214 FXUS64 KHUN 101408 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 808 AM CST Fri Nov 10 2023 ...New NEAR TERM... .NEAR TERM... (Rest of Today) Issued at 808 AM CST Fri Nov 10 2023 Stratiform rain continues to push across the Tennessee Valley this morning in wake of a cold front that moved through the region last evening. High chances (70-90%) for light rain will continue through late this morning, before tapering off from NW to SE this afternoon. Dense cloud cover will persist through the day, which combined with the northerly winds will keep temperatures in check. Don't expect much warming today because of this, with most locations struggling to reach much above the 60 degree mark. Only minor tweaks made to the forecast based on the latest obs/trends as everything remains on track. && .SHORT TERM... (Tonight through Sunday night) Issued at 407 AM CST Fri Nov 10 2023 The latest suite of short term model guidance suggests that little change in the overall synoptic pattern will occur through Saturday night, with seasonably strong WSW flow aloft of 45-55 knots predicted to continue over the region. Within this regime, the remnants of a positively-sheared shortwave trough (currently across AZ) will lift northeastward into OK/KS by 12Z Saturday, before accelerating into the Upper OH Valley/central Appalachians Saturday night in the flow ahead of the northern and more progressive portion of an upstream trough shifting eastward across the northern Plains. Although this will occur with little reflection in the surface pressure field, it will induce a strengthening southeasterly low- level jet across the TN Valley by late afternoon Saturday atop east-northeasterly flow at the surface, which will provide favorable lift for the northward expansion of light rain into the region once again. Thus, we have maintained low POPs in the grids for locations generally south of the TN River overnight and for much of the day Saturday (primarily due to some uncertainty on the precise location of the surface boundary), with chances for rain steadily increasing from SE-to-NW late Saturday afternoon, before precipitation ends late Sunday morning. Once again, QPF amounts will be on the low side given the weak nature of forcing for ascent, with amounts up to 0.25 inch possible across our southeastern zones and less than 0.10 inch further to the northwest. Temperatures will be dependent on both the coverage of clouds and precipitation, with highs ranging from the l-m 50s (SE) to l-m 60s (NW). Lows tonight and Saturday night will be in the mid 40s-lower 50s, but should drop into the l-m 40s Monday morning (especially if skies finally manage to clear). && .LONG TERM... (Monday through Thursday) Issued at 407 AM CST Fri Nov 10 2023 Brief, upper ridging will give way to an upper shortwave trough traversing the southeastern states from Tuesday through late week. Through the period, surface high pressure over the Appalachians will also gradually push east over the Atlantic as a low pressure system moves across Canada. Meanwhile, a surface low looks to develop over the northwestern Gulf of Mexico on Monday and track eastward through the week. This Gulf coast system may bring increased moisture to the region and be our next chance at rain; however, there remains model disagreement with its evolution as well as with the aforementioned upper trough. The ECMWF ensembles look more optimistic with regards to QPF over the Tennessee Valley compared with the GEFS since it favors a more northward track by the Gulf coast system. Overall, the trajectory of the Gulf coast low will have a significant impact on the amount of rain that will fall over the Tennessee Valley. The farther inland it moves would mean a higher probability of rain for the local area, but a more southward progression of the system over the Gulf waters would result in lower rain probability for our area. Because of this uncertainty, stuck close to the Blended guidance for PoPs, with low to medium (20-60%) chances from Tuesday through Thursday. The best chance for rain (medium, 40-60%) looks to be Tuesday night through Wednesday, but this will be monitored. Instability will be limited through the week and therefore, thunderstorm chances will be low. As for temperatures, highs are forecast to start out in the mid to upper 60s on Monday then decrease through midweek with the increase in precipitation chances. By Wednesday, highs merely top out in the upper 50s to lower 60s. As rain chances decrease through late week, temperatures will warm once again to be in the upper 60s to around 70 degrees by Friday. Meanwhile, lows will gradually increase through the period due to increased moisture, with values starting in the 40s Monday night and increasing to the lower to mid 50s Thursday night. Keep in mind that higher coverage of precipitation would dampen high temperatures to potentially be cooler than forecast. A lower coverage of rain would then potentially allow for high temperatures to be warmer. This will be monitored with subsequent updates and model trends. && .AVIATION... (12Z TAFS) Issued at 554 AM CST Fri Nov 10 2023 Postfrontal light rain and low stratus clouds will persist at the HSV/MSL terminals this morning, providing intermittent periods of MVFR vsby reductions and IFR-level cigs as low as 800 ft AGL. However, conditions are expected to improve by 16Z/MSL and 17Z/HSV, as a progressively drier airmass is advected southward in the wake of a cold front. Although spotty pockets of light rain may continue to occur this aftn and overnight, this should be confined south of the TN River, and we will leave the TAFs dry at this point. VFR-level As/Cs layers will provide cigs in the 8-25 kft range for much of the period, with a continued NNE flow of 8-10 knots (and gusts of 16-18 knots). && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...AMP.24 SHORT TERM....70 LONG TERM....26 AVIATION...70