Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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322 FXUS62 KJAX 172321 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 721 PM EDT Mon Jun 17 2024 ...New UPDATE, AVIATION... .UPDATE... Issued at 720 PM EDT Mon Jun 17 2024 For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf No major updates needed on the forecast this evening. Gusty easterly winds will continue overnight with very mild low temperatures along the coast in the upper 70s. && .SYNOPSIS... Issued at 242 PM EDT Mon Jun 17 2024 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, a slow moving, broad low pressure center (1003 millibars) has emerged into the Bay of Campeche (southwestern Gulf of Mexico). 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 1.1 inches across north central FL to around 1.6 inches for inland southeast GA. Spotty showers were moving quickly westward across our region, and breezy east-northeasterly winds have overspread northeast and north central FL as our local pressure gradient tightens. These breezy winds have developed a healthy cumulus field across our area, with thin cirrus also overspreading our skies. Temperatures ranged from the mid 80s to the lower 90s as of 18Z, with dewpoints ranging from the mid and upper 60s to the lower 70s at coastal locations. && .NEAR TERM... (through Tonight) Issued at 242 PM EDT Mon Jun 17 2024 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 overnight, especially for the Atlantic coastal counties. Breezy onshore winds will continue at coastal locations overnight, which will keep lows in the upper 70s to around 80. Winds at inland locations will gradually decouple as the night progresses, allowing lows to generally fall to the lower 70s. && .SHORT TERM... (Tuesday through Wednesday night) Issued at 242 PM EDT Mon Jun 17 2024 Low to mid level high pressure ridging remains the dominant feature during this period, as high pressure southeast of New England changes little in strength and orientation through Wednesday. Troughing east of the Bahamas which is expected to develop a tropical wave (more on that below) will help maintain a rather tight pressure gradient, and therefore continuing breezy onshore conditions which will start to strengthen a bit Wednesday and into Wednesday Night. This will help to cool temps a bit area wide and especially closer to the coast and St. Johns River, in which temps in the mid to upper 80s will be expected, warmer into the low 90s approaching I-75. Winds are expected to remain below any wind advisory criteria, though still in the 15-20mph range with gusts to 30-35 mph and perhaps a bit higher at times along the coast. Chances for showers and isolated t`storms does slowly increase Tuesday and into Wednesday with increase in tropical-like moisture, with the highest chances generally for areas east and southeast. && .LONG TERM... (Thursday through Sunday) Issued at 242 PM EDT Mon Jun 17 2024 Eyes continue to be on a tropical wave forming east of the Bahamas over the next few days, and starting to make its way northwestward towards the southeastern US by the end of the week. Guidance remains more split than one would like for the expected time frame regarding potential development and track, though there has been an overall slowing trend with respect to the progress and movement of the disturbance and therefore timing. Expecting the trough/wave to approach the southeast coastline around the Thursday to possibly even Friday time frame, though confidence is low with many other aspects regarding potential impacts. The main aspect that we are confident in is with respect to enhanced onshore conditions continuing, as high pressure over the Atlantic drifts a bit southward and tightens the pressure gradient with the troughing/disturbance approaching. Beneficial rainfall also remains very possible as well, though confidence is not very high at this time with regards to more widespread POPs. After the passage of the disturbance, high pressure ridging returns at the low levels, though weaker overall. Guidance has been suggesting the remnant upper low/trough may partially linger near the area, which would certainly impact rain chances in either direction. However, given the uncertainty and likely weak and/or onshore flow, leaning towards climo with respect to POPs for this upcoming weekend. Temperatures start near to slightly below average for the end of the work week (especially towards the coast), trending near to slightly above average by next weekend. && .AVIATION... (00Z TAFS) Issued at 720 PM EDT Mon Jun 17 2024 VFR conditions expected at the TAF sites with gusty easterly winds continuing through the TAF period. Potential for MVFR ceilings at SSI tomorrow afternoon, however winds will be too elevated for any fog formation. Isolated to scattered showers will move onshore beginning tomorrow morning throughout the day, thunderstorm chances remain low. && .MARINE... Issued at 242 PM 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 seas increasing to Caution levels of 15-20 knots and seas building to 4-6 feet. Winds offshore will then increase to Small Craft Advisory level speeds of around 20 knots offshore by late Tuesday afternoon, with these Small Craft Advisory conditions likely expanding to the near shore waters on Wednesday. Seas will build to 5-7 feet by Tuesday evening offshore, with near shore seas building to 4-6 feet. 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 thunderstorm activity will then increase late this week, 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 5-7 foot range near shore from Wednesday through Thursday night, while seas offshore peak in the 7-8 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 71 91 69 89 / 10 10 10 20 SSI 79 86 78 86 / 20 30 20 50 JAX 72 89 72 87 / 20 30 10 50 SGJ 79 87 78 87 / 20 30 20 50 GNV 72 92 71 90 / 10 20 0 50 OCF 73 92 73 92 / 10 20 10 50 && .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...Small Craft Advisory from 5 PM Tuesday to 5 AM EDT Friday for AMZ470-472-474. && $$