


Area Forecast Discussion
Issued by NWS Little Rock, AR
Issued by NWS Little Rock, AR
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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