Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 301012
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
512 AM CDT Thu Mar 30 2017

...ADDITIONAL SEVERE WEATHER EXPECTED LATER TODAY...

.DISCUSSION...

Today through tonight,

The first round of severe weather is winding down early this
morning as a coastal MCS anchored by split upper level jet shifts
east and gradually weakens. While this scenario was expected to
happen, it took place sooner than anticipated and helped to limit
severe weather occurrences with the exception of a couple of
significant tree damage reports. In addition, a fairly strong and
long-lived wake low event associated with the decaying northern
end of the MCS has been observed over north central MS resulting
in extensive coverage of 40 to 50 mph wind gusts.

We will see somewhat of a lull in the convective activity through
the morning with continued departure/decay of the current MCS.
During the early to mid afternoon, cyclonic flow aloft and strong
deep layer shear ahead of an approaching cold front will help to
destabilize the airmass (H500-H700 lapse rates > 7.5 C/km, ML CAPE
> 1500 j/kg) sufficiently to break through the cap and initiate a
broken line of storms. Per most CAM guidance, this should happen
along the I-55 corridor to the north of the I-20 corridor by
around 300 PM. Storms will intensify as they move east across
central/eastern MS in the general vicinity of today`s enhanced
risk area from SPC. Overall, the time window for severe weather
potential is short and not expected to last much into the evening.
Primary threats will be for large hail and damaging wind gusts as
low level shear will not be all that favorable for tornadoes. /EC/

Friday through next Wednesday,

A quiet period of weather is expected across the forecast area
Friday into Saturday as high pressure builds into and through the
region. With no appreciable airmass change expected over the
forecast area behind Thursday night`s frontal passage, warm
conditions will persist as highs Friday range from the middle 70s
to middle 80s, and top out in the low to mid 80s Saturday
afternoon. With some slightly drier air over the region, lows
Friday night will range from the low to middle 50s. Then with
clouds increasing from the west late, lows will range from the
middle 50s to middle 60s Saturday night.

Another period of active weather looks to setup across the forecast
area Sunday into Monday as another storm system is poised to affect
the region.  A closed mid/upper low will swing east northeast from
the Southern Plains into the Mid-South Region and Tennessee River
Valley Sunday through Monday night.  This will cause a surface low
to develop over East Texas Sunday afternoon, which will lift
northeast near or across the forecast area through Monday afternoon.
Deep moisture increasing over the forecast area and plenty of lift
associated with a couple of pieces of energy traversing the region,
will result in increasing chances for showers and storms as early as
Sunday morning, and continuing off and on through at least Monday
afternoon.

While there are some model discrepancies concerning the exact track
of this surface low in regard to the forecast area, it still appears
that there will be a window of time Sunday into Monday that at least
a portion of the CWA will see the potential for some severe weather.
This is supported by adequate instability and steep mid-level lapse
rates over the CWA, increasing deep wind shear, favorable jet
dynamics, and again the aforementioned strong forcing over the
region.  Given some model uncertainties, primarily the surface low
track, I`ll maintain the ongoing "Slight Risk" per SPC along and
west of the Mississippi River in the HWO.

While this is still 4-5 days out, given overall current model
consensus, advertised jet positioning, and QPF signals over the
region, I wouldn`t be surprised to see this risk for severe storms
perhaps shifted further south and east, encompassing more of my
southern zones as we approach the Sunday/Monday period.  In
addition, due to the deeply moist airmass that`ll reside over the
CWA during this time, and multiple bouts of convection advertised to
traverse portions of the CWA, confidence continues to increase that
there will be some potential for heavy rain, that could result in
flooding, across portions of the region with this system.

Clouds and rain chances gradually exit the region Monday night into
Tuesday.  High pressure will again build into the region Tuesday.
However, as we move into Wednesday, another fast moving cold front
is advertised to bring more showers and storms to the region
Wednesday afternoon. /19/

&&

.AVIATION...
06Z TAF discussion:

Expecting a good deal of MVFR flight cats around the region
(mainly due to ceiling reductions) late tonight through tomorrow
morning. Flight category reductions associated with heavy rain and
thunderstorms will be most pronounced over the next several hours
at JAN and HKS. Tomorrow the thunderstorm impact will be more
questionable and likely more brief. Confidence in impact is
highest in the midday through afternoon hours around CBM/GTR where
there is a decent chance of severe weather and hail. Elsewhere
severe weather cannot be ruled out for tomorrow. Active weather
should be moving out of all areas by tomorrow evening. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       78  53  82  53 /  61  30   0   0
Meridian      78  52  81  50 /  55  55   0   0
Vicksburg     76  52  83  53 /  40   6   0   0
Hattiesburg   78  53  85  54 /  67  37   0   0
Natchez       76  54  82  56 /  48   6   0   0
Greenville    73  51  78  53 /  32   5   0   0
Greenwood     75  51  78  52 /  57  18   0   0

&&

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

&&


$$


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