864
FXUS64 KJAN 131421 AAB
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
921 AM CDT Sun Jul 13 2025

...New MESOSCALE UPDATE...

.MESOSCALE UPDATE...
Issued at 919 AM CDT Sun Jul 13 2025

Rest of Today...High pressure aloft, currently centered to the
southeast of the forecast area, continues to slowly strengthen
across the Lower Mississippi River Valley today as it builds
northwest into the region.  Although some slightly drier air aloft
has made its way into the region, noted by the 1.88 inch
precipitable H2O value on the 12Z KJAN RAOB, hot humid conditions
will persist across the forecast area today.  Highs will warm into
the low and middle 90s, with afternoon heat index values approaching
105F. This will again lead to a "Limited" threat for heat stress
across the entire area this afternoon.

Diurnally driven scattered showers and storms will also be possible
through the evening hours.  Along with the unstable airmass during
peak heating of the afternoon, some slightly better flow aloft also
exists across western portions of the CWA.  As a result, a "Marginal
Risk" for isolated severe storms will be possible across areas
mainly along and west of the Mississippi River.  There, damaging
wind gusts to 60 mph will be the primary concern with storms, but
hail to the size of quarters is also possible.  Elsewhere, gusty
winds will be possible with the most intense storms.  Frequent
lighting strikes and heavy downpours will accompany all of today`s
convection.

The ongoing forecast is in good shape.  Other than some tweaks to
hourly elements of the forecast based on current trends, no major
changes will be made on this morning`s update. /19/

&&

.DISCUSSION...
Issued at 1157 PM CDT Sat Jul 12 2025

Sunday through Sunday night: An upper level trough over the central
and southern Plains will try to shift east into our region but high
pressure at the surface and aloft to our southeast will
strengthen over our CWA through the day. This will lead to more
isolated to scattered coverage of mainly afternoon and early
evening convection and a gradual warming trend. The 00Z SUN JAN
sounding showed a PWAT of 2.03in. Thus, a moist airmass across
our CWA will be maintained through Sunday night. With the lower
rain chances and warmer temperatures topping out in the low to mid
90s, heat stress concerns will increase in our west along the
Mississippi river especially. Peak heat index values will be
around 105F again Sunday. We will continue to highlight this area
with a "Limited" for heat stress in our graphics for now. /22/

Monday through Friday:

As we head into the new work week, model consensus from both the GFS
and the Euro show the surface high starting to gradually
retrograde across the southeast CONUS. As this high begins to push
north into the region, humid conditions will persist across our
CWA, which in turn will lead to increasing heat conditions through
the extended period. Looking at current forecast trends, it
appears that heat indices will be in the 105-110 range next
Tuesday through Friday given daytime highs forecasted in the
mid/upper 90s along with dewpoints in the mid to upper 70s (a few
spots could potentially see dewpoints in the low 80s). This will
likely result in the "Limited" risk for heat stress being upgraded
to an "Elevated" risk in our HWO graphics for the Tuesday-Friday
timeframe. It is possible that a "Significant" risk may be
introduced in subsequent updates. Furthermore, heat
advisories/warnings will eventually be needed. Afternoon/early
evening showers and t-storms will provide some relief from the
heat Global guidance shows convection dissipating by the evening
hours each day as daytime heating wanes. /CR/

&&

.AVIATION...
(12Z TAFS)
Issued at 633 AM CDT Sun Jul 13 2025

A few patchy areas of IFR category BR/FG are a threat early this
morning. This should dissipated shortly with focus then shifting
to potential impacts from isolated diurnally driven TSRA.
Otherwise, VFR conditions and light south-southwest surface wind
should prevail through the forecast period. /EC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       95  74  94  75 /  30  20  40   0
Meridian      94  73  95  74 /  40  20  30   0
Vicksburg     94  75  94  75 /  30  20  30   0
Hattiesburg   96  75  97  75 /  50  20  40   0
Natchez       92  73  94  74 /  60  20  40   0
Greenville    93  74  93  74 /  20  20  40   0
Greenwood     94  74  94  75 /  20  20  40   0

&&

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

$$

19