Expires:No;;873674 FXUS64 KHUN 061745 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 1245 PM CDT Sun Apr 6 2025 ...New AVIATION... .NEAR TERM... (Rest of Today and Tonight) Issued at 1036 AM CDT Sun Apr 6 2025 A broad axis of moderate-locally heavy rain and a few embedded thunderstorms (driven by shallow lift on the cool side of an extensive outflow boundary) continues to spread slowly southeastward across the forecast area this morning. However, as a positive-tilt 500-mb shortwave trough (currently extending from the southern Plains southwestward into northern Mexico) drifts southeastward, a weak area of surface low pressure will lift northeastward along the boundary from southeastern MS into the Smoky Mountain vicinity by early this evening. Mass convergence near the path of the low may foster redevelopment of light- moderate rain to the southeast of a cold front, which will enter the CWFA later this this afternoon. This could exacerbate preexisting flooding (especially across the southeastern half of the region), and we will monitor radar trends in the event that another Areal Flood Warning should become necessary. Although forecast soundings depict small amounts of CAPE (up to 250 J/kg) within the residual warm/moist airmass across the TN Valley (highlighted by afternoon temps in the u60s-l70s with dewpoints in the u50s-l60s), the risk for thunderstorms will be significantly hindered by widespread/overcast clouds and poor low-level lapse rates. The cold front will continue to advance southeastward through the remainder of the forecast area between 0-6Z Monday, with light- moderate rain continuing across our southeastern zones until the time of frontal passage. Although the postfrontal airmass will be slightly cooler/drier than the one currently in place (with NNW winds advecting dewpoints into the 40s by 12Z Monday), the low- levels will be sufficiently moist to support widespread stratus clouds and light drizzle (only worthy of a 5-10% POP) elsewhere across the region, especially as synoptic scale ascent strengthens downstream from the approaching shortwave trough. Due to these factors, lows will only fall into the 45-50F range. && .SHORT TERM... (Monday through Tuesday night) Issued at 1036 AM CDT Sun Apr 6 2025 Latest short range model consensus suggests that the mid-level trough (discussed above) will begin to accelerate east- northeastward tomorrow as it becomes absorbed in the flow around a stronger northern stream trough digging into southern Ontario. With the axis of the trough not predicted to cross the TN Valley until late afternoon, the regime of postfrontal low stratus clouds and patches of light drizzle will persist for much of the day on Monday, with POPs ranging from 10-20% across the southeast (where a pocket or two of light rain will be possible) to 5-10% elsewhere. As a result of this, highs will be in the 55-60F range. Dry northwest flow aloft (in the wake of the trough) will exist across the region from Monday night-Tuesday night, with a stronger cold front (marking the leading edge of a Canadian airmass which will spread southward in the wake of the northern stream wave) expected to arrive early Tuesday morning. Northerly winds will advect dewpoints in the 25-30F range southward through most (if not all) of our CWFA on Tuesday, and even with abundant sunshine highs will still only reach the 55-60F range (perhaps even a few degrees cooler across southern TN/northeast AL). As surface high pressure builds southeastward into the Mid-Atlantic states Tuesday night, calm winds will support radiational cooling, with lows in the 30-35F range and patchy frost possible region- wide Wednesday morning. && .LONG TERM... (Wednesday through Saturday) Issued at 945 PM CDT Sat Apr 5 2025 As we head into the second half of next week, the upper level pattern shows a more zonal flow across the Southeast. Seasonal temperatures and dry weather are forecast both Wednesday and Thursday with afternoon highs in the upper 60s to lower 70s. Another trough digs down across the Plains on Thursday which will bring another weak cold front into the Tennessee Valley. Low chances (20-30%) of showers and maybe even a rumble of thunder on Thursday night/Friday. The good news is that severe weather is not expected with this frontal passage. The upper level trough pushes to the east at the end of next week, bringing back dry weather to start the weekend. && .AVIATION... (18Z TAFS) Issued at 1245 PM CDT Sun Apr 6 2025 Bkn-ovc layers of stratus will prevail at the terminals this aftn, as the region still remains within a warm/moist airmass to the southeast of an approaching cold front. As an area of sfc low pressure tracks northeastward across the region, periods of lgt- occasionally mod RA will may occur at times, potentially resulting in IFR cigs and minor/MVFR vsby reductions. The front will arrive late this aftn/early this evening, with a wind shift to NNW expected to occur by 0Z/MSL and 2Z/HSV. Very low stratus will build into the region following fropa (and should persist for the remainder of the TAF period), with patchy lgt DZ/BR also possible from late this evening-early Mon morning. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Flood Watch until 7 PM CDT this evening for ALZ001>010-016. TN...Flood Watch until 7 PM CDT this evening for TNZ076-096-097. && $$ NEAR TERM...70/DD SHORT TERM...70/DD LONG TERM...GH AVIATION...70/DD