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

- Patchy to Areas of Frost Across Inland Southeast GA Late Tonight

- Severe to Extreme Drought Continues for Inland Areas

- Potential for Locally Heavy Rainfall Across Southeast GA Fri & Sat. Isolated Thunderstorms Possible Area-Wide

- Light Freezes and Frost Possible on Tues & Wed Nights Next Week

- Moderate Rip Current Risk Continues at Area Beaches

UPDATE

Forecast on track for cool temps tonight as scattered to broken high clouds continue to overspread the region through the overnight hours. Should still be thin enough to allow for low temps into the mid/upper 30s across inland SE GA and some patchy/areas of frost, while lower to middle 40s are expected elsewhere. Increasing high cloud cover and light north winds should keep any fog formation to a minimum.

NEAR TERM /UNTIL 6 AM THURSDAY MORNING/

Afternoon surface analysis depicts slowly strengthening high pressure (1024 millibars) building southeastward from the Tennessee Valley towards the southeastern states. Meanwhile, the cold front that passed across our region on Tuesday afternoon and evening was now slowing its forward progress across south FL. Aloft...brisk west- southwesterly flow prevails locally, as our area remains between flat ridging positioned over Cuba and the Bahamas and troughing that was digging southeastward from the Upper Midwest. A deck of stratocumulus cloud cover based around a stout subsidence inversion at 900 millibars (around 3,000 feet) was slowly eroding early this afternoon for locations south and east of Waycross, while this cloud cover has been thicker for locations north and west of Waycross thus far. Temperatures beneath this thicker cloud cover remain stuck around 50 degrees as of 18Z, and dewpoints were falling through the 30s as a drier air mass continues to advect into our region. Peaks of sunshine were countering cold air advection elsewhere, allowing temperatures to climb to the upper 50s and lower 60s at most locations. Dewpoints for these areas were generally in the 45-50 range.

Brisk west-southwesterly flow aloft will continue tonight, advecting a veil of mostly thin, high altitude cirrus across our skies. Surface ridging will continue to build into our region from the northwest, allowing for surface winds to decouple early this evening at inland locations. The veil of cirrus should be thin enough for radiational cooling, with patchy to areas of frost formation expected for inland locations in southeast GA after midnight, where lows will fall to the mid 30s. Lows elsewhere will fall to the upper 30s for inland locations along I-10 and 40s elsewhere, except around 50 along the northeast FL coast, where a light north northwesterly breeze will continue overnight.

SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/

Rounds of rain will move through the area mainly along and north of the I-10 corridor Thursday and Friday as a parade of upper shortwaves round a ridge and traverse across the Gulf states. At the surface, an area of low pressure develops in the NW Gulf and tracks eastward along the Gulf coast lifting a warm front up the FL peninsula. Rain will be mainly either light or sprinkles on Thursday as it has to overcome the dry airmass over the area. Developing SSW flow ahead of the approaching surface low will promote warm air and moisture advection inland. Showers become more widespread on Friday and limited elevated instability will support a few embedded thunderstorms. Convection continues into Friday night as the low and cold front move into northern FL. WPC Excessive Rainfall Outlook indicates a Marginal Risk of excessive rainfall across of inland SE GA due to the potential for continuous rounds of heavy downpours. Highs on Thursday will range from the upper 50s/low 60s in SE GA to the low/mid 70s in north-central FL. Temperatures increase to above seasonable on Friday with highs in the mid 60s to the low 80s.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

A cold front will stall over north-central FL Saturday into Saturday Night before finally shifting south into central FL later on Sunday. Deep Gulf moisture will increase PWATs into the 1.6-1.8 in. range which is above seasonable for this time of the year. Moist environment and the frontal boundary providing a focus for ascent will produce numerous to widespread showers with embedded thunderstorms moving across the area mainly Saturday afternoon into Sunday morning. This will bring beneficial rainfall to our severe/extreme drought areas with rainfall totals in the 1 to 4 inch range. However, minor flooding could occur in areas that continuously receive rounds of heavy rainfall in a short time period. The axis of heavy rain will generally be across inland SE GA where locally higher amounts are possible. WPC expanded their Marginal risk of excessive rainfall to include SE GA and NE FL for their Saturday outlook.

From Sunday night through Tuesday, a drier and colder airmass will settle over the area under building high pressure. Temperatures will fall to below normal for early December, with highs in the lower to mid 60s and overnight lows in the mid 30s to mid 40s. Guidance also suggest another, albeit drier, reinforcing front boundary Monday, supporting cool and dry conditions with good model agreement.

AVIATION /00Z THURSDAY THROUGH 00Z FRIDAY/

VFR with a slow thickening of mid and high clouds for the 00Z TAF period, along with light North winds of 3-5 knots tonight and 6-9 knots after 18Z Thursday. Have kept the brief MVFR fog in the TAF forecast for VQQ in the 08-12Z time frame tonight.

MARINE

High pressure will build over the southeastern states tonight and Thursday. Low pressure will then organize along the northern Gulf coast on Thursday night, with a warm front lifting northward across our local waters on Friday, accompanied by an increasing coverage of showers. Weak low pressure will move northeastward across southeastern Georgia on Friday evening, with this storm system's cold front then crossing our local waters on Friday night and Saturday morning. A wave of low pressure will then develop along this front just south of the northeast Florida waters on Saturday night, keeping showers and a few embedded thunderstorms over our local waters through Sunday. Low pressure will then strengthen as it moves offshore on Sunday night and Monday, resulting in strengthening north northwesterly winds as rainfall ends.

Rip Currents: SE GA Moderate Thursday NE FL Moderate Thursday

FIRE WEATHER

LOW DAYTIME DISPERSIONS AREA WIDE ON THURSDAY... LOW DAYTIME DISPERSIONS SE GA SATURDAY...

Light northwest winds become established later this afternoon, with Poor to Fair dispersions, becoming Poor by Thursday. Rounds of rainfall move through the area Thursday into this weekend ahead of an approaching cold front. Mainly light showers anticipated on Thursday along and north of I-10 corridor. Showers and embedded thunderstorms increase area-wide late Friday into Saturday. South- southwesterly flow increases on Friday developing fair dispersions.

FOG POTENTIAL AND OTHER REMARKS...Patchy frost possible Tonight into Thursday morning for interior locations in southeast Georgia. Heavy rain potential for inland southeast Georgia and Suwannee Valley Friday into the weekend.

PRELIMINARY POINT TEMPS/POPS

AMG 33 56 46 66 / 0 50 40 80 SSI 44 61 52 71 / 0 30 20 50 JAX 40 66 52 78 / 0 20 10 30 SGJ 46 68 57 80 / 10 10 10 10 GNV 42 71 54 80 / 10 10 10 20 OCF 44 74 55 81 / 10 10 0 10

JAX WATCHES/WARNINGS/ADVISORIES

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