Jump to content
  • Member Statistics

    18,987
    Total Members
    49,013
    Most Online
    Damisa
    Newest Member
    Damisa
    Joined

2026 Mid-Atlantic Severe Storm General Discussion


Kmlwx
 Share

Recommended Posts

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Baltimore MD/Washington DC
213 PM EDT Thu Jul 9 2026

The National Weather Service in Sterling Virginia has issued a

* Severe Thunderstorm Warning for...
  Southwestern Carroll County in north central Maryland...
  Northwestern Howard County in central Maryland...
  Central Montgomery County in central Maryland...
  Southeastern Frederick County in north central Maryland...
  Central Loudoun County in northern Virginia...
  Northern Fairfax County in northern Virginia...

* Until 245 PM EDT.

* At 213 PM EDT, severe thunderstorms were located along a line
  extending from near Linganore-Bartonsville to near Point Of Rocks
  to 6 miles north of Poolesville to near Leesburg to Purcellville,
  moving east at 25 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damaging winds will cause some trees and large branches
           to fall. This could injure those outdoors, as well as
           damage homes and vehicles. Roadways may become blocked by
           downed trees. Localized power outages are possible.
           Unsecured light objects may become projectiles.

* Locations impacted include...
  Germantown, Rockville, Gaithersburg, Leesburg, Olney, Damascus,
  Lansdowne, Lowes Island, Poolesville, Ashburn, Montgomery Village,
  North Potomac, Redland, Countryside, Purcellville, Round Hill,
  Boyds, Green Valley, Clarksburg, and Darnestown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Large hail, damaging wind, and continuous cloud to ground lightning
are occurring with these storms. Move indoors immediately. Lightning
is one of nature`s leading killers. Remember, if you can hear
thunder, you are close enough to be struck by lightning.

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
 
Link to comment
Share on other sites

 

https://forecast.weather.gov/product.php?site=NWS&issuedby=PHI&product=AFD&format=CI&version=1&glossary=1&highlight=off

 

While probability
outlooks could still change significantly being 7 days out, early ML
& AI outlooks have currently identified a 15%-30% probability for
severe weather occurrence associated with this system. As
details on this system become more defined, will have to
continue to monitor synoptic fluctuations in model guidance to help
identify any hazards associated with this system in the coming
days.
Link to comment
Share on other sites

https://www.spc.noaa.gov/products/exper/day4-8/

... Friday/Day 7 and Beyond -- Upper Great Lakes into the
   Mid-Atlantic ...

   Strong northwest flow will be established between the previously
   described western US ridge and eastern Canadian trough. Rich
   boundary layer moisture is expected to be present to the south of a
   residual cold front that will be draped somewhere from the Great
   Lakes southeast into the Mid-Atlantic/Southern New England. Strong
   diurnal heating each afternoon will support scattered thunderstorm
   development capable of producing damaging outflows. Severe
   probabilities were introduced for Day 7 with this outlook given
   increasing confidence in thunderstorms developing within surface
   troughing east of the Appalachians. The exact location of these
   highlights will likely be refined with subsequent outlooks.

   Additionally, the overall large-scale pattern seems conducive for
   one or more shortwave troughs to move through the broader
   northwesterly flow across this region. Given the (seasonably)
   strongly unstable and sheared environment, one or more southeastward
   moving MCSs may be possible during the Day 7 - Day 10 period.
   Ensemble guidance varies significantly as to the timing and location
   of these potential short-wave troughs, but the overall pattern would
   suggest additional severe weather potential at the end of the
   forecast period and in the days that follow.

   ..Marsh.. 07/11/2026
  • Like 5
Link to comment
Share on other sites

6 hours ago, high risk said:

The rare Day 7 SPC outlook for our area!

Yes, esp. this time of year when large-scale dynamic forcing and strong low pressure areas are less, yet enough of a signal in the probs for SPC to outlook an area.

NW flow aloft can lead to some of the best tornado events due to excellent directional shear.  We have good speed shear very often, but strong directional shear is much less common. NW flow promotes lee troughing which can back the low-level winds, so you can over 90 deg turning sfc to 500 mb.

And you tend to get solid EMLs for more CAPE overall.

  • Like 2
Link to comment
Share on other sites

https://forecast.weather.gov/product.php?site=PHI&issuedby=PHI&product=AFD&format=CI&version=1&glossary=1&highlight=off

KEY MESSAGE 4...Friday could be active and unsettled with a
chance for showers and thunderstorms, some of which could be
severe.

We are still several days out but we are monitoring the severe
weather setup on Friday. The Storm Prediction Center (SPC) has
highlighted most of the area in a Slight Risk (15% chance of
severe thunderstorms 25 miles from any point). Storms look to be
driven by a strong cold front swinging in from the northwest
and with ample daytime heating and instability, the ingredients
are certainly there for strong to severe thunderstorms and
damaging wind gusts.

In their long term outlook, SPC did mention some small MCS
potential during the day 7 to 10 period as some shortwaves are
likely to ripple through the northwest flow. Again, still
several days out, but we will have to monitor the severe weather
potential for the end of the week and possibly next weekend.
Link to comment
Share on other sites

 

https://www.spc.noaa.gov/products/exper/day4-8/#

 

day6prob.gif

 

... Friday/Day 6 -- Mid-Atlantic Region ...

   This evening's deterministic guidance suite (20260712 00 UTC), along
   with yesterday morning's deterministic guidance suite (20260711 12
   UTC), is faster moving the surface boundary south than last night's
   guidance suite (20260711 00 UTC). However, the overall ensemble
   guidance continues to suggest severe potential across the region,
   owing to differences in the position of the surface boundary and the
   timing of mid-level vorticity maxima. Severe probabilities (15%)
   have been retained with this forecast in a nod to the ensemble
   guidance suite, but if the current trend of pushing the surface
   boundary farther south on Thursday (Day 5) continues, severe weather
   probabilities may need to be removed as the surface boundary will
   push south of the better deep-layer shear.

   ..Marsh.. 07/12/2026

 

Link to comment
Share on other sites

Good disco from Marsh at SPC in the day 4-8 range

Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0405 AM CDT Mon Jul 13 2026

   Valid 161200Z - 211200Z

   ...DISCUSSION...
   All ensemble guidance suites are in broad agreement that the central
   US ridge will once again build westward in response to the
   development of a eastern North America long-wave trough during the
   forecast period. However, significant differences exist within and
   between ensembles regarding the timing and exact nature of this
   transition. 

   At the start of the forecast period, a frontal boundary will be
   pushing south and west in the wake of a strong short-wave trough
   that moved across New England in the prior days. The trend over the
   past 48 hours is for this front to push farther south and west,
   bringing a continental dry airmass into New England and portions of
   the Mid-Atlantic. For example, several days ago ensemble guidance
   was in good agreement that the front would be draped across the
   Mid-Atlantic on Friday. Many, but not all, of the recent runs now
   push the front south into southern Virginia and northern North
   Carolina. This results in significant uncertainty regarding the
   potential severe weather environment on Friday (Day 5) across the
   Mid-Atlantic. For example, the GEFS mean temperature for Washington
   D.C. is 93F on Friday afternoon, while the EPS mean temperature is
   102F. However, both ensembles have dewpoint temperatures in the
   50Fs.

   Given the increasing uncertainty as to the location of the surface
   boundary on Friday and the overall quality of the severe weather
   environment, unconditional 15% severe probabilities for Friday are
   removed with this forecast. It is possible that severe probabilities
   may be reintroduced in later outlooks should it become apparent that
   the surface boundary washes out earlier than expected and quality
   low-level moisture is able to return sooner.

   That said, the front should begin to dissipate by Saturday in
   response to a mid-level trough digging southeast across the Great
   Lakes. This will allow rich boundary-layer moisture to advect
   northeastward into the Mid-Atlantic and southern New England. This
   increase in boundary-layer moisture and strong diurnal heating will
   allow for afternoon MUCAPE values between 1000-2000 J/kg, perhaps
   locally higher on Saturday and into Sunday. 

   This unstable and vertically sheared environment will be ripe for
   thunderstorm/severe thunderstorm development ahead of any digging
   mid-level trough. However, as alluded to previously, the timing,
   magnitude, and number of these troughs is highly variable within the
   ensemble guidance, leading to too little confidence to pinpoint
   where and when unconditional severe probabilities should be added.
   As confidence in the timing, track, and strength of these embedded
   troughs becomes clear, severe probabilities will likely be needed
   somewhere across the region stretching from the Upper Midwest
   southeast into the Mid-Atlantic for one or more days.

   ..Marsh.. 07/13/2026
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...