669 FXUS64 KBMX 171751 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 1251 PM CDT Wed Jul 17 2019 .UPDATE... For 18Z Aviation. && .SHORT TERM... /Updated at 0336 AM CDT Wed Jul 17 2019/ Today and tonight. The southern end of a shortwave trough will affect the region today and will be responsible for enhanced rain chances across the northern half of the forecast area. PWAT values of 2.0 to 2.1 inches will exist in an corridor where low-level convergence has been present over the last couple of days in association with Barry's remnants. With the aid of the shortwave, scattered showers and storms should develop during the morning hours across our North and progress southward to near the I-20 corridor by early afternoon. South of I-20, a deep-layer ridge will be responsible for lower moisture quality and decreasing convective coverage with southward extent. Activity should decrease in coverage with the loss of daytime heating this evening, but the presence of the weak shortwave will be supportive of isolated convection in the northeastern counties tonight. 87/Grantham .LONG TERM... /Updated at 0336 AM CDT Wed Jul 17 2019/ Thursday through Wednesday. Despite upper-level ridging over the southeast, perturbations in the low and mid-level flow with a weak surface trough meandering over the eastern CONUS will bring periods of scattered rain and thunderstorms Thursday through the end of this week, particularly during the afternoon when peak instability can aid in intensity and coverage. Highs will rise into the 90s through the weekend until a cold front early next week brings increased rain chances and cooler temperatures. A shortwave trough will be in place over the eastern CONUS through the weekend with the base just reaching eastern Alabama. This feature is identified easiest at the surface, amplified by afternoon convective trends. Southerly winds will maintain PWATs in the 1.9 to 2.1 inch range each day, so at the very least, isolated to scattered afternoon rain chances will be carried through Saturday. Dewpoints will remain in the lower 70s each afternoon as highs reach the low to mid 90s. As a result, we will finish this week in hot summer fashion, especially on Thursday with heat indices just under Heat Advisory criteria in the southwest. Isolated thunderstorms in the south on Thursday should limit heat indices from reaching 105 degrees spatially and temporally such that a Heat Advisory is not expected at this time, but we will continue to monitor trends. It appears that a wet pattern will set up for the first half of next week. Deep-layer troughing develops over Hudson Bay extending south into the Great Lakes Region. As the thermal gradient strengthens, the wave pattern will amplify with meridional flow returning over the northern CONUS by Monday. A resulting surface low will develop over the northeast with the associated cold front ultimately approaching northern Alabama on Monday. There is some uncertainty on exactly how far south the boundary will progress, but increased rain chances are expected nonetheless on Monday, Tuesday, and potentially Wednesday as latest trends have the boundary stalling over northwestern Alabama. Plenty of moisture will be present ahead of the approaching boundary with PWATs remaining near 2.0 inches. Therefore, rain totals of 1 to 2 inches will be possible across Central Alabama through Wednesday with locally higher amounts possible as well. The rain and cloud cover will keep our highs in the upper 80s for the first half of next week. 86 && .AVIATION... 18Z TAF Discussion. Forcing associated with a passing upper level shortwave has allowed for development of scattered showers and thunderstorms across the northern half of the CWA this afternoon. For the northern sites, have gone predominately with showers/VCTS and TEMPO TSRA for the next 3-4 hours. High pressure across the northern Gulf has kept the airmass relatively dry in our southern counties. As a result, have not included the mention of showers and thunderstorms at KMGM and KTOI at this time. All activity is expected to dissipate with the loss of daytime heating by 00-01Z. Tonight winds remain out of the southwest, 2-3kts with high clouds. More showers and storms are expected tomorrow afternoon, however, probabilities are too low to mention at this time. 07 && .FIRE WEATHER... Scattered showers and storms should be mainly confined to areas along and north of I-20 through this afternoon. A potentially much wetter pattern appears to be developing for Friday through the weekend. With a moist airmass remaining in place, RH values will remain above critical thresholds. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 72 91 73 90 72 / 30 40 20 40 20 Anniston 73 91 74 90 73 / 30 40 30 50 20 Birmingham 74 93 75 91 75 / 20 30 20 40 30 Tuscaloosa 74 94 75 92 74 / 20 20 10 40 40 Calera 73 92 74 90 73 / 20 30 20 40 40 Auburn 73 90 74 89 73 / 20 40 30 60 40 Montgomery 74 94 75 92 74 / 20 40 20 60 40 Troy 72 93 73 91 73 / 10 40 20 60 50 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$