728 FXUS64 KBMX 081907 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 207 PM CDT Wed Jul 8 2020 .SHORT TERM... /Updated at 0145 PM CDT Wed Jul 08 2020/ Through Thursday. The old frontal boundary is situated near/along the AL/GA border where scattered convection continues to develop. Back to the west, the remnants of an MCS is moving into southwest Central AL. Surface-based CAPE is roughly 2000 J/kg ahead of this activity, and lift will be aided by a subtle shortwave tracking eastward across MS. So, current convection should continue to track ESE across the southwestern/southern counties through the afternoon. With the current instability and PWATs still around 2 inches, gusty winds and heavy rainfall will be the primary threats with today's activity. Convection should gradually decrease in coverage through the evening with some lingering activity mainly in the south. Thursday doesn't look much different from today, with scattered to numerous showers and storms expected across the forecast area 19 .LONG TERM... /Updated at 0126 PM CDT Wed Jul 08 2020/ Thursday night through Tuesday. /Daily intervals of showers & storms; potential for afternoon ~105F heat indices/ A West U.S. ridge/East U.S. trough 500mb flow pattern will become prominent late week through the weekend. Given the placement and orientation of the ridge/trough axes, the Gulf Coast region will be in line/downstream of the northwesterly jet. In turn, any MCS forming upstream would tend to have a trajectory toward our region. Still, guidance remains varied regarding the development, longevity, and path of potential MCS activity (for this sort of system, that's not atypical this far out in time); thus, certainty for a MCS to impact Central Alabama is low. Otherwise, locally-born showers and thunderstorms are forecast on a daily basis, varying in coverage. Some of the storms could be strong given environmental conditions. Afternoon heat indices may match 105F (advisory threshold) Friday through Monday for a portion of Central Alabama, barring any negating effects from convection. Hot daytime temperatures should continue through next week as 500mb ridging extends/builds eastward. 89^GSatterwhite 02 Previous long-term discussion: /Updated at 0313 AM CDT Wed Jul 08 2020/ Friday through Tuesday. Subtropical ridging centered over Arizona and New Mexico, with 500mb heights reaching 600 decameters at times, will be the main feature over the CONUS through the extended period. Downstream troughing along the East Coast will result in northwest flow aloft over Central Alabama. This will be a favorable pattern for MCSs to track from the Central Plains/Ozarks down into the Deep South, but with low confidence on exactly where/when these will track. A weak shortwave in the northwest flow aloft will move through on Friday. While currently a potential MCS is expected to stay west of the area over the ArkLaMiss, PWATs near 2 inches should support scattered to numerous showers and storms developing by afternoon. There will be enough DCAPE to support at least a lower end microburst threat as well. Guidance indicates mid to upper 70s dew points across the area, with ensemble situational awareness tables indicating 925mb specific humidity values in the 99th percentile through the period. Thus even with highs in the low 90s, heat indices could still potentially reach 105 degrees in West Alabama Friday depending on how quickly convection develops, and will continue to mention a low confidence threat of reaching heat advisory criteria in the HWO. Unsettled northwest flow continues on Saturday, though guidance is also indicating some lower PWATs sinking down into at least our eastern counties which could limit convection. Any storms that do develop would be strong, possibly severe with increasing mid-level lapse rates, dry air aloft, and 0-6 km bulk shear around 25 kts. With less convective coverage than Friday, confidence is a bit higher in reaching heat advisory criteria in West Alabama and potentially also in our southern counties. Some models continue to suggest that an MCS may track in the vicinity of at least our western counties late Saturday night into Sunday morning, but there is little in the way of model agreement/consistency. If this were to occur, would need to monitor for a potential damaging wind threat given the enhanced mid-level flow/mid-level lapse rates, but confidence in this happening is very low at this time. Will hold off on mentioning any heat impacts in the HWO for Sunday given the uncertainty of any possible cold pool. A northwest to southeast gradient in moisture/rain chances will set up early next week with lower rain chances in the northwest closer to the ridge and higher chances in the southeast closer to a trough axis. Heat indices may reach 105 in the southern counties on Monday, and will add a mention of this to the HWO. Heat may continue to be a concern through the rest of next week as the ridge builds eastward across the Ohio Valley, though ECMWF/European ensemble data suggests the highest temperatures will remain northwest of the area. 32/Davis && .AVIATION... 18Z TAF Discussion. Convection is rather isolated to scattered across Central AL at the moment, but a cluster of storms is approaching the MS/AL state line and will impact the southwestern portions of the forecast area over the next few hours. Have introduced a tempo for TSRA at TCL, but unsure how long it will hold together. So, have mentioned VCTS later on this afternoon for MGM/TOI. Activity should decrease in coverage through the evening with a stratus deck returning overnight. Expect MVFR/IFR ceilings after 08Z-09Z with ceilings slowly rising late morning. More showers and storms are expected again on Thursday. 19 && .FIRE WEATHER... There's a daily chance for showers and storms across Central Alabama. Transport winds will run below 10 knots each day, with varied trajectories. Minimum RH values will hold well above threshold-of-concern levels. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 70 89 72 91 72 / 40 50 20 60 30 Anniston 70 88 72 91 73 / 40 50 20 60 30 Birmingham 72 90 74 91 74 / 40 50 20 60 30 Tuscaloosa 73 89 75 92 75 / 40 50 30 60 30 Calera 72 88 73 91 74 / 40 50 20 60 30 Auburn 71 87 73 89 73 / 40 50 20 60 20 Montgomery 73 89 75 92 75 / 60 60 20 60 30 Troy 73 88 74 92 75 / 60 60 20 60 30 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$