Area Forecast Discussion
Issued by NWS Miami, FL
Issued by NWS Miami, FL
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933 FXUS62 KMFL 251752 AFDMFL Area Forecast Discussion National Weather Service Miami FL 152 PM EDT Wed Sep 25 2024 ...New SHORT TERM, AVIATION, MARINE, BEACHES... .SHORT TERM... (Rest of today through Thursday) Issued at 133 PM EDT Wed Sep 25 2024 *** KEY POINTS FOR HURRICANE HELENE *** Impacts for South Florida: Hurricane Helene will bring about heavy rain, gusty winds, storm surge across the Gulf Coast, and increased flooding potential as its outer bands move across the region. A Tropical Storm Warning is in effect for all of South Florida, including the local waters, until 2AM Friday morning. Flood Watch Issued: A Flood Watch is in effect for all of South Florida, as rainfall amounts of 2-6 inches are possible across inland and metro areas. Storm Surge Risk: 2-4 feet of storm surge is expected along the Gulf Coast from Bonita Beach to Flamingo due to Helene`s size and the shallow Florida shelf. Values as high as 5 feet may be observed. A Storm Surge Warning is in effect for these coastal areas. Limited Tornado Threat: Tropical tornado risk is limited but a few tornadoes may spawn tonight into early Thursday, especially along the southwest Florida and the Lake Okeechobee region. *** South Florida is already experiencing the effects of Helene today as the first few lines of convection have moved across the region. MFL soundings and ACARS data are showing high precipitable water (PWAT) values exceeding 2.2 inches, dew points in the upper 70s, and warm air aloft. Outer bands from Helene will continue to move northward across the region today, bringing periodic heavy rain with intervals of sunshine. Winds from the southeast will continue to strengthen throughout the day, with gusts exceeding 30 mph, especially along the coasts. The primary impacts from Helene will arrive late tonight into early tomorrow morning as the storm center progresses northward through the Gulf of Mexico. A significant moisture envelope will move into the region during this time, with PWAT values forecasted between 2.3 to 2.5 inches - nearing climatological highs for late September. Models also indicate a long, skinny CAPE profile, supportive of warm cloud processes and heavy rainfall. Given these parameters, there is potential for heavy rain and localized flooding across the area. Rainfall amounts between late Wednesday and Friday evening are expected to range from 2 to 4 inches inland, with metro areas potentially seeing 3 to 6 inches. Additionally, storm surge across portions of southwest Florida may reach 2-4 feet, with some vulnerable coastal areas possibly seeing up to 5 feet due to the large size of Helene and the shallow nature of the Florida shelf. Dangerous marine and boating conditions will also prevail across the entire region, with the most significant impacts felt in the Gulf waters. As Helene`s outer feeder bands move across the region, tropical storm-force wind gusts will also be possible throughout South Florida, with sustained winds up to 30 kts and gusts up to 40 kts possible tomorrow. Aside from the risks of storm surge, flooding rains, and wind, the threat of tropical tornadoes appears limited. South Florida`s residence time within the northeast quadrant of the system could reduce the window for tornadic activity, with the peak risk for tornadoes between 18Z-00Z due to dry air mixing and diurnal heating. Tornado potential may be confined to coastal areas of Collier, depending on the storm`s track. A second window for possible tornadogenesis may open in the Lake Okeechobee region Thursday afternoon as Helene moves further north in the Gulf of Mexico. Temperatures will remain near climatological norms, as cloud cover and widespread rain keep highs in check. && .LONG TERM... (Thursday night through Tuesday) Issued at 302 AM EDT Wed Sep 25 2024 Helene will have made landfall along the Big Bend/Gulf Coast region of Florida by late Thursday, and its direct impacts will be distant from South Florida. However, a stream of elevated moisture, characterized by PWAT values of 2.3-2.5 inches, will continue to drape over the region as breezy southwesterly flow persists. This southwest flow, associated with Helene`s extratropical transition, could enhance low-level convergence, further elevating hydrologic concerns, especially in areas prone to poor drainage. The moisture fetch will likely linger into the weekend, keeping humidity levels high across South Florida. Through the weekend, South Florida will experience a transitioning weather regime. Initially, low-level steering flow will come from the south and southwest, but it is expected to gradually shift to the west and northwest over time. The stream of moisture will become more diffuse, but enough will remain to produce scattered showers and thunderstorms. Localized flooding may occur, but overall impacts should be minimal. Looking beyond the weekend, some long-range models suggest the potential for a weak frontal passage, bringing a light northwesterly flow. However, it is too early to confirm this, and the event remains uncertain given its distance in time. && .AVIATION... (18Z TAFS) Issued at 133 PM EDT Wed Sep 25 2024 SCT SHRA/TSRA coverage will gradually increase as the day progresses and Hurricane Helene enters the SE Gulf of Mexico. SSE winds 15-20 kts with gusts 25-30 will be possible through the night and into tomorrow morning, when winds could strengthen up to 25-30 kts sustained and gusts up to 40 kts. Flight restrictions will be likely again tonight and tomorrow during periods of heavy rain. && .MARINE... Issued at 133 PM EDT Wed Sep 25 2024 Moderate easterly winds will gradually increase in magnitude as Hurricane Helene approaches across the Gulf waters. Winds and seas will become dangerous across the local waters as the system intensifies and moves northward alter tonight and tomorrow, with tropical storm conditions likely across all the local waters as Helene`s outer bands push across the area. Numerous to widespread showers and thunderstorms embedded within those outer bands will generally be observed today and tomorrow. && .BEACHES... Issued at 133 PM EDT Wed Sep 25 2024 Moderate to major coastal flooding can be expected over the Gulf coast late tonight into tomorrow as Hurricane Helene strengthens and tracks through the SE Gulf of Mexico. Strengthening onshore flow will result in an extended period of high rip current risk over the east coast (likely through the work week), with potentially hazardous surf developing over the Palm Beaches in the mid-week period. Additionally hazardous beach conditions look likely over the Gulf coast beaches starting Thursday as surf increases in association with Tropical Storm Helene. && .PRELIMINARY POINT TEMPS/POPS... Miami 80 89 80 91 / 80 80 70 70 West Kendall 79 89 80 91 / 80 90 70 80 Opa-Locka 80 89 81 92 / 80 80 70 70 Homestead 80 88 80 90 / 80 90 70 70 Fort Lauderdale 79 89 80 90 / 70 80 70 80 N Ft Lauderdale 80 90 81 91 / 70 80 70 70 Pembroke Pines 81 90 81 93 / 80 80 70 80 West Palm Beach 79 90 80 92 / 70 70 60 70 Boca Raton 79 90 80 92 / 70 70 70 70 Naples 79 87 82 89 / 80 90 80 70 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...Tropical Storm Warning for FLZ063-066>075-168-172>174. Flood Watch through Friday morning for FLZ063-066>075-168- 172>174. Storm Surge Warning for FLZ069-075. High Rip Current Risk through Friday evening for FLZ168-172-173. High Surf Advisory until 8 PM EDT Thursday for FLZ168-172-173. AM...Tropical Storm Warning for AMZ610-630-650-651-670-671. GM...Tropical Storm Warning for GMZ656-657-676. && $$ SHORT TERM...SRB/ATV LONG TERM....SRB AVIATION...ATV