I will not sleep well tonight because I live in the bulls eye of the developing bomb cyclone that is targeting the eastern Carolinas for severe weather tomorrow morning. I will probably check the forecast updates around 3AM to see how serious the developing situation is. Maybe I will get good news that it won’t be severe so I can get a few hours more sleep.
My hopes of a weak, low spin system have been dashed by the latest European model run which brings the surface low up the I-95 corridor tomorrow between 6AM and noon. The European model was the sole model to forecast a weaker system but it now agrees with the American GFS model and the American mesoscale models that extreme low level spin and extreme wind shear will bring exceptionally strong winds aloft down to the surface. There is a danger of severe straight line wind damage and a few strong tornadoes near and east of the surface low. It’s an exceptionally strong cold front. That’s the situation I’m in living east of I-95.
The technical description by NOAA’s SPC is, as usual, cold, dry, and understated. www.spc.noaa.gov/...
All hell is likely to break loose tomorrow morning east of I-95. Don’t let the jargon fool you. There will be an extremely intense mid level jet stream, exceptionally strong low level winds and extreme wind shear. A property called helicity, the upwards spin of air from the surface to the low and mid levels of the atmosphere, it extraordinarily high. Here's a good explanation of what a QLCS is. A QLCS is generally a bowed straight line system that causes straight line wind damage but sometimes they cause tornadoes.
Here’s what the SPC wrote at noon eastern time today about tomorrow morning.
A potent large-scale mid/upper trough will extend from the Upper Great Lakes to the central Gulf Coast Saturday morning. A 100+ kt midlevel jet will be oriented from the central Gulf Coast into the Carolinas at the beginning of the period and quickly shift offshore from the Atlantic Seaboard during the afternoon as the upper trough ejects eastward. In the lower levels, a 50+ kt southwesterly low-level jet will extend from northern FL northeast across southeast GA and into the NC/SC coastal plains and southeast VA. A surface low will be located over eastern NC with a cold front trailing to the south/southwest into southeast GA and northwest FL.
While deep-layer flow will largely be unidirectional and parallel to the eastward-advancing surface cold front, intense speed shear will result in effective shear magnitudes greater than 50+ kt. This will support an organized QLCS with embedded rotating cells possible, posing a threat for damaging wind gusts and a few tornadoes. The greatest threat will exist during the first 3-6 hours of the forecast period, with the greatest coverage of damaging wind potential expected from eastern NC/SC into far southeast VA close to the surface low. Instability will remain weak (250-500 J/kg MLCAPE) due to limited heating and poor lapse rates. Some modest low-level inhibition may temper downward transport of stronger winds somewhat, but 60+ kt within several hundred feet of the surface combined with fast-moving convection should overcome this. A moist boundary layer with surface dewpoints in the upper 60s and large, favorably-curved low-level hodographs will further support a few tornadoes.
I really, really don’t want to hear about favorably-curved low-level hodographs near me. A few strong long track tornadoes are not welcome in my neighborhood.
After the cyclone passes off of the Virginia capes low pressure will rapidly deepen and the whole eastern seaboard will be slammed by intense rain and or snow and very strong winds. In other words, it will bomb. It is forecast to develop winds of about 176km/hr — about 100mph — just offshore of Labrador, Canada. Behind the cold front temperatures will plummet possibly causing damage to crops and fruit tree buds in the southeast. This extreme front links back to the split in the polar vortex that recently took place that I discussed two weeks ago. There’s also an excellent discussion of this bomb cyclone and the polar vortex split at Severe weather Europe.
However, weather is not climate. My goal here is not just to warn people living on the east coast of bad weather but to show the link between the extreme weather and the unceasing uptake of heat by the north Atlantic ocean that’s associated with rapidly increasing levels of greenhouse gases.
The process that caused the Labrador current to head towards Ireland instead of Cape Hatteras in 2014 to 2016 is happening now. This bomb cyclone will reach minimum low pressure south of the tip of Greenland in the Labrador sea. The La Niña year of 2022 is a lot like the La Niña year of 2011 from the east coast of the U.S. to the east coast of Australia (which had severe flooding both years). The build up of ocean heat combined with the distribution of ocean heat caused by La Niña is the connection. Ocean heat levels are extreme off of both the east coasts of the U.S. and Australia. Australian scientists are researching the extreme floods, but based on studies of hurricane Harvey’s extreme rainfall we know that excessive rainfall is linked to excessive ocean heat.
Global ocean heat was the highest ever last year and the western north Atlantic was the epicenter of the extreme heat.
The build up of record, extreme heat in the upper ocean is the root cause of the increase in global severe weather but the east coast of the U.S. is where the heat build up is the most extreme. That’s leading to increasingly severe and destructive weather here.
Expect another well above average activity hurricane season this fall. I will write more on that later.