752 FXUS64 KHUN 141347 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 847 AM CDT Wed Aug 14 2019 .NEAR TERM...(Rest of Today) Issued at 847 AM CDT Wed Aug 14 2019 Areas of lower stratus continue in parts of the area, but we have seen a decrease since sunrise and should continue to do so. The secondary cool front was moving southeast through middle TN into far northwest AL. A few showers have already developed along this frontal band. As this moves southeast through the day, instability should increase sufficiently to continue producing a few showers and thunderstorms along and just ahead of the front through the the midday hours. The chances of showers and thunderstorms will end from northwest to southeast as the front makes progress this afternoon. Will maintain the forecast about as is with majority of this update on adjusting sky coverages. .SHORT TERM...(Tonight through Friday) Issued at 513 AM CDT Wed Aug 14 2019 Dry conditions will prevail across the TN Valley for the duration of the short term period, as a couple of additional mid-level waves tracking southeastward across the Great Lakes reinforce northwest flow aloft from tonight through Thursday. However, it does appear as if the flow will weaken considerably on Thursday night/Friday, as the subtropical ridge begins to expand eastward in response to an amplifying northern stream trough digging southeastward across Alberta/Saskatchewan. In the low-levels, light northerly flow will continue to advect drier air into the region, and this should result in pleasantly cool mornings, with lows ranging from the lower 60s in the northeast corner of the forecast area to the mid 60s elsewhere. Mostly sunny skies throughout the day will ensure warm temperatures during the afternoon, with highs warming back into the lower 90s region-wide by Friday. .LONG TERM...(Friday night through Tuesday) Issued at 513 AM CDT Wed Aug 14 2019 Extended range guidance indicates that further deepening of the aforementioned northern stream wave will occur this weekend, as it shifts slowly eastward into northern Ontario. To the south of this feature, the subtropical ridge will continue to become reestablished across the southern CONUS, with max temps warming back into the mid 90s for most of the TN Valley on Saturday and Sunday. Fortunately, low-level moisture will be slow to return to the region, and this should keep Heat Index values in the 100-105 degree range both days. By early next week, models suggest that a 500-mb trough axis trailing southward from the northern stream disturbance will become detached, and effectively create a broad weakness in the subtropical ridge extending from the northwestern Gulf of Mexico northeastward into the TN Valley. The reduction in subsidence aloft, coupled with PWAT values increasing back to around 2 inches, will lead to an environment more conducive for the development of scattered afternoon/early evening showers and thunderstorms, and we have included a chance POP for all forecast zones on Monday and Tuesday. As a result of this, we have also lowered high temps back into the u80s-l90s, but raised min temps into the u60s-l70s to indicate an increase in low-level moisture expected during this period. && .AVIATION...(For the 12Z TAFS through 12Z Thursday morning) Issued at 650 AM CDT Wed Aug 14 2019 Low stratus clouds and patchy light fog continue across portions of the region in the wake of widespread RA/TSRA yesterday evening. Although these conds have yet to be reported at HSV, MVFR cigs are being observed at the MSL terminal, and we will include overcast stratus thru 15Z, with cigs arnd FL015. Forecast sounding data indicates that stratus will lift prior to the arrival of a cold front later this morning, which should allow for sufficient boundary layer destabilization and the development of scattered convection invof the terminals btwn 16-19Z. Showers and thunderstorms will shift southeastward throughout the afternoon, with only few cirrus expected by early this evening. Lgt/vrbl sfc flow will continue this morning, with winds increasing to 5-10 knots and assuming a more pronounced northerly component this aftn. Elevated NNE flow should reduce the threat for fog development at the terminals toward the end of the TAF period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...17 SHORT TERM...70/DD LONG TERM...70/DD AVIATION...70/DD For more information please visit our website at weather.gov/huntsville.