Area Forecast Discussion
Issued by NWS Mobile, AL

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000 FXUS64 KMOB 211147 AFDMOB Area Forecast Discussion National Weather Service Mobile AL 547 AM CST Sun Jan 21 2018 .DISCUSSION...
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Updated for latest aviation discussion below.
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&& .AVIATION...
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21/12Z issuance...General VFR conditions through this evening (around 22/03z), when IFR to LIFR cigs (low status) and visibilities (fog) develop. Surface winds becoming southeast around 10 knots today and continuing through tonight. 12/DS
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&& .PREV DISCUSSION...
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/issued 426 AM CST Sun Jan 21 2018/ NEAR TERM /Now Through Sunday night/...The upper shortwave noted yesterday has now moved east of the forecast area, now over northern Florida, and will move off the Atlantic coast today. As the upper low moves off to the east, upper ridging will drift east across the forecast area today. Tonight, the upper ridging is expected to move quickly off to the east of the forecast area as deep low pressure and troughing develops over the plains states. Surface high pressure located along the southeast Atlantic coast early this morning will move out over the Atlantic through tonight, while a cold front associated with the developing plains system approaches from the west. This cold front will be approaching the Mississippi River by daybreak Monday, with perhaps a few showers moving into our far western counties very late tonight as the front approaches and upper ridging weakens. Persistent low level southeasterly flow today and tonight will bring increasing moisture into the region, and this onshore flow combined with the cool near shore marine waters will likely result in some fog across the area tonight, especially over the southern locations near the coast. High temperatures today finally return to the lower 70s for most locations, except along the immediate coastal areas where the onshore flow will keep highs in the mid to upper 60s. Warmer tonight too, with lows ranging from the upper 40s over northeastern counties to the low to mid 50s elsewhere. A few upper 50s possible along the immediate coast. 12/DS SHORT TERM /Monday Through Tuesday night/...Monday through Monday night, a closed upper system moves from over the Central plains east-northeast over the Mid/Upper Mississippi River Valley before getting a more northeast push due to a building upper ridge over the western Atlantic. This system pushes a surface front across southeast Mississippi late Monday afternoon, then east of central Alabama and the western Florida Panhandle shortly after midnight Monday night. Shra/Tsra pretty much a given ahead of the front Monday afternoon into the evening hours. Biggest question is the chance of any severe. Guidance remains on the marginal side for any strong to severe (topping out around 500 j/kg). 0-3km shear is enough (200-300 m^2/s^2 in the afternoon) for some rotators. Mid/upper level support has shifted north a bit, north of the forecast area in our case. SPC continues to advertise a marginal risk of severe weather with damaging winds the primary threat and see no reason to alter this at this point, with less overlap of surface and upper ingredients than yesterday. Temps above seasonal expected Monday. With cooler air moving over the area behind the front, Monday night`s lows will see a gradient of around seasonal lows west to above east. Tuesday through Tuesday night will see a return of near seasonal temps as cooler/drier air overspreads the entire forecast area. /16 LONG TERM /Wednesday Through Saturday/...Shortwave energy moves over the Plains mid week into the weekend, pushing surface high pressure from the Plains to off the Mid Atlantic coast. This prings back southerly flow off the Gulf by friday. Moisture levels increase into the weekend until another front moves across the area Saturday night. Rain returns Friday night, with a better chance of rain Saturday. Temps moderate slowly upwards from around seasonal mid week to above seasonal with the return of southerly flow end of the week. /16 MARINE...For the most part, no hazards in the near term except for winds nearing Exercise Caution levels for the offshore Gulf Zones this afternoon. A cold front approaches the marine area from the west tonight and early Monday bringing an increased chance of showers and embedded storms, as well as an continued increase in seas associated with the increased onshore flow. The front is expected to move east across the marine area Monday night. Showers and storms ending with the frontal passage and a moderate to strong offshore flow is expected in the wake of the front Tuesday through late week. Winds and seas primarily in the Exercise Caution category ( 15 to 20 knots and up to 6 feet)through most of the week for the offshore Gulf waters, but possibly reaching Small Craft Advisory levels (20 knots plus) by weeks end as a reinforcing surge of offshore flow develops. 12/DS
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&& .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

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