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 100-105 Degrees Friday through Sunday.

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.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

Main Highlights This Period:

- Isolated to Widely Scattered Mainly Afternoon and Evening Showers and Thunderstorms, Mainly Across Inland Southeast GA.

- Moderate Rip Current Risk Continues at All Area Beaches.

Prevailing flow will shift to become more out of the east and southeast as high pressure ridging extending from out of the northeast over the forecast area. Potential for isolated showers and storms building with daytime heating on Tuesday and Wednesday with developments becoming more likely throughout northeast Florida and southeast Georgia by Wednesday, with the most likely areas for development occurring over north central Florida, as high pressure gradually shifts towards the east. High temperatures will warm into midweek with daily max temps over inland areas rising from out of the mid to upper 80s on Tuesday up into the lower 90s on Wednesday. Overnight low temperatures will drop down into the lower 70s and upper 60s over inland areas and in the lower to mid 70s along the coastline.

LONG TERM /THURSDAY THROUGH SUNDAY/

Main Highlights This Period:

- Gradually Increasing Chances for Showers and Thunderstorms Late in the Upcoming Week and this Weekend.

- Summertime Humidity Returns, with Heat Index Values Climbing to the 100-105 Degree Range Later this Week and Next Weekend.

Chances for showers and thunderstorms will increase by the end of the week and on into Saturday and Sunday as high pressure near the coast to the northeast moves eastward and humidity levels increase as a surface ridge axis forms over the Florida peninsula. Near to and above average temperatures will persist through the end of the week and into the weekend with daily max temps rising into the lower to mid 90s. With the increasing humidity levels, heat index values during this period are expected to reach to values of up to about 100 to 105 Fahrenheit.

AVIATION /06Z MONDAY THROUGH 06Z TUESDAY/

Periods of MVFR visibilities are expected through around sunrise on Monday at VQQ. Otherwise, VFR conditions will prevail at the regional terminals, with increasing mid and high altitude cloud cover expected after sunrise. MVFR visibilities may redevelop at VQQ after 04Z Tuesday. Southerly surface winds sustained around 5 knots will continue overnight at the SSI and SGJ coastal terminals. Surface winds will briefly become southwesterly around 5 knots at the regional terminals towards 14Z before shifting to northeasterly at 5-10 knots by 16Z, followed by easterly surface winds increasing to around 10 knots after 20Z. Surface winds will then shift to southeasterly at 5-10 knots towards 03Z Tuesday, 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.

FIRE WEATHER

High pressure ridging will extend across the forecast area today with chances for isolated thunderstorms and showers developing over inland southeast Georgia and into northeast Florida for inland areas near and north of the I-10 corridor. High pressure will reform to the northeast on Tuesday with dry air shifting back in from the Atlantic waters with a widely isolated storms inland as the Atlantic seabreeze cruises well inland. High pressure will reform towards Bermuda with southeast flow midweek and widely scattered inland storms, then southwest flow prevails Friday over the region ahead of a slow moving cold front will increase moisture levels with numerous thunderstorms this weekend as the Atlantic seabreeze stays pinned near I-95 to US-17 corridors.

MinRH values ranging between about 40-50 percent today.

FOG POTENTIAL AND OTHER REMARKS: Significant fog developments are not expected.

PRELIMINARY POINT TEMPS/POPS

AMG 89 71 87 69 / 20 10 10 0 SSI 87 74 86 77 / 10 0 0 0 JAX 90 70 89 73 / 10 0 0 0 SGJ 88 74 87 75 / 10 0 0 10 GNV 92 70 90 71 / 10 0 10 0 OCF 93 70 90 73 / 0 0 10 0

JAX WATCHES/WARNINGS/ADVISORIES

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