November Banter 2024

[Jebman]

I am canceling it in New York in November as well. This damned snow band is dead on arrival. 

[Jebman]

On 11/1/2024 at 8:01 PM, George BM said:

Here we go ... Yet another one of George's weenie fantasies. 

 

12:52PM EST Wednesday, December 25, 2024

High Wind Warning in effect from 12PM EST Wednesday, December 25, 2024 until 3AM EST Thursday, December 26, 2024.

PDS Tornado Watch in effect until 6PM EST Wednesday, December 25, 2024.

Discussion:

We are about to experience the true limits of what nature can offer in the region.

A life-threatening tornado and severe weather outbreak will impact the region this afternoon as well as dangerous synoptic hurricane force wind gusts behind the cold front from late afternoon into the evening. A very potent and compact shortwave trough is racing eastwards out of the Ohio/Tennessee Valleys and into the Mid-Atlantic region this afternoon and is taking on a negative tilt as it does so. The cold front associated with it will blast through the entire region from west to east between 2pm and 5pm local time at around 65-70kts.

As the potent, compact shortwave approaches from the WSW an extraordinarily strong low-level jet ahead of the associated front is bringing in record shattering warmth and unseasonably high humidity from the south. Another thing that it is bringing with it are damaging southeasterly winds. With a tight surface pressure gradient along with the ample sunshine steepening low-level lapse-rates to above 7C/km some of the winds aloft will mix down to the surface resulting in gusts of around 55 to 65mph. With the sunshine in place, temps have already risen into the upper 70s to near 80F and will top out into the 80-82F range in most places before the cold front and associated storms arrive. Dewpoints have risen into the mid/upper 60s and will remain in the upper 60sF ahead of the front. A plume of steep mid-level lapse rates along with a shallow warm-layer aloft have advected into the region from Mexico. The steep environmental lapse rates, which will only get steeper as mid-level temps cool (down to -15C to -16C at 500mb), along with the record warm and moist low levels will allow MLCAPE to rise to 2000-3000J/kg which is just absurd for this time of year. A line of severe thunderstorms will move in along the cold front and several supercells are expected to form immediately ahead of the main line (mostly within 30-40 miles of the line). Mid-level southwesterly winds will increase to 120-140+kts as the potent and compact shortwave races over the region. The area will get under a region of strong lift as the left-exit region of a mid/upper-level jet streak moves overhead. Effective bulk shear will exceed 100kts and with the steep MLLRs and associated cool mid-level temps overhead, Lifted-Index values will drop to near -10. As a result, supercell updrafts will be strong enough to overcome the excessive shear allowing for extremely potent supercells.

Tornado threat:

All the above combined with excessive low-level shear (effective SRH of 500-800m2/s2) and large low-level CAPE will allow for very favorable conditions for several long-track and violent tornadoes with supercells. These tornadoes will be moving to the northeast at incredible speeds of up to and over 80 mph. Do not wait to be able to hear or see the tornado to take shelter as you will run out of time. Several QLCS tornadoes are likely with the main line as well, especially within bowing segments. With the very fast forward motion of the line, embedded circulations will have very fast winds on their southeast sides leading to EF2+ damage being likely with them, similar to what happened in the Great Plains on December 15, 2021.

Wind threat:

The wind threat will be widespread and destructive, particularly with bowing segments that develop in the main line of storms. With downdraft CAPE in excess of 1300J/kg and unusually moist Pwats of near 1.5” along with the strong instability in general, microbursts/macrobursts could occur allowing for swaths of extensive to extreme wind damage with gusts well over 100mph possible.

Hail threat:

The hail threat will also be extraordinary for the region. With the steep MLLRs allowing for large CAPE through the hail-growth zone along with the impressive mid-level shear, hail in excess of 4” in diameter could occur with supercells. The cool air aloft and dynamics will allow for severe hail (1-2” in diameter) even within the line.

Rainfall:

Most places will quickly receive between 0.5 and 1 inch of rain. Localized spots that get hit by both supercells and the line could get up to 1.5”+ of rain. The very fast storm motions will prevent higher totals.

Now comes what happens behind this cold front. As the front moves through there will be a strong pressure surge (rise in surface air pressure). With cold air advection allowing for more efficient mixing and an 80+ kt low-level wind overhead, winds will gust up to 80mph or so worsening the damage that will have already been done by the thunderstorms. During this time temperatures will rapidly fall into the lower 40s through the early evening hours. Thereafter, winds will weaken a bit. But that’s relative as they will still be gusting upwards of 50 to 60mph through around midnight and will still be gusting up to around 40 mph by dawn Thursday. Thursday morning it will be blustery with temps bottoming out in the lower 30s giving the airports a decent chance at the first freeze since December 9th. Windchills will bottom out in the mid/upper teens. This will mark the start of a colder pattern for the foreseeable future with increasing chances of measurable snow by the weekend with a shortwave moving northeast from the deep south and additional snow chances next week and into the new year.

- GBM

GBM I wanna see you write about a gigantic snowstorm hitting DCA for Dec 1 please!

 

[BuffaloWeather]

On 11/28/2024 at 8:10 PM, Jebman said:

Was about to say BuffaloWeather, you already know this but you probably need to head south from BUF to see heaviest LES. Map is illustrative (Captain Obvious). If it was me I'd head for Dunkirk or Watertown, because I can't chase but if I did I would be GREEDY for the MOSTEST snows!

I am gonna look for Watertown live feeds, those guys will get November Buried!

Here's a good Watertown live cam 

 

We got slammed Jeb! 31" in a day. Got this thundersnow on cam!

 

 

[Jebman]

10 hours ago, BuffaloWeather said:

We got slammed Jeb! 31" in a day. Got this thundersnow on cam!

 

 

CONGRATS on all your snow!