820
FXUS64 KJAN 050707
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
207 AM CDT Fri Jul 5 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 949 PM CDT Thu Jul 4 2024

Local radars showed a few isolated showers over north central
Mississippi that were being maintained by outflow boundary
collisions. These showers will likely dissipate within the next
hour but unlike the last couple of nights, additional convection
will be possible prior to sunrise in the north as a weak cold
front approaches the area. Similar to the last couple of nights,
there were raincooled areas; mostly in the southeast where the
greatest coverage of convection occurred. Morning lows remain on
track though. /22/

&&

.DISCUSSION...
Issued at 240 PM CDT Thu Jul 4 2024

Tonight through Friday...

Ridge is expected to flatten through Friday. Longwave trough
analyzed this morning over the northern Plains is progged to swing
eastward across the Great Lakes. This will help drive a frontal
boundary southeastward into the Mid-South to Gulf Coast states
tonight & into Friday. Ongoing rain & storm chances should wind
down into the evening, which could alleviate concerns for any
upcoming outdoor activities. With clouds & deep tropical moisture
persisting, expect seasonably warm lows, some 5-7 deg F above
normal, in the mid-upper 70s. Another night of record warm lows
are possible at most climate sites along & north of the I-20
corridor. Rain chances will begin to encroach into the Hwy 82
corridor before daybreak Friday, into the I-20 corridor by mid-
morning Friday & areawide into Friday afternoon. With anomalously
high tropical moisture, near climatological maximum around 2.25
inches, there remains continued support that some of these
downpours could be heavy (i.e. HREF prob match mean (PMM) of 3" &
localized PMM of >3-4" maxima). For now, there isn`t enough
confidence to narrow down an area for HWO graphics but localized
flash flooding can`t be ruled out. Also with some northerly mean
bulk shear >10kts in the 0-2 to 0-3km layers, some strong to
isolated severe storms can`t be fully ruled out but not enough
confidence to add to the HWO. There are low probs in CSU machine
learning probs for marginally severe convection Friday.

Main concerns will be dangerous heat but that is much more
uncertain than previous days. With the boundary moving into the
Gulf Coast region, scattered to numerous rain & storms are
expected. Mixing will remain limited, keeping dewpoints in the
77-80 degree range. Convective initiation (CI) will be forced
early due to moist convergence along the boundary & moist
boundary layer. This will also keep cloud cover around longer &
initiate earlier. Highs will still remain seasonable in the low to
possibly mid 90s, with dangerous heat possible across the good
portion of the area. There are too many caveats to add any heat
headlines, but left the areawide "Elevated" in the HWO graphics
for dangerous heat as is. /DC/

Friday night into Saturday: As a front stalls across the area Friday
night, convection ongoing from the daytime may persist into the
early evening hours, especially over the southern half of the area,
then decrease overnight. The brief surge of drier air coming in from
the north will focus convective coverage on Saturday across the
southern half of the area, though much of it may actually remain
closer to the coast as hinted at by the most recent model runs.
Minor airmass relief is possible with the front, albeit with temps
still around climatological norms. Dewpoints may dip into the upper
60s over the northern half of the area, with temps mainly in the
lower 90s. Given this, heat indices could briefly peak near 105
across south MS, but there are currently no plans to advertise heat
stress concerns given the anticipated brevity of these readings, the
limited area impacted, and the relative improvement from recent days.

Sunday through next Thursday: An upper level pattern characterized
by longwave troughing over the central CONUS with southwesterly to
westerly upper flow over our area will persist into early next week.
With the trough remaining to the west, the surface front will
retreat northward allowing a moisture rich airmass to return across
the entire area on Sunday. This airmass will result in above average
rain chances each day through the remainder of the forecast period,
with timing primarily driven by instability and the diurnal cycle.
The good news is increased coverage of clouds and precip may spare
most areas from the prolific heat stress issues that have plagued
the region in recent weeks. Though dewpoints will recover into the
middle and upper 70s, temps will remain closer to seasonal averages
at most locations, resulting heat indices that are more marginal.

Guidance remains rather consistent on the future track of Hurricane
Beryl, with no direct impacts on our immediate area. However, it is
possible that remnant moisture from the system could serve to
enhance rain chances in the area around the middle of next week. The
extent to which that might be the case remains to be seen. /DL/

&&

.AVIATION...
(06Z TAFS)
Issued at 204 AM CDT Fri Jul 5 2024

Will be monitoring for IFR/LIFR category stratus development and a
few areas of IFR category br/fg in mainly southeast portions of
the area through early morning. Thereafter, attention will turn to
convective rainfall potential through much of Friday with emphasis
on the aftn, and have included a mention of shra/ts in TAFs given
considerable coverage expected with the approaching front. /EC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       74  90  73  91 /  60  40  10  50
Meridian      73  92  71  93 /  60  50  10  50
Vicksburg     73  91  73  90 /  40  30   0  40
Hattiesburg   76  93  75  94 /  60  70  10  70
Natchez       74  90  73  91 /  60  50  10  50
Greenville    73  91  72  92 /  20  10   0  20
Greenwood     73  91  72  93 /  20  10   0  20

&&

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

$$

22/DC/DL/EC