984
FXUS64 KJAN 140030
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
730 PM CDT Sat Jul 13 2024

...New AVIATION...

.DISCUSSION...
Issued at 311 PM CDT Sat Jul 13 2024

Today through Next Saturday:

Looking at how today`s weather has trended, two features are worth
noting. First is the areas of convection over Southeast Texas and
southwestern Louisiana this afternoon. This activity is within a
plume of 2.0 inch PWAT air and beneath the right entrance region of
the jet stream associated with an upper-level trough in the region.
Increased lift and saturation in that area is generating a fair
amount of convection and spreading the cirrus blowoff clouds over
Northeast Louisiana. This has helped to shade the western half of
our area so far this afternoon and limit max temps by a few degrees.
Meanwhile, eastern Mississippi zones are sufficiently warming into
the mid and upper 90s as advertised. The other feature of note is
the sprawling surface high over the Southeast U.S. and the drier air
it is helping to mix down over northern portions of our area this
afternoon. Dew points even south of Interstate 20 have mixed out
into the lower 70s today. The resulting drier conditions have
limited expected heat index values today, with only the Pine Belt
retaining the peak heat and humidity for strict Heat Advisory
criteria. Areas through the I-20 corridor in Mississippi are still
near 105, so will keep current advisory in effect, but portions of
Northeast Louisiana and northwest Mississippi were removed from
today`s advisory. The NAM and GFS explicitly show some sort of mid-
level low or MCV feature evolving from the TX/LA convection this
evening and drifting northeast with the flow, and this seems like a
reasonable possibility given the jet dynamics and vorticity in the
base of the upper-level trough. Such a feature will continue at
least slight chance POPs into the evening, increase cloud cover for
tomorrow, and bring possible earlier start to rain chances tomorrow.
Either way, guidance pegs higher cloud cover and resulting lower
temps in the western zones again tomorrow. Have left the Heat
Advisory unchanged for tomorrow at this time, but current
projections have peak heat index values only near or exceeding 105
degrees in Southeast Mississippi. Will let the next forecast shift
evaluate trends into the evening.

The upper-level trough axis never truly clears out of the central
Gulf Coast region through the end of this week, so afternoon
convection and increased cloud cover will continue to challenge peak
heating potential. If convection should hold off any afternoon,
there is the potential for dangerous heat to be a concern . Will
continue to advertise the Elevated risk out through the middle of
this week. A shortwave rounding the base of the trough will usher a
cold front into the region around Thursday time frame, which should
limit any further heat potential and also will focus rain chances
again in our area. /NF/

&&

.AVIATION...
(00Z TAFS)
Issued at 730 PM CDT Sat Jul 13 2024

SCT-BKN cloud deck remains in VFR range but will persist the next
several hours. Slow-moving SHRA & TSRA remain possible south of
I-20, mainly near southeast TAF sites, PIB & HBG, through 14/02Z
Sunday. Some patchy fog/BR can`t be ruled out near PIB & psbl at
HBG just prior to daybreak 14/09-11Z Sunday. Low probs of light
SHRA & isolated TSRA are again psbl Sunday at central-southern
sites of JAN, HKS, MEI, HEZ, with more confidence of SHRA & TSRA
at HBG & PIB, mainly late Sunday aftn between 14/19-23Z. Light
westerly winds, less than 10mph, are expected through the next 24
hours. /DC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       76  95  75  95 /  10  50  30  60
Meridian      74  98  74  96 /  10  50  30  60
Vicksburg     75  94  75  95 /  20  40  20  40
Hattiesburg   76  97  76  95 /  40  70  20  70
Natchez       74  93  75  93 /  20  50  10  40
Greenville    76  94  75  95 /  10  30  10  20
Greenwood     76  96  75  95 /  10  30  10  30

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Heat Advisory from 10 AM to 7 PM CDT Sunday for MSZ040-041-
     047>049-053>057-059>066-072>074.

LA...Heat Advisory from 10 AM to 7 PM CDT Sunday for LAZ007>009-015-
     016-023>026.

AR...None.
&&

$$

NF/DC