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

- Moderate Rip Current Risk at Area Beaches through Wednesday

- Isolated Afternoon Thunderstorms on Today & Wednesday Across Portions of Northeast and North Central FL. Thunderstorm Coverage Increases from Friday through the Weekend

- Heat and Humidity Builds Late this Week through the Weekend. Dangerous Heat Possible Saturday with Heat Index Values of 104-108

- Drought Conditions Persist Across Our Region

NEAR TERM /THROUGH TONIGHT/

Main Highlights This Period:

- Isolated to widely scattered showers and thunderstorms across portions of northeast and north central FL.

- Moderate rip current risk continues at all area beaches as breezy onshore winds develop this afternoon.

Overnight surface analysis depicts strengthening high pressure (1027 millibars) centered along the Mid-Atlantic coast, with this feature located just north of a stalling frontal boundary that has wedged into the Carolinas. Meanwhile, an inverted trough extends from just north of the northwestern Bahamas to the Gulf Stream waters offshore of the northeast FL coast. Aloft...northwesterly flow continues over our region as ridging positioned over the northern Gulf flattens in response to a trough progressing eastward from the Great Lakes southward through the Tennessee Valley. Latest GOES-East derived Total Precipitable Water imagery indicates that a drier air mass was advecting onshore along the southeast GA and northeast FL coasts, where PWATs were falling to the 1.25 - 1.5 inch range, while deeper moisture values were located over interior southeast GA and along the Interstate 75 corridor, where values were generally in the 1.75 - 2 inch range. Thicker mid level cloud cover remains in place across these locations where deeper moisture is present, while thinner and mostly high altitude cloudiness prevails across coastal southeast GA and the rest of northeast and north central FL. Temperatures at inland locations at 06Z were generally in the 70-75 degree range, while coastal temperatures were in the upper 70s. Dewpoints mostly ranged from 65-70.

Ridging over the northern Gulf will continue to flatten and will retrograde westward today as troughing aloft settles over the southeastern states while weakening. Meanwhile, high pressure wedging down the southeastern seaboard should steer an inverted trough westward from the Gulf Stream waters towards the east central and northeast FL coast by late this afternoon. This trough will bring a pocket of deeper moisture across northeast and north central FL this afternoon and evening, with isolated to widely scattered showers and possibly an embedded thunderstorm expected to move onshore later this morning or early this afternoon along the northeast FL coast, mainly from around St. Augustine southward. This activity could progress inland across southern portions of the St. Johns River basin and perhaps portions of north central FL. Significant rainfall amounts are unlikely, with shower coverage expected to be spotty for locations along and west of I-95. Otherwise, our local pressure gradient will briefly tighten due to high pressure wedging down the southeastern seaboard and the inverted trough approaching from the east, creating breezy east- northeasterly winds along the I-95 corridor this afternoon that will shift to east-southeasterly this evening as the trough moves onshore before dissipating. A few showers could redevelop overnight tonight and early on Wednesday morning at coastal locations as low level southeasterly flow prevails.

Weakening troughing aloft will likely keep an abundance of mid and high altitude cloud cover in place today across our area, with this cloud cover then thinning out after sunset. Temperatures will remain near climatology, with highs generally in the upper 80s to near 90, although temperatures at area beaches will likely fall back to the low and mid 80s later this afternoon as breezy onshore winds develop. Lows tonight will generally range from 70-75.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

Main Highlights This Period:

- Heat Index Back into the Triple Digits by Thursday

- Gradual Increase In Afternoon Thunderstorm Chances Through the Week

- Moderate Risk for Rip Currents

Low level ridging will move eastward through Wednesday, with onshore flow prevailing over the area. Steering flow will be light and transition to a predominantly southerly direction by Thursday. While some increases in moisture, dry air lingering aloft coupled with marginal lapse rates is expected tamp down the convective coverage along the Atlantic sea breeze as it moves inland each afternoon with generally isolated to scattered showers and thunderstorms.

The true summer-time heat returns through midweek as highs push back into the low 90s, pushing heat index values into the triple digits by Thursday.

LONG TERM /FRIDAY THROUGH MONDAY/

Main Highlights This Period:

- Dangerous Heat for Sensitive Groups This Weekend

- Scattered to Numerous Thunderstorms Along the Coastal Counties Friday Onward

The high pressure centered east of Bermuda will lay it's western ridge axis across central and southern FL to end the week as a weak frontal feature stalls to the north. This will shift local steering flow to southwesterly as high grade moisture pooled ahead of the front is pushed into the region. Ultimately, more convective activity is expected through the weekend with scattered to numerous showers and thunderstorm focusing along and east of US 301 and toward the I-95 corridor. Needed rainfall will be welcome but the "optimistic" amounts are only around 2-3 inches through the next week.

Primary concern going into the weekend will be the increasing temperatures that may lead to widespread heat index values in the 105-108 degree range over the weekend, especially Saturday. This may require Heat Advisories, as Heat Risk increases to High levels. While it'll fell like the mid 100s, the ambient temperatures will near records as readings push into the mid and possibly upper 90s.

AVIATION /12Z TUESDAY THROUGH 12Z WEDNESDAY/

MVFR clouds have moved into SGJ this morning and will likely lift to VFR by 15Z. Showers developing over the Atlantic waters will shift onshore this morning into afternoon mainly affecting SGJ with a low chance at CRG. Light winds this morning become east around 10 kts later this afternoon. Easterly winds will then diminish to around 5 knots by 02Z Wednesday, except around 10 knots at SGJ.

MARINE

High pressure building along the Mid-Atlantic coast will briefly wedge down the southeastern seaboard today, creating breezy east- northeasterly winds this afternoon across the near shore waters. Meanwhile, a trough moving westward towards the east central Florida coast is expected to develop widely scattered showers and possibly a few thunderstorms to the northeast Florida waters today. This trough will move westward, dissipating over central Florida tonight, with a few showers possibly lingering over the northeast Florida waters. Otherwise, high pressure will weaken as it pushes southeastward towards Bermuda tonight and Wednesday, maintaining a prevailing southeasterly flow across our local waters through Thursday. Evening wind surges will increase speeds to near Caution levels during the evening hours from Wednesday through the weekend. Troughing will then develop over the southeastern states this weekend, creating a prevailing southerly wind flow that will gradually increase moisture levels, allowing scattered afternoon and evening showers and thunderstorms to develop across our local waters.

Rip Currents: Breezy onshore winds each afternoon will combine with a persistent easterly ocean swell of 9-10 seconds to maintain a moderate rip current risk at all area beaches through Wednesday , especially during the outgoing tide, which will occur during the late afternoon and early evening hours. A lower end moderate risk is expected from Thursday through the weekend at the northeast Florida beaches as the easterly ocean swell diminishes, with a low risk expected at the southeast Georgia beaches.

FIRE WEATHER

High pressure will be in a position to favor the Atlantic sea breeze through Thursday. Expect accompanying sea breeze wind speeds to be in the 8-12 mph range, or around 5-9 at eye level. Temperatures warm back to the 90s today and continue to heat up this week with mid 90s likely this weekend while lowest afternoon humidity be similar to the last few days around 40-45%. Anticipate the return of more regular bouts of scattered afternoon thunderstorms late this week as moisture begins to increase. Though fine fuels have dried to critical levels during the recent dry stretch, there is no glaring potential of concerning fire weather alignment.

FOG POTENTIAL AND OTHER REMARKS: Patchy inland fog is possible but significant fog development is not expected.

PRELIMINARY POINT TEMPS/POPS

AMG 88 70 91 73 / 0 0 10 0 SSI 85 75 87 77 / 0 10 10 0 JAX 87 72 92 74 / 10 10 10 0 SGJ 85 75 88 74 / 30 20 10 0 GNV 89 72 94 72 / 20 10 30 10 OCF 89 73 93 73 / 20 10 40 10

JAX WATCHES/WARNINGS/ADVISORIES

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