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

- Extreme Drought Expanding Across our Region. Increasing Wildfire Danger Exists throughout our Area

- Beneficial Rainfall Expected Sunday through Monday. A Few Strong T'Storms & Windy Conditions on Sunday Afternoon & Evening. Heavy Downpours Possible for Locations Along & North of I-10. Widespread Amounts around an inch, with Localized Totals up to 2 to 3 inches Possible

- Small Craft Advisory Conditions Expected Sunday & Sunday Night

- Moderate Rip Current Risk at Area Beaches

THURSDAY EVENING UPDATE

Minor tweaks to the forecast this evening with no significant concerns across the area through Friday Morning, with the exception of some patchy fog possible mainly over Marion and southern Putnam/Flagler Counties Friday Morning closer to a stalled frontal boundary just south of the region. Min temps will range from the upper 30s to mid 40s over inland areas to upper 40s to near 50 closer to the coast and St. Johns River Basin.

NEAR TERM /THROUGH FRIDAY/

A cold front is currently pushing through north central FL this afternoon and will reach south of the area by this evening. Behind the front winds have shifted to be a northeasterly flow as high pressure builds north along the eastern seaboard. With the onshore flow, there could be some light showers develop along the frontal boundary during the mid/late afternoon hours over north central FL. Cool marine air will keep daytime highs in the upper 60s along the coast and locations north and east of Waycross in SE GA, while the Suwannee Valley region and south towards north central FL reach into the lower to mid 70s as clearing skies and less influence from the onshore flow will allow for temperatures to warm a bit more.

Winds will begin to weaken during the overnight hours. Clearing skies will allow for better radiational cooling will bring temperatures to dip into the upper 30s to lower 40s over SE GA locations. Partly cloudy skies will keep locations in NE FL relatively warmer, with Lows expected in the mid to upper 40s, with 50s along the coast and St. Johns River Basin. With lighter winds and lingering moisture, locations along north central FL may see some patchy fog develop during the late evening hours into Friday morning.

SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/

Dry northwesterly flow aloft will prevail over our region from Friday through Saturday as troughing persists over New England and the Mid-Atlantic states. Surface high pressure situated over the Ohio Valley and the southern Appalachians early on Friday morning will shift slowly southeastward towards the Carolina coast by Saturday afternoon. This weather pattern will maintain a northeasterly surface wind flow on Friday, with breezy afternoon speeds at coastal locations keeping seasonably cool conditions in place due to cold shelf water temperatures that are in the 50s. Coastal highs will generally remain in the 60s on Friday. Meanwhile, fair skies and a dry air mass will allow highs to climb to the upper 60s and lower 70s across inland southeast GA, ranging to the low and mid 70s elsewhere. Winds will quickly decouple at inland locations on Friday evening, with some increase in thin cirrus expected from west to east during the predawn and early morning hours. Lows will range from the upper 30s across portions of inland southeast GA to the low and mid 40s elsewhere. A light onshore breeze will keep coastal lows in the upper 40s and lower 50s.

A potent trough migrating through the southern branch of the jet stream will shift eastward from the Desert Southwest on Friday night, across Texas on Saturday and Saturday night, emerging over the lower Mississippi Valley by early Sunday morning. Flow aloft will become zonal across our region on Saturday evening, with cirrus gradually increasing and thickening from west to east downstream of this storm system on Saturday afternoon and evening. Low level winds will veer to easterly by sunrise on Saturday and then southeasterly on Saturday afternoon. Filtered sunshine and a lingering dry air mass will allow highs to climb well into the 70s for most inland locations, while an onshore breeze keeps coastal highs mostly in the 65-70 degree range.

Surface low pressure will strengthen over the lower Mississippi Valley on Saturday night, with this feature lifting a warm front northward across our area during the overnight hours. A few showers will be possible ahead of this warm front, mainly for locations north of Interstate 10, although a few coastal showers cannot be ruled out overnight as well. Thickening multi-layered cloud cover and warm air advection will keep lows in the 50s area-wide.

LONG TERM /SUNDAY THROUGH THURSDAY/

Potent troughing aloft will migrate east-southeastward from the lower Mississippi Valley early on Sunday morning, along the Interstate 10 corridor through Monday afternoon, with this feature then progressing offshore on Monday night. Surface low pressure will only slowly weaken as it migrates across the southeastern states, with another low pressure center likely developing early on Monday morning along the Carolina coast, with this feature then strengthening as it accelerates offshore early next week. This storm system's cold front will cross our region on Sunday night and Monday morning, with strengthening and deepening southwesterly flow ahead of the front allowing for PWATs to surge to the 1.5 - 1.75 inch range. Our local pressure gradient will tighten early on Sunday morning, creating strengthening southerly winds that will shift to southwesterly by Sunday evening. Model guidance is trending slower with regards to timing of the frontal passage, which may allow for warm and breezy weather to encompass most of our area on Sunday as the storm system's associated warm front lifts to the north of our area. After a few morning showers, breaks in the multi-layered cloud cover and strong warm air advection should push highs to the upper 70s and lower 80s at most locations, while cool shelf waters potentially keep highs in the 70-75 degree range for coastal southeast GA.

A low level south-southwesterly jet of 40-50 knots at 850 millibars (around 5,000 feet) will arrive across inland portions of southeast GA and the Suwannee Valley on Sunday afternoon, with this feature then traversing our region on Sunday evening. ML CAPE values will rise to around 500 j/kg across these inland areas during the late afternoon hours, possibly developing a few strong storms before sunset along the I-75 corridor. Stronger storms may be capable of producing downburst winds of 45-55 mph, but severe weather chances may be limited by thickening cloud cover and poor low/mid-level lapse rates as rainfall overspreads our region. This storm system should provide for much needed rainfall across our area from Sunday afternoon through at least Monday morning, with widespread 1-2 inch rainfall amounts likely and localized totals of 3-4 inches possible. Instability will fade on Sunday evening, but a few rounds of downpours and embedded elevated thunderstorms should continue through the night and the morning hours on Monday. Lows on Sunday night should remain in the 55-60 degree range at most locations.

Upper troughing crossing our area on Monday could lead to increasing instability during the late morning and afternoon hours, especially across northeast and north central FL, where model soundings indicate ML CAPE values rising to the 500-750 j/kg range. Scattered showers and embedded thunderstorms may persist until the mid to late afternoon hours, with breaks in the multi-layered cloud cover allowing highs to reach the 70-75 degree range at most locations. Low stratus cloud cover may overspread our region in the wake of the departing storm system on Monday night, keeping lows in the upper 40s and lower 50s despite some weak cool air advection.

Northwesterly flow aloft on Tuesday will quickly transition to zonal flow by Tuesday night as another trough digs over the western U.S., and ridging will then build over the Gulf by midweek downstream of this evolving storm system. Northeasterly low level flow will likely keep coastal highs in the 60s on Tuesday despite plenty of sunshine, while inland highs climb into the 70s. Above normal warmth is then forecast by Wednesday and Thursday, with inland highs soaring into the lower 80s, while afternoon sea breezes keep coastal highs in the 70s. Lows next week will mostly remain in the upper 40s and lower 50s inland, with low to mid 50s at coastal locations.

AVIATION /00Z FRIDAY THROUGH 00Z SATURDAY/

VFR expected throughout the forecast period, with winds around 10 kts continuing to subside over the next few hours. Some patchy fog may set up over southern areas tonight with a low chance (less than 20%) of any impacts at both GNV and SGJ, and therefore have left out of the forecast at this time. Northeasterly flow increases diurnally again Friday, with winds around 10 kts likely for all airfields.

MARINE

A cold front will push across the southern waters and then stall south of the area by this evening. The front will then remain nearly stationary through Friday Night before lifting back northward Saturday and Saturday Night as a warm front. High pressure riding will persist along the southeastern seaboard through Friday, with a a northeast to easterly onshore flow persisting through the end of the week. High pressure then moves east of the region Saturday Night and Sunday as a frontal system approaches the area Sunday Night, moving across area waters through Monday. Showers as well as isolated thunderstorms will be expected Sunday Night through Monday as the system moves through. High pressure ridging will then build back down the southeastern coast on Tuesday before weakening by mid week.

Rip Currents: Moderate rip current risk today as easterly swells persist with periods of up to 11-13 seconds producing surf/breakers into the 3-4 ft range at local beaches. Easterly swells will diminish Thursday, but a moderate risk of rip currents expected due to breezy onshore north northeast winds.

FIRE WEATHER

CRITICALLY LOW HUMIDITY ACROSS INLAND SOUTHEAST GEORGIA THIS - Afternoon And Friday Afternoon MARGINALLY HIGH DAYTIME DISPERSION VALUES POSSIBLE ON SATURDAY - For North Central Florida ELEVATED FIRE DANGER POSSIBLE ACROSS NORTHEAST AND NORTH CENTRAL - Florida On Sunday

Long durations of critically low relative humidity values are forecast this afternoon and again on Friday afternoon for inland portions of southeast Georgia and for northern portions of the Suwannee Valley. Otherwise, surface and transport winds will shift to northeasterly this afternoon, with breezy conditions expected along the Interstate 95 corridor. These northeasterly winds will persist on Friday, resulting in fair to good daytime dispersion values. Surface and transport winds will shift to easterly by Saturday morning and then southeasterly on Saturday afternoon, with breezy conditions developing during the afternoon hours. These breezy winds will combine with elevated mixing heights to create good daytime dispersion values, with marginally high values possible on Saturday afternoon across north central Florida.

An Elevated Fire Danger will be possible across northeast and north central Florida on Sunday as strong southerly transport winds overspread our region. Increasing cloud cover is expected early in the day across southeast Georgia and the Suwannee Valley, where chances for showers and embedded thunderstorms will increase during the afternoon hours. This activity will then overspread the rest of our area by Sunday evening and night, possibly continuing into Monday. Strong transport winds, breezy surface speeds, and elevated mixing heights will create high daytime dispersion values on Sunday throughout northeast and north central Florida, with marginally high values possible for southeast Georgia before beneficial rainfall overspreads the region. Rainfall amounts of 1-2 inches are currently forecast from Sunday through Monday, with locally higher totals possible.

FOG POTENTIAL AND OTHER REMARKS: Significant fog formation is not expected during the next several days. Localized visibility reductions are possible during the predawn and early morning hours for locations near active or ongoing wildfires or prescribed burns.

PRELIMINARY POINT TEMPS/POPS

AMG 38 68 39 71 / 0 0 0 0 SSI 47 60 49 65 / 0 0 0 0 JAX 44 69 46 73 / 0 0 0 0 SGJ 50 68 52 71 / 0 0 0 10 GNV 46 74 47 77 / 0 0 0 0 OCF 48 75 48 78 / 0 0 0 0

JAX WATCHES/WARNINGS/ADVISORIES

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