Area Forecast Discussion
Issued by NWS Jackson, MS

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379
FXUS64 KJAN 272034
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
334 PM CDT Sat May 27 2017

.DISCUSSION...

Today through tomorrow...

A warm and humid afternoon is underway throughout the region.
Temperatures were mainly relegated to the mid 80`s throughout the
region until cloud cover being to decrease over the last two hours
allowing for us to warm to near and above 90 in a few locations.
Temps near 90, coupled with dewpoints in the lower to mid 70`s
have combined to result in heat indices around 100 degrees.
Expect these near 100 heat indices to stick around for the next
few hours before we begin to lose diurnal heating.

Several short term/high res models depict a complex of
thunderstorms associated with the ongoing convection over the
Plains, moving through the Mid-South this evening and approaching
our region tonight from the north some time near or slightly after
midnight. Some of these storms could be severe by the time they
reach the northern border of the JAN CWA, prompting the current
SPC Day one slight risk for a few of our counties tonight. This
cluster of storms will succumb to a capped environment as the
move further south into our region.

Temperatures will approach the 90`s again on Sunday. Severe
storms will be possible once again on Sunday afternoon through
Sunday night, this time for a greater portion of our region, as a
cold front nears the region, providing enough lift to finally
break the cap. A very unstable prefrontal airmass will exist ahead
of the front over the region with SBCAPE values in excess of 3000
j/kg and 0-6km lapse rates nearing 7 C/km. This threat of severe
weather prompted the inclusion of a great deal of our area in the
slight risk zone for day 2. The greatest threat for any severe
storms tonight or tomorrow will be damaging straight line winds
and large hail. /3/

Sunday night through Friday...

On Sunday night we will have an upper trough centered with a
closed low over South Central Canada which will extend down to the
Lower Mississippi Valley. A series of short waves in the southern
stream will keep our rain chances going through the upcoming work
week with pwats pushing toward 2 inches. There will be a risk of
some severe storms for Sunday night into Monday as well as
possibly at times during the work week. The primary risk will be
half dollar size hail,locally heavy rainfall, and damaging winds.
A cold front will be approaching the region from the northwest.
Rain chances will spread across the region on Sunday night as the
front enters the region by early Monday. Cam guidance shows an MCS
moving across the region during the overnight hours from west to
east. Latest 12z models shows that the best instability (MLCapes
2500+ j/kg) and deep layer shear of 40-50 knots. Cam guidance
shows another MCS moving across the region during the
afternoon,which will move along the boundary laid out by the first
MCS. The front will exit the region by early Tuesday, but will
wash out as a more humid airmass rebuilds over the region on
Tuesday night into Wednesday. Another front will move into the
region and become stationary across the north on Thursday into
Friday. The upper trough axis will move off to the east on
Thursday into Friday. A southern stream shortwave trough will
approach the region from the Southern Plains. This will send
additional rounds of rain chances for Friday into Friday night.
Models and ensembles had difference ideals on the evolution of
this system for the end of the work week. However all the models
and their ensembles show a wet work week is in store for the
ArkLaMiss as a series of shortwave bucked by the 591 dkm gulf
ridge will continue our rain chances during the work week.

Looking ahead our rain chances will continue into the weekend as the
short wave trough moves into the region./17/

&&

.AVIATION...
18Z TAF discussion:
MVFR conditions will remain possible throughout the day at each of
the region`s TAF site due to low CIGs. CIGs will improve for a few
hours at some sites after 00z but will fall again to MVFR/IFR
levels overnight. A weakening line of TSRA will begin to approach
the northern most sites tomorrow morning before falling apart.
Patchy fog may reduce VISIBILITIES at KHBG tomorrow morning also.

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       72  89  70  82 /  15  20  54  67
Meridian      72  89  70  83 /  12  17  46  64
Vicksburg     73  88  71  82 /  20  24  62  60
Hattiesburg   71  89  72  84 /   9  16  30  66
Natchez       73  88  71  80 /  13  21  49  66
Greenville    72  86  70  82 /  54  43  64  48
Greenwood     73  86  69  81 /  52  42  64  57

&&

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

&&


$$

JPM3/17



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