The Severe Weather threat has increased, The Storm Prediction Center has upgraded the Severe Weather Risk from areas south and west of Raleigh to Charlotte. A vigorous spring-like storm system will bring significant impacts to NC Thursday, Flash Flooding, and potentially Severe Weather. Widespread rainfall totals of 3"+ possible for a good portion of the state with 5"+ possible in the mountains. The Weather Prediction Center has issued a rare Moderate Risk for Flash Flooding for parts of the state. The Storm Prediction Center has issued a level 3/5 risk for Severe Weather. No, the world is not going to end, not everyone sees Severe Weather like snow or Hurricanes, but it is the time to stay aware and have many ways for alerts. This could be a Potentially dangerous situation for folks that don't have ways to receive warnings.
WHAT: A potentially record-breaking springtime storm system will move through the state Wednesday night into late Thursday night, the system has the potential to produce numerous impacts to the state. The system will be moving across the Gulf states Wednesday and then move north toward the state Thursday. A warm and humid air will combine with copious amounts of moisture to produce very heavy rainfall, for the Mountains, Foothills, and parts of Central NC. The Weather Prediction Center has already issued a rare Moderate Risk for Flash Flooding from Durham west. The driving force behind all of this will be a potential record-breaking low level and mid-level jet. The jet will be streaming over the state in the mid-levels at 110-130 kts with 60-75 kts in the low-level jet. I know all of this probably very confusing; just means tons of energy available.
A warm and humid airmass and an approaching Cold Front will combine to produce widespread storms, and many of these could be severe. The best combination of instability and shear will be over Charlotte to Raleigh (Central NC) North Carolina, over the "enhanced risk" by SPC where I believe the best chance to see 1 or 2 tornadoes. But strong to severe storms are possible for many Thursday and Thursday night Everyone needs to be weather aware this afternoon and tonight, and have a way of receiving warnings in case they are needed and be able to find shelter. There still remains some significant uncertainty is regarding CAPE (convective available potential energy) this important for the development of severe weather.
THREATS: The main mode of Severe Weather Thursday will be damaging winds, however, vertical shear through a deeper layer with winds up to 50-60 kt at 500 mb will support wind profiles at least marginally sufficient for mid-level updraft rotation thus a few embedded tornadoes possible in some storms, but multicellular convection will probably be the dominant mode as storms consolidate into lines and clusters. Strong to damaging wind gusts should be the primary.
HEAVY RAINFALL: While Severe Weather is also a threat, Flash Flooding is a bigger threat and impacts a significant more of the population. Folks, this is a huge deal from west of Raleigh into the mountains. Widespread Flash Flooding will be possible across areas seeing more than 4" of rain, this is Tropical Storm like rains. Training thunderstorms will bring hours and hours of rainfall, across a good portion of the state. The most torrential rain appears to be from Raleigh and points west. 3-6" possible across the Mountains and Foothills, Flash Flooding and mudslides will be possible. Along the Blue Ridge Escarpment 5-7+" of rain possible, if you live in an area that generally floods, be ready. I'm also concern about significant river flooding as well downstream. Timing the heaviest rain will be Wednesday night into Thursday night. The Weather Prediction Center has issued a rare Moderate Risk for Flash Flooding (3/4) from Durham west. This means there is a 20-50% chance of Flash Flooding within 25 miles of a point. Upslope in the southern mountains could see rainfall of 7"+ by Friday, as Flash Flood Watch has been posted for all from Raleigh west This system will transition into the already swollen rivers/lakes, likely causing river flooding across NC into the weekend. This is generally supported by both GEFS/NAEFS Ensemble River Forecasts, with flooding, especially likely along the Neuse, Haw, Cape Fear, and French Rivers through the weekend.
DAMAGING WINDS: A QLCS, which is a fancy name for a squiggly line of storms, will have the greatest threat for damaging winds and embedded Tornadoes. The QLCS will then pose a risk of widespread 40-55 mph winds, locally up to 65-75 mph, and a few mesovortices/tornadoes (embedded tornadoes).
TORNADOES: Models are showing some very high low and mid-level shear values which, could support a few Tornadoes however, most of the shear will be directional supporting damaging winds surface heating ahead of the line and the eventual strength and placement of the meso-low and attendant triple point. For now, the best Tornado values below on the map are the chances to see a Tornado in 30 miles of you. Any Tornadoes that do form will be rather weak and brief. Models have been trending the potential of discrete cells out ahead of the mainline, this will be something we will watch in later trends.
TIMING:
MOUNTAINS: Very heavy rainfall will start tonight and last through Thursday night, Flash Flooding expected with landslides possible. If you are in an area that normally floods, please be ready to move to higher ground.
FOOTHILLS: Flash Flooding likely and river flooding, the severe risk is lower but damaging winds will be the main threat.
CENTRAL (CHARLOTTE/ RALEIGH /FAYETTEVILLE) Flash Flooding and River Flooding a big concern, damming winds and a few weak tornadoes also possible.
EASTERN NC: The tornado threat is lower for, but damming winds and heavy rain possible.
COASTAL NC: Minor Coastal Flooding along the Outer Banks possible and gusty winds outside of thunderstorms. The line of storms should start to weaken as it approaches the coast, but gusty winds are possible.
WHAT TO DO: Don't freak out I got you covered! Please stay tuned for updates as things and will change, 24/7 updates throughout the storms will occur on North Carolina's Weather Authority. I am closely monitoring the situation, make sure you have many ways to receive severe weather alerts on Friday. It is imperative that you keep checking for updates tomorrow. Questions please message on the Facebook page not on the website!
CALL TO ACTION: People must have a way of hearing warnings, and that way should never, ever be a siren. Their purpose is only to reach a limited number of people outdoors. Every North Carolina home and business must have a NOAA Weather radio, properly programmed and with a fresh battery backup. Be sure WEA (Wireless Emergency Alerts) are enabled on your phone (check notification settings)... even with no good weather app installed you will receive a tornado warning with a loud audible alert.
If you live in a manufactured home, you have to GET OUT if a tornado warning is issued. Have a shelter identified, or other place identified that is open when you are at risk. Know how to get there quickly.