2026 Mid-Atlantic Severe Storm General Discussion

[87storms]

I missed out on the Friday storms in Frederick (was in DC/Harbor), so I'm all in.

[high risk]

2 hours ago, Nomz said:

RRFS simref eye candy. Outlier run, but it's fun to look at.

      In the 00Z suite, although they differ greatly on timing and coverage every CAM other than the NAM Nest has convection in our area at some point during Wednesday afternoon in a modestly favorable environment for severe.    I'd say that the initial Day 2 outlook will at a minimum keep us in a MRGL, and a SLGT isn't out of the question.    The only shot at severe is with the open warm sector storms, as whatever is on the front early Thursday will be weak.

[Nomz]

43 minutes ago, high risk said:

      In the 00Z suite, although they differ greatly on timing and coverage every CAM other than the NAM Nest has convection in our area at some point during Wednesday afternoon in a modestly favorable environment for severe.    I'd say that the initial Day 2 outlook will at a minimum keep us in a MRGL, and a SLGT isn't out of the question.    The only shot at severe is with the open warm sector storms, as whatever is on the front early Thursday will be weak.

I definitely think we go slight at some point. It's a bit of a balancing act with the NAM depiction vs some of the other models (thread the needle...). The NAM has a faster 700mb jet, which leads to a better EML over our area, but leaves subsidence in the exit region of the jet. The other models are much slower with the 700mb flow, so the EML is much weaker (<750 CAPE), but we are in the favorable area of the jet, so we get decent forcing for ascent and actual convection. 

[yoda]

4 hours ago, high risk said:

      In the 00Z suite, although they differ greatly on timing and coverage every CAM other than the NAM Nest has convection in our area at some point during Wednesday afternoon in a modestly favorable environment for severe.    I'd say that the initial Day 2 outlook will at a minimum keep us in a MRGL, and a SLGT isn't out of the question.    The only shot at severe is with the open warm sector storms, as whatever is on the front early Thursday will be weak.

Day 2 SLGT for all

 

[yoda]

Oh ok (morning AFD from LWX)

KEY MESSAGE 2...Severe thunderstorms are possible Wednesday
afternoon and evening as a strong cold front pushes through; a
significant drop in temperatures and gusty winds will accompany
the front Thursday.

A deep, digging, positively northern stream trough and its
associated strong cold front dive out of the Great Lakes
Wednesday. The cold front crosses the area late Wednesday
night into Thursday morning. Meanwhile, southern stream energy
will be lifting northward ahead of the boundary Wednesday
afternoon and evening. All of this creates a very complex severe
weather setup across the region. The latest update from the
Storm Prediction Center expanded the Slight Risk (level 2 out of
5) to include most of the area. However, it does come with some
caveats, which I`ll reiterate here. Primary among them is the
question of ongoing morning showers/convection, and the
potential impact that could have no destabilization during the
afternoon. As is typical, model guidance is very split on how
much instability is able to recover ahead of the pre-frontal
trough that will be the primary severe threat on the day. I do
think that seeing the latest CAM guidance in favor of 750-1250
J/kg of CAPE being able to develop has me a bit more concerned.
Assuming that we do get adequate CAPE, storms will fire along a
pre-frontal trough during the early afternoon hours across
eastern WV before moving east towards the metros during the
evening. The environment where storms may develop will be
impressive from a shear standpoint, with 40-50 kts of deep-layer
shear, and substantial amounts of Storm Relative Helicity (150+
m2/s2 0-1km, and 400+ m2/s2 in the 0-3 km layer). This is more
than favorable for supercell structures to develop, with
damaging winds, large hail, and even a tornado or two not out of
the question. Looking at the combination of shear and instability,
the STP is actually pretty impressive in model guidance. For
this reason, there is actually a CIG1 hatched area in our 2-5%
tornado probabilities across western MD and into the Potomac
Highlands. I wouldn`t even argue having with having that threat
even extended a bit further east along the MD/PA border in a
future update, but will let the 12z CAMs and machine learning
guidance come in for evaluation. Additionally, damaging winds,
large hail, and heavy rainfall will all be threats with any
storms that develop on Wednesday afternoon.

At any rate, Wednesday afternoon/evening is a day to watch
closely. Have your severe weather plans ready, in case you find
yourself needing to act on them. Continue to monitor the latest
forecasts from our office, as well as the Storm Prediction
Center, for the latest updates.

Confidence drops off significantly with the severe threat along
the immediate cold front given the projected timing late
evening into the overnight period. Even with that said, a gusty
line of showers could exist Wednesday night into Thursday as the
front pushes through. Would expect this to be more along the
lines of a gusty surge along the front (30-40 mph), followed by
increased synoptic winds shortly thereafter.

[TSSN+]

5 hours ago, yoda said:

Oh ok (morning AFD from LWX)

KEY MESSAGE 2...Severe thunderstorms are possible Wednesday
afternoon and evening as a strong cold front pushes through; a
significant drop in temperatures and gusty winds will accompany
the front Thursday.

A deep, digging, positively northern stream trough and its
associated strong cold front dive out of the Great Lakes
Wednesday. The cold front crosses the area late Wednesday
night into Thursday morning. Meanwhile, southern stream energy
will be lifting northward ahead of the boundary Wednesday
afternoon and evening. All of this creates a very complex severe
weather setup across the region. The latest update from the
Storm Prediction Center expanded the Slight Risk (level 2 out of
5) to include most of the area. However, it does come with some
caveats, which I`ll reiterate here. Primary among them is the
question of ongoing morning showers/convection, and the
potential impact that could have no destabilization during the
afternoon. As is typical, model guidance is very split on how
much instability is able to recover ahead of the pre-frontal
trough that will be the primary severe threat on the day. I do
think that seeing the latest CAM guidance in favor of 750-1250
J/kg of CAPE being able to develop has me a bit more concerned.
Assuming that we do get adequate CAPE, storms will fire along a
pre-frontal trough during the early afternoon hours across
eastern WV before moving east towards the metros during the
evening. The environment where storms may develop will be
impressive from a shear standpoint, with 40-50 kts of deep-layer
shear, and substantial amounts of Storm Relative Helicity (150+
m2/s2 0-1km, and 400+ m2/s2 in the 0-3 km layer). This is more
than favorable for supercell structures to develop, with
damaging winds, large hail, and even a tornado or two not out of
the question. Looking at the combination of shear and instability,
the STP is actually pretty impressive in model guidance. For
this reason, there is actually a CIG1 hatched area in our 2-5%
tornado probabilities across western MD and into the Potomac
Highlands. I wouldn`t even argue having with having that threat
even extended a bit further east along the MD/PA border in a
future update, but will let the 12z CAMs and machine learning
guidance come in for evaluation. Additionally, damaging winds,
large hail, and heavy rainfall will all be threats with any
storms that develop on Wednesday afternoon.

At any rate, Wednesday afternoon/evening is a day to watch
closely. Have your severe weather plans ready, in case you find
yourself needing to act on them. Continue to monitor the latest
forecasts from our office, as well as the Storm Prediction
Center, for the latest updates.

Confidence drops off significantly with the severe threat along
the immediate cold front given the projected timing late
evening into the overnight period. Even with that said, a gusty
line of showers could exist Wednesday night into Thursday as the
front pushes through. Would expect this to be more along the
lines of a gusty surge along the front (30-40 mph), followed by
increased synoptic winds shortly thereafter.

Confusing cause the point and click forecast says rain likely and doesn’t even mention thunderstorms. Haha 

[batmanbrad]

the next D2 outlook from SPC will be out in about 45 minutes.  Since the previous discussion had mentioned upgrade possibilities existed (but not at the time for our zones), wondering if they will get any more aggressive with their probabilities.

[MillvilleWx]

18 minutes ago, TSSN+ said:

Confusing cause the point and click forecast says rain likely and doesn’t even mention thunderstorms. Haha 

The overnight Met at Sterling mucked up the Wx grids as they did not include the mention of thunder anywhere in the CWA despite the AFD. That's very confusing and I'm not sure what happened there. An oversight. There is a chance of thunderstorms tomorrow, no question and should be updated with the afternoon package, if I had to guess. 

[TSSN+]

14 minutes ago, MillvilleWx said:

The overnight Met at Sterling mucked up the Wx grids as they did not include the mention of thunder anywhere in the CWA despite the AFD. That's very confusing and I'm not sure what happened there. An oversight. There is a chance of thunderstorms tomorrow, no question and should be updated with the afternoon package, if I had to guess. 

Ya for sure I’d hope it gets updated. I read the disco then seen the grids and was like huh? lol 

[yoda]

29 minutes ago, batmanbrad said:

the next D2 outlook from SPC will be out in about 45 minutes.  Since the previous discussion had mentioned upgrade possibilities existed (but not at the time for our zones), wondering if they will get any more aggressive with their probabilities.

Tor driven moderate on the day 1 1630z OTLK 

[yoda]

SLGT risk pushed further south and eastward all the way to the coast on the 1730z 

[yoda]

 

[yoda]

Oh @high risk @Kmlwx @Eskimo Joe

 

[yoda]

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1228 PM CDT Tue Mar 10 2026

   Valid 111200Z - 121200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER
   MISSISSIPPI VALLEY INTO THE UPPER OHIO VALLEY AND MID-ATLANTIC...

   ...SUMMARY...
   Isolated to scattered severe thunderstorms are expected on Wednesday
   from the ArkLaTex and Lower Mississippi Valley northeastward through
   the Ohio Valley and Mid-Atlantic.

   ...Synopsis...
   Another day of scattered severe weather is anticipated for
   Wednesday. Two upper waves - evident in early-afternoon water-vapor
   imagery over the northern Rockies and northern Mexico - will
   traverse eastward over the next 24 hours. Substantial amplification
   of the northern wave is expected as it migrates into the upper OH
   Valley through the day. Strong broad-scale ascent ahead of the wave
   and within the left-exit region of a strengthening upper jet will
   promote steady intensification of a surface cyclone as it progresses
   from the Great Lakes into southeastern Quebec by Thursday morning. 

   A broad fetch of southerly flow will support poleward moisture
   return as far north as the upper OH Valley by Wednesday afternoon. A
   trailing cold front attendant to the surface low will push
   east/southeast through the day, reaching the Mid-Atlantic and
   northern Gulf Coast by 12 UTC Thursday. Strong to severe
   thunderstorm chances will be focused along and ahead of this front
   through the day as it pushes east/southeast. 

   ...Upper OH Valley...
   A corridor of higher severe wind, and perhaps tornado, potential may
   emerge across OH into parts of WV and western PA Wednesday morning
   into the afternoon hours. Latest guidance shows reasonably good
   agreement in a swath of pre-frontal 40-50 knot flow within the
   lowest kilometer overspreading the upper OH Valley. Within this
   strong flow field, guidance also depicts a pronounced plume of
   higher theta-e values advecting northward along the western
   Appalachians. The intersection of the strong flow with subtle
   low-level warm advection will likely support a corridor of
   regionally higher buoyancy and enhanced effective SRH (on the order
   of 200-300 m2/s2) favorable for well-organized convection, including
   supercells. 

   The primary uncertainty pertains to antecedent storm coverage across
   the region during the morning hours. Residual convection from late
   Tuesday night will likely linger over the mid/upper OH Valley,
   though guidance shows some uncertainty regarding coverage and
   intensity of this activity. Sparse storm coverage should help
   maximize diurnal destabilization and will support a more robust
   severe threat. Greater coverage of morning convection will act to
   modulate the thermodynamic environment by muting the influence of
   daytime heating and the northward extent of richer moisture.
   Regardless, updraft/UH signals in CAM ensembles and recent
   calibrated guidance depict a corridor of stronger convection across
   far eastern IN into OH, WV, and southwest PA. Increased wind
   probabilities (30%) have been introduced across this corridor where
   one or more rounds of storms within a strong flow field will pose a
   threat for damaging/severe winds. Higher risk categories may be
   needed if morning storm coverage is minimal and a more potent
   thermodynamic environment emerges.

[yoda]

https://www.spc.noaa.gov/exper/conditional-intensity-information/

For those that missed it re the CIG

[Kmlwx]

9 minutes ago, yoda said:

Oh @high risk @Kmlwx @Eskimo Joe

*image snipped*

I know there's a lot of mixed thoughts about the CIG hatching - but this is probably where it is going to have a good amount of utility regardless of how confused people are. 

Bear in mind that prior to the new outlooks - this map would just be a straight 2% tornado prob for us. 

[yoda]

Just now, Kmlwx said:

I know there's a lot of mixed thoughts about the CIG hatching - but this is probably where it is going to have a good amount of utility regardless of how confused people are. 

Bear in mind that prior to the new outlooks - this map would just be a straight 2% tornado prob for us. 

True.  Interesting to note LWX in the morning AFD noted that they thought the CIG 1 would come further east due to the potential