328 FXUS62 KJAX 171046 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 546 AM EST Tue Nov 17 2020 .AVIATION... [Through 12Z Wednesday] Northerly winds around 5-12 knots expected at all regional airfields today, winds are expected to increase to 10-15 knots at airfields along the coast (KSGJ/KSSI) late this evening as onshore winds strengthen. Clear skies expected throughout the period. && .PREV DISCUSSION [327 AM EST]... .NEAR TERM [Through Tonight]... A cool, dry continental airmass in place has delivered clear skies and a Fall chill across northeast Florida and southeast Georgia this morning. Strong surface high will build southeastward to the Tennessee Valley today leading a tightened pressure gradient and strengthening winds along the coast tonight. Temperatures will be on the cool side this afternoon with highs peaking in the low 70s. A reinforcing shot of cold air will push across southeastern GA and northeast FL overnight lowering temps to the low 40s over interior southeastern Georgia and mid 40s across interior areas of northeast Florida. Increasing onshore flow tonight will limit coastal cooling to the mid and upper 50s. .SHORT TERM [Wednesday Through Thursday]... Reinforcing high pressure will settle over the Ohio Valley and the southern Appalachians early on Wednesday morning and will continue to wedge down the southeastern seaboard, tightening our local pressure gradient even further and creating windy conditions all along the Atlantic coast. A wind advisory may be required for portions of the northeast FL coast, especially for St. Johns and Flagler Cos, where the gradient will be the tightest and northeasterly winds will be sustained near 25 mph with frequent gusts of 35-40 mph throughout the day on Wednesday. A cool and dry air mass will continue to advect into our region, and highs will only reach the 60-65 degree range, except upper 60s in north central FL. These highs are about 8-11 degrees below mid-November climatology for our area. Meanwhile,troughing aloft will depart the U.S. eastern seaboard by Wednesday evening, with heights aloft expected to gradually rise over our region through the end of the work week. A coastal trough will begin to take shape over our Atlantic waters on Wednesday night as strong high pressure settles over the Mid-Atlantic region and the Carolinas. Convergent onshore flow will begin to drive stratocumulus onshore along the northeast FL coast, with showers developing over the Atlantic waters adjacent to northeast FL during the late evening hours. Isolated to widely scattered showers will move onshore during the predawn and early morning hours on Thursday, initially along the northeast FL coastal counties and then expanding northward over the southeast GA coastal counties by the mid to late morning hours on Thursday. This onshore flow pattern will set up a large temperature gradient over our region as winds at inland locations decouple overnight and cloud cover does not expand into inland southeast GA until the predawn hours on Thursday. Lows Wednesday night will range from the upper 30s near the Altamaha/Ocmulgee River basins to the 40s elsewhere at inland locations, except lower 50s for inland north central FL. Lows at coastal locations will generally fall to the 50s as northeasterly winds remain sustained in the 15-20 mph range on Wednesday night and Thursday. Highs on Thursday will again remain in the mid 60s for southeast GA, ranging to the lower 70s in north central FL as stratocumulus cloudiness continues to expand and thicken from southeast to northwest. Lows on Thursday night will continue to trend warmer as ridging aloft begins to take shape and coastal troughing prevails at the surface. Lows will range from the upper 40s near the Altamaha/Ocmulgee Rivers to the low and mid 60s along the northeast FL coast. .LONG TERM [Friday Through Tuesday]... Ridging aloft will prevail over our area on Friday and Saturday, and our local pressure gradient will gradually loosen as high pressure slowly weakens over the southeastern states and then shifts offshore towards the end of the weekend. Coastal troughing will continue to generate isolated to widely scattered showers, mainly for locations along and east of I-95 in northeast FL. Temperatures and humidity levels will continue to recover, with highs generally reaching the mid to upper 70s both days, while lows range from 55-60 inland and the upper 60s at coastal locations on Friday night and warming further by a few degrees on Saturday night. A shortwave trough that will traverse the Great Lakes region late in the weekend will flatten the ridge aloft over our area and will drive a cold front into the southeastern states by Monday. Low level onshore flow will continue on Sunday, followed by the coastal trough finally breaking down by Sunday evening as low level flow begins to veer ahead of the approaching frontal boundary. Highs on Monday will approach 80 at inland locations, with an afternoon sea breeze keeping coastal highs mostly in the upper 70s. Lows will continue to run above seasonal averages on Sunday and Monday nights, with values around 60 inland and the mid to upper 60s at coastal locations. .MARINE... Due to breezy winds and elevated seas, Exercise Caution conditions will continue across area waters through the early afternoon. As high pressure builds southeastward into the Tennessee Valley today, post-frontal winds will increase over the coastal and outer waters this afternoon leading to a prolonged period Small Craft Advisory conditions through at least Thursday. As pressure field weakens late in the week, Small Craft Advisory conditions are only likely offshore with Exercise Caution for the near-shore waters Friday and into the weekend. Rip Currents: Breezy northerly winds will lead to a moderate risk at all area beaches today. Onshore winds will strengthen Wednesday and continue through the end of the week leading to high rip current risk for all northeast FL and southeast GA beaches. .FIRE WEATHER... Red Flag criteria will not be met during the next several days across our region. Breezy northerly transport winds will funnel a cool and dry air mass into our region today. Long durations of critically low humidity values around 25 percent and marginally high dispersion values are expected this afternoon inland, while northerly surface winds become breezy at coastal locations. Strong northeasterly transport winds will then overspread our region early on Wednesday, with breezy surface winds expected throughout inland northeast and north central FL and windy conditions at all coastal locations throughout the day. Humidity values may approach critical thresholds on Wednesday afternoon across inland southeast GA, where sustained surface winds will remain below 15 mph. Transport winds will shift to easterly on Thursday, resulting in higher humidity values and widely scattered showers at coastal locations. .HYDROLOGY... Coastal Flood Advisory will continue for the Atlantic coast and inland waterways through this afternoon before a lull in elevated tides tonight. Strengthening onshore flow will increase water levels again on Wednesday. Prolonged onshore flow will elevate tides will through the rest of the week resulting in periods of minor tidal flood impacts. Generally, water levels are expected to reach 1-2 feet above normally dry ground at times of high tide. && .PRELIMINARY POINT TEMPS/POPS... AMG 70 39 60 39 65 / 0 0 0 0 0 SSI 72 50 60 51 65 / 0 0 0 10 30 JAX 72 49 63 46 68 / 0 0 0 10 30 SGJ 72 58 65 57 70 / 0 0 0 20 20 GNV 72 46 66 48 71 / 0 0 0 10 10 OCF 73 49 69 51 73 / 0 0 0 10 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 7 PM EST this evening for Clay- Coastal Duval-Coastal Flagler-Coastal Nassau-Coastal St. Johns-Inland Duval-Inland Flagler-Inland Nassau-Inland St. Johns-Putnam. GA...Coastal Flood Advisory until 7 PM EST this evening for Coastal Camden-Coastal Glynn-Inland Camden. AM...Small Craft Advisory from 4 PM this afternoon to 7 AM EST Thursday for Coastal waters from St. Augustine to Flagler Beach FL out 20 NM-Waters from St. Augustine to Flagler Beach FL from 20 to 60 NM. Small Craft Advisory from 7 PM this evening to 7 AM EST Thursday for Coastal waters from Altamaha Sound to Fernandina Beach FL out 20 NM-Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM-Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-Waters from Fernandina Beach to St. Augustine FL from 20 to 60 NM. &&