668 FXUS62 KJAX 071120 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 720 AM EDT Tue Apr 7 2020 .AVIATION... [Through 12Z Wednesday] Mainly VFR through the period with a slow increase in mid and high clouds at most TAF sites and local 8-12 knot sea breeze this afternoon at Atlc Coastal TAF sites. At SSI tonight despite the increase in mid level moisture the chance of rainfall is too low to include any VCSH at this time. At GNV the increase in moisture in the low level SW flow will increase the chance of low CIGS after 09z, for now to show a trend have place SCT005 OVC015 for MVFR conds, but they could trend lower towards 10-12z in future TAF packages as confidence increases. && .PREV DISCUSSION [438 AM EDT]... .NEAR TERM [Through Tonight]... Upper level ridge will remain centered over the Yucatan Peninsula as weak surface high pressure off the southeast Atlantic coast shifts southeastward. A weak mid level shortwave moves through the northern periphery of the ridge passing just north of our area. A few showers and storms could affect the Altamaha river basin late this afternoon into tonight. Otherwise, dry conditions prevail with increasing cloud cover. South-southwesterly low to mid level flow develops today causing temperatures to warm into the mid to upper 80s with low 80s along the east coast due to the afternoon seabreeze. .SHORT TERM [Wednesday Through Thursday]... Deep layer westerly flow develops as 1000-500 mb ridge dampens across the GOMEX and a couple of low level troughs pivot southward across the region. This pattern will continue above normal warmth with near record highs by Thu with a couple periods of wetting rainfall potential associated with the passing troughs. Wed & Wed night...a pre-frontal trough will slide south across the local area through the day with showers and isolated t'storm potential as convective ingredients phase under elevated westerly steering flow 30-35 kts. High moisture content under the sub- tropical jet will raise PWAT near daily record highs of 1.8" under healthy 0-6 km bulk shear of 40-55 kts. This dynamical & thermodynamic support combined with diurnal instability raising surface CAPEs near 1700 J/kg into the afternoon focused near the I-10 corridor and toward St. Johns River basin of NE FL support t'storm potential. Limiting factors for strong t'storm potential will be lack of cold air aloft (mid level lapse rates only 5-6 degC/km) and low level dynamical forcing with 850 mb winds of only 20-25 kts. Rainfall tapers off from south to north into Wed night as moisture settles southward & diurnal instability fades. Wed night a low chance of lingering showers is possible as yet the actual surface cold front approaches from the WNW. Thu & Thu night...Less deep layer moisture compared to Wed as the cold front moves south across the area Thu and begins to stall across north-central FL Thu night, thus less overall rain chances Thu compared to Wed. Breezy and warm westerly flow is expected with only a low chance of showers/isolated t'storms as near record highs rise into the low 90s. A brief break in rainfall potential into Thu evening as the surface front begins to stall across north-central FL, then rain chance increase from west after midnight as yet another front approaches from the north and an upper level disturbance (elongated PVA) streams over the region. .LONG TERM [Friday Through Monday]... Fri & Sat...Cooler Fri with highs in the 70s under mostly cloudy skies with a chance of showers across NE FL as a sheared lobe of PVA and another surface trough traverse the local area. Mostly dry Fri night with cool temperatures in the 50s Sat morning under cooler northerly drainage flow as surface high pressure builds north of the region. A low chance rainfall returning late Sat into Sat night as the front begins to lift northward as a warm front with a warming trend as temps warm back toward above climo values. Sun & Mon...Models in better agreement showing a progressive weather pattern with a warm front lifting across the local area Sun with a chance of showers/tstorms, then a pre-frontal squall line with strong/severe t'storm potential Sun Nigh or Monday. Timing differences remain, but trend is for a wetter, dynamic pattern with above normal temperatures. .MARINE... Surface high pressure will be offshore of the Florida Atlantic coast through mid-week. Long period northeast swells have begun to diminish over the area and subside by Wednesday. Prevailing offshore flow develops late Today and continues through Thursday. A cold front is forecast to move into the forecast area by Thursday night and Friday. Some risk for showers and isolated t-storms over area waters on Thursday and again on Friday. Rip Currents: Moderate risk for NE FL and SE GA beaches today. .HYDROLOGY... Water levels along the Atlantic coast are trending upward reaching Action stage during high tide with the approach of the full moon on April 7th (Super Moon/Pink Moon). A Coastal Flood Statement is in effect today to account for nuisance flooding along the coast as water levels more uniformly rise into Action Stage. Water levels will continue to rise through the next few days with the peak of astronomical tidal rise Wed night (Apr 8-9) coinciding with offshore flow with negligible 'surge' impact. By Wed, a coastal flood advisory may be needed to highlight minor flood potential along the Atlantic coast with total astronomical tide inundation of 1.5-2 ft possible per PETSS guidance. && .PRELIMINARY POINT TEMPS/POPS... AMG 84 65 85 68 88 / 20 20 50 20 20 SSI 79 66 83 69 86 / 10 10 30 20 20 JAX 86 66 87 69 91 / 10 10 40 20 20 SGJ 81 65 86 68 88 / 10 10 20 10 20 GNV 86 64 87 68 88 / 0 10 30 10 20 OCF 87 64 87 68 86 / 0 0 20 10 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. &&