Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL
Issued by NWS Tampa Bay Area, FL
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379 FXUS62 KTBW 261149 AFDTBW Area Forecast Discussion National Weather Service Tampa Bay Ruskin FL 749 AM EDT Thu Sep 26 2024 ...New AVIATION... .AVIATION... (12Z TAFS) Issued at 744 AM EDT Thu Sep 26 2024 We`re seeing worsening conditions across the region this morning as rainbands from Hurricane Helene spread north. This system will bring MVFR and occasional IFR conditions into tonight. Gusty southeast winds at 10 to 20 knots will increase to 25 to 35 knots by this afternoon then shift to southerly late this afternoon and evening. Wind gusts will also increase up to 45 to 55 kts in some of the stronger rainbands this afternoon. Winds will begin diminishing and conditions will begin to improve by 02/03Z. && .SHORT TERM... (Today and tonight) Issued at 221 AM EDT Thu Sep 26 2024 Hurricane Helene remains the dominant feature for our weather through tomorrow. Helene is centered in the Southern Gulf of Mexico north of the Yucatan Peninsula. It is forecast to rapidly strengthen through today as the storm moves north to northeast with an increasing forward speed, eventually making landfall in the Florida Big Bend Region. Widespread impacts are expected across West-Central and Southwest Florida beginning early today and lasting through Friday morning. * Storm Surge - Life threatening storm surge is expected today into Friday. Potential peak surge amounts are 10 to 15 feet from Chassahowitzka to Suwannee River, 8 to 12 feet from Anclote River to Chassahowitzka, 5 to 8 feet from Middle of Longboat Key to Anclote River, 4 to 7 feet from Englewood to Middle of Longboat Key, and 3 to 5 feet from Bonita Beach to Englewood. Elevated water levels are possible through Friday. * Flooding Rain - Flooding rain threat will run from today through this weekend with rainfall amounts of 3 to 6 inches with locally higher amounts up to 10 inches possible. Even after Helene pulls away, additional rounds of heavy rainfall are expected this weekend. * Wind - Hurricane and tropical storm force winds will be possible today and tonight with the highest probabilities along the coast. * Tornadoes - Several tornadoes are possible today and tonight across the area. && .LONG TERM... (Friday through Wednesday) Issued at 221 AM EDT Thu Sep 26 2024 As Helene pulls away on Friday, the trough axis pushing it off to the northeast will drag a frontal boundary into the vicinity of central Florida. This boundary is expected to stall out across the center of the state and will linger for several days to come. In the warm sector, a breezy southwest flow will prevail with scattered to numerous storms, aided by the moisture pooling along the boundary as well as the enhanced ascent. North of the boundary, conditions will be drier, but a WSW flow will still prevail. This setup means some impacts may linger. The SW flow could make it more difficult for all the water to drain as quickly; thus higher water levels could linger well after the storm is lifting north. Additional rainfall also has the potential to existing flooding concerns. By early next week, however, the gradient looks to collapse. While a SW flow will still prevail with the surface ridge to the east, the flow will be pretty weak. However, additional moisture will still keep scattered storms in the forecast through the week. This should be more typical diurnal convection. In a WSW flow, this means convection earlier in the day for the coastal areas, and early to mid-afternoon for inland areas. By mid-week, the frontal boundary will finally get the push it needs from another trough, bringing what should be a drier and more stable airmass in for the end of the week. This should at first yield a more northerly and eventually more easterly flow late in the week. While drier, warm conditions are expected to continue. && .MARINE... Issued at 221 AM EDT Thu Sep 26 2024 Tropical Storm and Hurricane Warnings are in effect for all waters as Hurricane Helene moves northward. The hurricane will continue to move northward today, with very dangerous marine conditions continuing as it strengthens into a major hurricane. Helene will make landfall around the Big Bend region later today or tonight with elevated winds continuing into Friday before decreasing for the weekend. Waves will continue to build for the rest of the day and remain elevated through Friday before beginning to decrease. However, a persistent southwesterly flow suggests that the sea state will take longer than normal to settle. && .HYDROLOGY... Issued at 221 AM EDT Thu Sep 26 2024 As Helene lifts northward, rain bands are overspreading the area. Overnight stability continues to be a limiting factor, however, and these bands are generally falling apart. Storm total accumulations remain low in response at only an inch-and-a-half for the last 26 hours or so. Most of this rain fell earlier in the day too, not posing much of an issue in the short-term if additional rainfall occurs. Once sunrise occurs, this instability will quickly increase and more convection will overspread. Forecast rainfall totals are for 3 to 6 inches, with isolated totals up to 10 inches. Most of the heaviest rainfall is likely to occur at the coast. When combined with storm surge, this could cause significant issues in urban areas. This combination also has the potential to impact rivers running near the coast, such as the Myakka River, Alafia River, Cypress Creek, and the Withlacoochee River. However, inland rivers like the Peace River are less likely to experience significant river flooding, or even significant water level rises at all. With additional rainfall through the weekend, the threat will not quickly subside even as the storm pulls away. Eventually, some drier weather should return for the middle of next week. This will be welcome, and should help dry things out. && .PRELIMINARY POINT TEMPS/POPS... TPA 87 80 89 78 / 100 80 30 40 FMY 88 81 90 79 / 90 80 80 70 GIF 88 80 91 78 / 80 60 40 40 SRQ 88 81 90 79 / 90 80 40 50 BKV 88 77 90 74 / 100 80 30 20 SPG 88 82 90 81 / 90 80 30 40 && Sea Breeze Thunderstorm Regime For Thursday: 7 Sea Breeze Thunderstorm Regime For Friday: 5 For additional information on sea breeze regimes, go to: https://www.weather.gov/tbw/ThunderstormClimatology && .TBW WATCHES/WARNINGS/ADVISORIES... FL...Flood Watch through Friday morning for Coastal Charlotte-Coastal Citrus-Coastal Hernando-Coastal Hillsborough-Coastal Lee- Coastal Levy-Coastal Manatee-Coastal Pasco-Coastal Sarasota- DeSoto-Hardee-Highlands-Inland Charlotte-Inland Citrus- Inland Hernando-Inland Hillsborough-Inland Lee-Inland Levy- Inland Manatee-Inland Pasco-Inland Sarasota-Pinellas-Polk- Sumter. Tropical Storm Warning for Coastal Charlotte-Coastal Hillsborough-Coastal Lee-Coastal Manatee-Coastal Sarasota- DeSoto-Hardee-Highlands-Inland Charlotte-Inland Citrus- Inland Hernando-Inland Hillsborough-Inland Lee-Inland Manatee-Inland Pasco-Inland Sarasota-Pinellas-Polk-Sumter. Hurricane Watch for Coastal Hillsborough-Coastal Manatee-Coastal Sarasota-Inland Citrus-Inland Hernando-Inland Pasco- Pinellas. Storm Surge Warning for Coastal Charlotte-Coastal Citrus-Coastal Hernando-Coastal Hillsborough-Coastal Lee-Coastal Levy- Coastal Manatee-Coastal Pasco-Coastal Sarasota-Pinellas. Hurricane Warning for Coastal Citrus-Coastal Hernando-Coastal Levy-Coastal Pasco-Inland Levy. Gulf waters...Tropical Storm Warning for Charlotte Harbor and Pine Island Sound-Coastal waters from Bonita Beach to Englewood FL out 20 NM-Coastal waters from Englewood to Tarpon Springs FL out 20 NM-Tampa Bay waters-Waters from Bonita Beach to Englewood FL out 20 to 60 NM. Hurricane Watch for Coastal waters from Englewood to Tarpon Springs FL out 20 NM-Tampa Bay waters-Waters from Bonita Beach to Englewood FL out 20 to 60 NM. Hurricane Warning for Coastal waters from Tarpon Springs to Suwannee River FL out 20 NM-Waters from Englewood to Tarpon Springs FL out 20 to 60 NM-Waters from Tarpon Springs to Suwannee River FL out 20 to 60 NM. && $$ DISCUSSION/MARINE/HYDROLOGY...Flannery/Shiveley AVIATION...ADavis DECISION SUPPORT/UPPER AIR...Carlisle/Pearce