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 strong to marginally severe storms possible this afternoon and early evening for southeast GA and much of northeast FL

- Hotter today; Peak Heat Index 100-107 degrees

- Moderate Rip Current risk at area beaches through Wednesday

NEAR TERM /THROUGH TONIGHT/

Highlights through Tonight:

- Isolated strong to marginally severe thunderstorms possible amid scattered to numerous thunderstorms for areas along and north of I- 10 this afternoon and early evening.

- Hotter conditions with heat index in the 100-107 degree range

After a generally dry day yesterday, afternoon thunderstorm chances will be much higher (50-70%) this afternoon particularly in areas along and north of I-10. Fueling the convection this afternoon will be building heat, a Gulf moisture return, and a incoming shortwave impulse. With the moistening southwesterly lower level steering winds remaining in place today, the sea breeze again will be kept east of the I-95 corridor this afternoon.

While a considerably dry airmass aloft (above 10,000 ft) will limit deeper convective develop across north-central FL, a slow feed of moisture aloft will destabilized the airmass north of the I-10 corridor where some broader lift will be offered by a weak impulse as it drops in from the northwest and is sheared between the upper trough to the east and dominant ridge to the west. The northern half of the county warning area will be where scattered to numerous showers, pulse storms, and thunderstorm clusters may develop through the mid afternoon and early evening hours before convection shuts down by midnight. There may be some overnight shower development toward the Suwannee Valley and I-75 corridor amid the convergent southwesterly flow.

The threat for the strongest thunderstorms, which may be capable of marginally severe wind gusts, will be along the I-95 corridor from Jacksonville northward to Brunswick where the interactions between the pinned sea breeze and outflow are likely. Forecast soundings do depict the potential for "pockets" of dry air to exist and amplify the potential downdrafts, possible leading to localized damaging microbursts (wind gusts 40-60 mph). The Storm Prediction Center has expanded the marginal risk (level 1 of 5) of severe storms to most of northeast FL for this afternoon due to uncertainty in the moisture return.

Temperatures will warm a few degrees compared to yesterday with highs pushing into the low to mid 90s before thunderstorm activity begins. With dewpoints mixing into the low to mid 70s, it'll feel like hotter as heat index today will peak in the 100-107 degree range. There's potential for slightly hotter conditions along the SE GA coast where heat index could push near 110 degrees but with the potential for showers to develop along the sea breeze confidence is too low to hoist a Heat Advisory for the coastal SE GA areas.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

Main Highlights This Period:

- Increase in showers and storms with return of moisture, higher chances heading into midweek.

- Heavy downpours and slow moving showers/storms could bring localized flooding.

The stalled frontal boundary over central GA will remain through midweek, with southwest flow persisting over the area. This will allow for moisture to continue to advect into the SE US, where PWATs are expected to remain near 2 inches across the local area. The wind regime will allow the Gulf breeze to remain dominant and push inland each afternoon. With light southwesterly flow and a good amount of moisture overhead, the development of slow-moving showers and storms on Tuesday and Wednesday could bring periods of heavy downpours, with the potential for localized flooding along urban areas and poor drainage areas. Currently the coverage of numerous to widespread showers and storms looks to be greatest on Tuesday, as most locations sit above 50% chance of precipitation. By Wednesday, the coverage of numerous showers and storms looks to be more focused along SE GA and coastal NE FL. Activity will be greatest during the afternoon hours as the sea breezes begin to move inland and meet towards the I-95 corridor.

With higher chances of precipitation and cloud cover, daytime highs will sit in the lower 90s to mid 90s on Tuesday and Wednesday, with overnight lows in the lower 70s across inland locations, and mid to upper 70s along the coast.

LONG TERM /THURSDAY THROUGH SUNDAY/

Main Highlights This Period:

- Active weather continues into the weekend.

- Warm temperatures, but Heat Advisory conditions is not expected at this time.

An active pattern is expected past midweek, with southwesterly flow continuing to bring the Gulf breeze inland, with diurnal heating bringing the potential for convective activity each afternoon. The ridge over the eastern US begins to lift by the weekend, causing for southwesterly flow to lessen and the onshore flow from the Atlantic to strengthen. This will bring higher chances of showers and storms east of the I-95 corridor during the upcoming weekend. Temperatures will trend slightly above average through the end of the week and the weekend as daily high temperatures reach into the lower 90s. Heat index values will rise to be over 100 during this period, but are expected to remain below heat advisory criteria each day.

Tropics Outlook: NHC has a 50% chance of tropical cyclone formation mid to late week across the central Atlantic. Locally, rip current activity could become more enhanced late week depending on the evolution of this system.

AVIATION /06Z MONDAY THROUGH 06Z TUESDAY/

Light southwesterly to southerly winds at or below 5 mph will trend toward calm through the rest of the predawn hours. Predominant VFR conditions are expected at area terminals will temporary low stratus development possible with low MVFR to IFR ceilings possible, mainly west of the I-95 corridor through 12z.

During the day, there will be an increase in shower and afternoon thunderstorm coverage. Confidence is higher for impacts at the Jax Metro airfields and other terminals along and north of I-10. Primary impacts will be erratic, sudden wind gusts potentially up to 35 knots or higher. Left, but enhanced, inherited PROB30 groups and extended it into the early evening hours. If moderate confidence remains, TEMPO groups will be justified in the following TAF forecast package. Anticipate most convective related impacts to tail off after 02z this evening.

SW to SSW winds prevail through the day with the Atlantic sea breeze wind shift expected during the mid afternoon hours for I-95 corridor and coastal airfields.

MARINE

A stalled front near the Georgia coastal waters will linger today before gradually dissolving through the week. Main maritime concern will be increasing potential for afternoon and evening thunderstorms each day this week. The steering winds will generally move thunderstorms from the shoreline toward the offshore waters during the evening hours. Outside of thunderstorm influences, low to calm seas and light offshore winds persist.

Rip Currents: Low risk today until the sea breeze develops then risk will increase to moderate through the afternoon. A solid moderate risk will develop on Tuesday as a marginally strong easterly swell pushes into the coast. No significant increase in breakers is expected with relatively low surf, around 1-2 feet.

FIRE WEATHER

West to southwesterly flow continues through the week, with east to southeast winds across coastal locations during the afternoon hours as the Atlantic sea breeze pushes inland. An increase in moisture across the area, with chances of showers and storms increasing through the week. Good min RH values is expected during the upcoming week with the increase in moisture. Warm temperatures will remain through the upcoming week with temperatures in the Lower to Mid 90s each afternoon. Heat Index expected in the upper 90s to mid 100s, with Heat Advisory conditions not expected at this time.

Fog Potential: Significant fog is unlikely, and any strong wind will be associated with nearby thunderstorm activity.

PRELIMINARY POINT TEMPS/POPS

AMG 96 73 94 72 / 60 20 80 30 SSI 94 77 91 76 / 50 40 60 40 JAX 95 73 92 72 / 50 50 80 30 SGJ 94 75 91 74 / 20 30 60 30 GNV 94 73 91 71 / 30 20 70 20 OCF 94 74 91 73 / 20 20 60 20

JAX WATCHES/WARNINGS/ADVISORIES

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