FXUS64 KMOB 112112 AFDMOB

Area Forecast Discussion National Weather Service Mobile AL 412 PM CDT Wed Sep 11 2024

New NEAR TERM, SHORT TERM, LONG TERM, MARINE

NEAR TERM
(Now through Thursday)
Issued at 410 PM CDT Wed Sep 11 2024

Hurricane Francine is beginning to move onshore along the central and southeastern LA coast, and will continue inland across southeast LA this evening and into MS during the late night and morning hours on Thursday. Should be weakening to a tropical storm later tonight as it moves further inland. At this occurs, we are still looking at some impacts across parts of the forecast tonight through Thursday.

Synoptic Overview...Hurricane Francine will be moving inland across southeast Louisiana this evening. The outer bands associated with Francine are just offshore of the AL and northwest FL coast at this time, and should gradually be spreading inland across most of our forecast area (especially the western half) this evening and overnight, and then persist across portions of interior MS and southwest and south central AL into the day on Thursday. A number of impacts are expected from Francine across our area and they can be noted below.

Coastal Hazards...As Francine approaches our coast and eventually moves west of our area, a significant swell packet and increasing winds will push towards our beaches. Life threatening rip currents and large surf of 5 to 7 feet possibly up to 8+ feet are expected at all area beaches. On top of large surf, minor to moderate coastal flooding is expected. As typical when these systems undergo what we call extra tropical transition, the wind field expands and in this case a rather stout 50 to 60 knot 850 mb southerly jet will overspread coastal Alabama by early Thursday morning. Strong southerly winds should be able to mix down to the surface resulting in water surging up Mobile Bay. This push will also coincide with the normal high tide cycle (which will also be around the time of the morning commute on Thursday), resulting in minor to potentially moderate coastal flooding in low lying areas of coastal Alabama including Mobile Bay. Water levels of 2 to 4 ft above normally dry ground will be possible in the Mobile Bay area, and a Coastal Flood Warning is now in effect for the Mobile Bay Region.

At around 3 feet inundation, much of the US 90/98 Causeway (both lanes), from just west of Battleship Park through the I-10 Interchange area, all the way east to near Mayer Park is flooded and closed to traffic with several feet of water on the lanes in some locations. Some shoreline areas and shoreline streets to the east of Water Street begin to flood. Portions of Conception Street near Three Mile Creek and parts of Telegraph Road near the Industrial Canal can flood. Also at around 3 feet inundation, flooding along Dauphin Island Parkway on the north side of the Dog River Bridge becomes more extensive with the roadway often becoming impassable.
At Fort Morgan Road between mile markers 4 and 6 become flooded.
Down on Dauphin Island at these water levels portions of Bienville Blvd on the west end of Dauphin Island could see flooding, with several feet of water on portions of the Blvd.

Tornadoes...Concern continues to increase with the tornado potential with this system. There is already a Tornado Watch in effect this afternoon for our western Gulf zones, and Watches will likely be spreading inland across much of our area overnight. After the system makes landfall, dry air will quickly wrap around the southern side of the system. A rather impressive theta-e gradient will surge northward along the eastern side of the system providing a focus for storms along an arching band that will likely progress across our forecast area late tonight into early Thursday morning. With some of that drier air aloft, instability looks to be on the higher side for a tropical system. With increased instability and the usual intense shear associated with the eastern side of a tropical system, the overall environment seems rather ripe for tornadoes associated with the outer bands. The threat will likely begin along the immediate coast as early as this evening and then move inland through Thursday morning.

Heavy Rainfall...While dry antecedent conditions might limit the flooding potential across the area, rainfall totals are expected to reach around 4 to locally 6 inches across southeastern Mississippi, coastal Alabama and parts of the northwestern Florida Panhandle.
Locally higher amounts could be possible if training bands set up, and this could result in localized flooding. The remainder of the area (primarily interior sections of southwest and south central Alabama) is expected to see widespread rainfall totals of 2 to 4 inches, with maybe some locally higher amounts possible. In general, rainfall totals of these amounts would likely just help alleviate drought, but heavy enough rainfall in our urban areas (especially in portions of southeast MS, coastal AL and the western FL panhandle)
could result in some minor flooding.

Wind...Lastly, gusty winds will be possible tonight through Thursday morning, especially over the western half of our forecast area. A Tropical Storm Warning is in effect for all of our southeast MS counties as well as our coastal AL counties. Tropical storm conditions are expected in those areas late this evening and overnight with gusts of 45 to 50 mph possible. We do also expect to see some potential gusts in the 30 to 40 mph range even into the western Florida Panhandle and interior southwest and south central Alabama tonight into Thursday, and a Wind Advisory has now been issued for those areas. These winds could help bring down trees and power-lines, especially across interior southeast Mississippi where soils will likely be most saturated due to the localized heavy rain in those areas.

Once Francine starts to depart the area on Thursday, things should quickly ramp down as the upper trough slowly sweeps across the area.
Be sure to remain weather aware throughout the week as the forecast is likely to change and update with time. DS/12
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