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 Thunderstorms Expected Each Day. Isolated Strong Storms Possible Late this Afternoon Along the I-95 Corridor. Hazards: Wind Gusts of 30-40 mph, Frequent Lightning & Heavy Downpours

- Heat and Humidity Builds Late this Weekend and Early Next Week. Heat Advisory Conditions Possible Sunday through Tuesday

NEAR TERM /THROUGH TONIGHT/

Main Highlights This afternoon and Tonight:

- Typically Hot and Humid Summertime Weather Returns Today

- Scattered Showers and Thunderstorms Will Push Eastward Across Our Area this Afternoon and Evening.

Early morning surface analysis depicts a stalling frontal boundary positioned along the Altamaha River in southeast GA, with this feature extending westward across the Deep South, the lower Mississippi Valley, and along the Red River Valley in northern Texas. High pressure centers (both 1021 millibars) were centered over southwest FL and also over the southern Appalachians on either side of this frontal boundary. Aloft...previously cutoff troughing continues to shear out as it retrogrades westward across the lower Mississippi Valley. Meanwhile, "heat wave" ridging was expanding southeastward from the Upper Midwest across the Ohio Valley and towards the Delmarva region and the Carolinas. Latest GOES-East derived Total Precipitable Water imagery indicates that deep moisture remains in place locally, with PWATS ranging from around 1.8 inches across north central FL to around 2.2 inches near the frontal boundary along the Altamaha River basin in southeast GA. Leftover showers were finally dissipating over coastal northeast FL, with mid and high altitude debris cloud cover beginning to thin from south to north across our area. Temperatures and dewpoints at 08Z were generally in the 70-75 degree range across our area.

Our weather pattern will transition to a more typical summertime pattern today as cyclonic flow exits our area. The frontal boundary that has stalled near the Altamaha River will begin to lift northward this afternoon as it weakens, leaving our area in a typically hot and humid air mass. Meanwhile, high pressure currently centered over southwest FL will slowly retrograde westward across the eastern Gulf this afternoon and tonight, creating low and mid level west-northwesterly flow. Thinning high altitude cloud cover will allow enough sunshine to boost highs to near mid-July climatology across our area, and near climatological moisture levels will allow for scattered convection to develop along mesoscale boundaries such as the Gulf and Atlantic sea breezes during the early to mid afternoon hours today, with low and mid level flow pushing the Gulf coast sea breeze a little more quickly eastward, while the Atlantic sea breeze progresses more slowly inland. Convection may pulse along the I-95 corridor late this afternoon or early this evening as mesoscale boundaries collide, but only isolated stronger storms can be expected as forcing shifts further away from our area. Relatively mild temperatures aloft will likely result in locally heavy downpours being the main threat with isolated stronger storms later today, rather than strong wind gusts. Frequent lightning strikes could also occur with a few pulsing convective cells later this afternoon.

High temperatures will generally top out in the lower 90s, with heat index values generally peaking in the 100-105 degree range this afternoon. Convection that lingers into the evening hours near a Atlantic and Gulf sea breeze collision near the U.S. Highway 17 corridor should dissipate before midnight, with thinning debris cloud cover overnight and low level northwesterly flow yielding lows in the low to mid 70s.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

Main Highlights During This Period:

-Daily bouts of showers and storms

Predominantly northwesterly flow will shift to become more out of the southwest before the end of the week as high pressure ridging extends in from out of the east towards the southern portion of the Florida peninsula and high pressure over the Gulf shifts northward, towards Louisiana. Otherwise, pattern for seasonal westerly flow with bouts of daytime convection will continue through the period with stronger convection occurring along boundaries and areas of collision. High temperatures through the latter part of the week will rise into the lower to mid 90s with overnight low temperatures dropping down into the lower to mid 70s. Heat index values will are expected to range upwards of above 100 with a potential for Heat Advisory conditions for the end of the week.

LONG TERM /SATURDAY THROUGH TUESDAY/

Main Highlights During This Period:

- Daily bouts of showers and storms - Potential heat advisory conditions this weekend and into next week

Typical seasonal pattern for this time of year will continue through the weekend and into next week with westerly flow, daily bouts of showers and storms, and hot weather. Above average temperatures, with max temps rising into the mid 90s, will continue through the weekend and into next week with heat index values potentially rising to Heat Advisory levels through the period.

AVIATION /12Z WEDNESDAY THROUGH 12Z THURSDAY/

VFR conditions will otherwise prevail a the regional terminals through at least 16Z. Scattered showers and thunderstorms are expected to develop along inland moving sea breeze boundaries towards 17Z, with initial impacts possible at GNV, followed by activity shifting towards the Duval County terminals, SSI, and SGJ after 18Z. Have TEMPO groups for brief wind gusts up to 25 knots, along with MVFR conditions during heavier downpours. Convection should then shift offshore or dissipate by 03Z Thursday. Light west- northwesterly surface winds with speeds increasing to around 10 knots before 16Z. The Atlantic sea breeze boundary will develop towards 21Z, shifting surface winds to east-southeasterly around 10 knots at SGJ and SSI.

MARINE

A frontal boundary stalled over the Georgia waters will lift slowly northward as a warm front this afternoon and tonight as it weakens. Meanwhile, weak high pressure centered over south Florida will shift slowly westward across the Gulf through Friday, creating a prevailing northwesterly flow across our local waters, with a late afternoon sea breeze developing today and then earlier in the afternoon on Thursday that will shift winds to onshore over the near shore waters. Scattered late afternoon and evening showers and thunderstorms will be possible today and Thursday, mainly over the near shore waters, followed by coverage decreasing to isolated on Friday afternoon and evening. Troughing developing over the southeastern states this weekend and early next week could bring widely scattered, mainly late afternoon and evening thunderstorms back to our local waters as southwesterly winds prevail.

Rip Currents:

Prevailing offshore winds and low surf heights will continue to keep the rip current risk low at area beaches during the next several days.

FIRE WEATHER

- Areas Of High Dispersions Through Thursday

The region will remain positioned between high pressure to the south and a gradually weakening frontal boundary to the north through the week. Daily afternoon and evening showers and thunderstorms are expected, with the greatest coverage occurring early in the week before becoming less widespread later in the period as the boundary dissipates. Above-normal temperatures will persist throughout the week, with a gradual warming trend developing late in the week.

Fog Potential and Other Remarks: Significant fog development is not expected tonight. Gusty and erratic winds will be possible in and near thunderstorms, with occasional outflow boundaries capable of producing sudden wind shifts well away from ongoing convection.

HYDROLOGY

Water levels on the Satilla River at Atkinson continues to lower and is now forecast to drop to the action stage this afternoon.

PRELIMINARY POINT TEMPS/POPS

AMG 91 72 91 75 / 30 20 30 10 SSI 90 76 94 79 / 40 20 30 10 JAX 92 73 94 75 / 60 40 40 20 SGJ 91 75 93 77 / 50 40 40 10 GNV 92 73 93 74 / 30 20 40 10 OCF 93 73 93 76 / 40 10 30 20

JAX WATCHES/WARNINGS/ADVISORIES

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