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

- Breezy with an Elevated Wildfire Danger this Afternoon

- High Risk of Rip Currents this Afternoon at the Northeast FL Beaches. Moderate Risk at the Southeast GA Beaches Today

- Strong to Isolated Severe TStorms & Beneficial Rainfall Late Tonight. Main Impact Area: Locations North of Interstate 10. Severe Storm Hazards: Wind Gusts of 40-60 mph & Frequent Lightning Strikes

- Strong TStorms & Widespread Beneficial Rainfall Possible Sat & Sat Night. Rainfall Totals of 1-2 inches, with Locally Heavier Totals of 3-4 Inches Possible

UPDATE

Overall threat for strong to severe isolated T'storms late tonight into sunrise Thursday has dimished for SE GA with consecutive runs of the HRRR, NAM, and GFS deflecting more robust convection further northward coser to I-20 into middle and northern GA where weak surface low will develop along the cold front across northern MS/AL/GA as it sinks southward into Thursday morning. A brief gust 40-50 mph cannot be ruled out with a widely isolated T'storms embedded with showers spreading ENE from the SE AL/SW GA/FL panhandle, but appears more likely any activity will consist of briefly heavy showers. Where the heavier showers pass, up to around a quarter of an inch of rain could fall before 8AM.

Some low stratus will stream onto the I-75 and highway 301 corridors after midnight into sunrise across NE FL, but too much wind for fog developement. Lows will be mild in the mid to upper 60s.

NEAR TERM /THROUGH THURSDAY/

Main Highlights This Period:

- Elevated Wildfire Danger for Inland Locations West of I-95 through Sunset.

- High Risk of Rip Currents through Early this Evening at the Northeast FL Beaches; Moderate Risk at Southeast GA Beaches

- Scattered Thunderstorms and Beneficial Rainfall Possible Late Tonight Across Southeast GA. Strong to Isolated Severe Storms Will Be Possible North of Interstate 10 through Sunrise on Thursday.

Afternoon surface analysis depicts weakening high pressure (1019 millibars) located near the northwestern Bahamas. Meanwhile, a cold front stretches from New England and the Mid-Atlantic states southwestward through the Ohio, Tennessee and lower Mississippi Valleys. Aloft...zonal flow prevails across the southern tier of the nation, with a shortwave trough embedded in this flow moving offshore of the northeast FL coast, creating subsidence and decreasing mid and high altitude cloud cover in its wake across our region. Otherwise, another shortwave trough embedded in the zonal flow pattern was traversing the Arklatex region, spreading the next round of upstream convection across the lower Mississippi Valley. Latest GOES-East derived Total Precipitable Water imagery indicates higher PWAT values around 1.5 inches along the I-95 corridor associated with the departing shortwave trough, with values west of the Suwannee Valley falling to around 1.25 inches. Higher PWAT values around 1.5 inches were advecting eastward across the FL panhandle, associated with the aforementioned upstream shortwave trough.

A cumulus field has developed across north central and northeast FL as well as coastal southeast GA as mid and high altitude cloud cover thins out, with fair skies otherwise prevailing in the subsident air mass further inland. Temperatures at inland locations have soared to the upper 80 and lower 90s as of 19z, where dewpoints have crashed through the 50s and lower 60s. A pinned Atlantic sea breeze boundary was developing east of I-95, with breezy onshore winds at area beaches dropping temperatures to the lower 80s, where dewpoints were rising to the upper 60s.

Fast zonal flow aloft will push an upstream shortwave trough currently traversing the Arklatex region and the lower Mississippi Valley eastward along the I-10 corridor later this afternoon and evening, with this feature moving overhead of our area during the early to mid morning hours on Thursday. Meanwhile, a cold front moving into the southeastern states tonight will slow its forward progress as it encounters the prevailing zonal flow pattern. Subsidence will prevail across our region through this evening, with deeper moisture values, featuring PWATS around or just above 1.5 inches then arriving from the west towards midnight for inland southeast GA and northern portions of the Suwannee Valley. Scattered showers and isolated thunderstorms will be possible for these areas beginning shortly after midnight.

A west-southwesterly low level jet of around 35 knots at 850 millibars (around 5,000 feet) will arrive in tandem with the shortwave trough towards sunrise, with MU CAPE values of around 500 j/kg per model soundings developing during the predawn hours across inland portions of southeast GA. These factors may create an environment conducive for scattered strong to isolated severe thunderstorms for locations north of the I-10 corridor during the predawn and early morning hours, with strong wind gusts of 40-60 mph, frequent lightning strikes, and briefly heavy downpours possible within stronger storms in the 2 AM - 6 AM time frame. Multi- layered cloudiness will otherwise increase from west to east during the predawn and early morning hours, with warm air advection ahead of the approaching cold front keeping lows in the mid to upper 60s area-wide.

SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/

Main Highlights This Period:

- Showers and Storms Thursday and Friday

A transition to a more unsettled weather pattern this period with deeper moisture and wavering fronts bringing daily shower and thunderstorm potential. Thursday, showers and isolated storms will be ongoing at the start of the period as a front and mid level short wave trough shift south and east across southeast GA. The front will begin to loose southward push into northeast Florida into Thursday afternoon as the short wave presses offshore, with a chance of showers and isolated storms into the afternoon and evening across northeast FL. The front will lingers north-central FL Thursday night into early Friday morning with a chance of passing showers, then the boundary begins to morph into a lifting warm front Friday afternoon and into Friday evening with stratiform rainfall developing across the cool sector across southeast GA with isolated brief embedded storm. South of the lifting warm front across NE FL, warmer and breezy conditions are expected under strengthening southwest flow, with a chance of afternoon sea breeze induced showers and storms. Friday night, stratiform rainfall will continue to lift northward across SE GA. The main window for isolated strong storms this period capable of gusty winds of 40-50 mph will be Friday afternoon and evening along boundary mergers mainly across northeast FL. Due to the front, there will be a north-south temperature gradient with highs ranging from around 80 to around 90 and lows in the 60s.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Main Highlights This Period:

- Unsettled weekend weather brings beneficial rain - Isolated strong/severe storms possible Saturday

A stronger cold front moves through the area this weekend bringing numerous showers, embedded thunderstorms and beneficial rainfall area-wide from early Saturday through early Sunday. There is high confidence of at least 0.25 to 0.50 inches Saturday through Sunday morning for all of southeast GA and northeast FL, with southeast GA having the better potential of realizing 0.5 to 1 inches with locally higher amounts of 3-5 inches. Overall, a welcomed and desperately needed soaking rainfall.

Sufficient shear and instability ahead of the front could bring a few strong to severe storms, with the general timing of stronger storms north of I-10 Saturday morning, shifting near and south of I- 10 into Saturday afternoon and evening. The main convective hazards on Saturday would be strong wind gusts of 40-60 mph and possibly a few rotating cells depending on the track of surface low moving along the front.

Convection wanes from north to south Saturday night as the front shifts into north-central FL. A reinforcing short wave trough slides across the region into Sunday with stratiform rainfall developing across NE FL and few storms possible across north-central FL Sunday near the lingering frontal zone. Drier conditions filter in from north to south across the area Sunday into early next week as surface high pressure builds eastward across the deep south.

Due to the front, highs on Saturday will range from upper 60s north to around 90 south. Temperatures then cool to near to just below seasonable in the wake of the front Sunday into Monday. Temperatures moderate back to near to above average Tuesday as a more typical diurnal sea breeze regime develops.

AVIATION /00Z THURSDAY THROUGH 00Z FRIDAY/

The 00Z TAF period will begin with VFR conditions with high pressure south and east of the region with southwesterly winds 6-10 knots and scattered mid level clouds 5.0-8.0 kft. Winds will decrease slightly overnight to 5-8 knots with increasing mid and high level clouds as a cold front approaches from the northwest late tonight. Ahead of the front scattered showers will shift to SSI by 06Z with VCSH, then a round of heavier showers and embedded T'storms expected through SSI from 09-12Z with tempo restrictions for MVFR ceilings and lowered visibility.

The round of heavier showers will traverse the duval county terminals from 12-16Z with similar MVFR restrictions. Low stratus will advect in from the Gulf in the westerly flow 10-14Z further to the south. Prevailing VFR should return 16-18Z as low level clouds scatter out under broken mid and high level clouds. VCTS will spread to all terminals in the afternoon where west to northwest flow and strong heating along the frontal boundary as it sinks southward from southern GA towards the Florida and Georgia border will develop isolated to scattered T'storms, However not enough confidence in the coverage and timing for for T'storms Thursday late afternoon for a PROB30 group as of this time.

MARINE

A cold front will enter the southeastern states this afternoon and tonight, with showers and thunderstorms after midnight, mainly across the Georgia waters through Thursday morning. This front will then stall across the northeast Florida waters from late Thursday through Friday, with scattered showers and thunderstorms possible throughout our local waters. A wave of low pressure will then develop over the Gulf by late Friday night or Saturday, with widespread showers and possibly a few strong thunderstorms overspreading our local waters on Saturday, with activity expected to continue into Sunday morning. Small Craft Advisory conditions may develop on Saturday afternoon as southwesterly winds increase ahead of this approaching wave of low pressure. The front will shift south of the northeast Florida waters late on Saturday night, resulting in winds shifting to northwesterly and then northerly on Sunday morning. Breezy northeasterly winds are then expected on Sunday afternoon and night as high pressure builds into the southeastern states.

Rip Currents:

Strengthening onshore winds in the wake of the inland moving sea breeze and increasingly rough surf conditions will combine with a persistent northeasterly ocean swell, featuring a primary swell period of 10-11 seconds, to maintain a high rip current risk at the northeast FL beaches. A high end moderate risk is expected this afternoon at the southeast GA beaches. Although surf conditions will gradually calm on Thursday and Friday, the persistent northeasterly ocean swell will likely maintain a moderate risk at all area beaches.

FIRE WEATHER

- High Daytime Dispersions Today And Saturday

- Beneficial Rainfall Expected Into This Weekend

A few lingering showers are expected early this morning especially across southeast Georgia. Scattered showers and embedded thunderstorms are expected area-wide today and Friday as a cold front moves into the area. Breezy westerly transport winds and elevated mixing heights will result in high daytime dispersions today. The front over northeast Florida on Friday will lift back northward as a warm front. Breezy southwesterly surface and transport winds will continue across north central Florida on Friday, where high daytime dispersions are expected. Surface and transport winds elsewhere will shift to northeasterly, with poor to fair values for locations north of I-10. A stronger cold front then moves through Saturday into Sunday. Widespread showers and the potential for strong to isolated severe thunderstorms are forecast on Saturday and Saturday night. Strong southwesterly surface and transport winds ahead of the front will result in very high dispersions on Saturday across northeast Florida.

FOG POTENTIAL AND OTHER REMARKS: Smoke from nearby fires may result in localized visibility reductions, especially during the overnight and early morning hours.

CLIMATE

Record High Temperatures at NE FL/SE GA climate sites for today:

Wed, April 29: KJAX: 93/1991 KGNV: 95/2017 KAMG: 93/2012 KCRG: 91/2021

PRELIMINARY POINT TEMPS/POPS

AMG 65 81 60 77 / 50 70 20 30 SSI 68 80 66 76 / 40 70 30 40 JAX 67 87 64 83 / 10 70 20 30 SGJ 68 86 66 82 / 10 50 20 30 GNV 67 90 65 88 / 10 40 10 20 OCF 66 88 67 89 / 0 30 10 20

JAX WATCHES/WARNINGS/ADVISORIES

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