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561 FXUS62 KJAX 151140 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 740 AM EDT Sun Aug 15 2021 .AVIATION... [Through 12Z Monday] Similar to yesterday, shower activity has increased along the immediate coast with support from a coastal trough this morning. Expect this activity to intensify and expand in coverage through the rest of the morning, with thunderstorms developing by 14z as this area of activity progresses inland. Impacts from the activity are expected at all area terminals with the exception of KGNV. Showers and storms will lift northward into inland southeast Georgia this afternoon allowing a brief dry/lull period this afternoon before showers develop along the coastal areas again this evening and overnight. Brief MVFR to IFR conditions are possible with heavy rainfall through the period, otherwise expect scattered cumulus between 2,500 to 3,500 ft and VFR ceilings. East to east southeast winds will continue through the period with 5-10 knots inland and 8- 13 knots along the coast. && .PREV DISCUSSION [420 AM EDT]... .NEAR TERM [Through Tonight]... The forecast area will continue to be between the circulation of Fred in the Gulf of Mexico and sfc high pressure centered around 33N73W. This will continue a deep southeasterly flow over the region today while Fred pushes northwest and the high remains nearly stationary. We will still have a south to southwest flow near 20-25 kt above 500 mb due to the upper level low over just of south of Apalachicola, with the upper low expected to lift northward and weaken through tonight. While we have plentiful moisture over the area early this morning, some drier air will advect into the region this afternoon from the southeast per RAP model. Initial isolated to scattered convection again expected to be over coastal counties and the adjacent coastal waters due to weak inverted sfc trough, with a couple of stronger cells possible near the JAX metro area. As the trough pushes inland and the Atlantic sea breeze forms, convection should again fire during the heating of the day and shift west to northwest. Unlike yesterday when the heaviest and more widespread occurred in northeast FL, today's precip will likely be focused further north and west, where better upper support and deeper moisture will exist during the afternoon and evening hours. The support aloft and the forcing suggests we won't see as much heavy rainfall as yesterday as well but locally heavy rainfall is certainly possible given the upper level wind support. Plenty of cloud cover and precip will keep the max temps held to the 85 to 90 degree range. Tonight, precip inland will fade through the evening hours while lifting northwest, and then another round of isolated to scattered convection will likely develop over the coastal waters, due both to a surge of moisture with PWATs nearing 2 inches and enhanced east-southeast flow as Fred moves into the east-central GOMEX. Lows will be in the lower to mid 70s with a light east to southeast wind. .SHORT TERM [Monday Through Tuesday Night]... Fred is forecast to move northward through the central Gulf waters towards the western FL Panhandle and AL coastline Monday through Monday night, then moving inland and dissipating Tuesday night. This will keep the forcing and thus the bulk of the rainfall for the next couple of days focused to our west. That said, model PWATs continue to be over 2" both Monday and Tuesday as plentiful tropical moisture east of Fred continues to feed into the local area. Scattered to numerous showers and isolated embedded thunderstorms are anticipated both days. WPC has our area in a marginal risk of excessive rainfall for the next couple of days. Extensive cloud coverage will keep daytime temperatures cooler with highs in the mid-upper 80s Monday and upper 80s-low 90s on Tuesday. Overnight lows will also be moderated by the clouds and rain- staying in the low-mid 70s, upper 70s along the coastline. .LONG TERM [Wednesday Through Sunday]... Fred will have dissipated by Wednesday, but Tropical Storm Grace is forecast to take a very similar path. Grace should move northwestward into the eastern Gulf waters Wednesday through Thursday night. Beyond that, model solutions become more divergent, so uncertainty increases as we approach the end of the week. For now, kept PoPs close to climatological normal (around 40%) for the latter part of the week. Temperatures will be near to slightly above normal. .MARINE... Seas are very slowly increasing over the area waters (granted only 2.5 to 3 feet as of 08Z from area buoys), and winds are still averaging about 8-12 kt per buoys and CMAN. The trend in the guidance shows winds and seas coming up a bit further on Monday and Monday night so we may need headlines for 15-20 kt winds, though seas may be limited to about 5 ft based on latest NWPS model estimates. Winds and seas expected to trend down Tue- Wed as the pressure gradient loosens as Fred pushes northwest of the area and dissipates. Other concern will be for showers and storms over the area waters that will produce occasionally higher winds and seas. Mariners still need to pay attention to forecast from the National Hurricane Center from Fred and Grace. Rip Currents: Solid moderate risk of rip currents today through Monday, likely to last into Tue and Wed due to east to southeast flow and long fetch of wind-sea swells with periods of around 8 seconds. .FIRE WEATHER... Elevated winds at the surface, at 20 foot, and throughout the mixing layer will be increasing through Monday as the remnants of Fred move north through the central Gulf waters and regains Tropical Storm strength as it approaches the AL and FL Panhandle coastline. This will lead to higher end dispersions today in NE FL south of I-10 and possibly along the I-75 corridor on Monday. Otherwise, we're in too wet of a pattern for fire weather concerns. .HYDROLOGY... River flooding continues along the Suwannee, Santa Fe, St. Marys, Satilla, and Ichetucknee Rivers. Moderate flooding is occurring on the Santa Fe River at Three Rivers Estates and on the Ichetucknee River near Ichetucknee Springs State Park. The Suwannee River at Suwannee Springs is forecast to crest right around moderate flood stage early next week. Tropical moisture will be in place through at least mid-week. Scattered to numerous showers and storms are forecast today through Tuesday night. Storm total rainfall through Tuesday night is forecast to be around 1-3 inches with locally higher amounts possible. As Fred's track has shifted westward, coastal convergence upon the SE GA coastline has become more relevant, so fortunately for our area, the higher 2-3" totals are now along coastal GA-where we are currently not as saturated. Still, these rounds of heavy rainfall could prolong or exacerbate ongoing river flooding, particularly along the Suwannee and Santa Fe rivers. This rain could also lead to localized flooding, especially in low-lying, urban, or poor-drainage areas. The Weather Prediction Center has our area in a marginal risk of excessive rainfall (i.e. exceeding flash flood guidance) today through Tuesday night. && .PRELIMINARY POINT TEMPS/POPS... AMG 89 73 85 72 88 / 70 30 70 40 80 SSI 87 78 86 78 88 / 60 70 70 50 70 JAX 88 76 86 76 90 / 40 40 70 40 70 SGJ 87 77 87 76 89 / 40 30 70 40 60 GNV 88 74 86 74 90 / 40 30 80 30 80 OCF 89 74 88 74 91 / 40 20 80 30 70 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&