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

- Moderate Rip Current Risk Continues at All Area Beaches.

- Isolated Thunderstorms Across Inland Southeast GA and Western Portions of the Suwannee Valley this Afternoon.

- Isolated Afternoon and Evening Thunderstorms on Wednesday Across North Central FL.

- Scattered to Numerous Afternoon and Evening Thunderstorms from Thursday through Sunday.

- Afternoon Heat Index Values Rise to the 100-105 Range from Friday through Sunday.

UPDATE

Tweaked down high temperatures for this afternoon as mostly cloudy skies will continue spreading in from the NW with highs around 90 for inland NE FL and mid to upper 80s for SE GA.

A lingering shortwave across central GA is generating isolated to scattered showers that were drifting SE across the Altamaha and Ocmulgee river basin this morning, but this activity will weaken towards noon as it approaches US-84 as it encounters dry air noted in the 12Z KJAX RAOB around 10.0 kft. Otherwise, widely isolated T'storms still expected this afternoon as the Atlantic seabreeze moves well inland and encounters the Gulf seabreeze near the Suwannee river, helping to spur widely isolated T'storms over the western Suwannee Valley and northward along US-441/221 corridor where a higher moisture axis resides (PWATS above 2.0 inches).

NEAR TERM /THROUGH TONIGHT/

Main Highlights This Period:

- Isolated to widely scattered showers and thunderstorms on Monday afternoon across inland southeast GA and western portions of the Suwannee Valley.

- Moderate rip current risk at all area beaches.

Overnight surface analysis depicts weakening Atlantic high pressure that was extending its axis westward across northern FL. Meanwhile, a "backdoor" cold front was pushing southward from the Ohio Valley eastward across the Chesapeake Bay towards the Tennessee Valley and the Carolinas, with another high pressure center (1022 millibars) building over the eastern Great Lakes and New England in the wake o this front. Aloft...ridging over the northeastern Gulf was deflecting a shortwave trough northeastward from the eastern Plains towards the Upper Midwest, while another shortwave trough was progressing offshore of New England. Latest GOES-East derived Total Precipitable Water imagery indicates that an unseasonably dry air mass persists across portions of northeast and north central FL, where PWATs were around 1 inch, while deeper moisture was advecting into interior southeast GA and western portions of the Suwannee Valley, where PWATs were rising above 1.75 inches. Mostly mid and high altitude debris cloudiness from upstream convection earlier this evening over the Tennessee Valley was overspreading southeast GA and the Interstate 10 corridor in northeast FL, while fair skies prevail for locations south of I-10. Temperatures were falling through the 60s for inland locations south of I-10, where radiational cooling was taking place, while thicker cloud cover elsewhere was generally keeping temperatures in the low to mid 70s as of 07Z. Dewpoints were in the mid to upper 60s area-wide.

Ridging aloft over the northeast Gulf will flatten and sink southward slightly today, allowing the base of the trough that was moving towards the Upper Midwest and the western Great Lakes to enter the Deep South. Deeper moisture associated with this approaching trough will remain in place across inland portions of southeast GA and western portions of the Suwannee Valley, where PWATs will rise to near or above 2 inches this afternoon. While better forcing will remain in place across the Tennessee Valley and southern Appalachians this afternoon, mesoscale boundaries such as the inland moving Gulf sea breeze should provide enough of a spark to generate isolated to widely scattered showers and possibly a few thunderstorms this afternoon, mainly for locations north and west of Waycross and Live Oak. Thicker multi-layered cloudiness should keep highs in the upper 80s for these areas today. Northwesterly flow aloft should advect some of this thicker mid and high altitude cloud cover across the rest of our region this afternoon, but filtered sunshine this morning should still allow inland highs to climb to the lower 90s, while an early developing Atlantic sea breeze keeping coastal highs in the mid to upper 80s. Dewpoints this afternoon will crash to the low and mid 60s inland, keeping heat index values in check.

High pressure building over the Mid-Atlantic coast tonight in the wake of a "backdoor" cold front that will be decelerating over the Carolinas will begin to wedge down the southeastern seaboard, with a drier air mass preceding this wedge that will advect from east to west across our area overnight, dropping PWATs below 1.25 inches along the I-95 corridor by sunrise on Tuesday. Otherwise, any convection that manages to develop this afternoon across interior southeast GA and the western Suwannee Valley will dissipate around sunset this evening, but thick mid and high altitude cloud cover should continue to advect into our region overnight. Lows will range from the upper 60s to lower 70s inland, while low to mid 70s prevail at coastal locations.

AVIATION /12Z MONDAY THROUGH 12Z TUESDAY/

VFR conditions will prevail at the regional terminals, with increasing mid and high altitude cloud cover expected this afternoon. MVFR visibilities are expected to develop at VQQ after 04Z Tuesday, with periods of IFR conditions possible from around 08Z- 11Z. Southwesterly surface winds will become sustained at 5-10 knots at the SSI and SGJ coastal terminals and around 5 knots elsewhere around 14Z before shifting to easterly at 10-15 knots at the coastal terminals by 17Z, with surface winds shifting to easterly around 10 knots at the inland terminals after 19Z. Surface winds will then shift to southeasterly at 5-10 knots towards 03Z Tuesday at the coastal terminals, while winds at the inland terminals diminish below 5 knots.

MARINE

Atlantic high pressure will continue to extend its axis across our local waters, keeping unseasonably dry weather in place through at least midweek. Breezy east to southeasterly winds will develop during the mid to late afternoon each day across the near shore waters as the Atlantic sea breeze pushes inland. High pressure will then weaken near Bermuda by Thursday and Friday, creating a prevailing southerly wind flow that will gradually increase moisture levels, allowing scattered to numerous afternoon and evening showers and thunderstorms to develop across our local waters, especially during the upcoming weekend.

Rip Currents: Breezy onshore winds developing during the mid to late afternoon hours will combine with a persistent easterly ocean swell of 9-10 seconds to maintain a moderate rip current risk, especially during the outgoing tide, which will occur during the late afternoon and early evening hours through midweek.

PRELIMINARY POINT TEMPS/POPS

AMG 87 71 87 69 / 20 10 10 0 SSI 86 74 86 77 / 10 0 0 0 JAX 89 70 89 73 / 10 0 0 0 SGJ 87 74 87 75 / 10 0 0 10 GNV 91 70 90 71 / 10 0 10 0 OCF 91 70 90 73 / 0 0 10 0

JAX WATCHES/WARNINGS/ADVISORIES

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