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 Thunderstorms Each Day Through the Weekend. Strong Storm Potential Each Afternoon and Evening. Daily Rounds of Heavy Downpours May Cause Localized Flooding

- Increasing Rip Current Potential Later This Week Through the Weekend

NEAR TERM /TODAY THROUGH TONIGHT/

Main Highlights:

- Isolated strong storms possible this afternoon into evening

The mid / upper level trough that has been affecting the area for a few days will be west of the forecast area at 12z Today, located from eastern TN southward to the western FL panhandle. It will continue to lift to the northwest today. Mean steering flow through about 500 mb will be south to southeast about 10-15 kt and PWATs will be just above 2 inches, but noting some drier air will filter in per the GFS and SREF guidance with PWATs lowering to about the 1.6 to 1.9 inch range by 09z Friday.

With the Atlantic sfc ridge essentially lifting into southern GA this morning, the developing background southeast flow will enable the east coast sea breeze to move in steadily inland during the day, with winds become east and southeast behind the sea breeze. Don't see the west coast sea breeze making it to our forecast area. With a moist and unstable airmass in place with plentiful low level moisture, we expect some isolated convection to be present over the marine waters where there will be some weak low level convergence and MLCAPE of 2000-2500 J/kg. After collaboration with CHS, there may be a risk of funnel clouds or a waterspout over the marine waters through the mid morning hours with favorable low level CAPE. Convergence along the east coast sea breeze and daytime heating should result in fairly quick development of scattered showers and a few thunderstorms from 8 AM to noon time, generally pushing westward from over the coastal counties and moving toward the Highway 301 corridor as well. During the afternoon, scattered showers and storms are expected with MLCAPE rising to about 2400-2800 J/kg range. Over some of the inland areas, numerous showers and storms are possible as indicated in some of the latest guidance. Main storm threats are heavy rainfall, gusty winds, and frequent lightning. DCAPE values are not excessive, and look to stay under 700 J/kg so winds of about 40-50 mph seem reasonable for possible downburst winds. Soundings and HREF show potential for localized 2-3 inch hourly rainfall, which if there were some brief training of cells, could dump 4+ inches of rainfall causing localized flooding. With plentiful moisture, clouds and precip will hold highs to the lower 90s inland and upper 80s at the coast.

Tonight, isolated to scattered showers and storms expected in the evening, most common well west of Highway 301 and close to the I-75 corridor. Near and after midnight, only isolated shower or a storm possible, which, after midnight would be more favorable along the coastal counties given the prevailing deep southeast flow. Lows tonight expected in the lower 70s inland and mid to upper 70s toward the coast where a gentle southeast sfc wind flow will continue.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/

Main Highlights This Period:

- Daily chances for isolated strong thunderstorms, with wind gusts and heavy rainfall the greatest hazards

Continuing onshore flow through the end of the week and into the weekend as high pressure extends westward from the Atlantic. As higher moisture will be in place over NE FL at the start of the period, coastal showers will be possible during the morning hours on Friday over coastal NE FL. As the day progresses, storms will begin to develop with the inland push of the Atlantic sea breeze, with most convective activity focused along the sea breezes mergers between US-301 and the I-75 corridor across NE FL. On Saturday, the onshore flow persists with the high pressure remaining in place as an inverted trough just off the Atlantic coast, allowing for coastal showers again during the morning hours. Higher moisture levels (PWATs in the 2+" range) combined with diurnal heating and the Atlantic sea breeze will drive development of numerous showers and storms by the afternoon hours across much of the area. Gusty downbursts with winds in the 40 to 60 mph possible with any storms, in addition to frequent lightning and heavy downpours at times.

Daytime temperatures will rise to the lower 90s area-wide aside from coastal locations which will be a bit cooler in the upper 80s thanks to the onshore flow. Overnight Lows will drop to the lower 70s.

LONG TERM /SUNDAY THROUGH WEDNESDAY/

Main Highlights This Period:

- Daily chances for isolated strong to severe thunderstorms, with wind gusts and heavy rainfall the greatest hazards

The high pressure situated over the eastern CONUS will begin to sink southward towards central FL late Sunday into Monday. This will have the southeasterly flow steadily become more southerly, where both the Gulf and Atlantic sea breezes will be able to push inland during the afternoon hours. The coverage of showers and storms will likely be limited due to drier air under the ridge of high pressure, but isolated storms during the afternoon hours will still be possible as the sea breezes merge over inland locations.

Daytime highs near average this weekend will increase to above average into early next week due to less storm coverage. Lows will be near normal this weekend and trend a bit above normal Tuesday into Wednesday.

AVIATION /06Z THURSDAY THROUGH 06Z FRIDAY/

Mainly VFR conditions except for usual suspect mist/fog at VQQ through the early morning hours. After about 11z/12z, a few showers are expected in the morning hours, from about 13z-16z, along the coastal TAFs, with activity gradually pushing inland through the afternoon. Anticipate showers and storms near GNV about 2-3 hours later than coastal TAFs. Restrictions in showers and storms are likely with MVFR and gusty winds. Estimated that highest chance of IFR showers/storms would be for VQQ and GNV this afternoon. Light to calm winds will become east and southeast at about 7 to 12 knots.

MARINE

High pressure centered over Bermuda will build westward toward the United States east coast through the weekend shifting flow from east and southeast today to more east late this week and into the upcoming weekend. Sea heights will gradually rise into early Friday due to the persistent southeast winds, which may reach up to 15 knots from Friday through Saturday. Daily rounds of showers and thunderstorms will also continue daily, some of which will produce gusty winds, heavy rain, and frequent lightning strikes.

Rip Currents: A wind shift to a more southeast/onshore flow along with some increase in wind waves will build surf/breakers to 2-3 feet later today with a Moderate rip current risk expected. Friday into the weekend sees potential surf/breakers of 3-4 feet and corresponding increased rip current risk.

FIRE WEATHER

Scattered to numerous showers for inland locations as southeasterly winds will be present once again as high pressure builds northeast of the area. Friday, more easterly winds will prevail with coastal showers moving onto the Northeast FL coast before midday with numerous thunderstorms inland in the afternoon. Isolated strong thunderstorm potential will remain each afternoon with storm outflows causing sudden and erratic wind shifts, locally stronger winds, and dangerous cloud to ground lightning in and near thunderstorms.

Overall light transport winds will keep dispersions in the fair range this afternoon, but breezier winds on Friday will allow for good dispersions to develop across inland locations away from the coast.

Fog Potential: Significant fog development is not expected, with shallow, patchy fog late overnight limited to areas that receive locally heavy rainfall.

PRELIMINARY POINT TEMPS/POPS

AMG 91 72 93 73 / 50 20 20 0 SSI 89 79 90 78 / 20 30 30 30 JAX 90 74 91 74 / 30 20 30 10 SGJ 89 76 89 76 / 30 40 60 20 GNV 90 72 90 73 / 50 10 60 0 OCF 90 73 91 74 / 60 20 70 10

JAX WATCHES/WARNINGS/ADVISORIES

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