066
FXUS64 KMEG 031552
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
1052 AM CDT Wed Jul 3 2024

...New UPDATE...

.UPDATE...
Issued at 1052 AM CDT Wed Jul 3 2024

High pressure continues to reign across the Mid-South with today`s high
temperatures in the mid to upper 90s. Return flow at the surface
has started to creep dewpoints into the mid-to-upper 70s as of 10
AM. Due to hot and moist conditions, an Excessive Heat Warning is
in effect for the entire Mid-South until 8 PM.

There is a chance of strong to severe thunderstorms tonight
across the extreme northern portion of our County Warning Area
(CWA). A weak shortwave trough will begin to impede on the ridge
later today, but the ridge may halt convective development. Latest
mesoanalysis depicts -100 J/kg of CIN and deterministic soundings
show plenty of dry air aloft (850mb and up). Precipitable Water
Values (PWs), however, are above normal for this time of year (~2"
or higher). The PWs being so high may aid in saturatation of the
column and bring heavy rainfall to the aformentioned areas. North
Mississippi may see a few isolated showers and thunderstorms as
moisture continues to surge from the Gulf of Mexico. Most likely
timing for any shower and thunderstorm activity would be this
afternoon into the evening hours. As daytime heating runs out,
this should help suppress storm development even further.

Previous forecast remains on track.

DNM

&&

.SYNOPSIS...
Issued at 427 AM CDT Wed Jul 3 2024

Hot and humid conditions will remain today and tomorrow as heat
index values climb greater than or equal to 105 across the area.
Excessive Heat Warnings will be in affect for much of the Mid-
South today and tomorrow. Dangerously hot conditions will suggest
limiting outdoor activities today and tomorrow. Rain chances
return to the forecast beginning this afternoon and extending
through early next week as several fronts push across the Mid-
South. As a result of increased rainfall, temperatures will be a
bit cooler Friday and into early next week.

&&

.DISCUSSION...
(Today through Tuesday)
Issued at 427 AM CDT Wed Jul 3 2024

A warm night is on display at this hour as current temperatures
are in the low 70s to upper 70s 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 have already begun soaring
into the low to mid 70s as southerly winds continue to usher in
moisture. This is not a good sign for heat indices today. Current
forecast afternoon dewpoints will continue to increase into the
mid 70s to low 80s areawide. As a result, heat index values >=110
F across our will be analyzed across the entire area. An Excessive
Heat Warning will go into affect at 10 AM today and remain
through 8 PM tonight.

Tomorrow will be another scorcher as afternoon highs will once again
climb into the mid to upper 90s. A few shortwaves look to begin
dampening the ridge slightly this evening and into tomorrow
resulting in temperatures being a degree or two lower than today.
Nonetheless, heat indices will once again soar >=110 F across
northeast Arkansas, the Missouri Bootheel, West Tennessee, and
northeast Mississippi. The rest of the area looks to be >=105 F.
Areas >=110 F will be under an Excessive Heat Warning, and the
rest of the Mid-South will be under a Heat Advisory for the Fourth
of July. A weak cold front will push across the region Friday
morning, as the ridge builds southeast, decreasing our daily highs
into the upper 80s to mid 90s through the early next week.

The aforementioned heat and humidity will also provide ample
instability for convection today and tomorrow. Diurnally driven
shower and thunderstorm chances begin to increase this afternoon as
a few shortwaves begin dampening the ridge over far northeast
Arkansas, the Missouri Bootheel, and portions of northwestern
Tennessee. Shower and thunderstorm chances begin to increase
farther on the Fourth as several shortwaves continue ejecting from
the west, dampening the ridge even more ahead of the
aforementioned front Friday. A conditional chance for severe
weather exists both today and tomorrow in the afternoon to early
evening hours over areas mainly north of the I-40 corridor. As
heights begin to fall and convection enters into these areas both
days, around 2500 J/kg of surface based CAPE, 20-25 kts of 0-6 km
bulk shear, and PWATs values upwards of 2" (nearing the 90th
percentile) will be present. Though severe chances remain on the
lower end both days, multi-cell clusters may be capable of
producing damaging winds and localized heavy rainfall.

As the aforementioned cold front moves through Friday and into
Friday evening, PWATs 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 rain chances
looks to exist Saturday afternoon through Sunday morning as high
pressure and quasi-zonal flow looks to move over the region.
Showers and thunderstorms will head back into the forecast Sunday
afternoon 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 early next week.
Stay tuned.

AEH

&&

.AVIATION...
(12Z TAFS)
Issued at 641 AM CDT Wed Jul 3 2024

No significant aviation weather impacts today, other than heat,
humidity and high density altitudes. Main TSRA corridor should
reside north of JBR after 21Z, while and upper ridge holds strong
to the south.

The upper ridge will weaken slightly on Thursday, with isolated
TSRA expected in the afternoon.

PWB

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Excessive Heat Warning until 8 PM CDT this evening for ARZ009-
     018-026>028-035-036-048-049-058.

     Excessive Heat Warning from 9 PM this evening to 9 PM CDT
     Thursday for ARZ009-018-026>028-035-036-048-049-058.

MO...Excessive Heat Warning until 8 PM CDT this evening for MOZ113-
     115.

     Excessive Heat Warning from 9 PM this evening to 9 PM CDT
     Thursday for MOZ113-115.

MS...Excessive Heat Warning until 8 PM CDT this evening for
     MSZ001>017-020>024.

     Excessive Heat Warning from 9 PM this evening to 9 PM CDT
     Thursday for MSZ001-007-008-010>012-020.

     Heat Advisory from 9 PM this evening to 9 PM CDT Thursday for
     MSZ002>006-009-013>017-021>024.

TN...Excessive Heat Warning until 8 PM CDT this evening for
     TNZ001>004-019>022-048>055-088>092.

     Excessive Heat Warning from 9 PM this evening to 9 PM CDT
     Thursday for TNZ001>004-019>022-048>055-088>092.

&&

$$

PUBLIC FORECAST...AEH
AVIATION...PWB