Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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736 FXUS64 KHUN 091410 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 910 AM CDT Sun Jun 9 2024 ...New NEAR TERM... .NEAR TERM... (Rest of Today) Issued at 910 AM CDT Sun Jun 9 2024 Complex weather setup today across the Tennessee Valley. Early morning convection has quickly waned in a stable environment over north Alabama. However, over southern Missouri another MCS is waiting in the wings as it continues to push ESE into portions of the Mid South and lower Ohio Valley. This feature is tied to another mid-level shortwave and it`s associated surface cold front. Guidance continues to keep broken cloud cover in place over much of the area for the remainder of the morning -- hindering heating and destabilization somewhat. However, by early/mid afternoon, these clouds shouldn`t be an issue with HiRes showing temperatures climb into the 85-90 degree range and SBCAPE values of 2000-3000 J/kg. This unstable environment will be primed for severe weather -- especially when we`ll add 30-40 kts of bulk shear from the approaching shortwave trough. The uncertainty lies with with where and how convection will evolve upstream today. Current thinking is that a remnant outflow boundary from storms currently over southern Missouri will initiate storms over north central Arkansas sometime early this afternoon. This activity will then push ESE with the mean flow across northern Mississippi, congealing into an MCS. Eventually, this feature will approach and move into portions of north and/or central Alabama by the evening hours -- depending on the trajectory of the MCS and where/when it forms upstream. Should storms be able to move into the Tennessee Valley, a favorable environment for damaging winds and at least marginally severe hail will exist -- along with the threat for locally heavy rainfall. Timing will need to be refined throughout the day by watching radar/satellite trends, but the main window may end up being a 6 PM to 11 PM timeframe from northwest to southeast. && .SHORT TERM... (Tonight through Tuesday night) Issued at 422 AM CDT Sun Jun 9 2024 We will carry a medium-high (50-70%) POP in the grids early this evening to reflect the potential for both convective regimes (discussed above) to continue for a few hours past sunset, and although POPs begin to decrease after Midnight, a narrow band of showers (and perhaps a few thunderstorms) will accompany the actual cold front as it shifts southward across the forecast area. Present indications are that the front will exit our southeastern zones between 12-15Z Monday, with any lingering shower activity expected to end with its passage. By Monday, afternoon, strengthening NNW winds will advect a cooler/drier Canadian airmass into the region, with dewpoints falling back into the mid 50s as temperatures struggle to reach the u70s-l80s. This will set the stage for a clear and cool night, featuring lows in the m-u 50s early Tuesday morning. Temperatures will exhibit little fluctuation on Tuesday and Tuesday night, with dry conditions continuing as a low-amplitude mid-level ridge translates eastward ahead of a weak southern stream trough tracking east-southeastward over OK/TX. && .LONG TERM... (Wednesday through Saturday) Issued at 422 AM CDT Sun Jun 9 2024 Although specific details remain unclear at this point, most of the global models now suggest that that southern stream trough (discussed above) will travel southeastward into the northern Gulf of Mexico during the first half of the extended period, before evolving into nearly stationary cutoff low on Friday/Friday night. Any northward movement of the low next weekend will likely be dictated by the strength and orientation of a blocking mid-level ridge to its north, which will in all likelihood lie across the TN Valley, providing an extended period of warm and dry conditions that could potentially extend into the first part of the following week. That said, we have included a very low (15-20%) POP across our southeastern counties on Friday and Saturday afternoons, due to a gradual increase in low-level moisture which will translate to a notable increase in CAPE given hot daytime temperatures. Highs will quickly warm into the lower 90s for most valley locations by Thursday/Friday/Saturday, with lows more gradually returning to the u60s-l70s by Saturday morning. && .AVIATION... (12Z TAFS) Issued at 647 AM CDT Sun Jun 9 2024 There have been no significant changes to previous aviation forecast reasoning, although we have removed TEMPO groups that were in place for the initial MCS now that it is to the S/E of HSV. Partial clearing in the wake of the MCS is still expected to occur later this morning (by 15Z), with redevelopment of additional TSRA possible this afternoon both in the vicinity of a mesoscale boundary across northern MS and along a southward- moving cold front across western/Middle TN. Should this activity impact either terminal, it would likely be btwn 22-02Z, which is also the timeframe of concern for lightning and wind-related AWWs. Additional SHRA will be possible until a cold front arrives arnd 6Z, veering sfc winds to NNW. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...AMP.24 SHORT TERM....70 LONG TERM....70 AVIATION...70