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

- Afternoon & Evening T'Storms Area-Wide Through Most of the Week. Scattered to Numerous Thunderstorms this Afternoon (2 PM 9 PM). Strong Storms with Gusty Winds, Frequent Lightning Strikes & Heavy Downpours I-95 & I-10 corridor and all of SE GA this afternoon

- Hot and Humid Conditions Return Late this Week and Continue this Weekend. Heat Index Values Peaking 102-110.

NEAR TERM /UNTIL 6 AM THIS MORNING/

Main Highlights This Period:

- Not as Hot Today, Especially for Southeast GA

- Scattered to Numerous Afternoon Thunderstorms, A Few Strong to Isolated Severe Storms Possible, with locally heavy rainfall

Another day featuring a southwesterly flow and a nearly stationary but weakening frontal boundary just north of the region. This will once again result in an early onset of convection, generally filling in from west to east throughout the day as the Gulf Sea breeze pushes inland, getting additional lift and energy from the above mentioned boundary as well as some shortwave energy aloft. Moisture is once again abundant with PWATs in the 2-2.25" range area-wide, leading to torrential downpours being the main concern with any thunderstorms as well as gusty winds of 40+ mph in any stronger cells. Storm motion looks to be pretty quick once again today, and therefore flooding concerns will generally low overall outside of any significant training. As mentioned above, high temps will be a few degrees lower today with both the earlier convection and more clouds cover across the area, but especially over southeast GA. Highs will range from the 80s north and west of I-10 to the low to mid 90s south and east.

Tonight, the frontal boundary to our north will continue to weaken and become more diffuse, but energy along the base of a longwave trough will continue to stream across GA through the overnight hours. This, combined with the very moist airmass in place, is expected to keep some scattered showers and perhaps an isolated t'storm going for north and western areas through at least the first half of the night and possibly towards Wednesday Morning. Low temps will be mainly in the low to mid 70s Tonight.

SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/

Main Highlights Wednesday through Thursday night:

- Isolated Strong Storms and Locally Heavy Rainfall Wednesday - Elevated Heat and Possible Heat Advisory Conditions Thursday

The leftover frontal zone will lift to the north as it dissipates Wednesday but moist southwesterly flow will keep elevated rain and diurnal thunderstorms, capable of heavy rainfall and localized flooding along with strong gusts. By Thursday, there is less certainty in the pattern and influence from a semi-tropical wave lifting out of the northern Gulf. Latest guidance keeps the lifting tropical wave mainly to the northwest, however, some interior areas of SE GA may be influenced by the passing wave. Timing the wave and its potential to shift east remain the primary forecast challenges with the feature on Thursday. There's potential for PoPs to increase for Thursday, especially for NE FL where pops are currently 30-50%. If everything tracks according to the current guidance, there will still be isolated to scattered thunderstorms along the I-95 corridor along a pinned Atlantic sea breeze.

A broad shield of cloud cover will limit heating Wednesday with highs in the mid/upper 80s along and north of I-10 and into the low 90s for areas south. A bit more of typical diurnal set up on Thursday will allow highs to commonly read in the low/mid 90s. With mid 70s dewpoints, it's possible that a Heat Advisory may need to be considered for Thursday afternoon as heat index values may peak in the 105-110 range.

LONG TERM /THURSDAY THROUGH MONDAY/

Main Highlights This Period:

- Daily rounds of thunderstorms, increasing over the weekend - Hot and Humid through the Weekend - Increasing Rip Current Risk, likely to moderate levels, over the Weekend

Moist southwesterly flow will promote elevated chances for Scattered to numerous showers and thunderstorms, especially for SE GA and the I-95 corridor to end the week.

Over the weekend, it appears long-range ensembles agree that a surface front will push possible into northern FL and stall and dissipate through Sunday. Initially an increasing chance for thunderstorms will focus along the front with potential for strong or marginally severe convection Saturday. As high pressure moves quickly of the Mid Atlantic coast, the Atlantic sea breeze will be favored, pushing the better storm chances inland. After the first front dissipates, another weaker front is projected to move into the southeastern US and possibly stall near the forecast area, setting up another couple of days of enhanced thunderstorm potential.

Hotter than typical conditions for late June are expected to end the week and into next week with triple-digit peak heat index readings expected especially across NE FL.

AVIATION /06Z TUESDAY THROUGH 06Z WEDNESDAY/

Isolated SHRA/-RA continue to stream across the area with moist southwest flow, but no significant impacts expected with any of this activity through the rest of the morning hours. MVFR ceilings are starting to develop across parts of the region, and expected to fill in at most or all terminals by around the 09-10Z time frame. There will be a chance of IFR ceilings as well in which have kept SCT low clouds in the latest forecast, though confidence not high enough to include full IFR restrictions at this time. Ceilings are expected to improve by the late morning hours, as daytime showers and storms also begin to develop and move generally west to east thereafter through the afternoon and evening hours. Continued to include PROB30 groups at all sites, which will be narrowed down further as convection evolves. At least some isolated SHRA or TSRA are likely to persist into at least the first half of tonight, with some lower clouds also likely to return.

MARINE

The region will be between high pressure to the south southeast, and a weakening frontal zone stalled just north of the local waters through at least the next several days. This will continue predominant southwest to west flow which will become breezy at times, with periods of Small Craft Exercise Caution conditions, mainly over the offshore waters and especially during the overnight hours. The offshore flow will continue to push strong storms with gusty winds and frequent lightning into the coastal waters at times through the period, mainly in the afternoon hours. Another frontal boundary drops southward toward the area Friday into Saturday.

Rip Currents:

A general low risk of rip currents continues today and likely through mid week as surf remains only in the 1-2 ft range in the predominant offshore flow. Some slight increase in east-southeast wind-sea is possible Thursday and Friday, but still looks relatively weak.

FIRE WEATHER

- High Dispersion for North-Central FL this Afternoon

Hot, moist, and unstable air will continue with predominantly a southwesterly wind through the end of the week. Periods of locally heavy rainfall, frequent lightning, and gusty winds will accompany the stronger storms. Outside of convection, favorable transport winds and mixing heights will lead to areas of high afternoon dispersion values. Temperatures are expected to remain near to slightly above seasonal normals throughout the period, accompanied by elevated humidity levels.

FOG POTENTIAL AND OTHER REMARKS: Areas that receive heavier rainfall may also experience patchy late-night and early-morning fog.

PRELIMINARY POINT TEMPS/POPS

AMG 85 70 86 74 / 90 80 80 10 SSI 88 75 87 78 / 80 50 70 0 JAX 91 73 90 76 / 80 50 50 0 SGJ 93 74 93 77 / 70 40 50 0 GNV 93 73 92 75 / 50 30 30 0 OCF 92 74 93 77 / 30 20 20 0

JAX WATCHES/WARNINGS/ADVISORIES

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