097 FXUS64 KMOB 211355 AAB AFDMOB Area Forecast Discussion...UPDATED National Weather Service Mobile AL 855 AM CDT Sun Jun 21 2020 .UPDATE...Have updated to include isolated showers over the near shore Alabama waters where some resilient convection has continued to linger. Made other minor adjustments. /29 && .PREV DISCUSSION... /issued 645 AM CDT Sun Jun 21 2020/ AVIATION... 12Z issuance...VFR conditions were present at issuance and will prevail through the TAF period. Increasing clouds and chances for isolated to scattered showers and storms are anticipated this afternoon, generally north of I-10; however, greater chances exist for areas along and north of Highway 84. Shower/storm activity will then decrease through this evening, with dry conditions returning for tonight. Shower and storm chances will increase yet again through Monday morning. At this point, did not include mention of any showers or storms in the TAFs due to uncertainty in whether the TAF sites would be affected. This will continue to be monitored. Outside of any storms, winds over inland areas will become southerly and be around 5 knots or less through this afternoon. Winds near the coast will also become southerly, but increase to be between 5-10 knots as a sea breeze develops this afternoon. Light, southerly winds are then expected area-wide this evening through tonight. /26 PREV DISCUSSION... /issued 404 AM CDT Sun Jun 21 2020/ NEAR TERM UPDATE /Now Through Monday/...The near term will begin as an upper level trough continues to make its way over the northeast CONUS and off towards the Atlantic. Meanwhile, the brief ridging that affected our area Saturday will move east as a shortwave trough traverses the Mississippi Valley. Expecting this shortwave to progress over the region this afternoon and over the Appalachians on Monday; however, the main trough over the central CONUS will start to amplify and a larger shortwave will move along the flow over the region Monday afternoon. At the surface, high pressure will maintain its hold over the northern Gulf of Mexico through this afternoon. At the same time, a boundary will affect the lower Mississippi and Tennessee valley regions through this afternoon (coincident with the upper level shortwave). By this evening, the high pressure will begin to shift east towards the coast of Florida and eventually make its way to be just off the west coast of southern Florida by Monday evening. During this time, a cold front will begin to progress over Illinois, southeast Missouri, and southeast Oklahoma heading towards the southeast CONUS. Dry conditions will persist through this morning. With the passage of the shortwave aloft as well as the expected development of a sea breeze this afternoon, scattered showers and thunderstorms are possible (mainly north of I-10 and particularly north of Highway 84). Shower and storm activity will then decrease through this evening, with dry weather returning tonight. Rain chances will start to increase Monday morning with the advancement of the second shortwave, with scattered to numerous showers and storms anticipated for most areas Monday afternoon. Models indicate PWATs between 1.7 to over 2.0 inches by Monday afternoon. In addition, DCAPE values are shown to be between 900-1000 J/kg, with SB/MLCAPE between 2000- 3000 J/kg as well. Low level lapse rates are also fairly steep, with values between 8.4-9.2 C/km. Given all of this, elevated microburst potential is expected Monday afternoon. Highs today will be in the lower to mid 90s north of I-10 and in the mid to upper 80s south. Lows tonight will be warm, generally in the lower 70s north of I-10 and in the lower to mid 70s for areas south. Highs Monday will be a hair cooler, but will still mainly be in the lower 90s over inland areas and in the upper 80s right along the coast. Lastly, a LOW RISK of rip currents exists today through Monday. /26 SHORT TERM /Monday night Through Tuesday night/...A deep upper trough pushes east from the upper Midwest over the Great Lakes through the short term, with its southernmost extension reaching portions of the lower Mississippi River Valley and Deep South. At the surface, high pressure over the western Atlantic and eastern Gulf maintain onshore flow across the Gulf coast, which continues to transport Gulf moisture into the region as PWATs rise to around 2 inches. Weak forcing associated with the upper trough, in combination with the increasing deep-layer moisture content, will support widespread shower and thunderstorm activity across the local region Tuesday afternoon and evening. The greatest rain chances (~80%) remain along and north/west of the Interstate 65 corridor, though even areas farther east and south will see at least a 60% chance. This greater coverage in showers and storms should act to mitigate daytime heating and limit instability during peak heating hours. However, still cannot rule out gusty winds and frequent lightning in any heavier storms that develop. Low temperatures both Monday and Tuesday nights remain in the low to mid 70s inland and upper 70s along the coast. High temps on Tuesday reach the upper 80s across much of the area. /49 EXTENDED TERM /Wednesday Through Saturday/...A continued trend towards a period of unsettled weather for the middle of the week appears likely. Ensemble guidance along with their respective operational runs continue to suggest large scale troughing developing across the eastern half of the United States. Both the EPS and GEFS are suggesting mid level height anomalies approximately one standard deviation below normal. Lower mid level heights combined with signals for a deeply moist airmass with PWATs approaching 2 inches advecting northward under broad southerly flow, expect above normal probabilities for precipitation for both Wednesday into Thursday. In addition, it appears that a surface frontal boundary will stall across the region through the end of the week and provide the low level focus for convective development. Daytime high temperatures should remain below average due to the increased cloud cover and storm coverage. Overnight lows will remain near seasonal averages along with persistent high humidity levels through the period. Upper heights begin to build back over the Gulf Coast from the western Atlantic by next weekend. This should support reduced storm coverage and increasing daytime temperatures. In addition, we will need to monitor the Saharan dust plume (SAL event) currently approaching the Lesser Antilles in the Eastern Caribbean Sea. This plume is forecast by the NASA GEOS model to advect around the building western Atlantic ridge and advance across portions of the northern Gulf Coast by next weekend. These events tend to suppress overall convective coverage but may also enhance storm intensity due to the presence of dry air aloft. This will be something to watch as we get towards the end of the extended forecast period. /JLH MARINE...Locally higher winds and waves are possible near isolated to scattered showers and thunderstorms. Otherwise, no impacts are expected. /26 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob