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

- High Risk for Rip Currents Continues at the Northeast Florida Beaches. Moderate Risk at Southeast GA Beaches.

- Scattered Thunderstorms Inland Late This Afternoon and Evening. Main Hazard Area: Inland Locations Along and West of U.S.-301

- Waves of Showers and Thunderstorms Beginning on Thursday. Heavy Rainfall and Localized Flooding will be a Concern. Widespread 2-4 Rainfall Totals Forecast through Tuesday

- Hot and Humid - Daily Heat Index 95- 105F for Portions of Our Area Through Friday.

NEAR TERM /THROUGH TONIGHT/

Main Highlights This Period:

- High Risk for Rip Currents Continues Today for NE FL Beaches

- Isolated Strong Storms Late this Afternoon through this Evening. Main Hazard Area: Inland Locations Along and West of U.S.-301 in SE GA. Primary Storm Hazards: Wind Gusts of 40-50 mph, Frequent Lightning Strikes, Heavy Downpours and Localized Flooding.

The Atlantic sea breeze will push inland this afternoon, sparking up convection mainly along and west of I-95 and bringing gusty winds near 20-30 mph. Storm coverage will increase further inland later this afternoon into the evening hours as southerly flow allows the sea breezes merge between I-75 and the US 301 corridor. This morning's 12Z sounding and current GOES analysis show PWATs around 1.5-2.0" with moisture likely to increase even more later today. Stronger storms from boundary interactions could produce gusty winds 40-50 mph, heavy downpours, and frequent lightning. Training storms could result in localized flooding, particularly for urban or normally flood prone, low-lying areas.

Thunderstorms will begin to taper off after sunset, but showers will linger mainly across inland northeast Florida through around midnight, with early morning isolated coastal showers. Very mild low temperatures expected, especially near the coast where southeasterly winds will keep temperatures in the mid to upper 70s.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

- Waves of Showers and Thunderstorms Overspread Our Region from South to North Beginning on Thursday.

- Strong Storm Potential on Thursday Afternoon along the I-95 Corridor. - Heat index 95-105 degrees for portions of our area during the afternoon hours on Thursday and Friday.

Deep-layered "Bermuda" ridging will shift southward on Thursday as troughing digs southeastward across New England and the Mid-Atlantic states. This change in the weather pattern will result in the the prevailing flow veering from southwest to westerly as the day progresses, which will tap a feed of tropical moisture that is currently firing off numerous thunderstorms over southern and central portions of the Gulf. Convection could get an early start for locations along the FL Big Bend / Nature Coast, with this activity potentially spreading inland across the Suwannee Valley and north central FL during the late morning and early afternoon hours, reaching the I-95 corridor in northeast and north central FL by the mid to late afternoon. Convection could potentially collide with a pinned Atlantic sea breeze boundary positioned along the I-95 corridor, potentially resulting in thunderstorms "pulsing" and becoming strong during the mid to late afternoon hours.

Meanwhile, troughing to our north will drive a "backdoor" cold front into the Deep South by Thursday night and Friday, with deep moisture pooling ahead of this boundary over southeast GA. This scenario should allow for waves of downpours to extend into southeast GA later this week, providing beneficial rainfall for our entire region. Highs on Thursday will be held to the 85-90 degree range at most locations, with higher heat index values possible along the I- 95 corridor, where convection should arrive later in the afternoon hours. Friday's highs should be similar, but will be highly dependent on how early convection develops, as well as overall cloud cover. Lows on Thursday and Friday nights will remain in the low to mid 70s for northeast and north central FL, with some upper 60s possible on Friday night across interior southeast GA, depending on where the "backdoor" frontal boundary stalls.

LONG TERM /FRIDAY THROUGH TUESDAY/

- Waves of Showers and Thunderstorms Expected to Continue, with Beneficial Rainfall Totals Forecast Area-Wide.

- Clouds and Cooler Temperatures Expected Early Next Week.

A highly amplified flow pattern is expected to evolve by late in the upcoming weekend and early next week across the U.S., featuring troughs over the Pacific Northwest and the Intermountain West and over the eastern third or the nation. Diffluent westerly flow aloft will prevail across our area, and deep tropical moisture is expected to pool along and south of a stalling frontal boundary over the Deep South. This weather pattern should result in waves of showers and embedded thunderstorms across our area on Saturday, with some potential for the digging trough over the eastern U.S. to drive a frontal boundary southward across the FL/GA border. Forecast confidence is thus lower for our area on Sunday and Monday, but waves of showers and thunderstorms are likely to continue for locations along and south of the I-10 corridor into early portions of next week. Longer term guidance also advects shortwave energy across our region towards the end of this forecast period, potentially developing a wave of low pressure along the frontal boundary across our region, which would maintain likely rain chances through the middle portion of next week. Blended guidance currently generates 2-4 inches of rainfall across our entire area from Thursday onward, with localized totals in excess of 5 inches possible through next Tuesday.

Increased cloud cover and rainfall chances should keep highs in the 80s throughout the long-term period, with lows potentially cooling off to the mid 60s for interior southeast GA by late in the upcoming weekend and early next week, depending on whether the frontal boundary sinks into northeast FL or not. Breezy onshore winds could also develop early next week at coastal locations if a more robust wave of low pressure traverses our region and subsequently pushes offshore.

AVIATION /18Z TUESDAY THROUGH 18Z WEDNESDAY/

The Atlantic sea breeze is making it's way inland, bringing gusts around 20-25 knots to the sites. Showers and storms will increase in coverage inland this afternoon and evening, impacting the Duval sites and GNV, where TEMPOs are in place. Light showers may linger past midnight near GNV, otherwise conditions will be mainly VFR overnight.

MARINE

A stalled frontal boundary stretching across the Mid-Atlantic states and into the lower Mississippi Valleys will lift slowly northward today as Atlantic high pressure centered near Bermuda remains over the southeastern seaboard. Breezy southeast to southerly winds will continue through midweek across our local waters, with exercise caution levels prevailing during the afternoon and evening hours as wind speeds surge to just below Small Craft Advisory levels. High pressure positioned off the southeastern seaboard will gradually weaken and retreat through the week as a cold front shifts southward towards our local waters during the upcoming weekend. Scattered showers and thunderstorms will tend to develop during the overnight and morning hours on today and Wednesday, with activity then increasing in coverage through the upcoming weekend.

Rip Currents:

Breezy SSE winds and breakers of 2-4 feet will maintain a high risk at NE FL beaches this afternoon and evening. A higher end moderate risk prevails at the southeast GA beaches today. High/Moderate risk continues into Wednesday.

FIRE WEATHER

- HIGH DAYTIME DISPERSION VALUES AT INLAND LOCATIONS THIS AFTERNOON.

Breezy southerly transport winds will create high daytime dispersion values this afternoon at most inland locations, with good values expected elsewhere. Scattered showers and thunderstorms are forecast this afternoon and evening, mainly at inland locations. Southerly transport winds will gradually weaken on Wednesday, yielding good daytime dispersion values for inland northeast and north central Florida, with fair values forecast elsewhere. Chances for afternoon and evening showers and thunderstorms will increase on Wednesday, especially for locations along and east of U.S. Highway 301. Transport winds will become southwesterly on Thursday, with decreasing speeds resulting in generally fair daytime dispersion values. Numerous showers and thunderstorms are expected to overspread north central and then northeast Florida from south to north on Thursday, with scattered to numerous mainly afternoon and evening showers and thunderstorms across southeast Georgia. Widespread waves of downpours are forecast area-wide from Friday through the weekend.

FOG POTENTIAL AND OTHER REMARKS: Significant fog is not expected into early next week, but patchy morning fog will be possible in areas where heavy rain fell during the previous afternoon. Erratic winds are expected during periods of thunderstorms.

PRELIMINARY POINT TEMPS/POPS

AMG 69 87 69 88 / 40 50 20 30 SSI 77 88 75 89 / 30 20 10 50 JAX 75 92 73 91 / 30 60 40 80 SGJ 76 90 74 90 / 10 40 40 80 GNV 72 91 72 88 / 70 50 40 80 OCF 73 90 73 87 / 80 60 50 80

JAX WATCHES/WARNINGS/ADVISORIES

FL...High Risk for Rip Currents through late tonight for FLZ124-125-138- 233-333. GA...None. MARINE...None.