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2022 Mid-Atlantic Severe Wx Thread (General Discussion Etc)


Kmlwx
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Mid February is usually when the early peeks at severe can sometimes start showing up. Judging by the models and the long range thread, looks like maybe a marginal threat for Thur night? 

General severe discussion, remembering past events, and all that usual stuff that goes in here each year can go in here again. Hopefully we get some good thunderstorms this spring and summer. Looking forward to plenty of copy and pasting from @yoda, downer posts from @Eskimo Joe, great analysis by @high risk, and plenty of sun obs that turn into nothing. 

Giddy up! 

And for humor sake - see below

 

58b726d83a08c_WxWatcherPredictionSystem.jpg.c523087658b1c2c3925b48f876fe5c63.jpg

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1 hour ago, Eskimo Joe said:

La Nina, so maybe we get a decent round or two this spring. Looking at our region's climatology, we're due for a derecho and a non-tropical tornado outbreak in these parts.

Some of the CFS and CanSIPS stuff seem to have a bit of a ring of fire style pattern possible in the warm season. 

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For Thursday into Friday time period for possible strong to severe from morning LWX AFD. .. yikes at the 100 kts 

A continued southerly advection of warm and moist air will lead to
PWs increasing up into the 1.35 to 1.50 range which is 3 to 4
standard deviations above normal. The frontal passage will be driven
by a strong upper level trough that will approach from the plains
states. Models aren`t agreeing on the strength and positioning of
this trough but all models agree that a strong wind field will be in
place with the frontal passage. Models are forecasting 60 knots in
the 850 to 925 layer with some models having close to 100 knots
aloft. Increasing temperatures and moisture will likely lead to some
marginal CAPE values up to 200 to 300 j/kg. Considering that shear
values will likely be well above 60 to 70 knots with this frontal
passage, even a few hundreds of CAPE could lead to a strong to
severe thunderstorm threat. I believe the biggest hazard for our
region Thursday into Friday will be flooding as this system will
have a lot of moisture associated with it along with increasingly
neutral to nearly negatively tilted trough. This suggests that the
frontal zone will intensify over our region leading to an
enhancement in precipitation production. Somewhere in our region has
the potential to see banding precip amounts above 2 inches but there
remains a lot of uncertainty at this time. I could also see the
threat for wind advisory level winds but there remains a lot of
uncertainty at this time range. High temps as the front pass through
the region will likely warm up into the 60s once again with
potential for a strong background wind field. The impacts from this
system should be focused in the Thursday to Friday period.
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Afternoon AFD from LWX... yikes 

LONG TERM /WEDNESDAY THROUGH SUNDAY/...
High pressure is expected to build into the region behind the
previous system and then move offshore. WAA thanks to southerly
flow from the offshore high pressure will continue warming up
temperatures with highs reaching the upper-50s to mid-60s for
most of the area by Thursday. Dry conditions are expected
Wednesday, with guidance showing precip moving into most of the
area by Thursday afternoon. Deterministic and ensemble guidance
is trending slower this cycle, but continue to suggest the
potential for heavy rain for our area as well as the threat for
severe with a strong wind field (850mb winds in excess of 80kt)
and possibly marginal CAPE. The Euro ensemble seems the most
aggressive regarding precip, bringing a large swath of >3 sigma
PWATS to the CWA. The Canadian ensemble is slightly less so,
while the GEFS is the least aggressive. We will continue to
monitor the flood and severe threat as the system into focus.
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As shown...the timing sucks in terms of the diurnal cycle on the 6z GFS. But timing I feel is less important in these cool season events since we can still advect in warm temps even at night. It's going to be a marginal CAPE environment no matter how you look at it (even during the day). GFS still gets 850mb winds into the 70-80kt range for a time Thur PM into Fri. 

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I peek at Mt. Holly's disco alongside LWX's once or twice a week....but they're not hepped up about this timeframe (yet).

.LONG TERM /THURSDAY THROUGH SUNDAY/...
The week will end with poor conditions as the next weather
system moves towards the area. An upper trough will swing across
the Great Lakes and down the St. Lawrence Valley. An
accompanying cold front will cross the area Fri morning. Ahead
of the system a period of rains and gusty winds will develop. On
Friday, temperatures will fall back closer to normal and the
rains/snows will end from W to E through Fri night. At this
time, it looks to be a mostly rain event with perhaps some minor
shows Fri night as the system pulls away. Gusty winds Thu and
Thu night could gust 30 to 40 mph at times. The gusty winds will
continue behind the front Fri as temperature cool thru the day.
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23 minutes ago, SnowenOutThere said:

With these types of severe setups the main concerns are wind and some spin-ups, assuming this is the main threat for Thursday as well.

My two (non-expert) cents:

        For Thursday night/early Friday the main threat would be gusty winds from a thin line of heavy rain along the cold front. As it looks right now, the trough seems too positively tilted for anything too significant especially given the (at most) maybe 200J/kg CAPE. It's the strong winds aloft with these off season systems which the heavy rains can bring down to the surface. The cold front and the flow don't look too far from parallel though (cold front orientated from 7:30-1:30 w/ mean flow from 8-2), less than 30 degrees. This limits the wind potential with convection.

        With the February 7th, 2020 event that brought 50-60+mph wind gusts and tornadoes especially in northern MD, the trough was negatively tilted with the mean flow and the cold front more perpendicular (line of low-topped storms extending from NNW to SSE w/ mean flow from the SW). That combined with a strong sub-980mb low moving along the Blue Ridge mountains helped back surface winds to the southeast creating high low-level shear which lead to lots of bowing segments along that line with tornadoes forming along the kinks of said line. 

        An event like that is probably the only way to get more widespread severe in these parts this time of the year (not that you or anyone here implied there could be widespread severe later this week. :)).

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17 minutes ago, George BM said:

My two (non-expert) cents:

        For Thursday night/early Friday the main threat would be gusty winds from a thin line of heavy rain along the cold front. As it looks right now, the trough seems too positively tilted for anything too significant especially given the (at most) maybe 200J/kg CAPE. It's the strong winds aloft with these off season systems which the heavy rains can bring down to the surface. The cold front and the flow don't look too far from parallel though (cold front orientated from 7:30-1:30 w/ mean flow from 8-2), less than 30 degrees. This limits the wind potential with convection.

        With the February 7th, 2020 event that brought 50-60+mph wind gusts and tornadoes especially in northern MD, the trough was negatively tilted with the mean flow and the cold front more perpendicular (line of low-topped storms extending from NNW to SSE w/ mean flow from the SW). That combined with a strong sub-980mb low moving along the Blue Ridge mountains helped back surface winds to the southeast creating high low-level shear which lead to lots of bowing segments along that line with tornadoes forming along the kinks of said line. 

        An event like that is probably the only way to get more widespread severe in these parts this time of the year (not that you or anyone here implied there could be widespread severe later this week. :)).

00z Euro / GFS still pushing this idea. Euro sounding for just after 7pm in Carroll County.

download.thumb.png.853bef39240bfb21424209dd7e627523.png

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:lol: the 6z NAM has 80-90kt winds at 850mb overnight Thur into Fri. Imagine having something like that in the warm season with beefy CAPE. It even places a little pocket of 1-2 supercell compositive paramter in the area - but at 12z Fri AM. Timing sucks. 

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38 minutes ago, Kmlwx said:

:lol: the 6z NAM has 80-90kt winds at 850mb overnight Thur into Fri. Imagine having something like that in the warm season with beefy CAPE. It even places a little pocket of 1-2 supercell compositive paramter in the area - but at 12z Fri AM. Timing sucks. 

Just give me big wind.

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The American models seem to be a bit more gung-ho on the wind threat. But really it's only a difference of 5-10mph. American models would (except the long range HRRR) get us close to High Wind Warning criteria at least in isolated spots. But seems like Wind Advisory criteria is a good bet for a pretty wide swath of the area. There were some 60mph pockets of gusts on the GFS and NAM - but most guidance seems to be in the 45-50mph range. 

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4 minutes ago, Kmlwx said:

The American models seem to be a bit more gung-ho on the wind threat. But really it's only a difference of 5-10mph. American models would (except the long range HRRR) get us close to High Wind Warning criteria at least in isolated spots. But seems like Wind Advisory criteria is a good bet for a pretty wide swath of the area. There were some 60mph pockets of gusts on the GFS and NAM - but most guidance seems to be in the 45-50mph range. 

Are you talking about the winds with the pre-frontal gradient tomorrow night/pre-dawn Friday or are you talking about the winds w/ the post-frontal surge?

Or is the answer to this question just, "Yes".

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2 minutes ago, George BM said:

Are you talking about the winds with the pre-frontal gradient tomorrow night/pre-dawn Friday or are you talking about the winds w/ the post-frontal surge?

Or is the answer to this question just, "Yes".

I was looking mainly at the 3z to 6z period on Thur night-Fri AM. 

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10 minutes ago, Kmlwx said:

I was looking mainly at the 3z to 6z period on Thur night-Fri AM. 

I too have been watching this period. hrrr_2022021612_fh42_sounding_38.99N_77_39W.thumb.png.7d0d5bd9994227c2ac4c46df0e74e048.png

 

On the 12z HRRR that's 75+ kt winds at 1km over a good part of the region with the 60kt wind barb at 925mb (2,500ft). Notice how the lapse rates in the lowest km of the atmosphere is, while certainly not "peak daytime-heating" steep, it is a little bit steeper. Now I'm certainly not expecting 75kt wind gusts! :lol: But if even some of that mixes down there could certainly be some "that roar woke me up" type gusts. I'll not be surprised at all to see High Wind Watches for, at least the mountains, issued at some point today. If we can stay cloudy tomorrow night w/o any rain showers to cool the near-surface atmosphere ahead of the front, then that would maximize the wind potential.

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7 minutes ago, dailylurker said:

Good to see you back. You have to be the #1 severe weather enthusiasts on this board. Very knowledgeable as well. I depend on and appreciate what you add to this board.

Aw shucks - I'm not THAT smart with this stuff. Most of my strength is anecdotal past stuff. I defer to the red taggers mostly, though. I'm closer to @yoda's copy and pasting than I am to the @high risk analysis. 

As much as I like snow - and hate 85+ degree weather, I do prefer spring/summer on the forums to winter. Much more of a cordial environment. Seems us severe weenies are way more able to accept that we just don't go big on severe very often versus the winter weenies who are seemingly "entitled to" all winter storms ;) 

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On 2/16/2022 at 11:17 AM, Kmlwx said:

Aw shucks - I'm not THAT smart with this stuff. Most of my strength is anecdotal past stuff. I defer to the red taggers mostly, though. I'm closer to @yoda's copy and pasting than I am to the @high risk analysis. 

As much as I like snow - and hate 85+ degree weather, I do prefer spring/summer on the forums to winter. Much more of a cordial environment. Seems us severe weenies are way more able to accept that we just don't go big on severe very often versus the winter weenies who are seemingly "entitled to" all winter storms ;) 

       So nice to see this thread!     Cheers to a great 2022 severe season!     That said, I'm not very excited about later tonight.     Temperatures should stay up overnight, but we need every degree we can get, and having the threat in the afternoon would have helped.     The shear is awesome, but the lapse rates suck, and there just isn't much chance of getting even a few hundred joules of cape.      There will be convective enhancement of the rain early Friday, but it seems like the SVR threat is really, really low.      

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