Life-threatening conditions expected**** · 2019. 5. 30. · seas . Surf zone and adjacent Atlantic...

Weather Forecast Office Presentation Created 9/11/2018 5:39 PM Wilmington, NC Follow us on Twitter Follow us on Facebook

Major Hurricane Florence ****Life-threatening conditions expected****

Decision Support Briefing # 10 As of: 530 PM Tuesday Sept 11, 2018

Prepared by: Steven Pfaff, WCM

What has changed? Hurricane Warning now in effect Storm Surge Warning now in effect Rainfall amounts have increased significantly across parts of the area Included Hurricane Threat Impact Graphics information

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Situational Overview

Life-threatening storm surge is likely along portions of the coast. A Storm Surge Warning is in effect.

Increase the pace of preparations for the potential of a land-falling major hurricane. Follow any advice given by local officials.

Damaging hurricane force winds are likely along portions of the coast as well. Strong winds could also spread well inland. A Hurricane Warning is now in effect.

The potential for life-threatening flooding impacts continues to increase, especially across a large swath of NC since the storm is expected to slow down as it approaches the coast and moves inland. A Flash Flood Watch will likely be required.






Main Points

Hazard Impacts Location Timing

Wind Extreme wind impacts are possible in some areas

northeast SC and southeast NC

Thursday afternoon into Friday

Storm Surge/ Inundation

Extreme storm surge impacts are likely in some areas

All coastal areas and tidally connected

creeks, rivers, bays, and waterways

Thursday into Friday

Flooding Rain Extreme Flooding Rain impacts are possible in many areas, especially

across NC

northeast SC, and especially southeast

NC Thursday into Sunday

Tornado A few tornadoes are possible southeast NC Thursday into Friday

Marine Extreme maritime and surf

conditions along with rip currents, large breakers, and very large/steep

seas

Surf zone and adjacent Atlantic

waters Through Saturday






Potential Impacts Wind: Limited Confidence – track dependent

Surge/Inundation: Limited Confidence – track dependent

Tornado: Limited Confidence – track dependent

Marine: Confident – regardless of track

Inland Flooding: Limited Confidence – track dependent

None Elevated Moderate High Extreme










Storm Surge Warning Area

- Surge estimated based on latest track - The water has the potential to reach the

following heights above ground level if peak surge occurs at the time of high tide

Note: This low resolution image is used to show general areas as to where the Watch is in effect. Please use the NHC Storm Surge Inundation Map on their website for inundation details.






Hurricane Florence Storm Surge Threat In Extreme Surge threat areas we need to prepare for the possibility of devastating impacts such as: • Inundation affecting homes near tidal

creeks and waterways farther inland than what people are accustomed to

• Surge combined with battering waves causing severe damage to many structures along the barrier islands

• A large amount of sand deposition onto barrier islands and blocked roadways

• The formation of new inlets • Wash-outs or severely flooded coastal

roads • Extreme beach erosion with significant

loss of dunes • Damage to marinas, docks, and piers • Aids to navigation may be off station or

missing, making navigation after the storm hazardous

• Delivery of drinking water and sewer services may be lost in coastal communities






Hurricane Florence Wind Threat

In Extreme Wind threat areas we need to prepare for the possibility of devastating impacts such as: • Structural damage to builds and complete

destruction of mobile homes • Widespread tree damage and downed

power lines • Debris and power lines down on roadways

creating impassable conditions • Widespread and long duration power

outages • Major communications disruptions or

complete loss • Vessels breaking free from moorings






Most Likely Arrival Time of Tropical Storm Force Winds

Most likely TS arrival times for the southeast NC coast will be during Thu morning, and early Thu afternoon for the northeast SC coast based on the latest track

Tropical storm force winds would spread farther inland during the day Thursday afternoon and Thursday night






Excessive Rainfall Outlook and Possible Rainfall Impacts

In Extreme flood threat areas we need to prepare for the possibility of devastating impacts such as: • Extreme flooding that may prompt

additional numerous evacuations, or result in numerous rescues

• Rapid rises in rivers and streams that overflow their banks in many places with deep moving water

• Flood waters entering structures, and cutting off people or communities with roads becoming flooded or damaged

• Road scours or complete road failure along with the potential for sinkholes

• Low-lying bridge closures with some weakened or washed away

• Hazardous materials or polluted in any flood waters






Hurricane Florence Potential Rainfall Amounts

Since the track is slower and the storm will reside over the area longer predicted rainfall amounts have become extreme.

15-20+ rainfall amounts are now forecast in the axis of heaviest rain

Life-threatening flooding expected






Hurricane Florence Tornado Threat

There is an elevated potential for tornadoes, especially from portions of southeast NC, to eastern NC and southeast VA Thursday through Friday morning.






Latest Information: Hurricane Florence OVERVIEW:

Florence is a dangerous major hurricane and could further strengthen

The storm is expected to turn toward a NW direction and track toward the coast tonight through Friday

The storm’s forward speed is expected to slow down considerably Friday through Sunday

NHC Advisory #50: 5 PM Tuesday Sept 11, 2018

Max Winds: 140 MPH (strong Cat. 4)

Location: 785 mi. ESE of Cape Fear

Movement: West-Northwest at 17 MPH

Pressure: 945 MB (27.91 inches)

Hurricane Florence – GOES East Band 02 527 PM Tuesday Sept 11, 2018

Florence

● Cape Fear






Official NHC Track Information and Hurricane Watch

Based on the latest track the bulk of wind and surge impacts are expected Thursday afternoon and persist through Friday.

115 MPH (Cat 3) 45 MPH (TS)

Life-threatening surge, wind, and rain impacts are likely

Florence will increase in size and have far reaching impacts, regardless of where the storm comes ashore

140 MPH (Cat 4)

A much slower track Friday and Saturday will enhance the flooding rain threat across a large area






Key Points

Continue to prepare for a potential land-falling major hurricane.

Stay informed and listen for instructions from local officials.

Please visit the following websites for information about protective actions:

https://www.weather.gov/safety/hurricane-plan or

https://www.ready.gov/hurricanes

Given the very slow motion of the storm as it approaches the coast and moves inland will create a long period of severe impacts.

This is a life-threatening situation from storm surge, to dangerous winds and extreme flooding





https://www.weather.gov/safety/hurricane-plan

https://www.ready.gov/hurricanes


Contact and Next Briefing Information

Disclaimer: The information contained within this briefing is time-sensitive, do not use after 4 AM Wed Sept. 12, 2018

Briefing Webpage: http://weather.gov/ilm/briefing

Web: http://weather.gov/ilm

E-mail: [email protected]

Facebook: NWSWilmingtonNC

Twitter: @NWSWilmingtonNC

Next Briefing When: By 730 AM on Wed Sept. 12, 2018





http://weather.gov/ilm/briefing

http://www.weather.gov/ilm/

mailto:[email protected]

http://www.facebook.com/NWSWilmingtonNC


Life-threatening conditions expected**** · 2019. 5. 30. · seas . Surf zone and adjacent Atlantic...

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