Area Forecast Discussion
Issued by NWS Mobile, AL

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000 FXUS64 KMOB 190153 AAB AFDMOB Area Forecast Discussion...UPDATED National Weather Service Mobile AL 753 PM CST Sat Nov 18 2017 .DISCUSSION...
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See updated information for land areas below.
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&& .UPDATE...
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A strong cold front is fast approaching from the northwest, currently extending from near Birmingham, AL to Baton Rouge, LA. This cold front will enter into the northwest portion of the forecast area with the next hour, and move south of the Alabama coast between 11:00 and 11:30 pm, and south of the Florida coast between 11:30 pm and 12:30 am. A thin line of light to moderate rain showers ahead of the front has just entered the extreme northwest portion of the forecast area, and will move quickly to the southeast at around 35 mph across the area, exiting the extreme southeast portion of the forecast area around 1 am Sunday. No lightning has been observed in the southern extent of the line, as most of the lightning has been confined to northern Alabama. Updated the public forecasts to adjust the timing of this fast moving line, removed mention of thunderstorms, and made a few changes to the expected precipitation amounts. Brief strong north-northwest winds will occur behind the front, with gusts to near 30 mph. These winds will be marginal for a High Wind Advisory inland areas, but due to the brief nature and only reaching borderline criteria, will hold off for now. A High Wind Advisory for the coastal sections of Alabama and the western Florida panhandle remains in effect, and will begin at midnight. Updated products have been sent. /22
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&& .PREV DISCUSSION...
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/issued 554 PM CST Sat Nov 18 2017/ DISCUSSION...Updated for latest aviation discussion below. AVIATION... 00Z issuance...VFR conditions will precede a narrow band of showers along a strong cold front approaching the northern gulf coast region from the northwest. MVFR visibilities due to light to moderate rain will occur with the passage of the line between 19.03z thru 19.05z for MOB and BFM, and between 19.04z thru 19.06z for PNS. Southwest winds 9 to 14 knots will shift toward the west as the line of showers nears the TAF sites. Winds will then shift to the north-northwest on the backside of the showers, with sustained winds between 15 to 20 knots, gusting to near 30 knots. Skies will clear early Sunday morning. /22 PREV DISCUSSION... /issued 355 PM CST Sat Nov 18 2017/ NEAR TERM /Now Through Sunday/...Gusty southwest winds at 18 to 28 mph will continue across many locations of the forecast area through this evening ahead of a strong cold front approaching from the west. Latest hi res data also shows some instability or cape combined with moderate vertical shear ahead of the front through this evening. With this have mentioned a slight chance for an isolated thunderstorm tonight, occurring mainly just ahead and along the cold front as it pushes east across the forecast area later this evening. Gusty straight line winds, possibly from 30 to 40 mph with occasionally lightning, will be the main concerns with some of the stronger convection just ahead and along the front. In the wake of the front expect wind gusts ranging from 18 to 28 mph for most inland areas and from 28 to 38 mph further south along the immediate coast. As result a wind advisory is now in effect for the immediate coastal areas of Alabama and Northwest Florida from midnight tonight through 9 am Sun morning. Northerly winds will slowly diminish through late Sun afternoon. Expect mostly cloudy skies with mild temps this evening followed by good clearing from west to east and much colder temps in the wake of the front early Sun morning through Sun afternoon. Lows tonight will fall to the low to mid 40s for most inland areas generally north of a line from Andalusia to Mobile in Alabama and the upper 40s to lower 50s further south to the immediate coast. Highs Sun will range from the upper 50s to lower 60s generally along and north of the I-10 corridor and the lower to middle 60s further south to the immediate coast. 32/ee SHORT TERM /Sunday night Through Tuesday night/...A longwave trof over the easternmost states moves off into the western Atlantic Sunday night into Monday while another amplifying upper trof advances across the Plains. This next upper trof continues to amplify while moving into the eastern states through Tuesday night. A dome of cold surface high pressure builds into the region Sunday night (in the wake of a cold frontal passage in the NEAR TERM period), and with winds becoming calm or light along with an open radiative window (precipitable water near 0.1 inch - very low), the potential for a light freeze exists for interior areas. Have issued a Freeze Watch for late Sunday night into early Monday morning from approximately New Augusta, MS to Luverne, AL where temperatures drop to freezing or slightly below. May see a few patches of freezing temperatures in normally colder spots further south and the Freeze Watch may need to be expanded further southward on later shifts, but for now expect lows in the mid 30s for the remainder of the area except for upper 30s at the coast. The surface high shifts eastward and well off into the western Atlantic through Tuesday while a surface low well to the north brings a cold front across the Plains to near the lower Mississippi river valley. A light southeasterly flow develops on Monday and promotes a modest increase in deep layer moisture ahead of the front, with precipitable water values increasing to 0.5-0.75 inches or about to 60 to 90% of normal. May see some isolated patches of rain generally over the coastal counties Tuesday into Tuesday night due to modest isentropic lift followed by the weak front moving through, but otherwise dry conditions are expected. Highs on Monday will be in the lower 60s with highs on Tuesday ranging from the mid 60s inland to upper 60s closer to the coast. Lows Monday night range from near 40 inland to the mid to upper 40s at the coast, then lows Tuesday night will be in the mid 40s inland with upper 40s at the coast. /29 LONG TERM /Wednesday Through Saturday/...A longwave upper trof over the eastern states weakens significantly on Friday as a powerful embedded shortwave ejects off into the Atlantic, but then another strong shortwave advances across the Plains on Saturday and reforms the longwave trof pattern, albeit a bit further to the west. A surface high builds into the region through Thursday in the wake of a frontal passage which occurred Tuesday night then shifts gradually eastward through Saturday with a light northwesterly flow prevailing over the forecast area through Friday then switching to a light southerly flow on Saturday. With the absence of any forcing mechanisms and deep layer moisture also remaining too limited to support much in the way of precipitation anyway, will continue with a dry forecast through the period. Highs on Wednesday range from the lower 60s well inland to the mid 60s for much of the remaining portion then trend cooler for Thursday with highs ranging from the mid 50s well inland to near 60 close to the coast. A warming trend then ensues Friday into Saturday with highs for Saturday in the upper 60s to near 70. Lows Wednesday night and Thursday night range from the mid 30s well inland to the lower 40s at the coast then trend warmer for Friday night with lows around 40 inland and in the mid 40s closer to the coast. /29 MARINE...A moderate to strong southwest to west wind with continue over the marine area through this evening ahead of a strong cold front approaching from the west. The front will move across the marine area from midnight tonight through about sunrise Sun morning with possible frequent gusts to Gale force occurring mostly over the open gulf waters of Alabama from 0 to 60 nm out and the open gulf waters of NWFL from 20 to 60 nm out from midnight tonight through about 9 AM cst Sun morning. As a result a Small Craft Advisory is in effect for the entire marine area this evening, upgrading to a Gale warning in the areas mentioned above Sun morning, followed by a Small Craft Advisory for the entire Marine area through late Sun afternoon. Seas will build to 5 to 7 feet out to 20 nm and 6 to 9 feet from 20 to 60 nm out through Sun afternoon. Northerly winds and seas will gradually subside Sun night through early Mon as a broad surface ridge of high pressure builds from the lower Mississippi River valley to the Southeast states through Mon afternoon. A light east to southeast wind is expected by Mon afternoon continuing through Mon evening then shifting mostly north to northeast and building Tue through Thu in response to another surge of colder air moving south over the northern and central gulf late Tue through the remainder of the week. As result a Small Craft Advisory may be needed for some areas later in the week. 32/ee
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&& .MOB WATCHES/WARNINGS/ADVISORIES... AL...Freeze Watch from late Sunday night through Monday morning for ALZ051>058. Wind Advisory from midnight tonight to 9 AM CST Sunday for ALZ263>266. FL...Wind Advisory from midnight tonight to 9 AM CST Sunday for FLZ202-204-206. MS...Freeze Watch from late Sunday night through Monday morning for MSZ067-075-076. GM...Small Craft Advisory until midnight CST tonight for GMZ650-670- 675. Small Craft Advisory from 9 AM to 6 PM CST Sunday for GMZ650-670- 675. Gale Warning from midnight tonight to 9 AM CST Sunday for GMZ650- 670-675. Small Craft Advisory until 6 PM CST Sunday for GMZ630>635-655. && $$ This product is also available on the web at: http://weather.gov/mob

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