ISAIAS BRIEFLY A TROPICAL STORM, EXPECTED TO REGAIN HURRICANE STRENGTH AS IT APPROACHES FLORIDA. PALM BEACH COUNTY NOW LIKELY A SUNDAY MORNING EVENT.
BOCA RATON, FL (BocaNewsNow.com) — Isaias — now briefly a Tropical Storm — is still heading for Florida. A Palm Beach County encounter remains almost certain as it regains hurricane strength. Now, New York is in the forecast advisory as well. Here’s the 5 p.m. advisory from the National Hurricane Center:
BULLETIN Tropical Storm Isaias Advisory Number 19 NWS National Hurricane Center Miami FL AL092020 500 PM EDT Sat Aug 01 2020 ...ISAIAS WEAKENS TO A TROPICAL STORM... ...EXPECTED TO RE-STRENGTHEN TO A HURRICANE OVERNIGHT WHILE IT APPROACHES THE SOUTHEAST COAST OF FLORIDA... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...25.1N 78.7W ABOUT 115 MI...185 KM SE OF FORT LAUDERDALE FLORIDA ABOUT 95 MI...155 KM S OF FREEPORT GRAND BAHAMA ISLAND MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...993 MB...29.33 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Tropical Storm Watch has been extended northward from Altamaha Sound Georgia to South Santee River South Carolina. The Hurricane Watch from Hallandale Beach to south of Boca Raton Florida has been discontinued. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Hurricane Warning is in effect for... * Boca Raton to the Volusia/Flagler County Line Florida * Northwestern Bahamas A Storm Surge Watch is in effect for... * Jupiter Inlet to Ponte Vedra Beach Florida A Tropical Storm Warning is in effect for... * North of Ocean Reef to south of Boca Raton Florida * Lake Okeechobee * Volusia/Flagler County Line to Ponte Vedra Beach Florida A Tropical Storm Watch is in effect for... * North of Ponte Vedra Beach Florida to South Santee River South Carolina Interests elsewhere along the southeast and mid-Atlantic coasts of the United States should monitor the progress of Isaias. Additional watches or warnings may be required tonight or Sunday. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. Preparations to protect life and property should be rushed to completion. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 500 PM EDT (2100 UTC), the center of Tropical Storm Isaias was located by an Air Force Reserve reconnaissance aircraft near latitude 25.1 North, longitude 78.7 West. Isaias is moving toward the northwest near 10 mph (17 km/h). A general northwestward motion with some decrease in forward speed is expected for the next day or so, followed by a north-northwestward motion by late Sunday and a turn toward the north and north- northeast on Monday and Tuesday with an increase in forward speed. On the forecast track, the center of Isaias will approach the southeast coast of Florida tonight and move near or along the east coast of Florida Sunday and Sunday night. On Monday and Tuesday, the center of Isaias will move quickly from offshore of the coast of Georgia into the southern mid-Atlantic states. Maximum sustained winds have decreased to near 70 mph (110 km/h) with higher gusts. Some restrengthening is forecast, and Isaias is expected to regain hurricane strength tonight. Slow weakening is expected to begin Sunday night and continue through Monday. Tropical-storm-force winds extend outward up to 105 miles (165 km) from the center. During hew past couple of hours, a Weatherflow observing site at the Dania Pier in Broward County, Florida, reported a wind gust to 59 mph (94 km/h) in an outer rainband. More recently, a wind gust to 41 mph (67 km/h) was reported by a Weatherflow site in Juno Beach, Florida. The estimated minimum central pressure based on reconnaissance aircraft data is 993 mb (29.33 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Isaias can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC, and on the web at www.hurricanes.gov/text/MIATCDAT4.shtml. STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Jupiter Inlet to Ponte Vedra Beach FL...2-4 ft North Miami Beach to Jupiter Inlet FL...1-3 ft The deepest water will occur along the immediate coast near and to the right of the center, where the surge will be accompanied by large waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office. A dangerous storm surge will raise water levels by as much as 3 to 5 feet above normal tide levels in areas of onshore winds in the Northwestern Bahamas. WIND: Hurricane and tropical storm conditions will continue to spread over portions of the Northwestern Bahamas tonight. Hurricane conditions are expected to reach the coast within the hurricane warning area in Florida on Sunday and will spread northward through Sunday night. Winds are expected to first reach tropical storm strength later tonight, making outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. Tropical storm conditions are expected within the tropical storm warning area in South Florida tonight. Tropical storm conditions are expected in the warning area in northeast Florida by Sunday night, and are possible in the watch area from northeast Florida to South Carolina on Monday. RAINFALL: Isaias is expected to produce the following rain accumulations: Bahamas: 4 to 8 inches, with isolated maximum totals of 12 inches. Cuba: 1 to 2 inches, with isolated maximum totals of 4 inches. Eastern Florida: 2 to 4 inches, with isolated maximum totals of 6 inches. Northeast Florida and coastal Georgia: 1 to 3 inches. Carolinas and the mid Atlantic, including the southern and central Appalachians: 2 to 5 inches, with isolated maximum totals of 7 inches. Southeast New York and much of New England: 2 to 4 inches, with isolated maximum totals of 6 inches. Heavy rainfall from Isaias could result in potentially life- threatening flash flooding in the Bahamas and flash and urban flooding along the East Coast of the United States. Minor river flooding and isolated moderate river flooding is possible across portions of the Carolinas and Virginia. SURF: Swells generated by Isaias are affecting portions of Hispaniola, eastern Cuba, the Turks and Caicos, and the Bahamas. These swells will spread along the east coast of Florida and the southeastern United States coast through Sunday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
We are also publishing the “forecast discussion” provided by the National Hurricane Center at 5 p.m.
Tropical Storm Isaias Discussion Number 19 NWS National Hurricane Center Miami FL AL092020 500 PM EDT Sat Aug 01 2020 The last data received from a previous Air Force Reserve reconnaissance aircraft, along with recent satellite and radar imagery, indicate that Isaias has weakened to a tropical storm due to a combination of shear, dry air and interaction with Andros Island earlier today. The initial intensity of 60 kt is based on SFMR surface wind speeds of near 60 kt in the northeastern quadrant on the last flight. A new reconnaissance mission into the cyclone is currently ongoing and will provide new data concerning the Isaias' intensity. The initial motion estimate is 315/09 kt. After making a slight west-northwestward jog a few hours ago after convection significantly weakened, Isaias appears to have returned to its base northwestward course. The new NHC model guidance is tightly packed but has shifted slightly westward, with some of the more reliable models now showing landfall along the east-central Florida coast in about 24 hours. Earlier NOAA G-IV jet dropsonde data and 12Z upper-air data reveal that the surface to 700 mb ridge extending east-west across central and northern Florida remains intact whereas the 500-300 mb ridge has completely eroded. The result is that lower level ridge will cause Isaias to slow its forward motion to northwestward at 6-8 kt during the next 36 hours. By 48 hours, the erosion of the ridge due to an approaching shortwave trough will allow the cyclone to move northward, followed by a gradual increase in forward speed toward the northeast on days 3-5. The new NHC track forecast was nudged slightly closer to the Florida east-central coast through 24 hours, with no significant changes made to the previous forecast after 36 hours. A combination of Isaias moving over the warm Gulfstream waters during the convective maximum period and increasing frictional convergence due to land interaction with Florida should lead to an increase in deep convection near and over the center, as shown by simulated satellite imagery from the ECMWF model. As a result, Isaias is forecast to regain hurricane status tonight, as shown by the HWRF and HMON model fields. By 36 hours and beyond, the global models are in good agreement that an approaching mid- to upper-level trough will increase southwesterly vertical wind shear, which should result in gradual weakening until Isais becomes an extratropical cyclone in about 96 hours. The new NHC intensity forecast is closest to the HMON in 12 hours and closely follows the IVCN and HCCA consensus models after 36 hours. Key Messages: 1. Hurricane conditions and dangerous storm surge will continue in portions of the northwest Bahamas tonight. 2. Hurricane conditions are expected along portions of the Florida east coast on Sunday with tropical storm conditions expected to begin tonight. Preparations to protect life and property should be rushed to completion. 3. Dangerous storm surge is possible along the Florida east coast from Jupiter Inlet to Ponte Vedra Beach where water rises of 2 to 4 feet above ground level are possible along the immediate coastline and adjacent waterways. Residents there should follow advice given by local emergency officials. 4. Isaias will produce heavy rains and potentially life-threatening flash flooding in the Bahamas, and flash and urban flooding, especially in low-lying and poorly drained areas, along the East Coast of the United States. Minor river flooding and isolated moderate river flooding is possible across portions of the Carolinas and Virginia early next week. 5. Tropical storm watches and warnings are in effect for portions of the United States East Coast from northeast Florida to South Carolina. Additional watches and warnings will likely be issued tonight and Sunday as Isaias is expected to move northward near or over the southeast and mid-Atlantic coasts early next week. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 25.1N 78.7W 60 KT 70 MPH 12H 02/0600Z 26.1N 79.4W 65 KT 75 MPH 24H 02/1800Z 27.4N 80.1W 65 KT 75 MPH 36H 03/0600Z 28.8N 80.7W 60 KT 70 MPH 48H 03/1800Z 30.7N 80.6W 55 KT 65 MPH 60H 04/0600Z 33.4N 79.1W 50 KT 60 MPH 72H 04/1800Z 37.4N 76.3W 45 KT 50 MPH...INLAND 96H 05/1800Z 45.4N 68.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 06/1800Z 50.7N 57.9W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart
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