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

- Isolated to Widely Scattered Afternoon & Evening Thunderstorms Thursday

- Dangerously Hot & Humid Conditions Late this Weekend. Heat Advisory Conditions Possible Sun & Mon, when Values Approach 110

- Minor to Moderate Flooding Along the Satilla River in Southeast GA

NEAR TERM /UNTIL 8 AM THURSDAY MORNING/

Main Highlights through Tonight:

- Isolated storms over north central FL will dissipate this evening.

A weak boundary will linger over the area through Tonight. Evening convection over north central FL will dissipate with loss of diurnal heating. The overnight is expected to be dry. A little bit of patchy fog will be possible inland. Overnight lows will range from around 70 inland to the mid 70s at the coast.

SHORT TERM /8 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/

Main Highlights This Period:

- Widely Scattered Inland Afternoon and Evening Thunderstorms Thursday and Scattered to Numerous Storms Closer to I-95 and Coastline Friday

- Seasonably Hot and Humid Weather Thursday and Friday

Thursday: Reverting back to a more typical summertime convective pattern as the stalled frontal zone dissolves through the morning, leaving a light southwesterly flow in place. Lingering dry mid level will moisten up late in the day but should minimize t'storm coverage, focusing the best potential for scattered thunderstorms generally along the US 301 corridor where the Gulf and Atlantic sea breezes will zipper south to north during the late afternoon and early evening hours. While the typical downward trend will occur after sunset Thursday, a few outflow interactions may keep showers and an isolated storms possible across SE GA until midnight. Temperatures will bounce back quickly with highs in low 90s and heat index readings back into the 100s.

Friday: Southwesterly flow will increase while deep moisture also increase. Pushing the focus and better chances for strong convection eastward to the I-95 corridor and coastal areas Friday afternoon and evening. Despite some warming aloft as the upper ridge centered east of the Bahamas exerts its influence, instability should still be at moderate levels and sufficient for strong pulse storm development. Warming trend continues into Friday with highs again pushing toward the mid 90s. Better mixing with a breezier southwesterly flow should keep heat index from pushing into the Heat Advisory range but increasing coverage in 100-105 degree "feels like" temps are expected.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Main Highlights This Period:

- Heat Advisory Considerations Saturday, Sunday, and Monday.

- Lower than Usual Confidence For Storms Saturday through Sunday, Numerous T'storms Returning Monday

Upper ridging will consolidate over the weekend with amplified ridging developing over the Mississippi River Valley where it will meander through next week. The position of the ridging puts the region on the southeastern periphery and leaves the door open to glancing shortwave or "ridge riders" early next week. Two considerations with the current forecast is significant model disagreement regarding deep moisture and the potential convective suppression beneath the congealing upper ridging. Right now, have maintain isolated to widely scattered afternoon t'storm potential over the weekend but an upward trend is possible if deeper moisture ends up trapped beneath the ridge. With the lower rain chances and warming low level temps, climbing above the climatological 90th percentile, will support temperatures climbing into the mid and upper 90s over the weekend which may require "Heat Advisory" considerations, especially on Sunday.

By early next week a backdoor front will attempt to slide into the area from the northeast and possibly stall over the area through the first half of next week. Moisture pooled with the front and a "ridge rider" mid level wave will set up the potential for scattered to numerous t'storms and potential for strong to severe storms on Monday. Convective timing will influence temperatures on Monday but expect dangerous levels of heat to continue. A breezy onshore flow and abundant cloud cover along the stalled front should keep temperatures more seasonal Tuesday and Wednesday, especially at the coast.

AVIATION /00Z THURSDAY THROUGH 00Z FRIDAY/

Patchy inland fog will provide the potential for a period of restrictions toward dawn at KVQQ, and KGNV, otherwise prevailing VFR conditions forecast for Tonight and Thursday morning. Thunderstorms are expected to develop Thursday afternoon, and the most favorable time period for this activity has been included in TAFs with PROB30 groups.

MARINE

A weakening frontal boundary positioned over the northeast Florida waters will dissipate tonight. Isolated showers and thunderstorms will be possible this evening, mainly for the waters south of St. Augustine. A weak pressure pattern will continue through Thursday, allowing for the Atlantic sea breeze to move onshore during the early evening hours. Atlantic high pressure will then extend its axis westward across the Florida peninsula from Friday through Sunday, creating a prevailing westerly wind flow during the overnight and morning hours, with winds becoming onshore each afternoon as the Atlantic sea breeze moves inland. Scattered showers and thunderstorms are expected to impact our local waters during the late afternoon and evening hours each day from Thursday through Sunday. A surface trough will then press southward across our area on Monday, providing an increasing coverage of showers and thunderstorms. Northeasterly winds will develop by Monday night and Tuesday as this trough shifts southward and high pressure builds over the southeastern states, with breezy conditions possible by Tuesday afternoon.

Rip Currents:

A lower end moderate risk will develop during the late afternoon hours each day through Friday 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

After seasonably low humidity this afternoon, humidity will trend higher and back to typical levels through the end of the week as the remnant front dissipates over the area. Returning moisture will support afternoon thunderstorms along the sea breezes with best chances lining up where the Gulf and Atlantic sea breezes are expected to converge, which appears to be along the US 301 corridor Thursday and then the I-95 corridor Friday. Potential for less thunderstorm activity over the weekend with heat building back to the mid 90s. More active thunderstorm pattern becoming more likely Monday as a backdoor front enters the area. Hotter temperatures and increasing southwesterly flow Friday may lead to areas of higher dispersion, mainly inland toward the I-75 corridor.

FOG POTENTIAL AND OTHER REMARKS: Dense fog is not expected, but shallow fog formation is possible.

PRELIMINARY POINT TEMPS/POPS

AMG 69 93 73 92 / 0 20 20 30 SSI 76 88 79 92 / 0 10 20 40 JAX 71 94 76 95 / 0 40 20 60 SGJ 74 92 77 93 / 10 40 30 50 GNV 71 95 73 95 / 10 40 10 40 OCF 72 93 74 93 / 30 40 10 40

JAX WATCHES/WARNINGS/ADVISORIES

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