Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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769 FXUS62 KJAX 171558 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 1158 AM EDT Mon Jun 17 2024 ...ONSHORE WINDS CONTINUE TO STRENGTHEN THROUGH THURSDAY... ...MARINE AND COASTAL CONDITIONS DETERIORATE TOWARDS MIDWEEK... ...BENEFICIAL RAINFALL POSSIBLE LATER THIS WEEK... For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf .UPDATE... Issued at 1159 AM EDT Mon Jun 17 2024 Early afternoon surface analysis depicts high pressure (1027 millibars) centered off coastal New England. Meanwhile, surface troughing was situated over the southwestern Atlantic Ocean to the east of the Bahamas. Otherwise, low pressure (1003 millibars) was emerging into the Bay of Campeche (southwestern Gulf of Mexico) from Mexico`s Yucatan Peninsula. Aloft...stout ridging centered over the Carolinas remains in control of our local weather pattern, while a trough was located just north of the Greater Antilles in the southwestern Atlantic Ocean. Latest GOES-East derived Total Precipitable Water imagery indicates that a drier than average air mass persists across our region, with values ranging from around 1.2 inches across north central FL to around 1.5 inches for inland southeast GA. A surge of easterly winds has triggered a few heavier showers that were moving quickly across inland portions of southeast GA, while isolated showers extended southwestward along this inland moving surge of onshore winds along the I-95 corridor in southeast GA. Breezy easterly winds have overspread northeast and north central FL as our local pressure gradient tightens, with the easterly wind surge and associated shower activity progressing across inland portions of southeast GA. These breezy winds have developed a healthy cumulus field across our area, with thin cirrus also overspreading our skies from west to east late this morning. Temperatures were generally in the mid to upper 80s area-wide as of 16Z, with dewpoints mostly in the low to mid 70s. Already stout ridging centered to our north will expand and strengthen further through Tuesday, resulting in a deepening east-northeasterly wind regime for our area. This flow pattern will generally advect a drier than average air mass over our region from the Atlantic waters, but strengthening and convergent onshore flow should be able to squeeze out a few showers, especially later tonight for the Atlantic coastal counties. The overall subsident air mass will likely limit the potential for sustained updrafts, and thunderstorm activity appears to be unlikely or very isolated at best, with the low-topped activity currently crossing inland southeast GA being the most likely possibility for a sporadic lightning strike through the early afternoon hours. Winds this afternoon will occasionally gust to the 25-35 mph range as our local pressure gradient continues to gradually tighten, and onshore winds will likely remain breezy at coastal locations well into the evening hours before slowly weakening overnight. Highs this afternoon will soar to the low and mid 90s for locations along and west of Interstate 75, where dewpoints will crash through the 60s due to the dry and subsident air mass in place, which will keep maximum heat index values to around 100 for these locations. Highs elsewhere will generally top out in the upper 80s to around 90. Lows tonight will fall to the lower 70s inland, while onshore winds keep coastal lows in the upper 70s to around 80. && .SHORT TERM... (Tuesday through Wednesday night) Issued at 102 AM EDT Mon Jun 17 2024 Tuesday...Not much change in the pattern as high pressure remains locked in north of the region and breezy to almost windy easterly flow will continue at 15-25G35-40mph range at the Atlantic Coast with a high risk of rip current and 10-20G30-35mph range over inland areas during the afternoon hours. This flow pattern will continue to stream rounds of scattered showers and isolated storms from the coastal waters and into land areas through the day with gusty winds the main threat from storm activity over inland areas during the afternoon hours. Temps at or slightly below normal levels with highs in the mid/upper 80s along the Atlantic Coast/I-95 corridor and into the lower 90s over far inland areas. Tuesday Night...Breezy easterly flow continues along the Atlantic Coast with continued scattered showers and isolated storms pushing onshore, while partly cloudy and mainly dry conditions will exist over inland areas. Lows in the 70-75 range inland and 75-80 along the Atlantic Coastal areas as the breezy winds keep temps elevated. Wednesday...Breezy onshore/easterly flow continue at 15-25G35-40mph range at the Atlantic Coast with a high risk of rip current and 10-20G30-35mph range over inland areas during the afternoon hours. This flow pattern will continue to stream rounds of scattered showers and isolated storms from the coastal waters and into land areas through the day with gusty winds the main threat from storm activity over inland areas during the afternoon hours. Temps at or slightly below normal levels with highs in the mid/upper 80s along the Atlantic Coast/I-95 corridor and into the lower 90s over far inland areas. Wednesday Night...Breezy easterly flow continues along the Atlantic Coast with continued scattered showers and isolated storms pushing onshore, while partly cloudy and mainly dry conditions will exist over inland areas. Lows in the 70-75 range inland and 75-80 along the Atlantic Coastal areas as the breezy winds keep temps elevated. && .LONG TERM... (Thursday through Sunday) Issued at 102 AM EDT Mon Jun 17 2024 Thursday...GFS/ECMWF model runs are still trying to spin up a low pressure system underneath mid level trough/disturbance pushing quickly westward from the Bahamas into the FL peninsula. Still way too early if this system becomes actual tropical low pressure system or more likely a disorganized area of widespread showers and embedded thunderstorms with a locally heavy rainfall and strong gusty wind potential during this period. Bottom line during this period will be an increase in rainfall chances to 50-80% with numerous to widespread showers and embedded heavy storms pushing onshore at times with strong gusty winds as the main threat. Max temps will remain at or slightly below normal levels with the increased rainfall chances with highs in the mid/upper 80s along the Atlantic Coast/I-95 corridor and still reaching into the lower 90s over inland areas. With most of the local NE FL/SE GA area having below normal rainfall so far this month, this will be welcome rainfall in many locations, but localized flood potential will mainly exist in urban areas and along the Atlantic Coast during high tide cycles and the stronger onshore flow may produce minor tidal flooding along the Atlantic Coast beaches with the approach of the full moon phase. Friday/Saturday/Sunday...In the wake of departing low pressure system, a weaker high pressure ridge will build in just north of the region and still expect near breezy East-Southeast winds at 10-15G20-25 mph, but more normal East Coast sea breeze convection expected as it moves inland both days and lingering deeper tropical moisture will still lead to above normal rainfall chances in the 40-70% range with daily scattered to numerous showers and storms. Max temps bounce back to slightly above normal levels with highs in the upper 80s/near 90 along the Atlantic Coast/I-95 corridor with lower to middle 90s over inland areas. By the weekend the steering flow begins to become more southerly and helps to push afternoon convection closer to the Atlantic Coast. The increase in Max temps back to above normal levels will push daily maximum heat indices closer to 105F at just heat advisory levels. && .AVIATION... (12Z TAFS) Issued at 614 AM EDT Mon Jun 17 2024 Restrictions in stratus coming off the Atlantic will be possible early this period. Otherwise, prevailing VFR conditions forecast Today. Gusty winds are expected at all area TAF sites, especially near the coast. Isolated to scattered showers and storms are expected from mid morning through the afternoon. Brief restrictions in and near these storms are possible. This convection will largely dissipate with loss of diurnal heating in the evening, but will linger over the coastal waters into the night. && .MARINE... Issued at 1159 AM EDT Mon Jun 17 2024 Strong high pressure will remain anchored off coastal New England through Thursday. This feature will create gradually increasing onshore winds and building seas across our local waters, with speeds today remaining just below Caution levels, with seas of 3-5 feet expected both near shore and offshore. Caution level wind speeds of 15-20 knots will develop tonight, followed by Small Craft Advisory level speeds around 20 knots setting in offshore on Tuesday, with these Small Craft Advisory conditions expanding to the near shore waters by Tuesday evening. Seas will build to 5-7 feet by Tuesday evening both near shore and offshore. Meanwhile, a trough situated to the northeast of the Bahamas will be steered westward towards the southeastern seaboard late this week, with weak low pressure possibly developing as this system traverses the Gulf Stream waters. Showers and thunderstorms will increase beginning around midweek, with activity likely continuing into the upcoming weekend. Winds may occasionally gust to Gale Force across the offshore waters on Wednesday and Wednesday night. Seas will peak in the 6-8 foot range near shore from Wednesday through Thursday night, while seas offshore peak in the 7-9 foot range on Wednesday and Wednesday night. High pressure will then weaken as it sinks slowly southward towards Bermuda, with the axis of this surface ridge extending across our area during the upcoming weekend. Winds and seas will gradually diminish as prevailing winds shift to southeasterly on Saturday and then southerly by Sunday. Rip Currents / Coastal Flooding / Beach Erosion / High Surf: Breezy onshore winds will result in a high risk of rip currents during the next several days. Breakers of 2-3 feet at the northeast FL beaches today will build to 3-5 feet on Tuesday and then 5-6 feet on Wednesday and Thursday. Values on Wednesday and Thursday are just below High Surf Advisory criteria, and some minor beach erosion during times of high tide will be possible later this week. Although we will be entering the Full Moon cycle later this week, astronomical tides are not particularly high at this time of the year, so water levels will likely remain around or just below minor flooding during the evening high tides from Wednesday through Friday. && .FIRE WEATHER... Issued at 1159 AM EDT Mon Jun 17 2024 Gusty easterly surface and transport winds will continue through midweek, creating high daytime dispersion values at inland locations and good to marginally high dispersion values at coastal locations. A drier air mass will prevail through midweek across inland southeast GA and the Suwannee Valley, where afternoon relative humidity values will fall to around 35 percent each afternoon. && .PRELIMINARY POINT TEMPS/POPS... AMG 93 71 91 69 / 10 10 10 10 SSI 87 79 86 78 / 10 10 30 20 JAX 90 72 89 72 / 10 20 30 10 SGJ 89 79 87 78 / 20 30 30 20 GNV 93 72 92 71 / 10 10 20 0 OCF 93 73 92 73 / 10 10 20 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through late Thursday night for FLZ124-125- 133-138. GA...High Rip Current Risk through late Thursday night for GAZ154-166. AM...None. && $$