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

- Heat and Humidity Builds this Week through the Weekend. Heat Advisory For All of Northeast FL & Southeast GA Coast Today. Extreme Heat Watch Coastal Southeast GA for Thursday. Heat Advisories Possible Rest of the Area Each Afternoon and Evening. Record highs possible Thursday into the Weekend.

- Scattered Afternoon & Evening TStorms Today- Thursday. Isolated Strong/Severe Storms Are Possible With Wind Gusts 40-60 mph

- Scattered Afternoon & Evening TStorms Friday - Monday

NEAR TERM /TODAY THROUGH TONIGHT/

Main Highlights:

- Heat Advisory in effect for Today for parts of the area

- Scattered Thunderstorms This Afternoon and Early Evening

- A few strong to severe thunderstorms possible with gusts up to 40-60 mph and very heavy rainfall Westerly surface winds continue today as the mean layer ridge into the mid levels is over the central Gulf. Deep layer flow up through about 500 mb is west or northwest about 10-15 kt. PWATs remain elevated at about 2 inches or slightly higher. Guidance shows perhaps a better chance of showers and storms this afternoon and evening than prior forecasts. These higher chances, up to 40-60 percent, are focused in a convergence zone that appears to be located along the I-10 corridor northward to Highway 82 in southeast GA. Outside side of these areas, rain chances look to be 20-40 percent. Given the amount of moisture and instability, isolated strong/severe storms are probable especially with any boundary collisions and mergers. Latest model soundings show MLCAPE that may be up to 3000-3500 J/kg and the downdraft CAPE that may be near 1000. That should be enough for gusts up to 40-60 mph. The SPC has shown a marginal risk of severe storms for most of our area today. Isolated to scattered showers and storms are anticipated tonight, and will eventually fade and dissipate by midnight and will show only 10 percent chances after midnight.

Biggest concern today will be dangerously hot temperatures and heat index values. High temperatures will be in the mid to upper 90s, even at the east coast beaches. Maximum afternoon heat indices will be around 105-110 degrees. Heat advisory remains in effect for parts of the area.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

Main Highlights This Period:

- Daily Isolated to Scattered Afternoon Thunderstorms, some of which could be strong

- Heat Index Values near Heat Advisory levels each day. Extreme Heat Watch in place along coastal SE GA Thursday

High pressure over the Gulf will begin to shift towards the northern Gulf coast late in the forecast period as a trough shifts south along the SE coast. With the high pressure over the Gulf, westerly- southwesterly flow will persist through the end of the week. Scattered showers and storms along the Gulf breeze as it pushes inland, with higher chances for locations south of the I-10 corridor as moisture will be slightly higher over NE FL. The Atlantic sea breeze will begin to push onshore during the afternoon hours, with coverage of showers and storms expect to inland from the coast of SE GA and NE FL as the sea breezes merge.

Warm temperatures will continue through the end of the week as daytime highs will remain in the upper 90s, close to 100F for some locations. A Heat Advisory will likely be needed for both days. An Extreme Heat Watch is currently in place for coastal SE GA as Heat Index values may rise to 112F to 114F Thursday afternoon.

LONG TERM /SATURDAY THROUGH TUESDAY/

Main Highlights This Period:

- Warm temperatures continue over the weekend, with Heat Advisories likely on Saturday

A dipping cold front along the SE coast will allow for higher chances of showers and storms across SE GA on Saturday, and then south towards NE FL on Sunday. Coverage of showers and storms look to shift further south towards NE FL on Monday, and back north as the front drifts northward on Tuesday. The above average temperatures will persist into the upcoming weekend, where we will continue to have temperatures rise to the upper 90s and heat index values rising to heat advisory criteria during the afternoon hours. But the timing of showers and storms may keep some locations from rising much as cloud cover may limit much heating to take place.

AVIATION /06Z WEDNESDAY THROUGH 06Z THURSDAY/

Mostly VFR debris clouds left over tonight which should diminish through sunrise. Once again, diurnal heating and sufficient moisture will lead to scattered TSRA at all TAF sites in the 18-24Z Wednesday afternoon and have TEMPO and PROB30 groups at all terminals for potential MVFR conds along with gusty winds. Lingering isolated to scattered showers and storms are still anticipated from about 00z-03z Thursday. Sfc sfc winds - westerly winds near 5 kt or less early this morning increase to about 8-11 kt by 14-15z. Could get a temporary wind shift to southerly or southeast to occur at SGJ and SSI around 20-21z associated with the sea breeze.

MARINE

Atlantic high pressure will shift south and westward as a trough forms over the southeastern states. Each afternoon, the sea breeze will shift winds southeasterly over the near shore waters through the upcoming weekend, followed by southerly evening wind surges which may briefly increase to near caution levels. Scattered mainly afternoon and evening thunderstorms will remain possible each day through the upcoming weekend. Some of these storms may be strong.

Rip Currents: Low surf heights at or below 2 ft and offshore flow will likely yield a low risk at area beaches today. This pattern will likely continue through Friday.

FIRE WEATHER

- PATCHY HIGH AFTERNOON DISPERSIONS OVER SE GA TODAY AND THURSDAY

Light west to southwest winds will keep the Atlantic seabreeze near the coast each day, with lower thunderstorm coverage expected Today. A few strong thunderstorms may produce gusty outflows with locally erratic winds. Warm temperatures continue as highs will be in the mid 90s inland and lower to mid 90s at the coast Today. Heat Advisory is in place across NE FL and coastal locations of SE GA as peak heat index values of 106-112. With warm temperatures expected to continue through the rest of the week, heat advisories will likely be needed. Patchy high daytime dispersions expected Today and Thursday as mixing heights increase with increasing westerly transport winds. Fog Potential: Significant fog development is not expected, with shallow, patchy fog late overnight limited to areas that receive locally heavy rainfall.

CLIMATE

Daily record high temperatures are possible Thu-Sat:

Thursday, August 13th: KJAX: 99/2023 KGNV: 99/2023 KAMG: 100/9999 KCRG: 96/2023

Friday August 14th: KJAX: 99/2023 KGNV: 97/2023 KAMG: 101/2023 KCRG: 98/2023

Saturday August 15th: KJAX: 99/1956 KGNV: 100/1918 KAMG: 99/1995 KCRG: 97/9999

PRELIMINARY POINT TEMPS/POPS

AMG 94 75 96 77 / 30 10 10 10 SSI 95 78 97 80 / 40 20 20 10 JAX 95 76 97 76 / 60 20 40 10 SGJ 94 77 94 77 / 50 20 40 10 GNV 94 75 95 75 / 20 30 40 10 OCF 95 75 95 75 / 20 20 40 10

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from noon today to 7 PM EDT this evening for FLZ021-023-024-030-031-035-038-120-124-125-132-136>138- 140-220-225-232-233-236-237-240-322-325-333-340-422-425- 433-522-533-633. GA...Heat Advisory from noon today to 7 PM EDT this evening for GAZ153-154-162-165-166. Extreme Heat Watch from Thursday morning through Thursday evening for GAZ153-154-165-166. MARINE...None.