783 FXUS64 KBMX 230006 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 706 PM CDT Sat Jun 22 2019 .UPDATE... For 00Z Aviation. && .SHORT TERM... Like mentioned previously, there are a few smaller scale boundaries south. These are leftover from previous nights convection and will be a focusing mechanism for storm development this afternoon and evening. Due to the microburst index being high and atmospheric conditions conducive for downburst, will leave mention of severe storms far south. The best shear, although on the weaker side, remains north and east. The activity northwest was building on the remnant outflow from last nights MCS, and this area has the potential to organize somewhat and produce damaging winds. Large hail also remains possible due to cold temperatures aloft, good lapse rates and dew point depression in the lowest levels. A Severe Thunderstorms Watch is in effect covering this activity. Due to an increasing number of boundaries and potential focusing areas for storms, some storms will last into the evening hours especially north and east. After making adjustments on the temperatures and dew points, the heat indices will top out in the 100-105 degree range this afternoon. Therefore, its going to be hot but not to any advisory criteria. Still exercise caution since this is the first real shot at these humidity levels. 75 Previous short-term discussion:Today through Sunday. Last night a remnant outflow boundary was left from near Pickens County to Lee County from a weakening segment of an MCS that moved into GA/SC. This boundary is likely to provide the spatial axis favorable for convective initiation this afternoon, though sporadic showers and thunderstorms have developed as a result of isentropic ascent just along the boundary's edge throughout the overnight period. As of now, looking at threat potential for today with overnight activity, a couple scenarios for severe weather potential exist today. A favorable thermodynamic parameter space will reside across a good portion of the Southeast this afternoon. Though effects from the ridge will act to resist development of thunderstorms with height rises and confluent flow aloft, the remnant boundary will help create a theta-e gradient for convective development as MLCAPE rises back into the 3,000-4,000 J/kg range. With mid-level lapse rates ~8 C/km & 500 mb temperatures from -9 to -11 C, robust updrafts are possible within areas across Central Alabama, especially with low- level moisture availability. Concern for today's severe threat is that discrete cells will contain potential for hail and downbursts given indication that DCAPE will range 1,200-1,500 J/kg with relatively cool temperatures aloft, though the weak shear environment (eff. bulk shear <20 kts) & synoptic scale subsidence suggest lifespan of storms may be short. Thus, uncertainty exists in whether lift will be sufficient to overcome inhibiting factors for vertical development in the afternoon. If lift is sufficient, areas generally along and north of the remnant boundary will see best chances for thunderstorms. Another scenario brings a MCS across portions of Central Alabama tomorrow evening (can happen whether isolated development takes place this afternoon or not). As of 04 Z, this MCS was positioned in southern IL & IN, heading south-southeastward. If this system can maintain intensity through this morning, it will move into further destabilizing environmental conditions and have a chance at impacting our north/east areas with damaging winds. This complex will also compete against effects of the ridge, including steering mechanisms that may keep it to our east as last night's threat did and unfavorable alignment of shear vectors. Nonetheless, severe weather has found ways to outdo expectations the past few days despite limiting factors, thus we're hedging with caution for today and outlining areas from Pickens to Lee County & northward in a Slight Risk for severe weather. This afternoon will be hot and muggy in many areas with heat indices 100-105 F. If you're outside today, take it easy and limit exposure and dehydration. Sunday's weather looks to be hot and humid as well, though chances for rain/thunderstorms are on the decrease. This is suggested as the low/mid-level ridge nudges more northwestward across our area allowing for flow aloft to steer potential storm complexes around our area, as well as more efficiently mixing the boundary layer & limiting shear values. Though we're bound to see some showers and storms somewhere Sunday, have left best chances in the northeast where better PWs (~1.5") are expected. Otherwise, stay tuned to for forecast updates today as we assess trends with observations throughout the morning. 40/Sizemore .LONG TERM... /Issued at 345 AM CT/ Monday through Friday. The ridge will begin to slide east on Monday allowing for southerly flow to increase across the area. This will again increase the rain chances, especially across the northwest as a front will try to work into the area or at least be nearby. The ridge will begin to build back into the region on Tuesday, however, moisture will remain and we will likely see scattered showers/storms on both Tuesday and Wednesday. On Thursday, the main ridge will break down and we will see moistures move into the region from the southeast. This will provide a little bit more in bulk moisture in place across the area and better rain chances. Friday looks to be the best chances and will likely need to raise these pops as we get closer and models begin to converge on an even better solution. With the summer time temperatures and afternoon heating, any storm good be on the strong side. But predictability is too low to mention anything for next week at this time. On a whole look for near normal temperatures through next week, with above normal rain chances. 16 && .AVIATION... 00Z TAF Discussion. Areas of showers and thunderstorms with multiple complexes are present on radar at present. The first is in an arc shape from near TCL to just north of MGM to near AUO sinking southeast. A second area is present from west to east near the Tennessee /Alabama border sinking south and southeast. I have tried to time convection based in the short term on radar. I am less confident with the 2nd northern area of convection as to if it will hold together and make it through Central Alabama, but I did account for some deteriorating activity to make it through the area. Gusty winds are possible with the storms. 08 && .FIRE WEATHER... A hot and humid airmass will remain in place with the potential for scattered showers and storms each day. Rain chances may become enhanced by an approaching front on Monday. There are no fire weather concerns. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 70 92 70 89 68 / 50 30 10 40 40 Anniston 71 92 71 90 69 / 50 30 10 40 40 Birmingham 73 95 73 91 71 / 40 20 10 50 40 Tuscaloosa 74 96 75 91 72 / 40 10 10 50 40 Calera 72 93 72 90 70 / 40 20 10 40 40 Auburn 72 92 72 91 72 / 50 30 10 20 30 Montgomery 73 96 73 94 72 / 30 20 10 30 30 Troy 72 94 72 93 70 / 20 10 10 20 30 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$ 75/40/16/08