to struggle as models seem to have somewhat different
picture on trough amplification. Regardless, expect another round of
light rain chances and maybe some thunder in the west on Friday-
Saturday, with most rain chances moving out by next weekend.
Thankfully, none of these fronts and systems look really concerning.
After that, expect strong surface ridging and drier air to build
in, helping cooler than normal temperatures to move back in by
next weekend. /DC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       75  54  68  53 /  99  18  18  14
Meridian      75  54  70  53 / 100  40  16  14
Vicksburg     75  54  69  54 /  81   6  14  14
Hattiesburg   76  55  73  54 / 100  18   6   9
Natchez       76  53  71  53 /  86   5   8   8
Greenville    73  55  67  53 /  75  23  38  16
Greenwood     72  55  66  53 /  88  26  42  23

&&

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

&&


$$

28



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