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

- Strong to Isolated Severe Thunderstorms Possible this Afternoon and Evening. Strong Storm Threats: Wind Gusts of 40-60 mph and Frequent Lightning Strikes

- Slow-moving Heavy Downpours will lead to an increased risk for flash flooding along the I-95 corridor this afternoon and early evening.

- Scattered to Numerous Afternoon & Evening TStorms Wed - Sun

- Moderate Rip Current Risk at All Area Beaches Today

NEAR TERM /THROUGH TONIGHT/

Highlights through Tonight:

- Strong to Isolated Severe Thunderstorms Possible this Afternoon and Evening. Strong Storm Threats: Wind Gusts of 40-60 mph and Frequent Lightning Strikes

- Slow-moving Heavy Downpours will lead to an increased risk for flash flooding along the I-95 corridor this afternoon and early evening.

A few showers lingered beyond midnight hour but the cirrus debris has continued to erode with quiet conditions developing. Chances for predawn showers remains along the I-75 corridor where coastal convergence and southwesterly flow may carry isolated showers inland through sunrise.

The general low level flow pattern hasn't changed much over the last 24 hours, as light but deep southwesterly flow prevails. Again, this will favor a more progressive Gulf sea breeze this afternoon while the Atlantic sea breeze moves inland gradually. Though the flow pattern is consistent, instability and deep layer moisture today will be the primary differences.

A shortwave aloft cooling the mid levels along with dewpoints in the mid 70s will allow strong destabilization during peak heating with Most Unstable CAPE pushing into the 90th percentile (3,000+ J/kg). With less dry entrainment today, expect numerous showers and thunderstorms to develop through the early afternoon, initially along the Gulf breeze. Strongest, and potentially isolated severe storms, are most likely along the pinned Atlantic sea breeze which is likely to be near or just east of the I-95 corridor during the mid to late afternoon hours (3-6 PM). Outflow collisions are likely to zipper northward along the Atlantic sea breeze into southeast GA along the I-95 corridor into the early evening hours (5-8 PM).

The primary hazards today will be threat of localized downburst winds possibly up to 60 mph and heavy, slow-moiving downpours that may result in flooding particularly in urban and poor- drainage areas. Slowest storms will be those along the Atlantic sea breeze (I- 95 corridor) and there's potential that localized amounts could reach up to 3-4" over just a couple of hours. Given the threat for the heaviest rain will coincide with urban centers, the potential for flash flooding will be higher this afternoon. The Weather Prediction Center has increased today's Excessive Rainfall Risk to Slight Risk for the coastal zones.

There will be plenty of energy to fuel convection today, but the atmosphere should become mostly worked over by sunset and should limit the threat of severe thunderstorm development after 9 PM. However, late night scattered showers and thunderstorms may persist as late as midnight while leftover outflows meander around interior areas of southeast GA.

Temperatures will be closer to normal this afternoon but still read in the low 90s prior to this afternoon's convection. Heat index will be in the upper 90s and low 100s this afternoon.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

Main Highlights This Period: (Wednesday through Thursday night)

- Chance for a few strong to severe storms each afternoon and evening this period

Summertime pattern for diurnal bouts of showers and thunderstorms will continue through this week as a prevailing southwesterly flow remains in place between the decaying frontal boundary to the north and high pressure ridging extending over Florida from out of the east. The presence of upper level troughing, ahead of an advancing front advancing from out of the northwest, could lead to stronger thunderstorm developments this period. Daytime high temperatures will be in the lower 90s for inland areas on Wednesday and Thursday, with max temps in the upper 80s and lower 90s along the coast. Overnight low temperatures will drop down into the lower 70s over inland areas and in the mid 70s for areas along the coast and near the St Johns River. Heat index values will rise to be over 100 during this period with a potential for some areas to reach heat advisory levels on Wednesday.

LONG TERM /FRIDAY THROUGH MONDAY/

Main Highlights This Period: (Friday through Monday)

- Chance for a few strong to severe storms each afternoon and evening this period

The surface pattern will remain fairly persistent with a frontal zone across GA, and weak high pressure extending across FL. The weak upper trough will continue through Saturday, with an upper ridge then building overhead Sunday. Daily rounds of afternoon and evening thunderstorms this period, with the greatest chances through Saturday due to the added instability from upper trough.

Temperatures will be a little above average this period.

AVIATION /06Z TUESDAY THROUGH 06Z WEDNESDAY/

Low level stratus and patchy MVFR fog chances are the highest at the inland TAF sites of GNV/VQQ through around 11Z, but it appears as though this stratus should remain generally SCT in nature through the morning hours. Another fairly active afternoon of TSRA activity expected on today and PROB30 groups remain at all TAF sites for MVFR ceilings/visibility and gusty winds to 30-40 knots. From 16-22Z for GNV, 17-23Z for JAX/VQQ/CRG/SGJ and 18-24Z for SSI. Convective activity at area terminals will subside after 02z, though trailing stratiform may linger at KSSI through 04z. For wind outside of convective influence, the Atlantic sea breeze will push through SSI/CRG/SGJ this afternoon while terminals inland favor a WSW wind around 5 knots.

MARINE

A stalled frontal boundary positioned just north of the Georgia waters will remain in place during the next several days. Afternoon and evening thunderstorms developing over coastal locations will push across our local waters each late afternoon and evening, with strong to isolated severe storms possible through midweek. Offshore winds will otherwise prevail during the overnight and morning hours, with the Atlantic sea breeze shifting winds to onshore each afternoon across the near shore waters. Southerly winds will then surge each evening, with speeds briefly approaching Caution speeds around sunset outside of ongoing thunderstorm activity. A transition to an onshore flow pattern is expected to develop over the weekend as stronger high pressure builds to the north.

Rip Currents: Although surf heights are low, generally in the 1-2 foot range, a persistent long period easterly ocean swell and onshore winds following the sea breeze will create a moderate risk at all area beaches. This pattern may continue through the rest of the week.

FIRE WEATHER

A fairly persistent pattern with high pressure over FL, and a frontal zone across SE GA will continue this period. Daily rounds of showers and thunderstorms are forecast, mainly in the afternoon and evening hours.

Fog Potential: Significant fog is unlikely. Gusty and erratic winds can be expected in and near thunderstorms.

PRELIMINARY POINT TEMPS/POPS

AMG 94 71 91 72 / 60 50 70 20 SSI 90 76 88 76 / 60 50 70 30 JAX 91 72 90 72 / 70 50 70 20 SGJ 91 74 90 74 / 70 50 60 20 GNV 90 72 90 71 / 60 20 50 10 OCF 91 72 91 72 / 60 20 40 10

JAX WATCHES/WARNINGS/ADVISORIES

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