Keystone Heights, FL 32631 Weather

Key messages

For the latest NE FL and SE GA Daily Key Messages please visit: https:/www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

- Coastal and Marine Hazards Continue into the Upcoming Weekend. Coastal Flood Warning Moderate Flooding along Portions of the Northeast FL Atlantic Coast & Intracoastal Waterway through Early this Afternoon. Extended Duration of Moderate Tidal Flooding within the St. Johns River Basin. Coastal Flood Advisory for Coastal Southeast GA and Coastal Nassau County FL for Minor Flooding Around Times of High Tide. High Surf Advisory through Late Thursday Night at Northeast FL Beaches. High Rip Current Risk at all Area Beaches through the Upcoming Weekend. Small Craft Advisories for the Atlantic Waters through Friday and Saturday

- Isolated Thunderstorms Possible on Sunday and Sunday Night

Near term

Main Highlights:

- Coastal Flood Warnings Remain in Effect through early this Afternoon for Most of the Northeast FL Atlantic Coast and Intracoastal Waterway. Coastal Flood Advisories are now posted along the Southeast GA Atlantic Coast and portions of the Northeast FL Atlantic Coast.

- Coastal and Marine Hazards Continue into the Upcoming Weekend. Extended Duration of Moderate Tidal Flooding within the St. Johns River Basin Continues. High Surf Advisory Continues through Tonight at the Northeast FL Beaches. High Risk for Rip Currents at all Area Beaches through the Upcoming Weekend. Additional Beach Erosion is Expected around Times of High Tide. Small Craft Advisory for the Atlantic Waters through at least Friday.

Early morning surface analysis depicts strong high pressure (1032 millibars) now centered east of coastal New England, with this feature extending its axis southwestward across the southern Appalachians. Meanwhile, a wavy and stationary frontal boundary was stretching from Cuba east-northeastward across the northern Bahamas. Aloft: ridging positioned over the southern Gulf continues to nudge its axis northeastward across our region, while troughing previously cutoff over the Bahamas was lifting northeastward and further away from our region. Latest GOES-East derived Total Precipitable Water imagery indicates that deep onshore flow was scouring out the seasonably dry air mass that was in place across inland southeast GA and the northern Suwannee Valley, where PWATs have risen slightly to the 0.75 to 1 inch range, while values elsewhere were now in the 1- 1.5 inch range. Low stratus cloud cover continues to expand in this increasingly moist air mass for locations south of Waycross, with breaks in this stratus over southern portions of the St. Johns River basin. Temperatures at 08Z were mostly in the low to mid 60s across inland southeast GA and the Suwannee Valley, ranging to the upper 60s and lower 70s elsewhere. Dewpoints ranged from the upper 50s for locations north of Waycross in southeast GA to the 60s elsewhere.

Low stratus cloud cover should continue to overspread locations to the south and east of Waycross through the early morning hours. This cloud cover should lift to a cumulus deck by the late morning hours, with additional marine stratocumulus cloud cover advecting onshore through tonight as weakening high pressure over the southeastern states and stubborn coastal troughing situated over our near shore Atlantic waters maintain breezy northeasterly low and mid level flow across our area. This convergent flow and ample moisture will likely bands of scattered to numerous showers through tonight over the Atlantic waters that will advect onshore across coastal northeast FL, mainly for locations south of Mayport. This activity should move across the St. Johns River to the south of Jacksonville later this morning, perhaps approaching locations along and east of the U.S. Highway 301 corridor in northeast and north central FL this afternoon and evening. Plenty of cloud cover and breezy northeasterly winds will keep coastal highs mostly in the mid to upper 70s, with breaks in the cloud cover late this morning and early this afternoon boosting inland highs to the lower 80s, with a few mid 80s possible across north central FL.

Marine stratocumulus will continue to stream onshore across our region tonight, which should limit the potential for lower stratus clouds to redevelop across our area overnight. Bands of isolated to widely scattered showers may continue to advect across coastal northeast FL and southern portions of the St. Johns River basin, mainly for locations from St. Augustine to Green Cove Springs and points southward. Winds will decouple at inland locations in southeast GA and the northern Suwannee Valley overnight, with breaks in the stratocumulus allowing lows to fall to the upper 50s and lower 60s. Lows elsewhere will remain in the mid and upper 60s, except around 70 at the northeast FL beaches.

Short term

Main Highlights This Period: Friday through Saturday Night

- Coastal Hazards Continue, Especially for the St. Johns River

- Thunderstorm Potential for Northeast FL Saturday Night

Onshore flow will remain rather unchanged and "status quo" on Friday with similar breezy flow and occasional coastal showers similar to the previous several days. The primary changes will come Friday Night and into Saturday, as a backdoor type of cold front quickly moves southward across our region, and a "re-enforcing" ridge of high pressure builds across the southeastern states in its wake. This will enhance the flow a bit on Saturday for northeast FL but especially southeast GA where this flow has been lighter on average. Isolated to scattered showers near the coast and portions of northeast FL will also persist, as temperatures also drop a bit as well with mid to upper 70s more common overall after more of a range of mid 70s to low 80s on Friday. A few showers will also be possible even into inland areas during the day on Saturday as well, as the front quickly drops southward. Instability will be limited, and therefore thunderstorms do not appear likely.

Things start to get more active Saturday Night as guidance is in good agreement with respect to some shortwave energy moving into northeast FL and southeast GA. This energy will interact with the now nearly stationary front just south of our region, and combined with the beginnings or moisture advection into our southern counties will result in an increase in shower activity as well as some isolated to widely scattered thunderstorm potential. This will spread northward into Sunday, though more on that below.

Regarding Coastal Hazards: Most if not all of the ongoing hazards are expected to continue Friday and into the weekend, especially within the St. Johns River as higher water levels will remain the most trapped. We will continue to evaluate levels over the coming days, but at least Coastal Flood Advisories are likely to continue area-wide, with Coastal Flood Warnings possible to continue for at least upstream portions of the St. Johns River.

Long term

Main Highlights This Period: Saturday through Wednesday

- Coastal Hazards Likely to Continue through at Least the Weekend

- Thunderstorm Potential Sunday

Sunday is expected to be a warmer, more humid and active day as short wave energy moves through the region, resulting in more widespread showers and t'storms, especially across northeast FL closer to the stationary boundary just south of the area. Onshore flow will then return for at least Monday and into Tuesday as high pressure to our northeast moves very little, before a much stronger front approaches the area around Wednesday/Wednesday Night. Though we will be moving away from the full moon, tidal flooding is likely to continue into the long term, especially for portions of the St. Johns River where elevated water levels will have the hardest time receding. Temperatures will start the period near normal Sunday and Monday before rising towards above normal next week.

Aviation

MVFR to IFR ceilings will continue through late morning/early afternoon, with light showers likely passing by SGJ throughout the day. Northeasterly surface winds will increase to around 10 knots by 14Z at the inland terminals and to around 15 knots and gusty at the regional terminals towards 18Z. Speeds will then diminish to around 10 knots for the inland terminals and 10-15 knots at the coastal terminals after 00Z Friday.

Marine

Strong high pressure stretching from coastal New England southwestward through the southern Appalachians will shift southward while gradually weakening through tonight. Meanwhile, a trough will remain situated across the Bahamas and southeast Florida through tonight. High pressure will continue to wedge down the southeastern seaboard, creating gusty north- northeasterly winds and Small Craft Advisory conditions through Friday. Otherwise, coastal troughing will remain situated over our near shore waters through early next week, with this feature generating scattered to numerous showers through Friday.

Another strong high pressure center building southeastward from the Upper Midwest on Friday will reach the Mid-Atlantic coast by Sunday, with this feature wedging down the southeastern seaboard this weekend and early next week. Although a brief lull in winds and seas is possible late Friday and early Saturday, easterly winds may strengthen to Small Craft Advisory levels this weekend. A wavy stationary frontal boundary lifting slowly northward across the Florida peninsula this weekend may generate numerous showers and a few embedded thunderstorms on Sunday and Monday across our local waters.

Rip Currents / High Surf: High Surf Advisories remain in effect for the northeast FL beaches through Thursday night, where breakers of 6 to 8 feet will prevail. Breakers of 3 to 6 feet will prevail at the southeast GA beaches through Friday. These elevated, rough surf conditions will maintain a high risk of deadly rip currents at all area beaches through the upcoming weekend, and additional beach erosion is likely to occur around times of high tide.

Fire weather

Onshore flow will persist through the rest of the week and into the weekend as well. Showers will continue to occasionally move onshore through Friday accordingly, mainly across northeast FL. Poor to fair dispersions will continue near the coast through Friday, while in the fair to good range inland with better mixing. Areas of high nighttime dispersion will also continue near the coast through Thursday Night. The pattern changes this weekend as a cold front approaches from the northwest, which will return chances for higher coverage of showers and thunderstorms this weekend. This will also bring a slightly stronger surge of onshore flow ahead of the front, and therefore more widespread good dispersions accordingly.

FOG POTENTIAL AND OTHER WEATHER REMARKS: Significant fog formation is not expected during the next several days.

Tides/coastal flooding

Breezy northeasterly winds will combine with lingering high astronomical tide values to maintain moderate tidal flooding through early this afternoon along our local Atlantic coast from Mayport southward, including the adjacent the Intracoastal Waterway (ICWW) and the entirety of the St. Johns River basin. Water levels will generally reach 2-2.5 feet above Mean Higher High Water (MHHW) during times of high tide. A Coastal Flood Advisory is now in effect for coastal Glynn, Camden, and Nassau Counties through Friday afternoon, where mostly minor flooding is expected around times of high tide, as water levels generally reach 1.5-2 feet above MHHW. Coastal Duval, St. Johns and Flagler Counties will transition to a Coastal Flood Advisory later this afternoon through Friday afternoon, as tide levels begin to gradually subside. Moderate tidal flooding may linger into the upcoming weekend within the St. Johns River basin. The long duration of this strong onshore wind event will produce additional beach erosion during each high tide cycle through at least Friday afternoon.

Preliminary point temps/pops

AMG 80 59 82 61 / 0 0 0 0 SSI 76 64 75 66 / 0 0 0 0 JAX 79 65 78 67 / 10 0 10 0 SGJ 78 70 77 70 / 60 30 50 20 GNV 81 67 82 68 / 10 10 10 10 OCF 82 68 83 69 / 20 0 10 0

Watches, warnings and advisories

FL: Coastal Flood Warning until 5 AM EDT Saturday for FLZ038-132- 137-325-633. Coastal Flood Advisory until 3 PM EDT Friday for FLZ124. High Risk for Rip Currents through Sunday evening for FLZ124-125- 138-233-333. High Surf Advisory until 2 AM EDT Friday for FLZ124-125-138- 233-333. Coastal Flood Warning until 2 PM EDT this afternoon for FLZ125- 138-225-233-333. Coastal Flood Advisory from 2 PM this afternoon to 3 PM EDT Friday for FLZ125-138-225-233-333. GA: Coastal Flood Advisory until 3 PM EDT Friday for GAZ154-166. High Risk for Rip Currents through Sunday evening for GAZ154-166. MARINE: Small Craft Advisory until 1 PM EDT Friday for AMZ450. Small Craft Advisory until 8 PM EDT Friday for AMZ452-454-470. Small Craft Advisory until 5 AM EDT Saturday for AMZ472-474.