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

- Isolated Afternoon Thunderstorms Today & Friday. Storm coverage increases this weekend and early next week. Locally heavy rainfall possible Sunday through Tuesday. Thursday: Peak Heat Index 105-111 Most Areas. Major Heat Risk through Friday and Saturday

- Moderate Rip Current Risk Beaches Today

NEAR TERM /THROUGH TONIGHT/

Main Highlights through Tonight:

- Heat Advisory Area-Wide Today - Isolated Afternoon and Evening Storms

Another hot day ahead today as mid to upper level ridging continues to build. Mostly sunny skies and southwesterly winds will allow high temperatures to climb into the mid to upper 90s, with max heat index values in the 105-111 degree range, prompting a Heat Advisory from 11am-8pm.

Convective chances are lower today due to the subsidence and drier air in place, however CAMs continue indicate a window for isolated storms later this afternoon near Marion/Putnam/St. Johns/Flagler counties. Less confidence for another area of isolated convection near the Altamaha river basin towards coastal southeast Georgia.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/

Main Highlights During This Period:

- Heat Advisory potential for Friday and Saturday - Lower convective chances Friday, but increased chance Saturday

Low to mid level ridge over central FL on Friday will nudge further north into Saturday while moisture continues to remain somewhat limited in the 1000-700 mb layer. In fact, there will be pockets PWATs that will be near or below 1.6 inches on Friday. We do see some increase in moisture across northeast FL on Saturday so appears we will see an uptick in rain chances for Saturday, at least for northeast FL. At this time, will show rain chances limited to about 10-20 percent for Friday and 20-55 percent for Saturday, with highest chances over northeast FL, and lowest over interior southeast GA. There is possibility of higher POPs for Friday over inland northeast FL as shown by recent HREF and HRRR guidance. Steering flow through about 500 mb continues to be southwest to south on Friday. However, on Saturday, as the mean layer ridge drifts north, flow transitions to south, even southeast over northeast FL, but still weak southwesterly for southeast GA.

The main concern continues to be dangerous heat risk both days. High temperatures will rise into the mid to upper 90s, even at the immediate Atlantic coast as southwesterly winds continue. Max temp may hit century max Afternoon heat indices will approach 102-110 degrees both days, Heat Advisories may be necessary for portions of northeast FL and the southeast GA. A couple of things that throw some uncertainty in the max temp forecast is that we may see more high clouds on Friday, and overall more clouds on Saturday with a better chance of precip.

LONG TERM /SUNDAY THROUGH WEDNESDAY/

Main Highlights During This Period:

= Sunday through Wednesday - Unsettled weather develops by Sunday Afternoon Onward - Not as hot Monday to Wednesday

The low to mid level ridge axis will shift back south Saturday into Sunday while flow turns more westerly and a frontal boundary slowly sags southward over the southeast. Pre-frontal troughing is possible across srn GA on Sunday, with the frontal boundary probably pushing into southeast GA by then or at least by Monday night. More abundant moisture pushes into the area on Sunday and continues Monday and Tuesday while ridging pushes well to the south over southern FL. The front looks ill-defined by Wednesday as preliminary data suggests it will be diffuse over south GA. Unsettled weather each day with rain likely chances (at 55-70 percent) Sunday, maybe up to 60-80 percent Monday. Likely rain chances continues Tuesday and Wednesday. There some concern for locally heavy rainfall, localized flooding Sunday through Tuesday though the recent dry weather should help to minimize some of the impacts.

By Sunday, temperatures drop a few degrees area-wide as more storms are expected. Higher cloud coverage and storm chances will lower temperatures back to near normal in the upper 80s to lower 90s Monday to Wednesday.

AVIATION /12Z THURSDAY THROUGH 12Z FRIDAY/

Mainly VFR conditions continue through period. SW flow develops again today and increase to around 10 kts. The Atlantic sea breeze will be pinned to the coast only causing winds to shift SSE at SSI and SGJ in the afternoon. Showers and storms look to be limited to coastal TAF sites this afternoon into the evening. Have placed VCTS/PROB30 for SGJ but with lower confidence near SSI and CRG, have left VCSH for now.

MARINE

High pressure ridge will remain anchored across central and south Florida this week as low pressure troughing develops to the north. This pattern will maintain a southwest flow through early afternoon followed by late afternoon and evening wind surges from the south and an increase to Small Craft Exercise Caution wind speeds. The offshore flow will allow for a slight chance of afternoon and evening thunderstorm over the local coastal waters through Friday, with increased chances of thunderstorms Saturday through early next week. Mariners should expect locally strong wind gusts and frequent lightning with any developing thunderstorms.

Rip Currents:

Low to moderate risk of rip currents continues through the end of the week due to fairly low surf conditions from prevailing offshore flow. Some enhanced potential still looks likely for the northern beaches by late afternoon from Mayport northward due to stronger southeast wind component each day. Surf remains generally in the 1-2 feet range.

FIRE WEATHER

AREAS OF HIGH DISPERSION NEAR AND TO THE NORTH OF I-10 FROM TODAY - Through Saturday

- Heat Advisory In Effect Today

High pressure ridge will prevailing just south of the area through Saturday. Drier than normal conditions are forecast today through Friday and then rain chances begin to increase Saturday through early next week as a front approaches from the north. Above average temperatures and dangerous maximum afternoon heat index values expected through Saturday. Southwesterly surface winds continue through Friday, with areas of high afternoon dispersion near and north of I-10 expected each day. Despite drier air in place, minRH will remain above critical values.

Fog Potential and other remarks: Significant fog potential is not expected through Friday night. Erratic wind gusts possible in and near thunderstorms, and at times, at a distance due to outflows.

CLIMATE

Summer heat continues. There is potential for some locations to get to the century mark today with probability of this occurrence at about 30 to 40 percent. These probabilities look a bit higher for Friday.

For the next few days, here are the record high temperatures that are within 3 degrees of the current forecast:

July 9th: KJAX: 101/1879 KGNV: 99/1932 KAMG: 100/1986 KCRG: 101/2016

July 10th: KJAX: 102/1879 KGNV: 99/1914 KAMG: 99/1980 KCRG: 99/2016

July 11th: KGNV: 100/1900 KAMG: 100/1980 KCRG: 99/1998

PRELIMINARY POINT TEMPS/POPS

AMG 97 76 98 76 / 20 20 10 10 SSI 96 79 97 81 / 20 30 10 10 JAX 98 77 99 78 / 20 10 20 20 SGJ 96 77 96 78 / 30 30 20 10 GNV 97 75 98 75 / 10 0 30 20 OCF 97 75 97 76 / 20 0 20 20

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory until 8 PM EDT this evening for FLZ021-023-024- 030-031-035-038-120-124-125-132-136>138-140-220-225-232- 233-236-237-240-322-325-333-340-422-425-433-522-533-633. GA...Heat Advisory until 8 PM EDT this evening for GAZ132>136-149- 151>154-162-163-165-166-250-264-350-364. MARINE...None.