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 Thunderstorms between 11 AM - 6 PM capable of heavy downpours and gusty winds to 40 mph, especially along the I-10 corridor.

- Hot and Humid Conditions for North-Central FL today, areawide Thursday.

- Hot, Humid, and Stormy pattern continues into early next week

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Numerous showers and scattered thunderstorms through the mid morning and early evening. - Minor flooding is the primary concern; Gusty winds around 40 mph are also possible - Hot and humid for north-central FL with Heat Index peaking around 100-106 degrees

A channel of "high-grade" deep layer moisture (PWATs 2-2.25") will narrow while it streams over the area through most of the day. This moisture influx will replenish convective "fuel" again this morning, sparking numerous showers and isolated thunderstorms by mid morning especially north of I-10 where the deepest moisture will be focused. Lapse rates aloft will be marginal due the degree of moisture but the environment should be still supportive of bouts robust convection, especially as vorticity ribbons embedded in zonal flow aloft drift over the area this afternoon.

The primary concerns today will be compounding bouts of heavy rain later this morning and afternoon, increasing the flooding potential. The nature of flooding should be at minor levels (i.e. ponding and street flooding in prone/poor drainage locations) this afternoon as storms zip eastward fairly quickly due to the 20-25 mph southwesterly steering flow. Given the breezy low level flow, it's possible that even showers may mix gusty winds around 30-40 mph down to the surface at times this afternoon especially in areas along I- 10 southward where low level lapse rates may be more conducive to surfacing strong winds aloft toward the surface.

For tonight, convective activity should fade after sunset with the loss of heating and as induced shortwave ridging develops, introducing some weak subsidence over the area.

As the moisture and cloud cover narrows north of I-10 this morning it'll keep temperatures cooler for areas beneath the cloud shield, with highs reading in the mid and upper 80s. Areas south will see more sunshine and isolated showers and storms allowing temperatures to rise into the low to mid 90s and peak heat index values in the 100-106 degree range.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

- Daily rounds of Afternoon and Evening T'storms - Elevated Heat and Possible Heat Advisory Conditions Thursday for most areas and Friday south of Jacksonville

A shortwave moving through the eastern Great lakes will continue carving a broad trough through the Midwest, OH, and TN valleys into the southern and central appalachian mountains. A cold front will extend from a strong surface low north Lake Erie near the border Ontario and Quebec southward into the interior Mid Atlantic states and west southwestward into the TN Valley. West to southwest flow aloft south of the frontal feature will steer the remnants of Potential Tropical Cyclone One northeastward across the deep south from AL into GA during the day and then through SC to the coast Thursday night, keeping the highest moisture content just NW of the area, but above normal moisture levels (PWATs 1.8-2.10 inches) will support scattered to numerous afternoon and early evening T'storms, most focused along the I-95 to coast corridor as the Gulf seabreeze gets a head start before interacting with a pinned Atlantic seabreeze near the Atlantic coast. Locations NW of Waycross will see a few rounds of heavier showers and T'storms where the higher moisture axis will be relative to the remnants moving through the deep south. Increasing 0-6km bulk shear to around 30 knots will support isolated strong to severe T'storms with gusty winds 40-60 mph, with frequent lightning and locally heavy downpours as well.

Thursday night, higher moisture content will drag into SE GA as the remnants of the system shifts to the SC coast, continuing rounds of showers and isolated T'storms into all of SE GA and the Suwannee Valley.

Friday, a cold front will sink SE towards the area from the north. High moisture content will trail through the area from the NE. The high moisture content will keep skies mostly cloudy, but lift from the incoming front and instability from shortwave energy passing east over the region will create numerous to widespread showers and T'storms over SE GA. More breaks in the clouds further south will allow the Gulf seabreeze another head start towards the NE FL coast, spurring afternoon and early evening scattered to numerous T'storms. Locally heavy downpours, frequent lightning, and gusty winds will be the main hazards with less shear making severe T'storm potential less likely.

High temperatures Thursday will rise into the mid 90s over the I-95 corridor from SE GA into much of NE FL on Thursday under partly cloudy skies while mostly cloudy skies NW of Waycross and into the Suwannee Valley lower highs into the upper 80s to lower 90s. Peak heat index values will likewise increase with dewpoints in the mid 70s to near heat advisory levels along I-95 and south of I-10 to 105-110 degrees while lowering to the NW 100-104 degrees.

Lows Thursday night will be muggy in the mid to upper 70s. Highs on Friday will be less hot to near normal levels for most areas except along the I-95 corridor south of Jacksonville where mid 90s are expected again, with peak heat index values 105-110 for a more limited area.

LONG TERM /SATURDAY THROUGH TUESDAY/

Main Highlights This Period:

- Numerous to Widespread Showers and T'storms Saturday - Hot and Humid through the Weekend, increasing to near Heat Advisory levels early next week - Increasing Rip Current Risk to moderate levels by Sunday - Decreasing chances for showers Afternoon and Evening T'storms early next week

Saturday, the frontal boundary will sink into NE FL as weak high pressure moves north of the region into the upper OH/TN valleys. This will promote the highest chances for showers and T'storms over NE FL as lift from the frontal boundary, shortwave energy aloft and high moisture content combine to create widespread showers and T'storms in the afternoon and early evening hours with scattered to numerous coverage over SE GA behind the front. Winds will shift from westerly to WNW with skies staying mostly cloudy. Locally heavy downpours will create minor flooding potential in low lying and urban areas with gusty winds likely sub-severe and frequent lightning.

Sunday, drier air aloft will arrive across SE GA and into portions of NE FL as the front stalls near north central FL, with scattered afternoon T'storm coverage. Light northwest winds turn variable in the afternoon and will allow the Atlantic seabreeze to move inland towards highway 301 with highs into the low 90s. Dewpoints will decrease slightly into the upper 60s to low 70s with heat index values around 98-102 degrees.

Early next week, ridging aloft will rebuild over southern FL with limited afternoon T'storm coverage. However, high temperatures will soar to the mid 90s Monday and Tuesday with peak heat index values rising to 105-110 as dewpoints rise back to the mid 70s. Temperature will begin the period near normal this weekend and rise to above normal early next week.

AVIATION /12Z WEDNESDAY THROUGH 12Z THURSDAY/

Very moist southwesterly flow may lead to occasional MVFR ceilings but multilayered VFR cloud cover will be the dominant flight condition. TSRA chances are highest from I-10 northward during the late morning and early afternoon hours. TEMPO groups have been added to the latest forecast for Jacksonville Metro airfields and KSSI. There should be an earlier downward trend in SHRA/TSRA activity today with vicinity activity fading around 00z. Breezy southwesterly winds are expected to develop with sustained winds around 10-14 kts and gusts around 20-25 kts the more frequent gusts are more likely to be at KGNV and KSGJ this afternoon. Decreasing gust potential expected after 20z with lighter (<10 kts) SSW flow prevailing during the late evening with VFR conditions.

MARINE

A breezy southwesterly offshore flow continues across the waters this morning and afternoon with Small Craft Exercise Caution conditions. Breezy offshore winds will continue through the end of the week as a remnant wave of low pressure tracks north of the waters through Friday. A weak front trailing the low pressure will stall north of the waters and weaken the offshore flow by Sunday. After a day or two of onshore flow, offshore flow pattern will return as another broader front approaches from the north around the Tuesday or Wednesday next week. During the period of offshore winds, elevated chances of daily scattered to numerous showers and afternoon thunderstorms will be possible.

Rip Currents:

A general low risk of rip currents continues today and likely through the end of the week as surf remains only in the 1-2 ft range in 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 Today - High Dispersion for inland locations just west of I-95 Thursday

Moist and unstable airmass will continue afternoon/early evening scattered to numerous T'storms this week as west to southwest winds allow the Gulf seabreeze to move quickly eastward to the Atlantic coast before interacting with the pinned Atlantic seabreeze near the Atlantic coast. T'storms will include locally heavy rainfall, frequent lightning, and gusty winds with isolated strong to severe T'storms Thursday. A front will sink towards the area Friday and move through Northeast Florida on Saturday with widespread showers and T'storms. The front will stall near north central or central Florida Sunday with slightly drier air aloft and only widely scattered afternoon T'storms.

Favorable transport winds and mixing heights will lead to areas of high afternoon dispersion values today over north central Florida. Temperatures are expected to remain near to slightly above seasonal normals throughout this week into this weekend 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. Potential Heat advisory conditions for much of the area on Thursday.

PRELIMINARY POINT TEMPS/POPS

AMG 83 75 89 74 / 90 10 70 70 SSI 89 79 92 79 / 70 10 70 30 JAX 91 78 95 78 / 50 10 60 10 SGJ 93 78 95 78 / 30 10 60 10 GNV 92 77 94 77 / 20 10 30 10 OCF 92 78 93 78 / 10 10 30 10

JAX WATCHES/WARNINGS/ADVISORIES

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