Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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926 FXUS62 KJAX 210155 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 955 PM EDT Thu Jun 20 2024 ...INVEST 92-L APPROACHES OUR LOCAL COASTLINE ON FRIDAY... ...HAZARDOUS MARINE AND COASTAL CONDITIONS CONTINUE... ...LOCALLY HEAVY RAINFALL ALONG THE I-95 CORRIDOR ON FRIDAY... .UPDATE... Issued at 955 PM EDT Thu Jun 20 2024 Late evening surface analysis depicts a gradually organizing, but weak low pressure enter (1014 millibars), labeled as Invest 92-L by the National Hurricane Center. This feature was centered about 300 miles to the east-southeast of Mayport as of 01Z. Thunderstorm activity has been bursting near a poorly defined center of circulation this evening, and the National Hurricane Center has increased the probability for development into a Tropical Depression to 50% on their evening Tropical Weather Outlook. Otherwise, high pressure (1028 millibars) was gradually weakening over the western Atlantic waters as it sinks southward towards Bermuda. Aloft...stout ridging was centered across the Tennessee Valley and the southern Appalachians, with a Tropical Upper Tropospheric Trough (TUTT) being steered quickly westward across the southern portions of the Gulf of Mexico beneath this ridge. A few weak rain bands on the western periphery of Invest 92-L were progressing west-southwestward across the offshore Atlantic waters to the south of St. Augustine. Scattered multi-layered cloudiness continues to progress across northeast and north central FL, with fair skies prevailing across southeast GA. Breezy northeasterly winds prevail at coastal locations, with winds decoupling further inland. Temperatures generally ranged from 75-80 degrees at 02Z, with dewpoints mostly in the 60s inland, ranging to around 70 at coastal locations. All eyes are on Invest 92-L tonight as this feature moves west- northwestward towards our coastline. This system could organize into a Tropical Depression overnight or Friday morning as it traverses the warm Gulf Stream waters, and outer rain bands should begin to move onshore along the northeast FL coast during the predawn hours on Friday. Beneficial rainfall is on its way to the Interstate 95 corridor, with a dry and subsident air mass closer to the ridge axis aloft over inland southeast GA and the Suwannee Valley likely reducing rainfall intensity and coverage as activity works westward after sunrise on Friday. Heavy downpours and a few embedded thunderstorms should overspread coastal southeast GA and locations east of U.S. Highway 17 by sunrise. Multi-layered cloud cover will otherwise gradually increase from east to west during the overnight and predawn hours, with lows falling to the upper 60s across inland southeast GA and remaining in the 70s elsewhere. && .SHORT TERM... (Friday through Saturday night) Issued at 237 PM EDT Thu Jun 20 2024 Area of low pressure with disorganized convection will move west- northwest toward SE GA and NE FL during the overnight hours and then move inland around or just after sunrise Friday morning. There is not much time for the system to get organized, but there is a small chance it can be a depression before it comes ashore. Either way, impacts are the same with rough surf, potential minor beach erosion during high tide, high risk of rip currents. Expecting numerous showers with embedded thunderstorms with this feature, along with elevated winds and gusts particularly I-95 eastward where some wind gusts exceeding 30 mph are possible. Highs Friday will be a little cooler than normal due the clouds and rainfall passing through with highs in the 85 to 90 degree range. High pressure will build to the northeast behind the low pressure area Friday night through Saturday. This pattern will continue the onshore flow pattern, but the gradient will be more relaxed, so so not expecting winds to be as elevated during this time frame. Above average shower chances will continue in the onshore flow. Diurnal heating could lead to a few afternoon storms on Saturday. Lows Friday night will generally be in the lower to mid 70s, except a little warmer near the coast. Temperatures Saturday will trend above normal, with highs ranging from the lower 90s at the coast, to the mid 90s inland. The high will move further away to the east northeast Saturday night, with the flow becoming more from the south/southeast. Lows away from the coast in the mid 70s, upper 70s coast. && .LONG TERM... (Sunday through next Thursday) Issued at 237 PM EDT Thu Jun 20 2024 The high will continue to drift away to the east this period, as a trough moves into the southeastern US and stalls. An increasingly moist southwest flow will become the trend this period. This pattern will produce above normal chances for showers and thunderstorms. Temperatures will be above normal throughout this period. && .AVIATION... (00Z TAFS) Issued at 817 PM EDT Thu Jun 20 2024 VFR conditions should prevail early this evening, followed by clouds lowering to MVFR after 02Z at SGJ, CRG, and JAX as showers begin to move onshore from the Atlantic waters. MVFR ceilings of 2,000-3,000 feet will overspread the VQQ and SSI terminals after 06Z, with VFR conditions otherwise prevailing overnight at GNV. Lower MVFR ceilings and chances for thunderstorms will increase after 08Z at SGJ, where periods of IFR visibilities will be possible after 10Z during heavier downpours. This activity will spread across the Duval County terminals and SSI during the morning hours on Friday, and ceilings further inland will also lower to MVFR at GNV after 12Z. Bands of heavier downpours and embedded thunderstorms will continue to impact the regional terminals through around 20Z, with confidence in coverage and intensity then falling during the late afternoon hours. Prevailing vicinity thunderstorm coverage was placed in each TAF during the late afternoon hours on Friday. Breezy northeasterly winds sustained around 15 knots will prevail at the SGJ and SSI coastal terminals overnight, while winds elsewhere subside to 5-10 knots after 03Z. Outside of gustier thunderstorm activity, northeasterly winds will remain sustained around 15 knots at the coastal terminals through late Friday afternoon, while speeds elsewhere increase to 10-15 knots after sunrise. && .MARINE... Issued at 955 PM EDT Thu Jun 20 2024 Weak low pressure situated about 300 miles to the east-southeast of Mayport, Florida late on Thursday evening may organize into a Tropical Depression overnight or early on Friday as it progresses west-northwestward across the Gulf Stream waters, with this feature approaching the northeast Florida coast late on Friday morning or during the early afternoon hours. Bands of gusty showers and embedded thunderstorms will increase in frequency and intensity during the overnight and predawn hours on Friday, with this activity continuing through late Friday afternoon before diminishing in coverage as this weak low pressure center progresses inland. Meanwhile, strong high pressure centered north of Bermuda will gradually weaken as it settles southward this weekend. Small Craft Advisory conditions will continue throughout our local waters tonight and Friday, followed by winds and seas diminishing to Caution levels on Friday night and then below Caution criteria on Saturday. Seas of 5-7 feet near shore and 6-8 feet offshore tonight and Friday will subside to 4-6 feet on Friday night and then 3-5 feet during the weekend. Rounds of showers and thunderstorms will continue to develop over our local waters this weekend and into next week as prevailing winds become southerly ahead of a weakening surface trough that will settle over the southeastern states through midweek. Rip Currents: Breakers of 5-7 feet will continue at the northeast FL beaches on Friday, with 4-6 foot breakers expected at the southeast GA beaches. This rough surf will create a high risk of dangerous rip currents at all area beaches through Friday. A moderate risk is expected during the weekend due to onshore winds and an easterly ocean swell. && .HYDROLOGY... Issued at 955 PM EDT Thu Jun 20 2024 The Weather Prediction Center has a Marginal risk of excessive rainfall from Friday through Saturday, as locally heavy rainfall totals of 2 to 3 inches will be possible along the Interstate 95 corridor as Invest 92-L impacts our region with bands of heavy downpours. Rainfall amounts further inland will likely remain below one inch. Rainfall will be mostly beneficial, but there will be concerns for flooding at urban locations where rain bands train repeatedly tomorrow and again on Saturday. && .PRELIMINARY POINT TEMPS/POPS... AMG 68 91 74 91 / 20 40 40 80 SSI 78 87 78 87 / 70 80 50 70 JAX 74 88 75 91 / 70 80 60 80 SGJ 78 87 77 89 / 80 80 70 80 GNV 73 91 73 94 / 50 70 60 90 OCF 74 91 74 95 / 50 80 50 90 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through late Friday night for FLZ124-125- 133-138. High Surf Advisory until 5 PM EDT Friday for FLZ124-125-133-138. GA...High Rip Current Risk through late Friday night for GAZ154-166. AM...Small Craft Advisory until 5 PM EDT Friday for AMZ450-452-454- 470-472-474. && $$