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

- Scattered Afternoon & Evening TStorms Saturday. Hazards: Winds of 40-50 mph, Frequent Lightning Strikes & Heavy Downpours. Isolated Afternoon & Evening TStorms Expected on Sunday

- Hot & Humid Conditions through Monday. Heat Advisories Possible Monday, when Afternoon Heat Indices Peak at 105 - 110 F

- Numerous TStorms Expected on Monday and Tuesday

- Minor Flooding Continues along the Satilla River in Southeast GA

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Isolated strong storm potential along NE FL I-95 corridor and St Johns River Basin

- Hot and humid Today with heat indices 100-107 F

Low level WSW flow continues today with the Atlantic high pressure ridge axis extending westward across the FL peninsula. Strengthening subsidence associated with the building "Heat Wave" ridge over the lower Mississippi Valley combined with slightly drier air (PWATs 1.6- 1.8 in) will limit convective coverage today. Isolated showers and storms develop along the inland-moving Gulf sea breeze in the I-75 corridor during the late morning to early afternoon hours. In the light WSW flow, the Atlantic sea breeze will generally remain pinned to the I-95 corridor. Coverage becomes widely scattered as the sea breeze and outflow boundaries collide in the St Johns River Basin and I-95 corridor later in the afternoon into evening. A few storms could become strong capable of producing gusty winds (40-50 mph), heavy downpours, and frequent lightning. Showers and storms gradually subside this evening with the loss of daytime heating. Slightly above seasonable temperatures today with highs rising into the low to mid 90s. With the drier air, heat indices should remain just below Heat Advisory criteria in the 100-107 F range. Lows will be in the mid to upper 70s.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

Main Highlights This Period:

- Daily chances for thunderstorms, with greatest chances Monday afternoon

- Heat Advisories Possible Monday, when Afternoon Heat Indices Peak at 105 - 110 F

High pressure ridge will be in place on Sunday. The east coast sea breeze will move inland Sunday afternoon to just west of I95. The greatest chance for showers and storms will be along the sea breeze, with a focus along and west of the I95 corridor. The high will help to limit activity to isolated to scattered in coverage. Any storms which do develop Sunday afternoon, are expected to dissipate Sunday evening with loss of diurnal heating. A dry night is forecast for Sunday night. Above average temperatures are forecast for Sunday and Sunday night.

On Monday, a surface trough is forecast to sink south into the forecast area, helping to focus above average chances for convection. Much of this convection will dissipate during the evening hours with loss of diurnal heating, but with the trough in the area, chances will linger through Monday night. Temperatures will be above average Monday and Monday night.

LONG TERM /TUESDAY THROUGH FRIDAY/

Main Highlights This Period:

- Daily thunderstorm chances, with greatest chances on Tuesday

The surface trough will sink to the south Tuesday and Wednesday, as high pressure builds to the northeast. With the proximity of the trough, Tuesday will be another active convective day. Wednesday will still be active, but less than Tuesday.

The high pressure ridge will build over the area Thursday and Friday, with greatest chances for convection over north central FL.

Temperatures this period be near to a little above average.

AVIATION /06Z SATURDAY THROUGH 06Z SUNDAY/

VFR conditions are expected through the period outside of storms. Calm winds overnight become southwest around 5 KTs after 15Z. Winds shift to south-southeast for coastal TAF sites after 17-20Z in the wake of the Atlantic sea breeze. Have placed VCTS in the TAFs beginning around 18-20Z for all TAF sites. Isolated showers and thunderstorms will develop along the inland moving sea breezes after 18Z. Stronger storms may develop near the NE FL sites bringing lower visibilities and breezy winds. Probabilities are too low at this time to include.

MARINE

Atlantic high pressure will extend westward across the Florida Peninsula just south of the area waters through the weekend. A pattern of overnight to early morning light westerly offshore winds and afternoon southeasterly winds expected due to sea breeze circulations. Afternoon and early evening isolated to scattered storms will develop across the nearshore waters each day into Sunday. A weak back door frontal boundary will approach the waters on Monday and stall over the waters Tuesday into Wednesday, supporting increased coverage for showers and thunderstorms for early next week.

Rip Currents:

A lower end moderate risk will develop during the late afternoon hours this weekend at area beaches as onshore winds become breezy following the passage of the sea breeze combined with a southeasterly ocean swell.

FIRE WEATHER

- Patchy High Dispersions Se Ga Sunday

Coverage of afternoon and evening showers and thunderstorms will diminish somewhat this weekend, with activity tending to cluster at locations along and east of U.S. Highway 301. Thunderstorm coverage will then increase on Monday afternoon and evening area-wide, with strong storms possible. Otherwise, westerly transport winds continue this weekend and then shift to west- northwesterly on Monday. The Atlantic and Gulf sea breezes will develop and progress inland each afternoon, resulting in surface winds becoming southeasterly for locations along and east of I-95 during the early to mid afternoon hours each day. Elevated mixing heights will generally yield fair to good daytime dispersion values at inland locations, with fair values expected at coastal locations. Some areas could reach high dispersion values across inland southeast Georgia on Sunday. FOG POTENTIAL AND OTHER REMARKS: Significant fog is not expected this morning, or Tonight. Daily chances for thunderstorms this period. The greatest chance for storms will be on Monday and Tuesday.

PRELIMINARY POINT TEMPS/POPS

AMG 92 75 95 76 / 20 10 10 20 SSI 92 78 95 80 / 30 10 10 20 JAX 95 76 97 78 / 40 20 20 10 SGJ 94 76 95 78 / 30 20 10 10 GNV 95 74 97 76 / 30 20 20 10 OCF 94 74 95 76 / 40 20 20 10

JAX WATCHES/WARNINGS/ADVISORIES

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