textproduct: Jacksonville

..NEW 18Z AVIATION DISCUSSION

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

- Dangerous Heat Continues Today. Heat Advisory along the I-95 & U.S.-301 corridors in Northeast FL & Southeast GA. High Temperatures: 93-99 and Peak Afternoon Heat Index Values: 103- 110

- Strong to Isolated Severe TStorms this Afternoon through Early Evening. Hazards: Damaging Winds of 40-60 mph, Frequent Lightning & Heavy Downpours

- Increasing Coverage of Afternoon Thunderstorms Monday & Tuesday. Heavy Downpours & Localized Flooding Possible

- Heat & Humidity Returns Late this Week and into Next Weekend

NEAR TERM /THROUGH TONIGHT/

Main Highlights This afternoon and Tonight:

- Heat Advisory Conditions Along the I-95 Corridor

- Isolated Severe Storms with damaging wind potential

Heat Advisory will remain in place for now, with mainly locations along the I-95 corridor reaching into the 105-110F range for heat indices, with highs in the middle 90s. Earlier convection over inland areas should hold Max Temps into the lower 90s across inland areas with peak heat indices around 105F. Low temps near seasonable levels tonight with lower/middle 70s inland, upper 70s along the Atlantic Coast/I-95 corridor.

Other than the heat, the main impact will be higher thunderstorm coverage this afternoon with numerous storms expected across NE FL and scattered storms expected across SE GA. Mid level lapse rates not as steep as yesterday, along with slightly less drier air aloft and DCAPE values not as high as yesterday. So while expected isolated severe storms to develop, the threat for damaging winds around 60 mph not as great as Saturday afternoon, and will be most likely near the Gulf/East coast sea breeze mergers along the I-95 corridor across NE FL and along outflow mergers across SE GA. With a later start to convection across SE GA, expect isolated severe storm threat there to linger well into the evening hours towards midnight, while the convection across NE FL should fade by the sunset time frame. Increasing SW steering flow ahead of southward moving front across the SE US states will allow for convection to develop over the NE Gulf during the overnight hours with some widely scattered showers and storms pushing into inland NE FL towards morning, mainly to the West of the I-75 corridor, impacting Marion, Alachua and Gilchrist counties.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

Main Highlights During This Period:

-Increased storm potential this period, with greatest chance for strong to severe thunderstorms and heavy rainfall north oF I10

The region will be between a high pressure ridge to the south, and a frontal boundary stalled just to the north this period.

The west southwest flow between these features will largely keep the east coast sea breeze from moving inland. Due to the proximity of the frontal boundary, precipitation chances will be greater than average, especially over SE GA.

Temperatures will be above average this period, but as high as recent days, due to forecast cloud and precipitation coverage.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

Main Highlights During This Period:

- Reduced chances for storms

High pressure ridge will extend across southern FL this period, with a weakening frontal zone just to the north. This pattern will keep a westerly flow going throughout the period, with the east coast sea breeze pinned near the coast. Daily convective chances will continue this period, mainly during the afternoon and evening hours. With the frontal zone weakening, chances will not be as high as earlier this week.

Temperatures will be above average this period, with highs in the mid 90s common.

AVIATION /18Z SUNDAY THROUGH 18Z MONDAY/

Storm chances higher today and will upgrade all of the NE FL terminals from PROB30 to TEMPO groups this afternoon, mainly in the 18-23Z time frame, for gusty winds to 30 knots, MVFR CIGS and potential IFR VSBYS in heavy rainfall. Storm arrival will be delayed at SSI along with slightly lower rainfall chances and will keep PROB30 there from 21-01Z time frame. VFR conds return to terminals after sunset across NE FL and by 03-04Z at SSI, with just leftover convective debris mid/high clouds. Fog chances likely too low to include at this time towards sunrise, but will monitor if any terminals receive heavy rainfall today that would help to produce fog formation. Late in the TAF period, morning convection will be possible at GNV in the 13-15Z time frame onward and will need to add at least VCSH and possible VCTS towards 18Z time frame. Outside of thunderstorms, westerly flow will keep the Atlantic sea breeze stuck at the coast and otherwise maintain southwesterly flow at or below 12 knots.

MARINE

A frontal boundary will sink southward towards the Georgia waters tonight into Monday, with this feature stalling over the Georgia waters on Tuesday before weakening later this week. Showers and thunderstorms will impact our local waters earlier during the afternoon hours on Monday and Tuesday, with a few strong storms possible, especially for the waters north of St. Augustine. Coverage of showers and thunderstorms will then decrease by Wednesday and especially on Thursday and Friday as the frontal boundary dissipates, with only isolated to widely scattered late afternoon and early evening activity possible for the near shore waters as a prevailing westerly flow continues during the overnight and morning hours each day.

Rip Currents:

Low to Moderate risk of rip currents will continue into early this week as offshore flow becomes SE/onshore during the afternoon/early evening hours with surf generally 2 feet or less.

FIRE WEATHER

AREAS OF HIGH DISPERSIONS TUESDAY THROUGH THURSDAY, ESPECIALLY - North Of I10

The region will be between high pressure to the south and a gradually weakening frontal zone to the north this week. While daily thunderstorm chances are forecast, above average chances can be expected early in the week. Temperatures will be above average, with a trend upward later in the week.

Fog Potential and other remarks: Significant fog potential is not expected Tonight. Erratic wind gusts possible in and near thunderstorms, and at times, at a distance due to outflows.

PRELIMINARY POINT TEMPS/POPS

AMG 96 73 89 72 / 40 40 70 50 SSI 94 77 92 75 / 40 50 80 50 JAX 96 75 93 73 / 60 40 80 40 SGJ 95 75 93 75 / 60 40 80 20 GNV 94 74 91 72 / 70 30 60 50 OCF 93 74 91 74 / 60 40 80 40

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory until 7 PM EDT this evening for FLZ023-024-030- 031-038-124-125-132-137-138-225-232-233-237-325-333-425- 433-533-633. GA...Heat Advisory until 7 PM EDT this evening for GAZ136-151>154- 165-166-264-350-364. MARINE...None.