Area Forecast Discussion
Issued by NWS Little Rock, AR
Issued by NWS Little Rock, AR
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881 FXUS64 KLZK 302347 AFDLZK Area Forecast Discussion National Weather Service Little Rock AR 647 PM CDT Sun Jun 30 2024 ...New SHORT TERM, LONG TERM, AVIATION... .SHORT TERM... (Tonight through Tuesday) Issued at 629 PM CDT Sun Jun 30 2024 Widespread convection Sunday afternoon and early this evening along with abundant cloud cover has resulted in heat index values that are well blow criteria for any type of heat related headlines. As such, the excessive heat warnings and heat advisories have been cancelled early. Latest surface analysis places a slow moving cold front somewhere over central Arkansas. This boundary will reach the Arkansas and Louisiana border early Monday morning. Slightly cooler but much drier air will continue to filter into the forecast area which will reduce the heat stress related conditions for at least a day or so, even through temperatures themselves will be very close to seasonal averages. && .LONG TERM... (Tuesday Night through next Sunday) Issued at 226 PM CDT Sun Jun 30 2024 In general west-northwest flow aloft will be in place over the central CONtinental United States (CONUS) from Saturday night through Wednesday. In the absence of a powerful upper level trough or ridge, shortwave troughs will generally provide the perturbations that cause the geostrophic flow aloft to alternate between pure westerly and shifts to northwesterly flow aloft. These shifts are important because they will have a cascading impact on surface weather conditions east of the Rockies to the Mississippi River. When the flow aloft is oriented westerly, as the westerly flow moves from the high terrain of the Rockies to the lower terrain of the plains, the atmospheric column expanding in depth will cause a surface trough to develop over the higher plains east of the Rockies. This is due to the conservation of potential vorticity which effectively creates surface troughing due to the atmosphere moving from a compressed to expanded vertical state simply due to elevation change alone. With westerly flow aloft causing cyclogenesis over the high plains, periods of northwest flow aloft will drive weak/Pacific type cold frontal boundaries southeast, providing synoptic scale lift east of the surface cyclones or troughs that develop during conditions of westerly flow aloft. The western troughs will cause south or southeasterly low-level flow to set up over Arkansas pumping moisture rich Gulf of Mexico air north across the state. Because this period exists in early June, the sun angle is just about as high as it gets over the CONUS leading to extremely efficient heating each day. The positive moisture flux combined with the efficient daytime heating will be consistent drivers of thunderstorm energy across the state Sunday through Wednesday. Everytime one of the pacific type cold fronts interacts with this energetic airmass, it will kick off a line of thunderstorms that will continue downstream into the axis of hot and humid air. As a result, this type of pattern is well known to send multiple linear mesoscale convective systems (MCSs) across the central CONUS this time of year. Each linear MCS will bring with it a threat for damaging winds and at least a marginal threat for hail and quick spin up tornadoes. Localized flooding is also possible, but widespread flooding is not common because these types of storm systems tend to move and don`t sit in one place all that long. This cycle of linear MCS, reset the atmosphere with southerly winds, just in time to allow another linear MCS roll through will continue throughout the extended forecast period will continue through Monday when a stronger upper trough digs southeast over the western Great Lakes region driving a Pacific type cold front well south of Arkansas interrupting the moisture reloading cycle of this weekend through early next week. After Wednesday drier air will move across the state leading to a period of drier weather beginning Thursday and likely continuing into next weekend. && .AVIATION... (00Z TAFS) Issued at 629 PM CDT Sun Jun 30 2024 Convection associated with a slow moving cold front continues to slowly wane with the loss of daytime heating but a few showers and thunderstorms will remain possible over the central and southern TAFS through mid evening. VFR conditions will continue with winds generally light and variable through the period. && .PRELIMINARY POINT TEMPS/POPS... Batesville AR 67 85 64 93 / 10 0 0 0 Camden AR 75 92 68 98 / 20 10 0 0 Harrison AR 67 87 65 95 / 10 10 0 0 Hot Springs AR 73 90 69 97 / 30 10 0 0 Little Rock AR 75 89 69 95 / 20 0 0 0 Monticello AR 77 91 69 96 / 20 0 0 0 Mount Ida AR 73 89 68 95 / 20 10 0 0 Mountain Home AR 67 84 64 93 / 10 10 0 0 Newport AR 68 85 64 92 / 0 0 0 0 Pine Bluff AR 74 89 67 95 / 20 0 0 0 Russellville AR 73 89 68 95 / 20 10 0 0 Searcy AR 70 87 64 93 / 20 0 0 0 Stuttgart AR 74 87 67 93 / 20 0 0 0 && .LZK WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...56 LONG TERM....67 AVIATION...56