208
FXUS64 KJAN 030936
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
436 AM CDT Wed Jul 3 2024

...New DISCUSSION...

.DISCUSSION...
Issued at 435 AM CDT Wed Jul 3 2024

Today and Tonight:

Taking a look at regional METAR obs - or stepping out into the early
morning air - confirms that the warm tropical air mass has indeed
spread back north across our forecast area. Dew point values at this
hour range from about 72 in southeast AR/northwest MS to a balmy 78-
79 in southeast MS and central LA. Overnight showers are festering
at the Gulf Coast, and we expect coverage of showers and
thunderstorms to increase over more of our forecast area as the day
wears on. Before rain becomes too widespread, temperatures climbing
into the mid and upper 90s will combine with the humid air to
produce heat index values mostly near 110 up to 115-120. Confidence
was lowest in the Interstate 59 corridor where rain chances are
expected to start earliest in the day, so stuck with a Heat Advisory
in those areas. The remainder of the forecast has a greater chance
to hit the 110+ heat index values before rain moves in, so an
Excessive Heat Warning is in place through the evening.

High PWAT values of 2+ inches driven by increased lower level
humidity and dry air aloft associated with upper-level ridge over
the region will yield steep vertical Theta-E differences and
approximately 3000-4000 J/kg of SBCAPE. Flow aloft is very weak and
easterly, and the lack of shear will limit storm updraft
organization or longevity. Organized severe storms are not expected,
but there will be some threat for damaging wind gusts with any of
the stronger pulse thunderstorms that develop today. /NF/

Thursday through next Tuesday:

High pressure will continue to gradually slide east through the
region, where it`ll remain centered and overall remain in control
of our weather during the forecast period. At the surface, high
pressure will likewise slide further east of the CWA, wedging
itself into the region from the east. As this happens, copious
amounts of deep moisture will feed into the CWA through early next
week. This`ll maintain high humidity levels across the forecast
area. Not only that, it will also result in increasing chances for
showers and storms each afternoon. These better rain chances will
be further aided by a frontal boundary that will drop south into
the region Friday afternoon. Over the weekend and into early next
week, this boundary is advertised to stall and eventually washout
out over the forecast area.

As far as temperatures are concerned, dangerous heat stress will
continue across much of the forecast area Thursday into Friday.
Temperatures will warm into the low and middle 90s both days. This,
coupled with the aforementioned high humidity levels over the area,
will result in afternoon heat index values climbing above the
century mark across the CWA. This will especially be the case
Thursday, when indices will be more in the 106-115 range areawide.
As a result, a "Heat Advisory" and an "Excessive Heat Warning" have
now been hoisted for portions of the CWA for Thursday, i.e.
Independence Day.

As the frontal boundary sinks into the region Friday afternoon,
relief from the heat will come in the way of scattered to numerous
showers and storms over the CWA. This frontal boundary is again
forecast to stall and washout over the forecast area Saturday into
early next week.  With some slightly drier air filtering into mainly
far northern parts of the area over the weekend, and the better
coverage of convection over the CWA, relief from the oppressive heat
is expected to be more widespread across the area as highs range
from the upper 80s to middle 90s Saturday through Tuesday. However
with the boundary washing out early next week, deep moisture will
again engulf the entire forecast area ahead of another frontal
boundary that`s currently forecast to impede upon the forecast area
from the northwest Tuesday night. /19/

&&

.AVIATION...
(06Z TAFS)
Issued at 124 AM CDT Wed Jul 3 2024

There is some chance for BR and low stratus to produce MVFR
conditions near KHBG and KPIB before 12Z to 15Z today, but main
impacts to the TAF sites will be possible SHRA and TSRA generally
between about 19Z today to 01Z Thursday. Gusty and erratic winds
could occur near any storms, but otherwise expect south-
southeasterly winds around 5-10 kts through the period. /NF/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       96  77  93  77 /  60  10  50  10
Meridian      96  75  94  76 /  60  20  60  10
Vicksburg     97  78  94  78 /  40  10  30  10
Hattiesburg   95  78  94  77 /  90  20  70  10
Natchez       96  77  93  76 /  50  20  40  10
Greenville    99  79  96  78 /  20  10  20  10
Greenwood     98  78  94  78 /  30  10  30  10

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Excessive Heat Warning from 10 AM this morning to 8 PM CDT this
     evening for MSZ018-019-025>045-047>050-053>056-059>065-072.

     Excessive Heat Warning from 10 AM to 8 PM CDT Thursday for
     MSZ018-019-025>027-034>036-040>042-047-053.

     Heat Advisory from 10 AM to 8 PM CDT Thursday for MSZ028>033-
     037>039-043>046-048>052-054>066-072>074.

     Heat Advisory from 10 AM this morning to 8 PM CDT this evening
     for MSZ046-051-052-057-058-066-073-074.

LA...Excessive Heat Warning from 10 AM this morning to 8 PM CDT this
     evening for LAZ007>009-015-016-023>026.

     Excessive Heat Warning from 10 AM to 8 PM CDT Thursday for
     LAZ007>009-015-016-023>026.

AR...Excessive Heat Warning from 10 AM this morning to 8 PM CDT this
     evening for ARZ074-075.

     Excessive Heat Warning from 10 AM to 8 PM CDT Thursday for
     ARZ074-075.

&&

$$

06/19