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

- Locally Dense Fog Possible Early Saturday Morning

- Strong to Isolated Severe Thunderstorms for SE GA Saturday

- Extreme Drought Prevails Across Most of the Region. Red Flag Conditions Possible Monday

- Moderate Rip Current Risk at Area Beaches Today

- Small Craft Advisory Conditions Sunday through Monday

- Freeze and Frost likely Monday night and Tuesday night

NEAR TERM /UNTIL 6 AM SATURDAY MORNING/

Potential for scattered showers to build across southeastern Georgia this afternoon with a chance for isolated thunderstorms forming over inland southeast Georgia as the moist southwesterly prevailing flow over the area remains situated between the steadily advancing frontal boundary to the north and high pressure ridging to the south. Low level stratus widespread patchy to areas of fog are expected to develop overnight and continue through Saturday morning throughout the forecast area with more dense developments occurring over north central Florida and for areas south of the I-10 corridor. High temperatures today are expected to reach up into the lower to mid 80s with overnight low temperatures dropping into the lower to mid 60s with warmer temps occurring over inland southeast Georgia and the Suwannee Valley region.

SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/

MAIN WEATHER CONCERNS (Saturday - Monday Night: - Widespread Dense Fog Mainly Inland Areas of NE FL Friday Night.

- Isolated Thunderstorms for areas of SE GA north of Waycross; One or two Strong to Marginally Severe Storms possible along the Altamaha River Basin

- Breezy to gusty winds / Fire Weather Concern Monday.

- Widespread Freeze & Dangerously Cold Wind Chills Monday Night.

A prefrontal southwesterly flow and moist low level airmass appears to be aligning for a Dense Fog event across inland areas of NE FL Saturday morning as Gulf sea fog is advected inland, potentially reaching portions of I-75 by midnight. Importantly, any smoldering wildfires still emitting smoke may lead to localized "superfog" areas in its vicinity. Visibility conditions are likely to begin to improve around 9 AM with southwesterly flow in place.

Troughs between the northern and southern streams will phase across the central US through Saturday before the phased upper trough amplifies across the eastern US. At the surface, a weak Gulf low will organize along a left over stationary boundary situated north of the area. That surface low is progged to slide along the boundary and establish a warm sector extending across all of southern GA. However, better instability more conducive to a severe threat will likely be situated to the north where less dry air aloft and steeper lapse rates are expected. Isolated to widely scattered storms are expected across portions of SE GA, generally north of Waycross, and will be capable of producing gusty winds up to 50 mph. Overall the severe thunderstorm threat is diminishing for our area. That said, SPC has a portion of the area highlighted in a "Marginal" risk and has identified convective winds as the primary threat.

After the low shifts offshore Saturday night into Sunday morning, a trailing cold front will move through the area. A strongly amplified ridge across western North America will send a long fetch of modified arctic air into the region. This airmass will be a rapid return to Winter with dewpoints falling into the teens by Monday. This will result in a dramatic 48 hr change in high temperatures with highs near record levels on Sunday followed highs 12-18 degrees lower than "normal", reading the low 50s Monday afternoon!

The dry, cold air will set up a fire weather risk given the dry fuels (more detail in the subsequent FIRE WEATHER section) as well as delivering multiple nights of subfreezing lows that'll become widespread Monday night. The departing surface low is progged to possibly "bomb" along the Mid Atlantic coast Sunday night. Between the bombing cyclone and strong arctic surface high, the local pressure gradients will remained tightly packed through Monday Night leading to dangerously cold wind chills down to the lower 20s. This may require Cold Weather Advisory headline later this weekend.

LONG TERM /TUESDAY THROUGH FRIDAY/

Main Hazards This Period: - Light Freeze and Widespread Frost Tuesday Night - Increasing Morning Fog Potential Thursday Night

Temperatures will sharply rebound by the middle of next week as high pressure settles across southern FL turning winds westerly and then southwesterly late in the week ahead of the next frontal system which may bring some needed rainfall to the area Thursday night or Friday next week. Moist airmass should promote increasing nightly fog potential late in the week.

AVIATION /00Z SATURDAY THROUGH 00Z SUNDAY/

Prevailing VFR conditions to continue this evening. Low stratus and fog is expected to advect across area from the Gulf overnight, leading to restrictions that will then last through mid morning. Prevailing VFR conditions are then expected from late morning through the afternoon hours.

MARINE

High pressure east of the Florida Peninsula will continue to extend a ridge axis westward across area waters through Saturday. Patchy dense sea fog is also expected during the late night and morning hours through Saturday. Shower and isolated thunderstorm potential will increase Saturday Night through Sunday Morning as a strong cold front moves through, with a breezy northwest flow developing behind the front resulting in likely Small Craft Advisory conditions. High pressure north and west of the region will then be the main weather feature early next week, slowly moving almost directly over the area by mid week.

Rip Currents: Rip current risk will be moderate today thanks to breezy offshore flow and some remnant long period swells. Surf/breakers of 1-3 ft today will trend downward to around 2 feet or less this weekend.

FIRE WEATHER

ELEVATED CONDITIONS ARE EXPECTED SUNDAY AND CRITICAL FIRE WEATHER - Conditions Likely Monday

HIGH DAYTIME DISPERSION WILL INCREASE AND BECOME WIDESPREAD - Through Sunday And Remain High Monday

- High Overnight Dispersion Expected Sunday Night

A frontal system will move through the region this weekend and send a powerful, mostly dry, cold front through the area on Sunday. This will lead to strong northwesterly winds Sunday afternoon with gusts up to 30 mph. These elevated winds will linger through Monday before settling down on Tuesday. Incoming cold and very dry air mass will lead to plummeting humidities Sunday afternoon, though they aren't likely to get to critical levels on Sunday. However, this dry airmass will set a stage for alignment of critically low humidity, gusty winds and dry/loaded fuels. Red Flag conditions are very likely Monday and a Fire Weather Watch will be considered over the next 24 hours to highlight this risk.

FOG POTENTIAL AND OTHER REMARKS: Areas of fog are likely across inland NE FL tonight with more widespread and dense fog Saturday morning as sea fog is pushed inland from the Gulf. Super fog development is possible in the vicinity of smoldering fires, especially ones producing copious amounts of smoke. Isolated thunderstorm will be possible for areas of SE GA Saturday afternoon for areas along and north US-82.

CLIMATE

Record High Temperatures possible today into the weekend.

Fri, February 20: KJAX: 86/1961 KCRG: 83/2014 KGNV: 86/2019 KAMG: 83/2014

Sat, February 21: KJAX: 86/2019 KCRG: 84/2019 KGNV: 89/2019 KAMG: 87/2018

PRELIMINARY POINT TEMPS/POPS

AMG 65 82 53 64 / 40 60 90 30 SSI 61 79 57 67 / 20 30 80 50 JAX 62 86 58 71 / 0 10 60 50 SGJ 60 84 60 72 / 0 0 50 70 GNV 60 85 60 71 / 0 0 60 50 OCF 59 85 60 73 / 0 0 50 60

JAX WATCHES/WARNINGS/ADVISORIES

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