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George BM

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

    in Mid Atlantic

    Posted

    My two amateur cents about this 'event':

    To @high risks point the HRRR was doing a very bad job with the handling and even initialization of the Chicago-Ohio MCS.

    @Kmlwx with great similar points about it.

    By mid-evening it was apparent that the HRRR was significantly underdoing the Chicago-Ohio MCS which would, obviously, in turn result in a less organized MCS following it from northern MI (the one the HRRR kept keying on to hit our region).

    Something else that I'll like to point out that I noticed were the storms that formed early in the afternoon yesterday in Indiana. No, not the one that brought a 98mph wind gust to Fort Wayne, IN, but the storms that grew upscale into an MCS that moved ESE through WV and into the central Appalachians by midnight (same activity that got @wxdude64 some late evening action). What that MCS created was a region of limited/no instability, especially in WV. In the time-sensitive loop below you can see how the MCS that hit Chicago and Fort Wayne splits into two separate convective line segments as it hits this 'used up' atmosphere with the SW segment going SSE through western WV and into far southwestern VA and the NE segment moving east into northern/central MD and southern PA.

    https://weather.cod.edu/satrad/?parms=regional-eastcoast-comp_radar-200-1-25-1&checked=map&colorbar=undefined

    The Cincinnati to WV MCS also left an MCV which may have tugged the OH MCV a little further south further limiting the impressive NW mid-level winds over us and shifting it southwest although I admittedly know far to little about this to say this is occurred for sure. 

    In my opinion these things are what left most of VA without any real convection this morning. Of course, there are probably other more subtle features that affected things but those are the main ones I caught with my limited knowledge compared to actual meteorologists. :) 

    • Like 3

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

    in Mid Atlantic

    Posted

    8 minutes ago, high risk said:

    I do love how the Day 2 Outlook discussed a "weakened carcass of an MCS".        That said, there is still a lot of uncertainty about how and where this MCS will evolve overnight.    I'm still not overly worried at this time about widespread wind potential into the metro areas, given the poor timing and lack of instability, but these systems can certainly surprise if they develop a sufficiently strong cold pool.

    Yeap. I remember the June 3, 2020 derecho to our north producing hurricane-force wind gusts despite only weak to modest CAPE available and early time of day owing to the MCSs cold pool/ rear-inflow jet. Granted there were a couple hours of solar heating before the storms got to New Jersey where the most extreme damage occurred. But it was still solidly before peak heating with relatively modest LLLRs.

    Not that I expect that here, of course. ;) Just pointing that out.

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

    in Mid Atlantic

    Posted

    Day 2 SLGT

    2/15/15

    Exerpt for MidAtl...

    ...  

    At this time, one area of potentially greater storm coverage -- and
   thus severe potential, given the favorably strong wind field
   forecast atop the region -- will be along and east of the higher
   terrain of the central Appalachians.  Storms should develop by early
   afternoon, and spread east-southeastward with time. 
   Organized/rotating updrafts should evolve, given the available
   shear, with these stronger storms capable of producing large hail
   and damaging winds.  Risk may continue well into the evening across
   portions of the area, as one of the more pronounced disturbances
   aloft shifts southeastward out of the Midwest and across the
   mountains during the evening/overnight.

     

     

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

    in Mid Atlantic

    Posted

    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

    • Like 3

    June Discobs 2022

    in Mid Atlantic

    Posted

    6 minutes ago, kgottwald said:

    Didn't a cold front supposedly pass with the pre-dawn thunderstorms? The DC area still has SW winds and DPs in the upper sixties.

    The storms outran the cold front to an extent. The wind shift and following lower dewpts seem to be located near I-81 atm.

    • Like 1

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

    in Mid Atlantic

    Posted

    2 hours ago, Kmlwx said:

    12z GFS continues to look intriguing around the June 15th timeframe. 

    Afternoon of June 15th on this run has 5000+ SBCAPE, nearly 4000 MLCAPE (over 4000 to the NW of the metro areas). Ripe supercell composite maps as well. Really impressive considering it's the GFS and not the NAM. Again, it's a eternity away at that timeframe...but it keeps the general potential on the table. 

    Pulling a model forecast sounding from near the M/D line in northern Maryland yields this on the College of Dupage site - 

    SFC CAPE = 5425
    ML CAPE = 4554
    SFC LI = -12

    Sfc to 1km shear = 18kts
    Sfc to 3km shear = 32kts

    Sfc to 1km SRH = 116

    Supercell Composite = 26.0
    STP (cin) = 4.2
    STP (fix) = 3.6

    PWATS over 2 inches. 

    I really hope we get a pattern similar to what's being advertised by the GFS. Obvious uber-long range caveat aside, that would easily be a MOD risk worthy day from the MidAtl up into the Northeast verbatim. 

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

    in Mid Atlantic

    Posted

    2 minutes ago, Kmlwx said:

    So my best friend CIPS isn't particularly exciting for anything both in the standard and extended range. 

    HOWEVER, I'd be lying if I said i wasn't kind of excited for the day 10-15 period. GFS/Euro and their ensembles have some form of a big ridge to our west setting up. The exact position and "tilt" of this ride varies (of course...this far out it's to be expected). But almost all of them put us on the eastern side of a sprawling ridge...could be good for NW flow events if the stars align. Not saying the D-word this far out - but we might start to see some big time analogs on CIPS if the general looks keeps up. The 6z GFS has a high parameter day or two around the 270ish hour mark (usually GFS is pretty conservative on supercell composite paramter). 

    This is from the 0z GEFS - I'd take this as a severe weenie

    image.thumb.png.b997c5c4f65e94fe6317062e9de12483.png

    And here's the Euro Ensembles

    image.thumb.png.7a98d3b3bc9e545157ac3b67fa0d5ddb.png

     

    So you can see the ridge axis and position varies - but on that EC ENS run it kind of wiggles around a bit before and after this frame. 

    Central US ridges and NW flow over the Mid-Atlantic in June = a happy weenie

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

    A happy SEVERE weenie people! Calm down. 

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

    in Mid Atlantic

    Posted

    30 minutes ago, yoda said:

    Probably won't see hail sizes this large again in a watchbox for our region unless we get some huge EML lol 

    URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 551
   NWS STORM PREDICTION CENTER NORMAN OK
   120 PM EDT MON JUN 16 2008
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          SOUTHWESTERN CONNECTICUT
          DISTRICT OF COLUMBIA
          DELAWARE
          MARYLAND
          NEW JERSEY
          SOUTHEAST NEW YORK
          PARTS OF SOUTHERN AND EASTERN PENNSYLVANIA
          MUCH OF NORTHERN AND CENTRAL VIRGINIA
          PARTS OF EASTERN WEST VIRGINIA
          COASTAL WATERS
   
   EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 120 PM UNTIL 900
   PM EDT.
   
   HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80
   MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

    Where did you retrieve this?... As I cannot seem to retrieve it from SPCs Severe Watches archive ATM. 

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

    in Mid Atlantic

    Posted

    1 hour ago, CAPE said:

    Need to watch this shortwave digging S and E under that closed upper low over eastern Canada Wed into Thursday. For now, as depicted it's probably a bit too far north for our area.

    gfs_z500_vort_us_22.png

     

     

    I'll definitely become a little more intrigued for the Wed/Thurs shortwave if timing can change a bit. It's probably easier to root for a slightly faster system (late Wed) rather than a slower system (Thurs) as of now as slowing it down by 18 hours may be a bit of a tall order compared to speeding it up by 6 hours. Either trend would maximize daytime heating as you probably know. :)

    June Banter 2022

    in Mid Atlantic

    Posted

    Weenifying Thursday!

    Forecast Discussion

    Thursday, June 2, 2022 2:50PM EDT

     

    Temps have continued into the lower/mid 90s with dewpts into the lower/mid 70s. This combined with moderately steep MLLRs (6.5-7.5C/km) is yielding MLCAPE of 2500-4000J/kg. Swift flow between 600-400mb of 40-50kts will lead to effective bulk-shear of similar magnitudes leading to a mix of supercells and bowing line segments. With at least moderate low-level shear in place (ESRH 100-150m2/s2) a tornado or two cannot be ruled out, especially with any LEWPS that may develop. Otherwise, with large DCAPE in place (1000-1500J/kg), swaths of widespread damaging winds w/ a few significant gusts potentially up to 80mph will be commonplace, particularly with any bowing segments. Large to possibly very large hail will be a threat, particularly with any supercells that form.

    Tornado: 5%

    Wind: 45%(hatched)

    Hail: 15%

    Severe Thunderstorm Watch in effect for Northern/central VA, most of MD, Delaware, southern PA, southern NJ and the District of Columbia until 10PM EDT Thursday, June 2, 2022.

    Hazards:

                    Widespread damaging winds w/ a few significant gusts to 80 mph likely.

                    Scattered large hail likely w/ isolated very large hail to 2” diameter possible.

                    A tornado or two possible.

    Watch Probs:

                   TOR: 20%/10%

                   WIND: 90%/70%

                   HAIL: 60%/40%

     

    "Forecaster": George BM

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