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


Kmlwx
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Just now, high risk said:

I still don't understand how we ended up with a few modest supercells in the area.     The shear on the 00Z IAD sounding is nothing of note.    And the Howard County rotation suddenly emerged at the back edge of the complex that brought torrential rain to that corridor.     That cell was definitely not ingesting high theta-e air.

/Mid Atlantic Severe

In all honesty, if you take a look at the 0.5 degree reflectivity and velocity in the hour leading up to this event, you'll notice two or three subtle boundaries across Charles, Montgomery, Howard, and Calvert counties. Might have been enough to touch things off tonight.

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19 minutes ago, Eskimo Joe said:

//time sensitive//

Check out the left moving low topped supercell in Garrett County going clank clank into the Laurel Highlands.

https://weather.cod.edu/satrad/?parms=local-Virginia-comp_radar-24-0-100-1&checked=map&colorbar=undefined

        That's a beaut!    As I mentioned a bunch of posts back, the shear closer to the shortwave and sfc low is way stronger than what we currently have, and hat shear is going to overspread our area later tonight.    The HRRR thinks that instability will fall off too much to sustain the convection and take advantage of the shear, unless you're further north, but I wouldn't be surprised if there are several warnings in the LWX CWA after midnight.

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@Eskimo Joe @George BM @Kmlwx

From this mornings AFD... sounds tasty lol


Upper-level high pressure will build over the Tennessee Valley
and into the Great Lakes Monday through Wednesday while the
upper-level trough slides to our north and east, centering
itself over the western Atlantic. A northwest flow aloft is
expected in between these systems, and a surface boundary will
likely remain stalled out over our area during this time. Warmer
conditions are expected due to rising heights, but with the
northwest flow aloft and the boundary in place, this may trigger
some showers and thunderstorms. Details remain uncertain, but
the better chance for storms may be Tuesday and Wednesday.
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58 minutes ago, yoda said:

@Eskimo Joe @George BM @Kmlwx

From this mornings AFD... sounds tasty lol


Upper-level high pressure will build over the Tennessee Valley
and into the Great Lakes Monday through Wednesday while the
upper-level trough slides to our north and east, centering
itself over the western Atlantic. A northwest flow aloft is
expected in between these systems, and a surface boundary will
likely remain stalled out over our area during this time. Warmer
conditions are expected due to rising heights, but with the
northwest flow aloft and the boundary in place, this may trigger
some showers and thunderstorms. Details remain uncertain, but
the better chance for storms may be Tuesday and Wednesday.

Yea that's nice. This is a setup that I'm not going to kick out of bed.

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6 hours ago, Eskimo Joe said:

Yea that's nice. This is a setup that I'm not going to kick out of bed.

Seems LWX in their afternoon AFD have same idea as you lol... but they do add caveats 

 

Behind the weak frontal passage, high pressure is forecast to build
over the region as the upper ridge to the west shift eastward toward
our region. The weather for the early and middle parts of next week
has some uncertainty at this time due to the strength and position
of the ridge axis . A strong ridge is forecast to build into parts
of our region. Depending on the positioning of the ridge, shortwave
energy passing over the ridge and dropping into our region could
combine with some modest Shear/instability to produce a potential
MCS in the late Monday to Wednesday period. If the ridge shifts
overhead, the region will likely remain dry and see an enhanced
warming trend. If the ridge is further westward, the region could
remain relatively stable but if the ridge is positioned in just
right position, we could see shortwave energy pass over the ridge
and drop into our region. A combination of a southerly flow at the
surface along with a northwest flow aloft could lead to an unstable
environment and combine with the lift from the shortwave to bring an
organized MCS into our system. We will need to monitor the strength
and position of the ridge over the next few days
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1 hour ago, yoda said:

Kinda surprised to see Day 3 MRGL risk for Sunday 

Sunday has actually had one of my eyes for the past 36-48 hours. Not for anything too major but some models have been showing fairly decent deep-layer shear for the day. It's just the CAPE that looks rather modest for anything too significant att.

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7 hours ago, George BM said:

Sunday has actually had one of my eyes for the past 36-48 hours. Not for anything too major but some models have been showing fairly decent deep-layer shear for the day. It's just the CAPE that looks rather modest for anything too significant att.

12z NAM has me intrigued for Sunday evening looking at the soundings... 1500-2000 SBCAPE and MLCAPE

ETA -- in fact, decent tornado potential in them too lol... though the hodos aren't exactly large and curved... but would be enough with low LCL heights, decent SRH at both levels (150+), and decent MLCAPE in the 0-3km layer.  Supercell potential is near 80% at DCA at 00z MON with EHI around 3

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1 hour ago, yoda said:

12z NAM has me intrigued for Sunday evening looking at the soundings... 1500-2000 SBCAPE and MLCAPE

ETA -- in fact, decent tornado potential in them too lol... though the hodos aren't exactly large and curved... but would be enough with low LCL heights, decent SRH at both levels (150+), and decent MLCAPE in the 0-3km layer.  Supercell potential is near 80% at DCA at 00z MON with EHI around 3

Yeah. Some CAMs such as the 18z HRRR is starting to hint at moderate instability and deep-layer shear in place by Sunday afternoon. 

Would be nice to get some action in these parts on Sunday before our early/mid week derechos. :P

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Interesting read from the afternoon AFD from Mount Holly..

 

Unsettled weather on tap for the short term period. Surface high pressure will be over the eastern Atlantic Saturday night, and the area will be in between return flow behind the high and a warm front lifting north as low pressure tracks from the Great Lakes into eastern Canada. A mid-level trough with a strong shortwave will dig down through the Appalachians late Saturday night, and the base of the trough will cross the Mid-Atlantic and Delmarva Sunday morning. An area of showers and possible thunderstorms will develop late Saturday night and early Sunday morning with a focus on Delmarva. 12Z/10 NAM indicating between 500 and 1000 J/kg of surface-based CAPE as surface temperatures rise into the mid and upper 60s and surface dew points rise into the low to mid 60s. 0-6 km Bulk Shear will be from 35 to 40 kt. A few rumbles of thunder are possible, and cannot even rule out a couple of stronger storms with some locally heavy rain. A second round of showers and thunderstorms will develop Sunday afternoon and evening as a cold front approaches from the west. A warm and humid airmass will spread into the region Sunday behind the earlier warm front. Surface-based CAPE values will be upwards of 1000 to 1500 J/kg, MUCAPE values will be over 1500 J/kg, and 0-6 km Bulk shear will be upwards of 55 to 60 kt. PWATs will be over 1.5 inches. Bottom line is that a severe weather and possible flash flooding event is becoming likely Sunday afternoon and evening. Followed NBM guidance for PoPs and ramped up to categorical and likely for the area.

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2/5/5 on new DAY 2 OTKLK... but disco is interesting

  ...Midwest into the Ohio Valley and Mid-Atlantic...
   Neutral to rising mid-level heights are forecast over much of the
   Midwest into the OH Valley and Mid-Atlantic as an upper ridge builds
   slowly eastward, and as an upper trough lifts northward into New
   England and Quebec. There is still a considerable amount of
   uncertainty with where/if robust thunderstorms may develop Sunday
   afternoon. A surface front draped from northern IL/IN into OH/PA may
   serve as a focus for possible convective initiation. Eastern
   portions of the Midwest into the OH Valley may have a slightly
   better chance for thunderstorms, as a low-level temperature
   inversion/cap should be weaker with eastward extent across these
   regions. Moderate to strong instability will likely be in place
   along/south of the front Sunday afternoon, as rich low-level
   moisture characterized by mid/upper 60s to low/mid 70s surface
   dewpoints will be present. A belt of enhanced west-northwesterly
   mid-level flow should also be in place on the northern periphery of
   the upper ridge.

   Given the degree of deep-layer shear forecast, any thunderstorms
   that develop could become supercellular and pose an isolated threat
   for severe hail and damaging wind gusts. Although low-level flow is
   not expected to be overly strong, it may be sufficient for modest
   low-level rotation and a brief tornado or two. Have opted to expand
   the Marginal Risk across the OH Valley into the Mid-Atlantic since
   there is still large spread among model guidance with placement and
   coverage of convection Sunday afternoon/evening. If a more focused
   corridor of severe potential becomes evident, then greater severe
   probabilities would be needed given the favorable thermodynamic and
   kinematic environment. 
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22 minutes ago, Eskimo Joe said:

Tomorrow looks like one of those days where you get two rogue supercells drifting through the area and they get warned with no watch box so it catches people by surprise.

This.  I cannot count how many times this has happened to me personally.  Always have to be on your toes. ;)

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