SHORT TERM
(Thursday through Friday night)
Issued at 355 AM EDT Wed Sep 18 2024

Troughing will lift slowly northeastward across the Mid-Atlantic region on Thursday, nudging a stubborn frontal boundary southeastward across inland portions of southeast GA by late afternoon as deep-layer flow veers to northwesterly. Enough moisture may be in place for isolated to widely scattered afternoon and early evening convection to develop along the frontal boundary as it crosses coastal southeast GA and the rest of northeast and north central FL. Highs on Thursday will climb to the upper 80s and lower 90s, with maximum heat indices peaking in the 95-100 degree range during the afternoon hours.

Convection that manages to develop during the afternoon hours should push offshore of the northeast FL coast towards sunset, with fair skies expected area-wide overnight. A drier and more subsident air mass may allow for areas of locally dense fog to develop by early Friday morning, especially across inland portions of southeast GA and the Suwannee Valley. Lows will fall to the upper 60s inland, ranging to the low to mid 70s at coastal locations.

Troughing will persist along the U.S. eastern seaboard on Friday, while stout ridging aloft resides over Texas. This weather pattern will result in deep northerly flow across our area, and our local pressure gradient will begin to tighten during the afternoon hours as strong high pressure over eastern Canada begins to wedge down the spine of the Appalachians, resulting in breezy onshore winds developing along the I-95 corridor during the afternoon hours. This breezy and increasingly convergent low level flow could develop a few showers and thunderstorms along the I-95 corridor in northeast FL early in the afternoon, with activity then spreading south-southwestward towards north central FL during the mid to late afternoon hours. Dry weather is expected elsewhere, with inland highs again climbing to the upper 80s to around 90. Breezy onshore winds will keep coastal highs in the mid to upper 80s.

Breezy onshore winds will continue at coastal locations on Friday night, keeping lows in the low to mid 70s. Winds at inland locations will decouple by late in the evening, with a seasonably dry air mass and fair skies allowing lows to fall to the mid and upper 60s by sunrise on Saturday.



LONG TERM
(Saturday through Tuesday)
Issued at 355 AM EDT Wed Sep 18 2024

Troughing aloft will be slow to depart the Mid-Atlantic and New England coasts this weekend, while stout ridging centered over the southern Plains begins to flatten as it expands eastward along the northern Gulf coast.
Surface low pressure may strengthen well off the Mid-Atlantic coast as it meanders this weekend, while strong high pressure over Atlantic Canada continues to wedge down the U.S. eastern seaboard. This weather pattern will keep a tight local pressure gradient in place through early next week. This flow may advect isolated to widely scattered showers and possibly a few embedded thunderstorms onshore along the northeast FL coast, with activity potentially shifting inland towards north central FL during the afternoon hours each day.
A seasonably dry and subsident air mass will prevail for southeast GA and the Suwannee Valley, where a dry stretch of weather is expected through at least Monday.

Breezy onshore winds during this period should keep coastal highs in the low to mid 80s, with mid to upper 80s forecast for most inland locations. Highs may trend down a few degrees by Monday across inland southeast GA as high pressure wedges into the Deep South. The drier and more subsident air mass will allow lows to fall to the mid to upper 60s at most inland locations through the period, while onshore winds keep coastal lows in the low to mid 70s.

Long term guidance remains in overall disagreement on the potential for tropical low pressure consolidating over the northwestern Caribbean Sea this weekend and early next week as the Central American Gyre (CAG) spins up. This is a climatologically favored area for tropical cyclone formation as we move into late September, so the National Hurricane Center will continue to closely monitor the potential for tropical development later this weekend and early next week over the northwestern Caribbean Sea.

AVIATION
(06Z TAFS)
Issued at 128 AM EDT Wed Sep 18 2024

A lone storm over KJAX moves away within the next hour. Potential for early morning fog developments by around 08-12z for inland sites, reducing visibility to MVFR and IFR levels and then lifting by around sunrise. West-southwesterly winds around 5 kts develop today. The Atlantic sea breeze shifts inland to the I-95 corridor shifting winds to southeasterly. Scattered showers and storms will be possible in the afternoon across the TAF sites. A couple of storms may be strong at the KJAX, KCRG and KSGJ when the sea breezes collide.

MARINE
Issued at 355 AM EDT Wed Sep 18 2024

A weak frontal boundary and pressure pattern will linger over the region through the middle of the week. The sea breeze returns with afternoon wind shifts to onshore for the nearshore waters through Thursday. A frontal passage is expected late this week with high pressure building down the eastern seaboard by this weekend. This will lead to an increase in Northeast winds by Friday and into the weekend with Small Craft Advisory headlines possible.

Rip Currents: Moderate risk of rip currents continues for area beaches through Thursday.

HYDROLOGY
Issued at 355 AM EDT Wed Sep 18 2024

Have expired the Coastal Flood advisories along most of the NE FL Atlantic coast and downgraded Duval county to an advisory with lighter onshore winds anticipated for this afternoon. Lingering trapped tides and higher astronomical tides will continue minor to moderate coastal flooding within the St. Johns through at least mid-week. The moderate flooding will be mainly confined to areas south of Jacksonville. The higher tides with this full moon cycle will continue into September 26th with the peak levels between Sept. 19th and 21st. Will likely need to reissue a Coastal Flood Advisory along the Atlantic coast for Friday into the weekend with the high tides and a surge of northeasterly winds.



PRELIMINARY POINT TEMPS/POPS
AMG 86 69 88 67 / 40 10 10 10 SSI 84 72 87 73 / 50 20 20 10 JAX 88 72 90 70 / 60 40 20 10 SGJ 88 73 89 74 / 70 30 20 20 GNV 89 71 90 69 / 40 10 20 10 OCF 91 72 90 70 / 30 10 20 20

JAX WATCHES/WARNINGS/ADVISORIES
FL...Coastal Flood Warning until 5 AM EDT Friday for FLZ033-038-132- 137.

Coastal Flood Advisory until 5 AM EDT Friday for FLZ125-225-325.

GA...None.
AM...None.