Current Details from the National Hurricane Center (NHC)

Transcription

1 Current Watches and Warnings A Hurricane Warning is in effect from South Santee River, South Carolina (SC) to Duck, North Carolina (NC); Albemarle and Pamlico Sounds A Hurricane Watch is in effect from Edisto Beach, SC to South Santee River, SC; north of Duck, NC to the North Carolina/Virginia border A Watch is in effect from north of the North Carolina/Virginia border to Cape Charles Light, Virginia; Chesapeake Bay south of New Point Comfort A Surge Warning is in effect from South Santee River, SC to Duck, NC; Albemarle and Pamlico Sounds, including the Neuse and Pamlico Rivers A Surge Watch is in effect from Edisto Beach, SC to South Santee River, SC; north of Duck, NC to the North Carolina/Virginia border Current Details from the National Hurricane Center (NHC) COORDINATES: 27.5 north, 67.1 west LOCATION: 785 miles (1,260 kilometers) east-southeast of Cape Fear, North Carolina MOVEMENT: west-northwest at 17 mph (28 kph) WINDS: 140 mph (220 kph) with gusts to 165 mph (270 kph) RADIUS OF TROPICAL STORM-FORCE WINDS: 175 miles (280 kilometers) RADIUS OF HURRICANE-FORCE WINDS: 60 miles (95 kilometers) MINIMUM CENTRAL PRESSURE: 945 millibars SAFFIR-SIMPSON SCALE RANKING*: Category 4 24-HOUR LANDFALL POTENTIAL: NONE Risk. Reinsurance. Human Resources.

2 Latest Satellite Picture Source: NASA/NOAA Discussion Hurricane Florence, located approximately 785 miles (1,260 kilometers) east-southeast of Cape Fear, North Carolina, is currently tracking west-northwest at 17 mph (28 kph). Satellite data indicates that Florence completed a full eyewall replacement cycle earlier today, and recent visible and infrared imagery suggests that the eye has contracted slightly. Cloud outflow continues to expand in all quadrants, and the outflow jets to the northwest and east have become better defined. This suggests better organization of the system. Satellite intensity estimates have all increased this afternoon. This is unsurprising due to the eye having mostly cleared of cloud cover and has warmed. Due to these factors, the NHC has set an initial intensity at 140 mph (220 kph), and this could be conservative. This keeps Florence as a Category 4 storm. Also, the wind field has continued to expand in all quadrants. There remains no significant adjustment to the previous track forecast or reasoning. Overall, the forecast models have done a good job capturing the evolving flow pattern across the continental United States, with an amplifying frontal boundary moving onshore the U.S. Northwest coast, which is inducing the development of a ridge of high pressure across the U.S. Northeast and the Northwest Atlantic Ocean. Water vapor imagery indicates that the blocking high pressure northwest of Bermuda is continuing to build and shift slowly eastward. Cat Alert: Hurricane Florence 2

3 Several models have made changes in output, including the GFS (U.S. model) which has significantly shifted to the west, while the UKMET made a shift to the east. The ECMWF (Euro) track has remained basically unchanged through 72 hours. As a result, the consensus models have made only minor track shifts to the west. However, what is increasingly important to note is that nearly all of the models now show a collapse of steering currents in three days. This will be in tandem with Florence approaching the U.S. coast. The weak steering currents are expected to continue through the weekend, which makes the forecast track on days 3-5 quite uncertain. Such a stalled pattern would increase the likelihood of substantial rainfall totals in some parts of the Carolinas. The latest NHC forecast track is very similar to the previous two advisory tracks and lies the middle of the guidance envelope. During the next 24 hours, Florence is expected to remain in a very favorable environment consisting of low wind shear, an expanding upper-level outflow pattern, and above-average sea surface temperatures. This should lead to additional strengthening. By 48 hours, the decreasing forward speed along with the large inner-core wind field should induce some upwelling and gradual weakening. Although some of the more dependable intensity guidance is indicating stronger southwesterly wind shear, this could be due to the models capturing Florence's own strong outflow. Despite the NHC showing weakening at 72 hours, Florence is still expected to remain a dangerous hurricane through landfall. After Florence moves inland, the slow forward speed should cause a rapid weakening of the hurricane's circulation. The new NHC intensity forecast is a little above the highest guidance based on the aforementioned very favorable synoptic outflow pattern, and to maintain continuity with the previous forecast. Key Messages from the National Hurricane Center 1. A life-threatening storm surge is now highly likely along portions of the coastlines of South Carolina and North Carolina, and a Surge Warning is in effect for a portion of this area. All interests from South Carolina into the mid-atlantic region should ensure they have their hurricane plan in place and follow any advice given by local officials. 2. Life-threatening, catastrophic flash flooding and significant river flooding is likely over portions of the Carolinas and Mid-Atlantic States from late this week into early next week, as Florence is expected to slow down as it approaches the coast and moves inland. 3. Damaging hurricane-force winds are likely along portions of the coasts of South Carolina and North Carolina, and a Hurricane Warning has been issued for a part of this area. Damaging winds could also spread well inland into portions of the Carolinas and Virginia. 4. Large swells affecting Bermuda and portions of the U.S. East Coast will continue this week, resulting in life-threatening surf and rip currents. Cat Alert: Hurricane Florence 3

4 Additional Information 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 has the potential to reach the following heights above ground if peak surge occurs at the time of high tide: Cape Fear to Cape Lookout, including the Neuse and Pamlico Rivers: 9-13 feet North Myrtle Beach to Cape Fear: 6-9 feet Cape Lookout to Ocracoke Inlet: 6-9 ft South Santee River to North Myrtle Beach: 4-6 feet Ocracoke Inlet to North Carolina/Virginia Border: 4-6 feet Edisto Beach to South Santee River: 2-4 feet The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. RAINFALL: Florence is expected to produce total rainfall accumulations of 15 to 25 inches with isolated maximum amounts of 35 inches near the storm's track over portions of the Carolinas and Mid-Atlantic States from late this week into early next week. This rainfall would produce catastrophic flash flooding and significant river flooding. WIND: Hurricane conditions are expected to reach the coast within the Hurricane Warning area on Friday. Winds are expected to first reach tropical storm strength on Thursday, making outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. SURF: Swells generated by Florence are affecting Bermuda and portions of the U.S. East Coast. These swells are likely to cause life-threatening surf and rip current conditions. Cat Alert: Hurricane Florence 4

5 National Hurricane Center (NHC) Forecast Cat Alert: Hurricane Florence 5

6 Most Likely Arrival Time of -Force Winds Cat Alert: Hurricane Florence 6

7 National Hurricane Center: Wind Speed Probabilities -Force Wind Probabilities ( 40 mph (65 kph)) Cat Alert: Hurricane Florence 7

8 Wind Probabilities ( 60 mph (95 kph)) Cat Alert: Hurricane Florence 8

9 Hurricane-Force Wind Probabilities ( 75 mph (120 kph)) Cat Alert: Hurricane Florence 9

10 NHC: Surge Inundation Cat Alert: Hurricane Florence 10

11 NHC: Surge Watches/Warnings Cat Alert: Hurricane Florence 11

12 Weather Prediction Center: Rainfall Potential Cat Alert: Hurricane Florence 12

13 Weather Prediction Center: Flash Flood Potential Cat Alert: Hurricane Florence 13

14 Current Spaghetti Model Output Data Source: NHC Additional Information and Update Schedule Wind intensity forecasts and forecast track information can be found via the National Hurricane Center at NEXT CAT ALERT: Wednesday morning after 10:00 AM Central Time (15:00 UTC). Cat Alert: Hurricane Florence 14

15 * Intensity Classifications for Global Basins WIND SPEED KTS 1 MPH 1 KPH NE Pacific, Atlantic National Hurricane Center (NHC) Depressio n NW Pacific Joint Typhoon Warning Center (JTWC) Depressio n BASINS AND MONITORING BUREAU NW Pacific Japan Meteorological Agency (JMA) Depression SW Pacific Fiji Meteorologica l Service (FMS) Depression Australi a Bureau Of Meteorology (BOM) Low SW Indian Meteo-France (MF) Depressio n North Indian India Meteorologica l Department (IMD) Deep Depression Cat. 1 Cat. 2 Cat. 1 Cat. 2 Moderate Cyclonic Cyclonic Cat. 1 Hurricane Cat. 3 Cat Cat. 2 Hurricane Cat. 3 Major Hurricane Typhoon Typhoon Cat. 4 Cat. 4 Intense Very Cyclonic Cat. 4 Major Hurricane Cat. 5 Major >140 >160 >260 Hurricane Super Typhoon Cat. 5 Cat. 5 Very Intense Super Cyclonic Cat Alert: Hurricane Florence 15

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