Area Forecast Discussion
Issued by NWS Mobile, AL

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000 FXUS64 KMOB 271040 AFDMOB Area Forecast Discussion National Weather Service Mobile AL 540 AM CDT Tue Jun 27 2017 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION... 12Z issuance...Mostly VFR through the period as surface winds veer from light northeasterly to more easterly by this TAF period`s end. Mid and high clouds will continue streaming across the area. An isolated thunderstorm is possible from 27.21 UTC to 28.01 utc. /23 JMM && .PREV DISCUSSION... /issued 349 AM CDT Tue Jun 27 2017/ NEAR TERM /Now Through Tuesday night/...Early this morning a stationary front was located offshore with developing precipitation along it across southern LA east to well south of the Alabama coast. Light NE surface wind flow was in progress. Deep layer moistening is in store next two days as upper tropospheric wave moves east out of TX today and beings to reflect down into the mid-troposphere. This happens in the well know `break between two ridges.` The approach of the wave excites the lower tropospheric winds to veer to a more SE direction by tonight. As far as thunderstorm development today, expect them to mostly remain offshore with the exception of the immediate coast. The light E->NE boundary layer wind flow will oppose the developing seabreeze and with the moisture return, so there may be some very isolated deep convection from 20Z-01Z, or so. Any deep convection will diminish during the early evening, but thunderstorm coverage will be above average however over the AL coastal waters tonight as return flow begins and the aforementioned upper low shear zone orients itself from SSW to NNE across our area. /23 JMM SHORT TERM /Wednesday Through Thursday night/...Surface high pressure over the Mid Atlantic states will slowly migrate offshore by mid day Wednesday. Moisture levels begin to increase with southerly return flow around the southwestern periphery of the surface high. Accordingly, pops will increase into the chance category for Wednesday afternoon. Southerly flow will be firmly in place Thursday morning with increasing deep layer moisture. Precipitable water values will be above two inches with some areas approaching 2.2 inches. A subtle weakness in the mid level height field between a strong ridge over the southwestern Atlantic and another over northern Mexico will provide modest support for upward vertical motion across the area, which, when combined with ample deep layer moisture, will result in likely pops for most areas Thursday afternoon. Showers and storms will likely be ongoing near and offshore Thursday morning and will spread inland as the day progresses. Temperatures will be held down Thursday afternoon due to increased coverage of showers and storms and associated cloud cover, generally low 80s are expected with a few mid 80s across our northern counties where storm coverage will be slightly reduced. Low temperatures Thursday into Friday will be in the low 70s with mid 70s at the beaches. 05/RR LONG TERM /Friday Through Monday/...Not much change on the large scale pattern for Friday with a continued weakness in the mid level height field near the area and copious Gulf moisture in place. Will show likely pops for Friday afternoon into the evening. Coverage should decrease a few hours after sunset but some showers and storms will be possible into the overnight. Temperatures will be slightly warmer on Friday with mid 80s across the area. Continued warm overnight temps with low to mid 70s expected. The weakness between the two ridges will begin to fill on Saturday and Sunday leading to lower coverage of showers and storms for the weekend. Absent much in the way of mid and upper level support, storm initiation will likely be closely tied to mesoscale boundaries (Gulf/bay breezes and old outflow boundaries from previous convection). This pattern will continue into the first part of the work week with generally climatological pops expected. With decreased shower and storm coverage we will see an uptick in afternoon high temperatures with mid to upper 80s for most Saturday with perhaps a few 90s inland by Sunday and Monday afternoons. 05/RR MARINE...Today a light NE wind flow becomes more easterly. By early Wednesday, surface winds will become southerly and increase and seas will then once again build solidly to around 2 feet wednesday night and early Thursday. Also shower and thunderstorm coverage increases from the southwest. Waves continue around 2 feet Thursday with an increase to 3 feet in our southwestern zones late Thursday into Friday with continued southerly flow. Greatest coverage of showers and storms will come Thursday and Friday before backing off modestly for the weekend period. 23/05 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: is the U.S. government's official web portal to all federal, state and local government web resources and services.