864 FXUS64 KMOB 111111 AAA AFDMOB Area Forecast Discussion...UPDATED National Weather Service Mobile AL 611 AM CDT Sat Jul 11 2020 .AVIATION... 12Z issuance...VFR conditions prevail through the period with the exception of MVFR conditions in patchy late night/early morning fog and also possibly with some isolated convection near the coast. Northwesterly winds 5 to 10 knots today become light northerly tonight. /29 && .PREV DISCUSSION... /issued 433 AM CDT Sat Jul 11 2020/ NEAR TERM UPDATE /Now Through Sunday/...A vigorous shortwave system progresses from the Northern Plains into the interior eastern states through Sunday and slightly strengthens an upper trof pattern over the eastern states while an expansive upper ridge remains generally in place across the southwestern states into the Gulf. A weak frontal boundary will have advanced into the southern portion of the area by early this morning and continues to along the immediate coast by midday where it stalls before continuing into the near shore waters this evening. Drier deep layer air flows into the area through this afternoon within the northerly flow with precipitable water values dropping to around 1.0 inch, possibly lower. The potential for convective development looks dubious today although have opted to keep slight chance pops for this afternoon along and south of a line from Wiggins, Mississippi to Mobile to Valparaiso, Florida where the weak frontal boundary and the sea breeze may manage to generate a few showers and storms. The frontal boundary returns slowly northward into the central portion of forecast area on Sunday aided by a weak sea breeze circulation while increasing deep layer moisture works into the area. A forecast uncertainty during the period is the potential for Mesoscale Convective Systems (MCS') to develop to the north and advance southeastward into the area. An MCS may develop tonight near the mid Mississippi river valley and advance southeastward, but current indications are that the MCS would weaken before reaching the forecast area Sunday morning such that have just included slight chance pops over interior areas Sunday morning. Another MCS could develop Sunday afternoon over northern Mississippi or northern Alabama and advance towards the area and have included chance pops over interior areas Sunday afternoon for this potential with slight chance pops elsewhere where the frontal boundary/sea breeze could initiate convection. A marginal risk of severe storms exists over much of the area on Sunday, generally along and north of the I-65 corridor, where MLCAPE values possibly as high as around 2500 J/kg will be present along with dry mid level air and DCAPE values around 1000 J/kg. Highs today will be mostly in the mid 90s and while dewpoints will be trending lower through the day, heat index values still look sufficient to keep the Heat Advisory in place today along coastal portions of the western Florida panhandle, extreme southwest Alabama and much of interior southeast Mississippi. Lows tonight range from the lower 70s inland to the mid 70s at the coast. Highs on Sunday will be in the mid to upper 90s, and another Heat Advisory may be required in nearly the same area as for today. A low risk of rip currents continues through the period. /29 SHORT TERM /Sunday Night Through Monday Night/...The local area remains sandwiched between an upper level ridge building east out of the Desert Southwest and an upper level trough along the East Coast. A shortwave dives through the northwest flow aloft on Sunday, which favors the development of an MCS late in the near term. While the MCS may not make it into the local area, residual cloud cover will stream into the area and an outflow from the earlier convection has the potential to spark more convection as we head into the overnight hours Sunday into early Monday. For now, keeping scattered showers and storms in the forecast for much of the area, especially across south central Alabama and northwest Florida, through the overnight hours on Sunday into early Monday. As we head through the day on Monday, scattered thunderstorm activity is expected during the heat of the day generally to the south and east of I-65 where precipitable water and instability remain higher. Further to the north and west of I-65, drier air aloft filters into the region and should act to suppress some of the convection. Showers may linger a little past sunset across south central Alabama on Monday night, but otherwise it should be a dry night. Afternoon highs will top out in the mid to low 90s on Monday. The heat index will generally range from 102°-109° on Monday (near Heat Advisory criteria yet again). The overnight lows will not provide any relief from the heat as we only fall into the mid to low 70s inland with upper 70s to nearly 80° at the beaches on both nights. 07/mb EXTENDED TERM /Tuesday Through Friday/...East Coast U.S. upper trough lifts out to the northeast Tuesday through Wednesday as the large upper ridge axis over the Southern Plains begins to extend eastward over the southeastern states. This ridge axis should be centered just to the north of the coast through late week with increasing mid layer easterly flow developing mid to late week. Weak upper level disturbances in the easterly flow aloft will aid in the development of showers and thunderstorms each day, primarily of the diurnal nature as a very moist low level airmass will remain in place and residual thunderstorm outflow boundaries and afternoon sea breezes near the coast will all act as a low level focus. Convective coverage should be rather low during the overnight hours of the extended term period. The hot and humid conditions will continue through the period as well with daytime highs ranging from lower 90s near the coast to mid (and even localized upper) 90s over the interior. This heat will only be tempered each day by the diurnally driven afternoon showers and storms. Daytime heat indices still easily in the 102 to 107 degree range during the extended period, and we may still have the potential for even higher heat indices and possible continuation of Heat Advisories across portions of the area. Overnight lows stay warm and muggy during the extended term as well, mainly in the mid 70s for inland locations and upper 70s for coastal locations. /12 MARINE...No impacts are forecast except winds and waves higher near showers and storms. /29 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...Heat Advisory from 11 AM this morning to 6 PM CDT this evening for ALZ263>266. FL...Heat Advisory from 11 AM this morning to 6 PM CDT this evening for FLZ202-204-206. MS...Heat Advisory from 11 AM this morning to 6 PM CDT this evening for MSZ075-076-078-079. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob