965
FXUS64 KLZK 081928
AFDLZK

Area Forecast Discussion
National Weather Service Little Rock AR
228 PM CDT Tue Jul 8 2025

...New KEY MESSAGES, DISCUSSION...

.KEY MESSAGES...
Issued at 1254 PM CDT Tue Jul 8 2025

+ Rain shower and thunderstorm chances and coverage look as though
they will be at their maximum this afternoon and evening across
Arkansas when compared to other days in this 7 day forecast.

+ Fairly common July heat and humidity will remain in place over
the next several days. Today is probably the coolest day in the
forecast given all the cloud cover, but highs will routinely be in
the low to mid 90s and dew points in the lower 70s resulting in
daily max heat index values of 100 to 105 degrees. Hot and humid
yes, but not unusually so.

+ Daily afternoon/early evening thunderstorm chances remain in the
forecast each day, however the coverage is expected to fall back
to pop up/isolated hit and miss type of activity with most areas
missing out on the daily showers and storms.

Cavanaugh

&&

.DISCUSSION...
Issued at 1254 PM CDT Tue Jul 8 2025

Early afternoon water vapor satellite imagery showed the large
scale atmospheric flow over the southeastern United States is more
or less converging over Arkansas early this afternoon. This is due
to weak trough over the central plains moving our way combined
with a Tropical Upper Tropospheric Trough (TUTT) over the western
Gulf sending large scale motions from the Gulf towards Arkansas.
This large scale convergence has led to near record levels of
atmospheric moisture measured by the Little Rock morning weather
balloon, and satellite and mesoscale sounding analyses. Regional
radar imagery shows a distinct cyclonic circulation over northwest
Arkansas consistent with a mesoscale convective vortex (MCV) that
resulted from the extensive latent heat release from thunderstorms
that produced extremely heavy rain over parts of east central
Oklahoma that led to flash flooding primarily around the Sallisaw
area. This MCV, now that it exists, could set the stage for new,
focused thunderstorm activity that could produce heavy rainfall
and flooding across Arkansas for the remainder of the day today.

For more information for what an MCV is and how it works, please
read the passage below. If you`re not interested, skip to
Wednesday`s forecast discussion below it.

An MCV is the atmosphere`s response to prolonged intense,
often slow moving thunderstorm activity. A thunderstorms who
purpose for existing is to remove an imbalance in the atmosphere.
The primary source of imbalance is usually too much hot and humid
air near the ground and too much cool or cold air aloft. In order
to get rid of the imbalance, the atmosphere literally moves the
warm air up and cold air down. In our atmosphere this is done most
efficiently by exchanging heat stored in water. Thunderstorms take
the hot water vapor and lift and cool it and as the water vapor
rises and cools it eventually cools to saturation. When the water
vapor turns back into water droplets all of the heat that
initially caused the water to become a vapor in the first place is
released into the atmosphere aloft. Of course as rain falls to the
ground it drags down cooler air from aloft to the ground, but for
the MCV, it`s inception is due to the release of heat aloft.

This release of heat aloft is the atmosphere doing its job,
converting heat near the ground to heat thousands of feet above
the ground. As the heat builds up thousands of feet aloft, it
eventually reaches a critical point. Too much heat release aloft
creates a new imbalance, but this time in terms of pressure. Hot
air is less dense than warm air so if you get too much heat
released aloft, the pressure drops. This creates a low pressure
system aloft. If that low pressure imbalance becomes strong enough
it starts to spin and draw air into itself in an effort to once
again remove this new imbalance. This basic process describes how
hurricanes form and are maintained, but on a smaller scale this
is why MCVs develop in areas of persistent thunderstorm activity.
The development of the MCV is important because once it exists, it
tends to cause new thunderstorms to develop all around it by
drawing in heat and humidity from many miles away into its center
to fill in the area of low pressure aloft. The presence of an MCV
in northwest Arkansas from this morning`s storms could set the
stage for more focused thunderstorm activity this afternoon as the
MCV moves away from rain cooled air in northwest Arkansas towards
the warm and humid environment across the rest of the state.

With near record values of deep moisture measured over the state
and an MCV moving into a warm and humid airmass this afternoon,
one of our primary concerns is going to be new areas of focused
heavy rainfall that could lead to flooding across Arkansas from
late this afternoon through this evening. Of course thunderstorms
that develop during the peak heating hours of the day will tend to
become very tall because the atmosphere is so warm this time of
year. With little wind shear in place to help keep the updraft and
downdraft of storms separated it`s very likely that some of these
tall storms will cause themselves to collapse as each individual
storm`s rainfall can knock the flow of warm and humid air out of
the way. When this happens the storm collapses all at once sending
wind down to the ground as a microburst. As a result, microbursts
and localized flash flooding are things we`ll have to watch
closely across Arkansas through tonight. While neither threat is
expected to become widespread, today is the day where we are
expecting the highest amount of storms across the state, so folks
should keep an eye on the weather if they have outdoor plans
today. The remainder of the forecast calls for less storms each
day in this forecast.

Wednesday through Friday...

The trough that is helping put the squeeze on Arkansas today is
expected to move over the state on Wednesday. While we may not
notice much of a difference at the surface in terms of changes in
heat and humidity, several thousand feet aloft, this trough will
be dragging some drier air in over the state from the north
towards the south. On Wednesday this will make afternoon
thunderstorm activity most numerous over the southern part of the
state and less likely over the north. Storms are still technically
possible all over the state because the trough isn`t really strong
enough to suppress anything, but with the dry air aloft over the
north, those thunderstorm attempts during the peak heating hours
of the day are more likely to fail. At any rate, Wednesday
afternoon, we`ll still see some storms, but the coverage is
expected to be much lower than today, even across southern
Arkansas.

By Thursday this weak trough will have sent its dry air aloft over
the entire state of Arkansas. This dry air is expected to remain
in place aloft, it certainly won`t feel any drier on the ground,
and we should see a greatly diminished coverage of afternoon
showers and storms Thursday and Friday afternoon`s as a result.
Because it`s still hot and humid on the ground, isolated storms
will remain possible each afternoon with microbursts and locally
heavy rainfall posing the primary hazards. Most people are
expected to miss the shower and thunderstorm activity by the end
of the week. With dry air aloft, that does mean less cloud cover
overall which will translate to slightly warmer temperatures.
Expect temperatures to climb slowly, a degree or two each day as
we move through the end of the work week.

For the upcoming weekend...

Another trough is expected to move over the northern and central
plains, sending some weak forcing for ascent and possibly a weak
frontal boundary down across the state beginning on Saturday. On
Saturday this will likely lead to a slight uptick in afternoon
thunderstorm coverage, especially across the northern portions of
the state. On Sunday, assuming a weak frontal boundary made it
into Arkansas on Saturday, thunderstorm activity along that weak
front may send the front farther south into Arkansas for
redeveloping storms on Sunday. It`s hard to say for sure where the
highest concentration of storms will be on Sunday as it depends on
where thunderstorms on Saturday send a weak frontal boundary
Saturday night into Sunday. Suffice to say we`ll have an uptick in
thunderstorm coverage, but it will be important to check forecast
updates to see where we can refine the area most likely to see
storms in later forecasts. The hazards/threats are essentially the
same as what we are seeing this work week - microbursts and
locally heavy rainfall and potentially flooding.

As we get into early next week it looks as through a slow moving
trough will set up over the southern plains, once again promoting
a very deep tropical airmass over Arkansas. At the very least
we`ll see a continuation of afternoon showers and storms driven by
the peak heating hours of the day, but we could once again see an
uptick in thunderstorm coverage if the trough focuses activity
over the state. For now the forecast calls for slightly higher
precipitation chances than what you would expect from peak heating
alone driving thunderstorm activity. It`s the most likely scenario
to pan out given the uncertainties this far out in the forecast.

Cavanaugh

&&

.PRELIMINARY POINT TEMPS/POPS...
Batesville AR     71  89  71  92 /  20  40  10  40
Camden AR         72  88  71  92 /  40  70  20  50
Harrison AR       68  88  69  90 /  10  30  10  20
Hot Springs AR    71  88  71  93 /  40  50  10  40
Little Rock   AR  73  88  74  92 /  30  50  10  40
Monticello AR     73  87  73  91 /  40  70  20  60
Mount Ida AR      70  88  71  92 /  30  50  10  30
Mountain Home AR  69  88  70  90 /  10  30  10  30
Newport AR        72  90  74  92 /  20  40  10  40
Pine Bluff AR     72  87  72  92 /  40  60  20  50
Russellville AR   71  90  72  93 /  20  40  10  20
Searcy AR         71  89  71  92 /  30  40  10  40
Stuttgart AR      74  87  74  92 /  40  50  20  40

&&

.LZK WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...LONG TERM...AVIATION...Cavanaugh