2020 Mid-Atlantic Severe Weather - General Thread

[high risk]

1 hour ago, Newman said:

Updated Day 2 outlook, 15% wind, 15% hail (new to this outlook), 2% tornado.

        The outlook is pretty legit, but as Amped noted above, the timing now definitely favors those west of the a line from Fredericksburg to Frederick.       I'm not really seeing the tornado potential in the forecasted wind profiles, but there is definitely enough deep layer shear (accompanying the modest instability) for SVR.

[yoda]

This afternoons LWX severe threat disco for tomorrow... mentions cap for i95 corridor till evening... also mentions supercells possible 

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
A potent mid-upper level trough will approach the area during
the day tomorrow. Low clouds will be in place to start the day
to the east of the Blue Ridge, with a mix of sun and clouds to
the west of the Blue Ridge. The clouds to the east of the Blue
Ridge will gradually burn off through the morning, with ample
heating occurring across the area. Temperatures are expected to
climb well into the 80s across the entire area. The combination
of warm temperatures, dewpoints around 70, and height falls
aloft in association with the mid-upper level trough will result
in 1500-2500 J/kg of MLCAPE by late afternoon. As flow
increases aloft ahead of the mid-level trough, ample shear will
also be in place, with 0-6 km shear values of 30-50 knots. As a
result, strong to severe thunderstorms are expected to develop
tomorrow afternoon. The storms are initially expected to form
across western MD and the WV panhandle and gradually progress to
the east. Model soundings indicate capping between 800 and 900
mb through much of the day along the I-95 corridor, so storms
aren`t expected to make it into the metro areas until very late
afternoon or evening. Overall, the greatest severe threat
appears to be across western portions of the forecast area,
where winds will be strongest aloft. Both multicell clusters and
supercells appear possible given the parameter space in place.
In terms of hazards, damaging winds will be the greatest threat,
with hail also possible in any supercells that form. The low-
level wind field will be on the weaker side until evening, so
the tornado threat is expected to be low, but non-zero. Current
thinking is that storms should be rather progressive, so the
flood threat should be minimized. However, it`s worth noting
that consecutive runs of the HREF have highlighted the
potential for heavy rainfall across portions of western
MD/eastern WV panhandle, so that potential will need to be
monitored as well.

[yoda]

00z HRRR has some morning activity between 09z and 11z coming up from the south into DC metro... nothing severe... but might make for quite a soupy airmass in the morning as the sun appears... waiting for the rest of the run to see what happens in the afternoon around here

ETA:  Nothing really through 23z so far... kinda surprised tbh

[yoda]

This looks fun

  

Just now, frd said:

Next week has some interest.

 

 

 

 

[yoda]

2/15/15 on the new Day 1 OTLK

[yoda]

From the SPC 4-8 day OTLK disco:

   Into Day 6/Wednesday and Day 7/Thursday, a more favorable pattern
   for MCS development may materialize across parts of the Midwest/Ohio
   Valley to central Appalachians and Mid-Atlantic States as an
   increasingly moist/unstable air mass will reside along and south of
   a roughly west/east-oriented front across these regions. The
   north-central High Plains may also be a continued regional focus for
   at least isolated severe thunderstorms.

[Kmlwx]

For next Wednesday PM. Not too shabby from the GFS at this range. 

[George BM]

For todays risk look out for how much high level cloud cover we get from the storms currently developing in the Carolinas. 

[LP08]

[high risk]

Still unsure whether storms will make it into the DC metro area.    There is a better signal for storms moving northeast through northern MD, but anything in DC metro may be an iffy late evening show.    It's reflected in last night's HREF members showing 40 dbz which show a clear minimum of members showing storms for DC and points east between 4 and 8pm.   (Yes, the 6z NAM came in with a better solution, as shown in the previous post).

[Eskimo Joe]

46 minutes ago, high risk said:

Still unsure whether storms will make it into the DC metro area.    There is a better signal for storms moving northeast through northern MD, but anything in DC metro may be an iffy late evening show.    It's reflected in last night's HREF members showing 40 dbz which show a clear minimum of members showing storms for DC and points east between 4 and 8pm.   (Yes, the 6z NAM came in with a better solution, as shown in the previous post).

 

Hey that's a neato tool.  Where can a poster find that on SPC's site?

[high risk]

10 minutes ago, Eskimo Joe said:

Hey that's a neato tool.  Where can a poster find that on SPC's site?

https://www.spc.ncep.noaa.gov/exper/href/      (under forecast tools)

and if you want information on the upcoming HREFv3 upgrade:    https://www.emc.ncep.noaa.gov/users/meg/hrefv3/

 

[MN Transplant]

18 minutes ago, Eskimo Joe said:

Hey that's a neato tool.  Where can a poster find that on SPC's site?

Forecast Tools > HREF > Storm Attributes has an assortment of these.

[osfan24]

Latest 3K is a lot less impressive than the 6z was.

[Eskimo Joe]

2 minutes ago, osfan24 said:

Latest 3K is a lot less impressive than the 6z was.

Today looks really unimpressive.

[canderson]

12 minutes ago, osfan24 said:

Latest 3K is a lot less impressive than the 6z was.

Mind sharing how it looks for PA (I'm in Harrisburg)? On a work virtual machine and can't access hardly anything. 

[osfan24]

5 minutes ago, canderson said:

Mind sharing how it looks for PA (I'm in Harrisburg)? On a work virtual machine and can't access hardly anything. 

Looks ok in Southern PA. Harrisburg might be a bit too far north verbatim, but you are close enough that you could see action.

[yoda]

Severe tstorm watch coming soon for C VA into C PA

[high risk]

54 minutes ago, osfan24 said:

Looks ok in Southern PA. Harrisburg might be a bit too far north verbatim, but you are close enough that you could see action.

        I'd say overall that southern PA has a slightly higher threat for SVR than the DC area, with a clear CAM consensus for a batch of storms to develop by mid afternoon over far eastern WV and northwest MD and track northeast towards the York and Harrisburg area.

[yoda]

https://www.spc.noaa.gov/products/md/md0758.html

 

 

   Mesoscale Discussion 0758
   NWS Storm Prediction Center Norman OK
   1127 AM CDT Fri May 29 2020

   Areas affected...Northern Mid Atlantic Coast region

   Concerning...Severe potential...Severe Thunderstorm Watch likely 

   Valid 291627Z - 291730Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms may develop across the Poconos and Catskills
   vicinity as early as the next hour or or so, with a more general
   increase and intensification of thunderstorm during the 3-5 PM EDT
   time frame.  With strongest storms expected to pose at least a risk
   for severe wind and hail, one or more severe weather watches seems
   probable.

   DISCUSSION...Insolation within a seasonably moist boundary layer
   (surface dew points around/above 70F) is contributing to moderately
   large CAPE on the order of 1000-2000+ J/kg, within deepening surface
   troughing to the lee of the Appalachians.  Mid-level flow remains
   broadly anticyclonic, however deepening convective development is
   underway aided by orography, particularly across the Poconos into
   Catskills vicinity.  

   As a short wave trough accelerates northeast of the middle Ohio
   Valley/central Appalachians region, mid-level flow appears likely to
   trend increasingly cyclonic across northern Virginia through eastern
   New York state.  This should contribute to an environment
   increasingly conducive to thunderstorm initiation and
   intensification.  A coinciding strengthening of southwesterly
   mid-level flow (30-50 kt around 500 mb), will provide sufficient
   shear for organizing lines and clusters of storms, with isolated
   discrete supercells also possible.  At least some of this activity
   will pose a risk for large hail, potentially damaging wind gusts,
   and perhaps a tornado or two.

   ..Kerr/Grams.. 05/29/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...OKX...ALY...PHI...BGM...AKQ...CTP...LWX..

[Kmlwx]

Take a look at mid-level lapse rates at hour 264 on the 12z GFS. If only that weren't an eternity away. 

[osfan24]

HRRR is basically a whiff here. Looks like the best shot is west of Philly.

[Eskimo Joe]

Looks like a cap or something between 800 - 900 mb...stuff tries to get up and then just collapses.

[poolz1]

Looking West from Jefferson Maryland.

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[high risk]

Blue box issued.   Montgomery and Howard are in the far southeastern corner, consistent with the idea that this first show will mainly be a fair distance northwest of the I-95 corridor.

[Eskimo Joe]

Just now, high risk said:

Blue box issued.   Montgomery and Howard are in the far southeastern corner, consistent with the idea that this first show will mainly be a fair distance northwest of the I-95 corridor.

Baltimore Metro left out. Kinda weird orientation of the WCN.

[mappy]

toasty out there today. loving the radar to my west. 

[MDphotog]

Fredrick area has a Svr Warning till 3:45PM for that storm.

[WxUSAF]

Not loving the radar for the 95 corridor right now

[mappy]

Watch expanded along the MD line