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

- Numerous Afternoon and Evening Thunderstorms through Around Midnight Ton, with Strong to Isolated Severe Storms Possible. Where: Interior Southeast GA and Locations Between the I-75 and I-95 Corridors in Northeast and North Central FL. Main Hazards: Wind Gusts of 40-60 mph, Frequent Lightning Strikes, and Localized Flooding at Urban and Normally Flood Prone Locations Possible.

- High Risk of Rip Currents Continues at the Northeast FL Beaches. Moderate Risk for Southeast GA Beaches.

- Scattered to Numerous Thunderstorms Each Afternoon & Evening from Sunday through Next Week.

- Daily Heat Index 95 - 105 F During the Next Several Days.

- Historic Drought & Elevated Wildfire Danger Continues.

NEAR TERM /THROUGH TONIGHT/

Main Highlights This Period:

- Numerous Afternoon and Evening Thunderstorms through Around Midnight Ton, with Strong to Isolated Severe Storms Possible. Where: Interior Southeast GA and Locations Between the I-75 and I-95 Corridors in Northeast and North Central FL. Main Hazards: Wind Gusts of 40-60 mph, Frequent Lightning Strikes, and Localized Flooding at Urban and Normally Flood Prone Locations Possible.

- High Risk of Rip Currents Continues at the Northeast FL Beaches. Moderate Risk for Southeast GA Beaches.

Afternoon surface analysis depicts a wavy, stationary frontal boundary wedging down the spine of the southern Appalachians, as well as across the Ohio, Tennessee, and Lower Mississippi Valleys. Meanwhile, strong high pressure (1035 millibars) positioned over coastal New England, while Atlantic high pressure (1027 millibars) centered near Bermuda continues to extend its axis southwestward across our region to the south of this stationary boundary. Aloft...deep-layered Atlantic ridging has been nudged just enough eastward by troughing over southern Canada and the northern Plains states to create a gradually deepening southwesterly flow above 600 millibars (around 15,000 feet) per the 18Z sounding at Jacksonville, with prevailing light southerly winds below 600 millibars.

Latest GOES-East derived Total Precipitable Water imagery indicates moistening area-wide in the prevailing south to southwesterly flow pattern, with PWATs mostly in the 1.75 - 2 inch range now in place. Widespread convection earlier this morning along the FL Big Bend / Nature Coast decayed as it pushed inland towards I-75, leaving behind a cirrostratus canopy across most of our area that continues to gradually thin out. Convection developed rather quickly and increased in coverage and intensity for locations west and north of Waycross thus far this afternoon, while widely scattered showers were developing elsewhere. Temperatures were generally in the 80s to around 90 as of 19Z, while dewpoints remain in the upper 60s to mid 70s.

Abundant tropical moisture and thinning debris clouds from convection earlier this morning along the FL Big Bend and Nature Coast should lead to an expanding coverage of showers and a few strong to possibly severe thunderstorms later this afternoon. We expect that higher coverage of convection will shift from locations west and north of Waycross to areas along the U.S. Highway 301 and I- 95 corridors during the mid to late afternoon hours, with mesoscale boundaries such as the Atlantic sea breeze then shifting coverage further inland across southeast GA and the Interstate 75 corridor in the Suwannee Valley and north central FL during the late afternoon and evening hours. Southwesterly flow may advect enough shortwave energy across our area later today to keep numerous showers and thunderstorms ongoing this evening, with some convective debris showers possibly being steered back towards the U.S.-301 and I-95 corridors before midnight.

Colliding mesoscale boundaries will have an unstable and moist environment to feed off of, with ML CAPE values rising to 1,500 - 2,000 j/kg this afternoon, likely resulting in a few storms pulsing to strong to possibly severe levels. The main hazards with these pulsing strong to severe storms will be downburst winds of 40-60 mph, accompanied by frequent lightning strikes and locally heavy downpours. Slower moving or back-building storms could present a localized flood risk, mainly for urban or low-lying, normally flood prone locations. Highs this afternoon will climb to the upper 80s and lower 90s before convective coverage increases, with max heat index values of 95-100 expected. Cloud cover will be slow to thin out after midnight, keeping lows in the 70-75 degree range at most locations.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

Main Highlights This Period:

- Isolated Strong Storms Possible Inland Sunday Afternoon/Evening.

- Hot and humid conditions conditions.

Sunday, the region will be between a closed mid/upper level trough to the west over TX and mid/upper level ridging near Bermuda to the ENE with prevailing SW flow above 10,000ft into the mid levels. low level flow around a Bermuda high pressure ridge axis extending WSW across north central FL will be from the SSE to start the day and shift more southeasterly into the afternoon as the ridge axis lifts into northern FL. Partly cloudy skies early with light SSE winds 4-8 mph will become breezy 10-15 mph with gusts to 25 mph along the coast. Precipitable Water levels in the 1.8-2.0 inches due to the SW flow aloft will allow diurnal cumulus clouds in the morning to tower and grow as the Atlantic/river/lake breezes develop and turn breezy at the coast 12-18 mph with gusts to 25 mph and 10-15 mph along I-95 into the St Johns river and 5-10 mph well inland as the Atlantic seabreeze presses inland with light south to southwest winds behind the Gulf seabreeze shifting across the Suwannee River towards I-75 in the late afternoon.

Strong diurnal heating and lift along the developing and inland moving river/lake/seabreezes will produce scattered showers and T'storms during the late morning/midday hours, then become numerous as shortwave energy passes over the area downstream of the closed mid level trough. The Gulf seabreeze will shift inland and merge with the Atlantic seabreeze near I-75 in the late afternoon hours, allowing numerous T'storms to continue into sunset before ending by 10PM with scattered showers persisting into midnight under thinning debris clouds.

While 0-6 km shear will be light, mainly at or below 20 knots, high moisture content, strong heating and somewhat steep mid level lapse rates 6.0-6.5 C/km will support isolated strong T'storms with gusty downburst winds the primary hazard threat for winds up to 40-55 mph, along with frequent lightning. Slow storm motions will also support a threat for localized minor flooding due to very heavy rainfall rates as indicated by 12Z HREF neighborhood probabilities of at least 3 inches of rain Sunday afternoon over 50 percent along and west of highway 301 from Santa Fe river north to US-82 in SE GA. Overall, most locations in the area will receive at least 0.25-0.75 inches Sunday afternoon and evening with a few isolated spots.

Showers and T'storm coverage will keep highs Sunday near normal over SE GA and into the I-10 corridor and along the coast with mid to upper 80s and slightly above normal with low 90s southward into north central FL. Mid and high level cloud will gradually thin overnight.

Monday, Bermuda ridge axis lifts northward into SE GA with flow in the low levels from the SE as ridging aloft to the ENE shifts more east of the region. A slight increase in the local pressure gradient will bring breezier ESE winds along the coast behind the dominant Atlantic seabreeze 15-20 mph with gusts 25-30 mph at the beaches, but decreasing to 10-15 mph west of I-95 and 5-10 mph over inland NE FL and SE GA west of highway 301. Slightly drier air (PWATS 1.6-1.9) and absent shortwave energy over the area due to ridging aloft to the east deflect it NW of the area will lead to less overall coverage of T'storms, scattered over NE FL and the coast, but more scattered to numerous over the Suwannee Valley of NE FL and inland SE GA where PWATs will be closer to 1.8-2.0 inches.

Highs will be above normal, rising into the lower 90s for NE FL and SE GA areas south of Waycross, with near normal highs in the mid to upper 80s northward to the Altamaha river basin due to more showers and T'storm coverage and also along the coast due to the elevated onshore flow.

LONG TERM /TUESDAY THROUGH SATURDAY/

- Hot temperatures Tuesday.

- Chances of showers and storms each day increasing in coverage later in the week.

Tuesday high pressure ridging aloft will shift SW away from Bermuda across the Atlantic waters to our east. This shift will help deflect shortwave energy to the NW with low level southeasterly flow and mid level southerly flow. The result will be Seabreeze pattern of inland moving Atlantic/Gulf seabreezes yielding scattered afternoon T'storms ending in the evening with higher coverage over SE GA areas north of US-82 where high moisture levels will be. Scattered showers and T'storm coverage increases to more scattered to numerous coverage Thursday, then numerous by Friday as Bermuda high pressure retreats to the southeast and an upper low feature lifts northward from the southern Gulf/western Cuba into the FL peninsula into the start of next weekend. A threat for gusty wet downburst winds 40-50 mph, frequent lightning, and locally heavy rainfall rates leading to localized minor flooding concerns will be present each day through the period.

Highs will be above normal Tuesday in the low 90s with isolated mid 90s south of I-10 and decrease to near normal Wednesday and Thursday with upper 80s to near 90, then near to slightly below normal Friday into next Saturday with highs in the 80s. Lows will be above normal in the upper 60s over SE GA and low 70s over NE FL with mid 70s at the coast during the period.

AVIATION /18Z SATURDAY THROUGH 18Z SUNDAY/

MVFR ceilings around 3,000 feet will continue through around 19Z at SGJ. Showers and thunderstorms may begin developing towards 20Z along and west of the I-95 corridor, with activity then potentially expanding westward across the U.S. Highway 301 and Interstate 75 corridors after 22Z. TEMPO groups for brief surface wind gusts up to 30 knots, along with IFR visibilities during heavier downpours at JAX, VQQ, and GNV, with activity potentially extending past 02Z at these TAF sites. Confidence in thunderstorm impacts remains somewhat lower at CRG, SGJ, and SSI. PROB30 groups for briefly wind gusts up to 30 knots, along with MVFR visibilities during heavier downpours, were used at the CRG and SGJ terminals through around 04Z Sunday. Confidence was only high enough for vicinity shower coverage this afternoon and evening at SSI, as thunderstorm activity may cluster over inland portions of southeast GA during the late afternoon and evening hours.

IFR to LIFR visibilities are likely after 06Z tonight at VQQ, with periods of MVFR visibilities possible at the rest of the northeast FL terminals after 06Z. VFR conditions should then prevail at the regional terminals by 13Z Sunday, with periods of MVFR ceilings around 1,500 - 2,000 feet possible after 15Z at SGJ. Southeasterly surface winds will increase to 10-15 knots at the regional terminals this afternoon away from developing convection. Speeds will remain sustained at 10-15 knots through around 04Z tonight at the SSI and SGJ coastal terminals as surface winds veer to a south-sourheasterly direction, with speeds elsewhere diminishing to around 5 knots or less by 05Z. Southerly surface winds will then increase to around 10 knots at the inland terminals by 15Z Sunday, while surface winds likely shift to southeasterly at 10-15 knots before 17Z at the coastal terminals.

MARINE

A stationary frontal boundary located to the north and northwest of our local waters will lift northward as a warm front on Saturday night and Sunday. Meanwhile, Atlantic high pressure centered near Bermuda will continue to extend its axis southwestward across our local waters through early next week, maintaining a prevailing south to southeasterly wind flow, with southeasterly wind surges during the late afternoon and evening hours increasing speeds to Caution levels for the northeast Florida waters. Widely scattered showers and thunderstorms will remain possible through Sunday across our local waters, with activity then becoming more isolated on Memorial Day and Tuesday. Atlantic high pressure will then shift southward during the mid to late portions of next week, with increasing chances for showers and thunderstorms across our area as prevailing winds become southerly.

Rip Currents:

A longer period (9-10 second) east-southeasterly ocean swell and slightly elevated surf conditions, featuring breakers of 2-4 feet, will combine with strengthening onshore winds behind the inland moving sea breeze to create a high risk of rip currents at the northeast FL beaches this afternoon. Lower surf heights, featuring breakers around 2 feet, will keep a higher end moderate risk at the southeast GA beaches this afternoon. Similar conditions are expected on Sunday and Memorial Day, with an elevated risk (likely high) expected at all area beaches due to breezy onshore winds combining with a persistent ocean swell and slightly elevated surf conditions to increase the risk, especially during the late afternoon and early evening hours on both days.

FIRE WEATHER

- Isolated Strong To Severe Storms Possible through this Evening.

- Patchy High Dispersions Monday And Tuesday.

Numerous showers and storms this weekend will limit afternoon dispersions into the fair to good range. Sea breeze thunderstorm pattern with Bermuda high pressure extending over the area is in place this weekend with added instability aloft developing numerous showers and thunderstorms that will continue into the evening hours as the sea breezes shift inland and merge. In the south-southeast flow, the sea breeze merger will likely be between the I-75 and US 301 corridors in the late afternoon into early evening today and Sunday. Isolated strong to severe thunderstorms are also possible into early this evening especially across inland Southeast Georgia Georgia. Potential hazards still expected to be damaging wind gusts, heavy downpours, localized flooding, and frequent lightning this afternoon and early evening.

As Bermuda high pressure shifts closer to the region from the Atlantic, some drier air aloft will move in early next week leading to lower T'storm coverage to scattered for most of the area except over portions of Southeast Georgia north of US-82. Elevated mixing heights and slightly increasing transport winds early next week will lead to good to patchy high dispersions Monday and Tuesday.

FOG POTENTIAL AND OTHER REMARKS: Significant fog is not expected into this weekend. Erratic winds during periods of thunderstorms.

CLIMATE

While record highs are not anticipated over the next several days despite the upward trend, the very mild low temperatures (lower to mid 70s) may result in some record warm minimums at Jacksonville, Craig Airport, and Gainesville. This pattern starts today and continues into early next week.

PRELIMINARY POINT TEMPS/POPS

AMG 70 86 68 87 / 80 70 50 80 SSI 75 87 76 87 / 50 50 30 30 JAX 73 89 74 90 / 50 60 30 50 SGJ 75 89 76 89 / 50 50 20 30 GNV 72 91 72 92 / 70 70 50 50 OCF 72 90 73 90 / 60 70 50 40

JAX WATCHES/WARNINGS/ADVISORIES

FL...High Risk for Rip Currents through late tonight for FLZ124-125-138- 233-333. GA...None. MARINE...None.