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960
FXUS64 KMEG 041148 AAA
AFDMEG

Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
648 AM CDT Thu Jul 4 2024

...New AVIATION...

.SYNOPSIS...
Issued at 305 AM CDT Thu Jul 4 2024

Hot and humid conditions will remain for your Fourth of July holiday
as heat index values climb greater than or equal to 110 across the
area. As a result of these dangerous heat indices, an Excessive
Heat Warning is in affect for the entire Mid-South today.
Dangerously hot conditions will suggest limiting outdoor
activities today. A few strong to severe storms may be capable of
producing damaging winds and localized heavy rainfall this
afternoon and into the overnight hours. A brief lull in
precipitation will exist Saturday and Sunday as high pressure
moves across the area. Rain chances will ramp up once again Monday
through through at least mid-week. As a result of increased
rainfall, temperatures will be a bit cooler Friday and into next
week.

&&

.DISCUSSION...
(Today through Wednesday) Issued at 305 AM CDT Thu Jul 4 2024

Another warm night is on display at this hour as current
temperatures are in the upper 70s to low 80s with mostly light winds
at the surface, under mostly clear skies areawide. We remain
fixed under a 596 dm subtropical ridge resulting to hot and humid
conditions across the entire Mid-South. Dewpoints remain on the
uncomfortably high end with current dewpoints in the upper 70s as
southerly winds continue to usher in moisture. This is not a good
sign for heat indices for our Fourth of July holiday activities.
Current forecast afternoon dewpoints will continue to increase
into the upper 70s to low 80s areawide. As a result, heat index
values >=110 F will be analyzed across our entire area today. An
Excessive Heat Warning is in affect for our the entire Mid-South
through 9 PM tonight. A weak cold front will push across the
region tomorrow morning, as the ridge builds south/southeast,
decreasing our daily highs into the upper 80s to low 90s through
mid-week.

The aforementioned heat and humidity will also provide ample
instability for convection today. Shower and thunderstorm chances
will continue to increase later this morning as a few short waves
continue to dampen the ridge over northeast Arkansas, the Missouri
Bootheel, and portions of northwestern Tennessee. As heights fall
this afternoon and into the evening hours, convection looks to ramp
up over areas mainly north of the I-40 corridor. A few multi-cell
clusters look to form and enter into an environment of around
2500-3000 J/kg of surface based CAPE and around 20-25 kts of 0-6
km Bulk wind shear ahead of the aforementioned cold front. PWATs
will also be around 2-2.25", nearing the 90th-97th percentile for
this time of year. Bottom line, a conditional chance for severe
weather exists this afternoon and through the early overnight
hours with primary threats of damaging winds and localized heavy
rainfall.

As the aforementioned cold front moves through Friday, PWATs
continue to soar upwards of 2.25 inches (nearing the 97th
percentile). Large rainfall rates will result in a localized heavy
rainfall threat for Friday. A brief lull in precipitation looks
to exist Saturday and Sunday as high pressure and quasi-zonal flow
looks to move over the region. Showers and thunderstorms will
head back into the forecast Monday morning as a positively tilted
trough axis looks to push in from the West with a possible
combination and lift from Hurricane Beryl. Though uncertainty
remains high on onset impacts, showers and thunderstorms remain in
the forecast through at least mid-week. Stay tuned.

AEH

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 648 AM CDT Thu Jul 4 2024

Convective inhibition will weaken through the afternoon. Weak
shear and outflow interactions limit confidence in TSRA timing and
location. Temporal overlap of modest midlevel height falls and
convective instability will likely support scattered TSRA between
21Z and 03Z, but isolated TSRA will be possible outside this time
frame.

A second TSRA episode is anticipated overnight with continuing
midlevel height falls, modest low level jet and approaching
surface cold front. Generally followed HRRR and TCF on TSRA timing
late tonight.

PWB
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&&

.MEG WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
AR...Excessive Heat Warning until 9 PM CDT this evening for ARZ009-
     018-026>028-035-036-048-049-058.

MO...Excessive Heat Warning until 9 PM CDT this evening for MOZ113-
     115.

MS...Excessive Heat Warning until 9 PM CDT this evening for MSZ001-
     007-008-010>012-020>024.

     Excessive Heat Warning until 9 PM CDT this evening for
     MSZ002>006-009-013>017.

TN...Excessive Heat Warning until 9 PM CDT this evening for
     TNZ001>004-019>022-048>055-088>092.
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&&

$$

PUBLIC FORECAST...AEH
AVIATION...PWB