Area Forecast Discussion
Issued by NWS Melbourne, FL
Issued by NWS Melbourne, FL
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381 FXUS62 KMLB 270146 AFDMLB Area Forecast Discussion National Weather Service Melbourne FL 946 PM EDT Thu Sep 26 2024 ...New UPDATE... .UPDATE... Issued at 945 PM EDT Thu Sep 26 2024 Hurricane Helene is a major Category 4 hurricane, and is located approximately 65 miles west of Cedar Key, Florida, as of 9 PM. Helene is forecast to continue moving northward in the northeastern Gulf of Mexico, where it is forecast to make landfall along the Florida Big Bend over the next several hours. Locally, outer rainbands from Helene will continue to move across the Florida peninsula tonight, moving from the south toward the north. Windy and gusty conditions and the potential for brief tornadoes persist into the overnight hours across the area. A Tornado Watch remains in effect for Lake, Seminole, Orange, Osceola, Volusia, and Brevard counties through 6 AM. Heavy rainfall will also be possible with these squalls, and minor localized flooding cannot be fully ruled out in areas that see repeated rounds of rain. Residents and visitors are encouraged to ensure they have multiple ways of receiving weather alerts before heading to bed, and make sure alerts are loud enough to wake you up. In addition to the gusty winds and tornado threat overnight, conditions across the local Atlantic waters and all east central Florida beaches remains hazardous. Wave run-up to the dune line and sea walls will result in beach erosion, especially during this morning`s high tide between 3 AM and 5 AM. Marine conditions will remain dangerous and small craft operators should remain in port. Visitors and residents should stay off the beaches and out of the surf, especially during the overnight hours! Additionally, numerous life-threatening rip currents and a powerful longshore current will exist. Rainbands are expected to become less frequent into Friday as Helene continues northward into Georgia, though gusty winds and some scattered showers and storms will likely prevail through most of the day on Friday. Made very minimal adjustments to the overall forecast, and bumped up PoPs slightly across the far western portions of the CWA based on the rainband that was setting up. Skies are expected to remain mostly cloudy overnight across east central Florida, with overnight lows remaining warm and muggy in the upper 70s to low 80s. && .PREVIOUS DISCUSSION... Issued at 341 PM EDT Thu Sep 26 2024 Current-Tonight... Occasional fast-moving rainbands are expected to sweep from south to north this afternoon and evening as Helene moves northward. Tropical storm force winds extend far to the east from the center of Helene, which includes all of the Florida peninsula. Frequent tropical storm force gusts will be possible across the area today into this evening. Winds and gusts will continue to ramp up and become more frequent by late morning and continue into the evening, with speeds around 40-50 mph. By midday, wind gusts up to 60 to 65 mph will be possible, particularly northwest of I-4, along the Atlantic coast and in vicinity of Lake Okeechobee. Wind gusts of this magnitude can turn lightweight objects into flying debris, cause sporadic power interruptions, and perhaps result in some tree or minor structural damage. The timeframe for the highest potential for these wind gusts looks to be between 2 PM and 9 PM. Please remain indoors if at all possible. Tropical storm force gusts will diminish after midnight. In addition to very windy conditions and strong wind gusts, a few to several tornadoes embedded in the rain bands are also possible through this evening. The Storm Prediction Center has highlighted most of east central FL in a Slight Risk (level 2 of 5) for severe storms (primarily for the threat of a few tornadoes), with a Marginal Risk for St Lucie & Martin Counties today. A Tornado Watch is in effect for all of east central Florida into this evening. We will continue to monitor these fast- moving rain/storm bands for this potential. Have multiple ways of receiving warnings through tonight! Due to the fast nature of these occasional rainbands, rainfall totals will average about 1-2" through tonight across east central Florida. While the overall rainfall is not high for the local area, the threat for flooding in low- lying and urban areas, still exist, especially in areas which have already received heavy rainfall this month. A Flood Watch remains in effect for east central Florida. Remember, if you encounter a flooded roadway, turn around, don`t drown! Tropical storm force gusts will diminish after midnight. Hazardous marine and dangerous beach conditions into tonight. Wave run-up to the dune line and sea walls will result in beach erosion, especially during this afternoon`s high tide. Marine conditions will become dangerous and small craft operators should remain in port. Visitors and residents should stay off the beaches and out of the surf through tonight! Additionally, numerous life-threatening rip currents and a powerful longshore current will exist. Otherwise, afternoon high temperatures will reach in the upper 80s to low 90s due to the breaks in the rain and cloud cover. Conditions are expected to improve late tonight, mainly after midnight. Winds will back to the southwest and decrease gradually through the overnight hours (especially after midnight) with speeds becoming around 20 mph with gusts up to 30 mph possible around sunrise. The number and frequency of the outer rainbands moving over east central Florida will also decrease after midnight. Isolated to scattered showers and embedded lightning storms will be possible late tonight and into early Friday morning. Warm and muggy tonight, with overnight lows in the mid to upper 70s to around 80 degrees. Friday-Sunday... (Modified Previous Discussion) Once Helene makes landfall in the Big Bend region of Florida this evening, it will quickly push inland across Georgia and Tennessee Friday. Models are in pretty good agreement that Helene will merge with the cut- off low over the Tennessee Valley on Friday and Saturday. The upper level low will slowly weaken over the weekend as a high pressure ridge over the western Atlantic builds westward over the Florida peninsula and the Deep South. Locally, winds will remain southwesterly through the weekend, with speeds around 15 mph Friday, decreasing to around 10 mph on Saturday, and 5-10 mph on Sunday. Deep tropical moisture from the Caribbean will remain over the local area through the weekend, with the moisture oscillating from South-Central FL on Friday to Central Florida on Saturday and Sunday. Beneath it, scattered-numerous (50-70%) shower and storm coverage is forecast particularly in the afternoon/evening hours. Additional rounds of heavy rainfall can not be ruled out, thus increasing concerns of flooding over locations that have already seen a lot of rainfall this month. With deep moisture in place, high humidity will persist over the area, with dew points in the mid to upper 70s. Combined with the offshore flow, afternoon highs will be in the low 90s. These temperatures combined with humidity will produce near heat advisory criteria with heat indices ranging from 102-107F each afternoon. Overnight lows will be in the low to mid 70s each night. Monday-Wednesday... (Modified Previous Discussion) The upper level ridge will begin to retreat into the Atlantic through mid week. As the upper ridge sits nearby, the deep tropical moisture overhead will trend closer to normal. Some members show bouts of even drier air infiltrating the area from time to time, but confidence lessens overall. This yields continued 30-50% shower/storm coverage each day with highs in the upper 80s to lower 90s. Heat indices will subtly "dip" closer to 98-103F as surface moisture trends toward normal values. Overnight lows will remain in the low to mid 70s. && .AVIATION... (00Z TAFs) Issued at 830 PM EDT Thu Sep 26 2024 Rain bands associated with Hurricane Helene gradually shift east thru 06z-09z, impacting LEE now and eventually reaching MCO/ISM/SFB by 02-03z. Activity will push toward coastal sites like DAB/TIX after 06z. Frequent gusts above tropical storm force will continue through 09z before gradually decreasing to 25-30kt by 12z Fri. Locally higher gusts may remain at coastal terminals for several hours longer Fri. morning. Lingering SHRA will persist as conditions improve, turning drier from midday thru the end of the TAF. && .MARINE... Issued at 341 PM EDT Thu Sep 26 2024 Today/Tonight... (Modified Previous Discussion) Major Hurricane Helene will produce extremely dangerous marine conditions. All operators should remain in port through tonight. Nearshore seas are forecast to peak from 9-11 FT by this evening, increasing to 10-15 FT in the Gulf Stream. Sustained tropical-storm-force winds are likely along with southerly gusts as high as 50-55 KT. Winds will start to decrease overnight but tropical storm force gusts will persist through the overnight. Numerous showers and storms with waterspouts are possible! Friday-Sunday... (Previous Discussion) Seas quickly subside through the period: 5-7 FT nearshore / 6-10 FT on Friday, 2-3 FT nearshore / 3-5 FT offshore this weekend. However, fresh southerly winds continue at 20-25 KT Friday before becoming SW 8-15 KT this weekend. Scattered-numerous showers and storms with offshore-moving activity expected. && .PRELIMINARY POINT TEMPS/POPS... DAB 79 92 76 91 / 60 40 20 60 MCO 78 92 77 90 / 70 50 30 70 MLB 80 92 77 91 / 40 70 50 70 VRB 81 92 77 92 / 30 70 50 70 LEE 79 90 77 89 / 90 30 20 50 SFB 78 91 77 90 / 60 40 20 70 ORL 80 92 78 91 / 70 50 30 70 FPR 80 92 77 92 / 30 70 50 70 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...Tornado Watch until 6 AM EDT Friday for FLZ041-044>046-053-141- 144-247-347-447-547-647-747. Tropical Storm Warning for FLZ041-044>046-053-058-141-144-154- 159-164-247-254-259-264-347-447-547-647-747. Flood Watch until 8 AM EDT Friday for FLZ041-044>046-053-058-141- 144-154-159-164-247-254-259-264-347-447-547-647-747. High Surf Advisory until 11 AM EDT Friday for FLZ141-154-159-164- 347-447-647-747. AM...Tornado Watch until 6 AM EDT Friday for AMZ550-552. Tropical Storm Warning for AMZ550-552-555-570-572-575. && $$ UPDATE...Tollefsen AVIATION...Schaper