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

- Widely Scattered Afternoon & Evening TStorms through Sunday. Strong Storms Possible During the Late Afternoon & Evening Hours, Mainly Along. Numerous TStorms on Monday, decreasing towards Midweek Next week

- Dangerously Hot & Humid Conditions from Friday through Monday. Heat Advisory Conditions Possible, Peak Afternoon Heat Indices: 105 -110 F

- Minor Flooding Continues along the Satilla River in Southeast GA

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Widely Scattered afternoon T'storms becoming more Numerous along the I-95 and US-17 corridors mid to late afternoon

- Isolated strong storm potential along I-95 corridor

Skies have largely cleared tonight as T'storms faded after 10PM across inland SE GA and westerly upper level winds shoving the remaining debris clouds into the coastal waters. Temperatures in the mid 70s and around 80 at the coast will cool some to the low 70s inland and mid 70s coast before sunrise. Very isolated shallow ground fog may form in locations that received rainfall through the rest of the Pre-dawn early morning hours. Otherwise a few showers will drift towards the Gulf adjacent counties to near I-75 due to increasing SSW and moisture into the area with a quick T'storm possible along US-129 south of I-10.

Today, the low to mid level flow will be a little faster compared to Thursday as ridging aloft across the Atlantic waters between Bermuda and the Bahamas builds westward closer to the region and a weak shortwave trough lingers across AL/GA/SC. This will bring in higher moisture levels and PWATs ranging 1.9-2.2 inches (above the 90th percentile). This high moisture content and SSW flow above the surface will shift the Gulf seabreeze north and east across I-75 and through north central FL and Ocala national forest by the early to mid afternoon hours.

Strong diurnal heating pushing highs in to the mid 90s inland and lift along the seabreezes will create isolated to widely scattered T'storms late morning to midday into the start of the afternoon. Then, Seabreeze convergence near I-95 will increase coverage of T'storms to scattered to numerous with a threat for gusty downburst winds of 40-50 mph as storms zipper northward along I-95 and US-17 to Jacksonville, then into the SE GA coastal counties. Gulf seabreeze will also press northward across the Suwannee Valley to FL/GA state line and US-84 towards sunset with widely Scattered T'storms then spreading towards the Altamaha river just after sunset with T'storms dwindling in coverage after 8PM. Frequent lightning and locally heavy downpours will be the other T'storm hazards through early evening 3-9PM with a quick 1-2 inches that could bring some minor flooding concern briefly for low lying and urban areas.

Heat index values will spike to 100-105 degrees across NE FL and portions of SE GA east of US-84. Highs in the low 90s west of US-441 will rise in to the mid 90s eastward to I-95, then only reach the low 90s at the beaches.

By tonight, the faster flow will also bring scattered T'storms to the nearshore waters from the coast as upper level SW winds steer them more to the east northeast. Skies will clear inland and more gradually near the coast from lingering storm anvils with partly clouds skies after midnight. Lows will be in the low to mid 70s over inland areas and mid to upper 70s along the coast.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

Main Highlights This Period:

- Isolated to Widely Scattered Afternoon/Evening T-Storms Saturday - Seasonably Hot and Humid Weather this Weekend

Bermuda high pressure surface ridge axis continues to extend across the FL peninsula as strong mid/upper level ridging gradually lifts northward this weekend. Low level WSW flow will allow the Gulf sea breeze to shift far inland while the Atlantic sea breeze will be pinned to the I-95 corridor. Subsidence and slightly drier air will decrease convective coverage. Isolated showers and storms develop along the inland-moving sea breezes becoming widely scattered along the merger within the St Johns river basin and I-95 corridor in the afternoon and evening. Slightly above seasonable temperatures with highs rising into the low to mid 90s and heat indices 100-107 F. Will need to monitor if a heat advisory (heat index >= 108 F) is needed this weekend. Lows will be in the mid to upper 70s.

LONG TERM /MONDAY THROUGH THURSDAY/

Main Highlights This Period:

- Heat Advisory Conditions Possible Monday.

- Numerous T'storms across the area Monday, decreasing coverage into Midweek

Monday, an mid/upper level trough will dive along the southeast coast as a strong heat dome mid/upper level ridge builds over the mid south and mid MS valley. The upper trough will bring a surface "back door" cold front towards the area, but another hot afternoon will result ahead of this front before it arrives providing plenty of instability. The NNW flow aloft will allow inland progression of both seabreezes before merging with above normal moisture levels supporting numerous T'storm coverage area-wide. The high humidity and hot temperatures could develop peak heat index values at heat advisory levels of 108-110 before T'storms, rain, and gusty outflows cool temperatures down.

Tuesday, strong ridging will shift across the OH valley while sfc high pressure builds to the NNE over the Mid Atlantic states with increasing northeast onshore flow and breezy winds 10-15 mph, but gusting to 25 mph. This will push the Atlantic seabreeze SW to the I-75 corridor. Highest coverage of T'storms will be inland south of I-10 inland into north central FL with widely scattered T'storms away from the coast northward as drier air aloft presses in from the north and northeast. Highs will cool to the low 90s along I-95 and the mid 90s near I-75 with upper 80s along the coast. Heat index values will peak 104-108 inland.

Wednesday, the heat dome ridging aloft will build to the NNW over the upper OH valley with NE flow aloft. High pressure to the north will retreat to off the New England coast with ENE winds still breezy with a a long fetch of low level moisture from the Atlantic underneath drier air aloft due to the ridging north of the region, lowering overall moisture levels a little below normal. Scattered inland T'storm coverage is expected in this pattern. Highs in the low to mid 90s inland will again limit heat index values below heat advisory levels.

AVIATION /06Z FRIDAY THROUGH 06Z SATURDAY/

VFR conditions will prevail for most TAF sites with exception of MVFR/IFR restrictions at GNV and VQQ for localized shallow fog 08- 12Z due to rainfall yesterday afternoon. Very light southwest winds below 5 knots expected through sunrise. Southwest winds increase to 5-8 knots after 14Z, with Atlantic seabreeze turning winds east to southeasterly after 17Z around 10 knots, but winds will be southerly at JAX around 10 knots and southwesterly inland 6-8 knots.

Another afternoon similar to Thursday expected with scattered to numerous storms developing during the afternoon hours. These storms have potential for erratic, gusty outflow winds. Keeping PROB30 groups for temporary restrictions to IFR or lower between 18z-24z as storms will zipper up the coast from near SGJ to the duval county terminals to SSI in the mid to late afternoon hours.

Storm coverage will trend away to the northeast from GNV by 22Z and end at coastal sites by 01Z with lingering high anvil storm clouds.

MARINE

Atlantic high pressure will extend westward across the Florida Peninsula just south of the area waters today through the weekend. A pattern of overnight to early morning light westerly offshore winds and afternoon southeasterly winds expected due to sea breeze circulations. Afternoon and early evening isolated to scattered storms will develop across the nearshore waters each day into Sunday. A weak back door frontal boundary will approach the waters on Monday, supporting increased coverage for showers and thunderstorms for the first part of early next week.

Rip Currents:

A lower end moderate risk will develop during the late afternoon hours today into this weekend at area beaches as onshore winds become breezy following the passage of the sea breeze. A developing southeasterly ocean swell will combine with onshore winds developing during the mid to late afternoon hours this weekend to maintain a lower end moderate risk at all area beaches.

FIRE WEATHER

- Patchy High Dispersions Through The Weekend

Generally westerly flow will shift the Gulf sea breeze well inland each day with the Atlantic sea breeze being pinned to the I-95 corridor. Scattered showers and storms will develop along the sea breezes as they shift inland this afternoon into evening, becoming numerous along the sea breeze merger near the St Johns river basin and I-95. Similar setup continues through the weekend though storm coverage decreases to isolated to widely scattered. Breezy southwesterly transport winds coupled with deeper mixing heights will support good dispersions with some areas reaching high dispersions each afternoon into the weekend.

FOG POTENTIAL AND OTHER REMARKS: Significant fog is not expected the through the weekend. Any developing thunderstorm will be capable of producing gusty winds to 40-50 mph, frequent cloud to surface lightning strikes, and locally heavy downpours.

HYDROLOGY

Minor Flooding will continue along the Satilla River Basin into the upcoming weekend.

PRELIMINARY POINT TEMPS/POPS

AMG 92 73 93 74 / 50 20 20 0 SSI 92 76 91 78 / 40 20 20 10 JAX 95 75 94 76 / 60 20 30 10 SGJ 93 76 93 76 / 50 20 30 10 GNV 94 73 94 74 / 40 20 30 10 OCF 93 74 94 74 / 40 10 40 10

JAX WATCHES/WARNINGS/ADVISORIES

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