513 FXUS64 KBMX 140455 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 1055 PM CST Fri Dec 13 2019 .UPDATE... For 06Z Aviation. && .SHORT TERM... /Updated at 0937 PM CST Fri Dec 13 2019/ The best elevated moisture convergence, lift associated with approaching trough, and deepest moisture from Montgomery to Heflin. All of the associated measurable precipitation was east of this axis and the trend will be for this activity to move out of Alabama around midnight. Although there could be a few lingering showers near the Georgia state line, most of the measurable activity will be done. Elevated instability was high enough that several thunderstorms developed near and south of I-85, and this activity has moved well south and east of the Alabama at this hour. Model soundings, observations and satellite imagery indicates the deeper moisture decreasing in western Alabama. But a hefty inversion remains into Saturday morning with moisture trapped underneath. Therefore, a tricky cloud and fog forecast overnight. There has been very low clouds and patchy dense fog late this afternoon and evening due to Central Alabama's post frontal position and rain. The chances of area of dense fog look best near the Mississippi state line dew to very low to zero dew point depressions. The fog formation and low clouds are already mentioned and the zone of potential areas of dense fog remain somewhat questionable. Therefore, will hold off on an advisory at this time. Would not be surprised if one is needed before morning. 75 Previous short-term discussion: /Updated at 0230 PM CST Fri Dec 13 2019/ This afternoon into this evening, a broad longwave trough will continue digging into the Mississippi River Valley, bringing another round of showers that are beginning to move into the western portions of the forecast area. Convection overall looks relatively benign, but a slight chance for thunderstorms will still exist for southeastern and portions of east central Alabama going into the overnight hours, the final line of showers and storms expected to exit the forecast area around midnight. By Saturday morning, the axis of the upper-level trough will have swept through into Georgia. Providing enough subsidence to reduce precip chances, but not enough to completely dissolve the low-level shield of stratus, but we should expect some it to begin breaking up by the late morning with some sunlight peaking through. Highs will increase slightly but remain in the mid- to upper-50s. Thiem .LONG TERM... /Updated at 0230 PM CST Fri Dec 13 2019/ No major changes to the long term portion of the forecast were made. See previous discussion. NLIST Previous Discussion... Saturday night through Thursday. Overall an active pattern will continue through the extended. Severe weather possible on Monday afternoon/evening. Best chances for sunshine will be on Sunday and again on Wednesday. High pressure will be in place on Sunday but will not last long as the next system will begin to work into the area overnight Sunday and push through the area on Monday. Rain will linger through Tuesday morning in the northwest to Tuesday afternoon in the southeast. This system will be another potential beneficial rain for the extended period. Highs will warm into the mid 60s to low/mid 70s degrees in the south in Monday ahead of the front that will move through sometime overnight Monday night into Tuesday afternoon. Model consensus continues to agree that there is a severe chance during the day on Monday into Monday night. There will be a good window for a moist and unstable environment across the Southeast. Strong vertical shear will be available across the area with the best locations across the northwest. Here we could see 0 to 6 shear around 60 kts, 0 to 1 km helicity around 300, bulk shear of 50 to 55 kts. Mid-level lapse rates will support the threat as well along with a strong LLJ working into the area. Forecast soundings and hodographs support supercell environments during the day as well. Will continue with the severe weather threat on Monday/Monday night, including the threat for tornadoes. Adjusted the timing only a touch to be a little later. Much more on this over the next few runs. Dry weather returns on Wednesday behind the cold front, with highs in the upper 40s and low 50s. 16 && .AVIATION... 06Z TAF Discussion. The previous terminal forecast trend was kept intact for this issuance. The showers and thunderstorms have mostly exited at this time and have only mention of -dz. The main challenge this period will be the low clouds and vis and how long the restrictions hold. Will keep IFR/LIFR ceilings/vis at most locations through 14-16z and it is possible that conditions bottom out on the low side for a time. Improved the ceilings and vis to MVFR between 15-19z and held them the remainder of the period. Several guidance indicators have the ceilings becoming VFR and believe this may be short-lived if it occurs at all. Leaned pessimistic at this time. Isentropic ascent ahead of the trough and north of a surface front will keep clouds IFR/LIFR for the most part the next several hours. A strong inversion in the soundings will help trap the moisture low to the ground. Although ceilings and vis may bounce around the next 6 hours or so, expect prevailing IFR/LIFR. Winds will generally be light and variable but trending toward the west within the next several hours. On Saturday, west winds around 8kts are expected. 75 && .FIRE WEATHER... Scattered showers and a few thunderstorms will continue this evening especially east. Most of the measurable rain will decrease from west to east later this evening. Isolated showers and areas of drizzle may linger through Saturday morning as a disturbance slides across the north. Saturday night and Sunday will be dry, but moisture will begin to increase again by Sunday night. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 42 53 36 60 46 / 20 20 0 10 20 Anniston 44 54 37 63 48 / 30 20 0 10 10 Birmingham 41 54 39 62 51 / 20 20 0 0 20 Tuscaloosa 41 57 39 64 51 / 10 10 0 0 20 Calera 43 54 38 63 50 / 20 10 0 10 10 Auburn 44 55 39 64 48 / 100 10 0 0 10 Montgomery 46 58 40 68 51 / 30 10 0 0 10 Troy 46 58 41 68 50 / 90 10 0 0 10 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$