textproduct: Jacksonville

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

- Severe Thunderstorm & Flood Risk this Afternoon & Evening

- Moderate Rip Current Risk Northeast Florida Beaches Today

- Heat Index near 107 Today

- Daily Afternoon & Evening Thunderstorms This Coming Week

- Patchy Inland Late Night & Early Morning Fog

UPDATE

No major changes to the forecast this morning.

Today will be an active day, with a more 'typical' summertime pattern impacting northeast Florida this afternoon through evening. Southwesterly winds will push the Gulf sea breeze far inland, interacting with the Atlantic boundary closer to the I-95 corridor, sparking up numerous showers and storms. There will be potential for isolated strong storms through sunset closer to the east coast, with gusty winds and heavy rainfall as the primary threat as DCAPE will be high and PWATs are above 2 inches.

A second area of concern will be along and north of I-10, later this evening through around midnight, where strong to severe thunderstorms are possible associated with a front sinking southward. Again, damaging winds and locally heavy rainfall are the primary concerns. The Storm Prediction Center maintains a 'Slight' risk (level 2/5) for severe storms this evening near the Altamaha River basin, with the rest of southeast Georgia still under a 'Marginal' risk (level 1/5). The convective models are fairly consistent with having storms weakening by midnight as they drift into northeast Florida into a more stable region, however the HRRR remains an outlier with keeping strong storm potential a littler later and further south into the Suwannee Valley. The Weather Prediction Center also maintains a 'Slight' risk (level 2/4) for Excessive rainfall, mainly for the Atlantic coast Duval county northward and much of southeast Georgia. Overall, after midnight, expect mainly light showers with a few isolated storms possible.

SHORT TERM /THROUGH TUESDAY NIGHT/

Main Highlights This Period:

- Localized Flooding Rain Threat

- Daily Thunderstorms Chances

A stalled cold front over the area on Monday will begin to shift towards north central FL by Tuesday. With elevated levels of moisture aloft and the proximity of the front, the coverage of numerous showers and storms is expected to span across the area on Monday and Tuesday. The highest chances will generally be during the afternoon and evening each day, with some activity lingering during the overnight hours Monday to Tuesday. Behind the front, stronger onshore flow will direct offshore activity back towards the coast and then inland locations by the afternoon hours. Gusty conditions can be expected for coastal locations with the stronger onshore flow, particularly for SE GA.

With the cold front making its way across the area, cooler temperatures will develop from north to south. On Monday, SE GA locations will likely top out in the upper 80s, while NE FL will be in the upper 80s to lower 90s. By Tuesday, highs in the mid to upper 80s will develop behind the front.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

Main Highlights This Period:

- Daily Thunderstorms Chances

- Elevated Tidal Levels with Approach of Sept 11 New Moon

Behind the front, relatively drier air (PWATs 1.8" to ~2") filters into the area by midweek. With drier air moving in, chances of precipitation will steadily lessen through the end of the week. During midweek, the continuing onshore flow will steer any showers and storms towards inland located during the afternoon hours. Southerly then southwesterly flow develops by the end of the week. Guidance suggests another cold front will push towards the SE US by the upcoming weekend as high pressure develops north of the area along the eastern seaboard.

Temperatures in the mid 80s to lower 90s midweek behind the front, will begin to increase back to near normal levels as southwesterly flow develops heading into next weekend.

AVIATION /12Z SUNDAY THROUGH 12Z MONDAY/

Outside of convection and showers, VFR conditions are forecast today. Showers and storms will pick up for the northeast Florida sites early this afternoon, with likely impacts later in the afternoon through around 00Z-01Z. Another round of storms will enter southeast Georgia associated with a front, with impacts to SSI lasting through around 02-03Z. Vicinity showers/light rain will be possible for most of the sites through at least 06Z, with potential for MVFR ceilings/mist closer to sunrise.

MARINE

High pressure will continue south of the local waters today as a front approaches from the northeast. Strong thunderstorms are possible this afternoon and evening as the front approaches. The front will stall across north Florida Monday, then shifts south of the waters Monday night into Tuesday as high pressure strengthens to the northeast. A brief period of Small Craft Exercise Caution conditions is possible mainly over the Georgia waters Tuesday as a coastal trough develops offshore. The coastal trough weakens Wednesday into Thursday. Friday into Saturday, high pressure extends across south Florida with a return of westerly winds and the afternoon east coast sea breeze nearshore.

Rip Currents: Will maintain a moderate rip current risk for northeast FL beaches given a small but consistent 10-14 second periods from the east. Low rip current risk for southeast GA beaches today. Rip current risk increases from north to south Monday as onshore flow develops with moderate risk likely for all local beaches. By Tuesday, solid moderate to possibly high rip current due to stronger and more persistent ENE onshore winds.

FIRE WEATHER

- Patchy Low Dispersions Northeast Florida Monday And Tuesday

West to southwest winds continue Today allowing for the west coast sea breeze to push across the area. Morning showers and isolated storms will begin to move inland form the Gulf, with rainfall expanding in coverage into the afternoon and early evening across inland areas toward the Atlantic coast where the east coast sea breeze will be near the Interstate 95 corridor to the coast. A risk for stronger to severe storms Tonight across southeast Georgia with a stalled front over the area. The front is expected to shift southward across northeast Florida Monday, with low daytime dispersion, more cloudiness and bring elevated rain chances through the day. Winds will transition to northeast behind of the front Monday.

Fog Potential: Gusty and erratic winds will occur with thunderstorm activity. Patchy inland morning fog each day.

HYDROLOGY

Coastal water levels begin to increase next week with the approach of the New Moon on Sept 11th and breezy onshore easterly winds late Monday through Wednesday, with the peak winds across the local waters and coast Tuesday. At this time, extended probabilistic guidance keeps water levels below action stage late Tuesday through Wednesday both along the local Atlantic coast and within the St. Johns River basin.

PRELIMINARY POINT TEMPS/POPS

AMG 94 73 87 72 / 40 60 80 30 SSI 92 76 86 76 / 50 40 80 80 JAX 93 74 88 73 / 70 60 90 50 SGJ 92 75 87 74 / 70 40 80 60 GNV 92 74 89 72 / 50 40 90 40 OCF 91 74 89 73 / 40 30 80 30

JAX WATCHES/WARNINGS/ADVISORIES

FL...None. GA...None. MARINE...None.