County monitoring tropical depression today


300-BEACH-STORM_2364National Weather Service Jacksonville has informed Historic City News that St Johns County Emergency Management is at “Level-3 Monitoring” status this morning as a result of a low pressure front developing to our east, over the Atlantic Ocean.

Marine and coastal impacts are likely late Tuesday through Wednesday from these low pressure activities if they continue.

Synopsis and Forecast Confidence:

An area of low pressure was about 200 miles ESE of St Augustine early this morning. Conditions are still favorable for this low to develop into a tropical system (likely a tropical depression) over the next several days as remains east of the Florida Atlantic Coast, and then tracks northward track toward the Carolinas after mid-week. Forecast models have come into some agreement with this low through early Tuesday, then, however, continue to diverge with the strength and track of the low as it begins a northward trek late Tuesday through Wednesday. This is the time period when the system will near the local coastline.

Impacts and Timing:

Based on the latest forecast, the greatest impact from this system will likely be over the adjacent Atlantic waters and along the immediate coastline Tuesday and Wednesday, with conditions improving Thursday as the low tracks farther NNE away from the region.

Marine Impacts:

NNE winds will increase into the 15-20 kt with combined seas of 3-5 ft expected to build to 4-6 ft offshore today as swells increase. As the low drifts farther south of the waters Mon and Tue, wind speeds may decrease into the 10-15 kt range then increase again Tue night-Wed as the low begins lift northward along the Florida Atlantic coast. At this time, winds 20 kts or less are forecast through the upcoming week with seas 6 ft or less. These magnitudes could change if the storm track shifts or the storm strengthens. Mariners are encouraged to continue to closely monitor this system.

Coastal Impacts:

As onshore flow increases today through midweek and swells build, the chance of dangerous rip currents along the coast will also increase. Today there is a moderate risk of rip currents, with at least a moderate risk of rip currents expected to continue through midweek.

Thunderstorm/Rainfall Outlook:

Coast: Below normal rain chances in the 20% or less range today. As the storm develops tonight into Tuesday, onshore winds will bring a low 20-30% chance of showers with the best chances south of St Augustine through midday Tuesday. Rain chances increase late Tue night through Wed into the 50-60% range as the storm drifts northward, likely paralleling the Florida Atlantic coast with squalls brushing the coastline and making some inland penetration. Squalls are the outer rain bands of the storm, and brief locally heavy rainfall as well as gusty winds of 25-40 mph will be possible in the rain bands as well as isolated thunderstorms.

Inland: Below normal rain chances in the 20-30% range are expected during the afternoon and evenings, except for a corridor of higher rain chances in the 30-40% during the late afternoon and early evening near the I-75 corridor today and again Tuesday since the area will be on the drier, west side of this low pressure system. Therefore, rainfall is not a major concern at this time. Wednesday, moisture is expected to increase as the low begins to track northward, possibly paralleling the local coastline, and rain chances increase into the 30% range for SE Georgia and 40% for inland NE Florida.

Once again, this forecast is highly dependent on the eventual track and strength of this developing area of low pressure.

Additional Information Resources:

NWS Jacksonville Twitter: