465 FXUS62 KJAX 031325 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 925 AM EDT Fri Jun 3 2022 .UPDATE... Mid and upper level dry air remains established this morning with the latest RAOB showing near steady moisture levels through the atmospheric column, with PWAT ~1.3" (typical value for early June ~1.5"). As of 9 AM, a slow-moving, weak frontal boundary has crossed the Ocmulgee River in southeast GA. This frontal zone will continue to slow and eventually stall; it will be the primary focus of convection this afternoon and evening across inland southeast GA. A secondary focus for convection will be along the Atlantic sea breeze where scattered showers may develop and perhaps an isolated storm as it reaches the St Johns river breeze this afternoon. Thunderstorm coverage will ramp up along the I-75 corridor early this evening as the Atlantic sea breeze collides with the GOMEX sea breeze. In addition to the enhanced surface convergence along the sea breeze merger, weak upper lift will be offered by a subtle shortwave trough as it lifts northeastward out of the GOMEX this evening. With the aforementioned dry air in place, storms that develop will be capable of strong wind gusts due to evaporative cooling enhancement (DCAPE 1000-1200 j/kg). Weak southwesterly steering flow will lead to slow storm motion this afternoon, around 5 mph. This may lead to localized heavy rainfall and nuisance ponding. Tonight, convection will wane but lingering showers and isolated storm may continue through the late evening along the frontal boundary as it slowly sags southward to the FL/GA border. Most eyes will be on Potential Tropical Cyclone One, which may become Tropical Storm Alex later today, as it approaches southern Florida tonight. Associated moisture will increase across north-central FL as the system nears and showers along the northern fringe may advect from the Atlantic into coastal St Johns and Flagler counties near daybreak Saturday. Outside of higher risk of rip currents, local impacts are not expected with this system but a few southern zones may receive beneficial rain. && .PREV DISCUSSION [748 AM EDT]... .NEAR TERM [Through Tonight]... Weak high pressure ridging axis extends over the area from the western Atlantic waters WNW into the north central FL and west along the gulf coast. A pocket of drier air is situated above the area with PWATs around 1.2 inches ahead of a cold front moving through the I-20 corridor of AL amd GA. Dewpoints range from the mid 60s over inland SE GA to the upper 60s along the SE GA coast and into interior NE FL near 70 along the NE FL coast and north central FL areas, which is just a bit higher compared to yesterday morning at this time. Some cirrus is shifting slowly north from central FL into southern zones areas south of a Gainesville to Palatka to Saint Augustine line as high level winds stream clouds well downstream of Potential Tropical Storm One that is well SW of the region near the Yucatan Peninsula slowly moving NE towards the southeastern Gulf of Mexico at this time. Mostly clear skies prevail for most of NE FL and SE GA with light southerly winds that are becoming a land breeze along the coast 5-10 mph and less than 5 mph inland. Temperatures are a bit milder than yesterday with low to mid 70s at most locations, with a few inland spots in the upper 60s. Some patchy, shallow ground fog may develop inland over NE FL areas that received rainfall yesterday, mainly west of Highway 301. Light westerly winds after sunrise will become southeasterly by the lunch hour over NE FL and the SE GA coast with light winds from the SW over GA areas ahead of the approaching cold front. Scattered showers and Thunderstorms will develop first over inland SE GA by early afternoon as the combination of lift along the front, diurnal heating and strong instability coincide with some pulse strong to severe storms that may create downburst wind gusts up to 40-60 mph as the presence of dry low and mid level air will yield high DCAPE values over 1,000 J/KG this afternoon. The Atlantic seabreeze will move inland over NE FL and encounter the Gulf coast seabreeze near I-75 with isolated to scattered storms initiating during the mid to late afternoon time frame. A few strong storms may develop wind downburst wind gusts, but the potential for severe wind gusts will be less likely due to lower DCAPE values under 800 J/Kg south of I-10. Showers and storms will linger after sunset along the frontal boundary over the Altamaha river basin of inland SE GA south and west into the Suwannee valley as the boundary sinks slowly into the area and shortwave energy moves in from the west. Highs will be hot today into the mid 90s along and west of I-95 with low 90s immediately east of I-95 and in the 85-90 range at the beaches. The mixing down of some drier air will limit heat index values to the same values as the air temperature, mid 90s or lower. Tonight, skies will be partly to mostly cloudy from low and mid level clouds associated with the periphery of Potential Tropical Storm One moving in from the south into north central FL and debris clouds and a few showers and storms lingering inland due to the frontal boundary. Also, rain showers associated with the northern fringe of Potential Tropical Cyclone One may begin to graze into extreme southeast zones from Flagler Beach westward into eastern Marion county just before sunrise, but amounts through late tonight will be light. Light southeast winds will become NE over much of SE GA behind the front as it sinks to the FL/GA state line with light easterly winds over NE FL through dawn. Lows will be milder in the mid 70s at the coast and around 70 inland. .SHORT TERM [Saturday Through Sunday]... Lingering frontal boundary will remain just north of the Florida / Georgia border on Saturday. Meanwhile, Potential Tropical Cyclone One, currently northeast of the Yucatan will be tracking across the southern part of the Florida Peninsula Saturday and pushing northeast away from the state of Florida late Saturday night and Sunday morning. Timing and Development of this system still has some uncertainity. Showers and storms will increase in coverage during the day on Saturday as moisture increases across the region with PWATS increasing between 1.30 to 1.70 inches with much deeper moisture further down the peninsula to the right of the system. During Saturday afternoon and early evening, scattered storms will be possible across SE GA and NE FL, and N Central FL could see scattered to numerous showers and storms. The highest chances for localized heavy rainfall will be primarily over eastern Marion and Flagler Counties where the tightest moisture gradient will reside. It is possible that 0.75 to 1.5 inches of 24 hour rainfall can fall over north central Florida with some locally higher amounts depending on the ultimate track of the developing system. Winds are expected to shift from easterly in the early morning to east-northeasterly late Saturday morning as the low approaches, and winds will become breezy along the coast and adjacent Atlantic waters. The low pulls further away to the northeast Sunday with high pressure building over the mid Atlantic with tailing trough lingering over southern FL which will keep some breezy or heightened winds over the offshore waters and our immediate coast with gradient relaxing inland. east coast sea breeze will push inland with isolated to widely scattered showers across SE GA and NE FL. With persistent onshore flow Sunday, rip current risk will be heightened this entire weekend. Highs this weekend will be mostly in the mid to upper 80s, with some maximums near 90 over interior portions of SE GA and north central FL. Lows will be mainly in the upper 60s interior sections to mid 70s near the coast. .LONG TERM [Monday Through Friday]... Lighter winds Monday through the rest of the long term period will allow daily sea breezes to return each afternoon and evening. Isolated to widely scattered showers will be possible area wide on Monday with east coast sea breeze. Isolated showers and storms are expected in NE FL Tuesday and Wednesday with merging west coast and east coast sea breeze. Storms should be limited with riding building into the middle of next week. Coverage will increase again Thursday and Friday with isolated to widely scattered showers area wide with a cold front boundary moving toward and into the region. An increasing trend in temperatures is expected through the long term period with highs gradually increasing each day and reaching the middle to upper 90s by Thursday and Friday. Low temperatures are expected to increase from the upper 60s and lower 70s Sunday night to the lower to middle 70s Thursday night. .AVIATION... [Through 12Z Saturday] VFR conditions and light southwest winds will continue this morning as a weak, slow-moving front presses farther southeastward toward the area. A gusty east coast seas breeze will press inland late around noon, reaching the I-95 corridor (JAX) around 18z- 19z. Vicinity showers and potentially a thunderstorm will be possible along the sea breeze as it pushes inland. The best thunderstorm potential will be early this evening at GNV as west and east coast sea breezes merge. Showers may linger along the stalling front in southeast GA but this activity is not likely to impact any TAF sites overnight. VFR conditions are likely to continue at all sites with the exception of GNV where IFR low stratus may develop toward sunrise Saturday. Potential Tropical Cyclone One will begin to move across south FL Saturday morning and as it does associated showers are possible at SGJ. .MARINE... A weak cold front will approach from the northwest today then stall over the waters through Saturday as a tropical disturbance tracks east across the southern Gulf of Mexico. This tropical low will cross the southern Florida peninsula late Saturday and depart offshore of the south-central Florida Atlantic coast early Sunday. Local winds and seas will increase this weekend as the tropical system tracks to the south of the local waters and Small Craft Advisories may be needed Saturday night through Sunday. The low will track farther offshore over the Atlantic Monday as high pressure builds northeast of the region. The high will build east of the local waters through mid-week with lingering troughs northwest of the region. Rip Currents: Moderate risk at NE FL beaches and SE GA beaches today. A high end moderate risk is expected at all beaches on Saturday as onshore flow increases at the coast. .HYDROLOGY... Based on the current track of Potential Tropical Cyclone One, about 0.75 to 1.5 inches of 24 hour rainfall may fall over north central Florida areas with some locally higher amounts. Should the system track a little farther south, less rainfall may be realized while a more northward shift may increase values up a bit, but any flash flood concerns as of now appear to be minimal as the bulk of the system's rainfall falls generally south of our area over central and southern FL. && .PRELIMINARY POINT TEMPS/POPS... AMG 93 68 88 68 88 / 50 60 50 20 20 SSI 90 75 86 74 86 / 20 20 50 30 30 JAX 93 72 86 71 86 / 20 20 50 30 30 SGJ 89 72 84 73 85 / 20 30 60 40 30 GNV 92 69 86 69 89 / 50 40 50 30 30 OCF 91 71 85 70 90 / 60 50 60 30 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&