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 

[yoda]

Wow... LWX went all out with a long, detailed, and excellent afternoon discussion for tomorrow 

KEY MESSAGES...
- 1) Severe Thunderstorms are possible Wednesday afternoon and
  evening.

- 2) Well above normal temperatures through Wednesday
  afternoon.

- 3) A series of cold fronts crossing the area into early next
  week will lead to multiple temperature swings.

&&

.DISCUSSION...
KEY MESSAGE 1...Severe Thunderstorms are possible Wednesday
afternoon and evening.

Tomorrow`s forecast is an extremely challenging one. At this point,
there`s a wide range of potential solutions on the table, with very
low confidence in which solution will ultimately verify. Forecast
details follow below...

A potent northern stream trough will continue to amplify as it
tracks eastward from the Northern Plains toward the Great Lakes
during the day tomorrow. A corresponding surface low will deepen as
it tracks northeastward from Lower Michigan across the Lower Great
Lakes and into the St. Lawrence Valley. The low-level mass response
to the deepening cyclone will lead to strengthening low-mid level
winds, as a 700 mb jet of 50-70 knots develops over the Ohio Valley
tomorrow morning, and then spreads northeastward over our forecast
area by peak heating tomorrow afternoon. Southerly flow at low-
levels will draw deeper moisture (low 60s dewpoints) northward into
the area, which when combined with daytime heating (surface temps
climbing into the upper 70s and lower 80s) will lead to surface-
based destabilization (MLCAPE values around 500-1500 J/kg). Assuming
that storms occur, the environment in place with MLCAPE values of
500-1500 J/kg and effective bulk shear values of around 50 knots
(with nearly all of it below 700 mb) will be very favorable for the
development of severe thunderstorms. However, many questions remain
with respect to the coverage of storms, the storm mode, hodograph
shape, and resultant storm impacts locally.

00z/12z CAM guidance is in good agreement that there will be plenty
of ongoing convection tonight upstream in the Ohio Valley. Some of
this activity will likely impact the West Virginia Panhandle,
western Maryland, and potentially north-central Maryland tomorrow
morning. Much of this activity will likely be elevated in nature,
but some heavier downpours, lightning, and maybe even a little small
hail may be possible during the morning hours as this activity moves
through. Further south and east, conditions will likely remain dry
through the morning, with daytime heating occurring through a broken
cloud deck.

Forecast uncertainty increases moving into the afternoon hours, with
various sources of model guidance advertising a wide array of
potential solutions. On one extreme lies the 3km NAM, which fails to
produce any additional storms after the elevated activity moves
through during the morning. Inspection of 3km NAM forecast soundings
shows strong capping, which in turn inhibits the development of new
storms. A tendency toward under-mixing and overcapping is a well
known forecast bias of the 3km NAM. In this type of scenario, there
would be no severe weather threat across the bulk of the forecast
area tomorrow. A potential exception would be with any remnant
squall line moving into the Alleghenies from the Ohio Valley
tomorrow evening. On the other end of the spectrum lies the HRRR,
which produces numerous additional storms during the afternoon and
evening hours. Most of these storms actually form upstream in the
Ohio Valley during the morning and persist into the forecast area
during the mid afternoon to evening hours. Inspection of HRRR
forecast soundings shows much deeper mixing, which is unsurprising,
since overmixing/undercapping is a known bias of the HRRR. In terms
of storm mode, the HRRR solution shows both supercells and smaller
bowing segments.

Other sources of guidance lie somewhere between these scenarios. The
Hi-Res Canadian falls into the 3km NAM camp, keeping things capped
and producing no additional storms locally. The FV3 is the next
lowest in terms of storm coverage, only producing a few isolated
cells, primarily across northern Maryland and northern portions of
the West Virginia Panhandle. The RRFS also keeps activity
predominantly confined to northern WV/MD, but more in the form of an
organized squall line. The WRF-ARW develops a much larger
QLCS/squall line with embedded bowing segments out of pre-exisiting
convection that emanates out of southern WV. In that scenario, the
QLCS could would impact most of the forecast area. The WRF-NSSL is
much different that any of the above solutions, tracking a strong,
elevated QLCS across northern MD during the morning hours, which
lays out an east-west oriented outflow boundary. Then in the
afternoon, it has a string of intense, isolated supercells
developing along the differential heating boundary produced by the
outflow, which then track eastward across northern Maryland.

Beyond the differences in convective evolution/mode, there are also
significant hodograph shape differences between the models. More
overmixed models like the HRRR show close to straight hodographs,
while undermixed models like the 3km NAM show much more hodograph
curvature. The WRF-NSSL shows the greatest hodograph curvature of
all, as a result of the remnant outflow boundary.

The uncertainty with respect to convective mode and hodograph
curvature cascades into uncertainty with regard to the potential
hazards as well. The environment in place will make damaging winds
possible with any storms that form. However, that threat would
likely be maximized in scenarios that produce a more linear
convective mode, with a QLCS or smaller bowing segments. A more
cellular mode would likely lead to supercells, a greater threat for
both severe hail and tornadoes, and lesser areal coverage of
damaging winds compared to a linear mode. At the moment SPC has most
of the area outlooked in a Slight Risk, driven by damaging wind
potential. They also have a 5 percent hail contour, and 2/5 percent
tornado contours, along with a CIG 1 hatching (suggesting that a
reasonable max tornado intensity of EF-2, if a tornado were to
occur). The CIG1 hatching hints at the higher end potential of the
severe threat tomorrow. There is no CIG 1 hatching for wind
tomorrow, but hurricane force gusts (74+ mph) are needed to justify
wind hatching. It wouldn`t be a shock to see some 60-70 mph gusts in
any bowing segments, if storms do occur.

With the high level of forecast uncertainty, following observations
will be critical over the next 24 hours. The level of mid-level
capping, along with how upstream convection over the Ohio Valley
evolves will be critical factors in determining what ultimately
occurs here tomorrow.

A brief summary of the main takeaways follows below:

-Forecast uncertainty is very high tomorrow. Plausible scenarios
range from no severe thunderstorms at all, to a very impactful
severe thunderstorm event.

-Confidence in elevated storms impacting the WV Panhandle/western MD
tomorrow morning is high, but those storms likely won`t pose much of
a severe threat.

-Any storms that do form tomorrow afternoon will likely turn severe,
posing at least a threat for damaging winds, and potentially large
hail and tornadoes too (if the storm mode is supercellular).

-The timing of the most intense storms is expected to be in the
afternoon and evening hours, with the strongest storms (if they
occur at all) expected to move through the I-95 corridor between
roughly 3 and 8 PM.

-A squall line will likely approach from the Ohio Valley and
 track toward the Alleghenies tomorrow evening, but will likely
 be weakening as it does so. Any severe threat with this line
 will likely stay confined to along/west of the Allegheny Front.

 

 

[batmanbrad]

3 hours ago, TSSN+ said:

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

The latest forecast for me (Gaithersburg) STILL has no mention of severe for tomorrow, doesn't mention thunder at all!  I checked the point-and-clicks for several other cities/counties in our area... nada.  

[high risk]

1 hour ago, yoda said:

Wow... LWX went all out with a long, detailed, and excellent afternoon discussion for tomorrow 

          Yeah, that was impressive.   I agree that there is a lot of uncertainty, but there does seem to be some consensus that the best shot at storms and severe weather tomorrow is north of I-66 in VA and Route 50 in MD.   And the real threat might be another county north.    

[high risk]

2 hours ago, 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. 

         Yeah, I like the 2% hatched.    It reflects that there right now is an overall low threat of tornadoes in this area, but if we were to get one, it could be a strong one.

[high risk]

Ugh.  The evening CAMs have really backed off, and the NAM Nest never liked it from the start.   If this idea is correct, any severe threat may be confined to along I-70 and north.

[SnowenOutThere]

10 minutes ago, high risk said:

Ugh.  The evening CAMs have really backed off, and the NAM Nest never liked it from the start.   If this idea is correct, any severe threat may be confined to along I-70 and north.

And we’ve gained anafront “snow”. What a reversal 

[yoda]

3 hours ago, high risk said:

Ugh.  The evening CAMs have really backed off, and the NAM Nest never liked it from the start.   If this idea is correct, any severe threat may be confined to along I-70 and north.

SPC new Day 1 still holds for now... adds 15 hail and moves 30 wind east

 

 

[yoda]

5% tor also shifted ESE

 

[yoda]

Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1229 AM CDT Wed Mar 11 2026

   Valid 111200Z - 121200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
   MISSISSIPPI VALLEY...ACROSS THE TENNESSEE/OHIO VALLEY INTO THE
   MIDDLE ATLANTIC...

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

   ...Ohio Valley/Middle Atlantic...

   Northern-stream trough is digging east-southeast across the northern
   Rockies/High Plains early this morning and should advance into the
   upper MS Valley by 18z as a 500mb speed max translates through the
   base of the trough, then increases in intensity as it moves across
   lower MI during the afternoon. Large-scale height falls will
   overspread the Great Lakes/OH-TN Valley region as southwesterly flow
   strengthens across the downstream warm sector. Latest model guidance
   suggests the sharp cold front associated with this feature will
   extend across lower MI-central IL-northern MO at the start of the
   period. This boundary will serve as a primary focus for thunderstorm
   development through the period. By mid day, the front will have
   surged into northwest OH-central IN and modest boundary layer
   heating is expected across the warm sector downstream.

   Current thinking is modest destabilization will be noted across much
   of the OH/TN Valley such that MLCAPE values should be on the order
   of 1500 J/kg within a strongly sheared environment. Forecast
   soundings support this and supercells are expected to develop, in
   addition to possible line segments and clusters. Large hail is
   possible with supercells, along with damaging winds and a risk for a
   few tornadoes. This activity will spread east toward the Middle
   Atlantic by late afternoon.

[yoda]

In all 3 "zones" of the HWO from last night 

DAYS TWO THROUGH SEVEN...Wednesday through Monday

Multiple rounds of scattered severe thunderstorms are possible,
most likely between 2 PM and 10 PM Wednesday afternoon and evening.
Severe thunderstorms may be capable of producing damaging wind
gusts of 60 to 70 mph, a few instances of large hail, and a couple
tornadoes which could even be strong.

Monitor the latest forecast for updates and watches, and be sure
to have a way to receive warnings promptly.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed Wednesday

[Nomz]

Just barely in the spc 5# tornado risk

[yoda]

Hazardous Weather Outlook
National Weather Service Baltimore MD/Washington DC
532 AM EDT Wed Mar 11 2026

ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508-
VAZ053>057-527-120945-
Chesapeake Bay north of Pooles Island MD-
Chesapeake Bay from Pooles Island to Sandy Point MD-
Chesapeake Bay from Sandy Point to North Beach MD-
Chesapeake Bay from North Beach to Drum Point MD-
Chesapeake Bay from Drum Point MD to Smith Point VA-
Tidal Potomac from Key Bridge to Indian Head MD-
Tidal Potomac from Indian Head to Cobb Island MD-
Tidal Potomac from Cobb Island MD to Smith Point VA-
Patapsco River including Baltimore Harbor-
Chester River to Queenstown MD-Eastern Bay-
Choptank River to Cambridge MD and the Little Choptank River-
Patuxent River to Broomes Island MD-
Tangier Sound and the inland waters surrounding Bloodsworth
Island-District of Columbia-Cecil-Southern Baltimore-
Prince Georges-Anne Arundel-Charles-St. Marys-Calvert-
Central and Southeast Montgomery-Central and Southeast Howard-
Southeast Harford-Fairfax-Arlington/Falls Church/Alexandria-
Stafford-Spotsylvania-King George-
Central and Southeast Prince William/Manassas/Manassas Park-
532 AM EDT Wed Mar 11 2026

This Hazardous Weather Outlook is for the Maryland portion of the
Chesapeake Bay, Tidal Potomac River, and I-95 corridor through
central Maryland, northern Virginia, and District of Columbia.

.DAY ONE...Today and Tonight

Severe thunderstorms are possible today, most likely between 4 PM
and 9 PM. Severe thunderstorms may be capable of producing
damaging wind gusts of 60 to 70 mph, a few instances of large
hail, and a few tornadoes which could even be strong.

Monitor the latest forecast for updates and watches, and be sure
to have a way to receive warnings promptly.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Wind gusts could approach gale-force over the waters on Friday
afternoon into Friday evening, particularly closer to shore.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed this afternoon.

[yoda]

DISCUSSION...
KEY MESSAGE 1...Severe Thunderstorms are possible this afternoon
and evening.

Today`s forecast remains a very challenging one in regards to
the potential for severe thunderstorms. At this point, there`s
a wide range of potential solutions on the table, with very low
confidence in which solution will ultimately verify.

However, ahead of any thunderstorm threat, very warm
temperatures again this afternoon with temperatures in the upper
70s to lower 80s. Record high temperatures may again be in
jeopardy (see Climate section below for more information). This
is ahead of a powerful cold front, which will bring a substantial
change to the weather thereafter.

Now, shifting gears to the more pressing topic, which is today`s
severe weather threat. First, current conditions differ a bit
from the previous forecast, with no morning convection to deal
with at this time anywhere in our forecast area. Looking
upstream though, a piece of shortwave energy branching off of
the southern stream energy over the southern Plains sparked a
few showers overnight across the MS River Valley, but those
never really got going. However, there is some cloud debris from
this activity that is heading in our general direction,
currently over the OH Valley. The more potent convection has
generally followed the evolution portrayed form the 00z NAM,
keeping us clear from convection this morning, unlike some of
the global guidance. Latest runs of the HRRR are also capturing
this pretty well, so at least for now, that may be a good point
to start from. Now, looking into the future, there is still a
great deal of uncertainty with the evolution today, but the lack
of substantial convection this morning does lend me to believe
that we don`t get completely capped today, so will lean
generally in that direction with this morning`s forecast.

The primary feature at play today is a potent northern stream
trough, which will continue to amplify as it tracks eastward
from the Northern Plains toward the Great Lakes today. A
corresponding surface low will deepen as it tracks northeastward
from Lower Michigan across the Lower Great Lakes and into the
St. Lawrence Valley. The low-level mass response to the
deepening cyclone will lead to strengthening low-mid level
winds, as a 700 mb jet of 50-70 knots develops over the Ohio
Valley this morning before spreading over our area by peak
heating this afternoon. Southerly flow at low-levels will draw
deeper moisture (low 60s dewpoints) northward into the area,
which when combined with daytime heating (surface temps climbing
into the upper 70s and lower 80s) will lead to surface-based
destabilization (MLCAPE values around 500-1500 J/kg). Assuming
that storms occur, the environment in place with MLCAPE values
of 500-1500 J/kg, steep lapse rates, and effective bulk shear
values of around 50 knots (with nearly all of it below 700 mb)
will be very favorable for the development of severe storms.

Per the most recent guidance, and using the guidance with the
best current initialization, this is the current thinking for
convective evolution today. First, the showers over the OH
Valley are beginning to increase in coverage, but are generally
moving towards PA and should largely stay north of our are this
morning. Some clouds are likely to move into our area as a
result. The biggest question is, will they clear out enough to
realize the aforementioned CAPE value this afternoon? Looking at
forecast soundings, even in those that don`t really initiate
convection, leads me to believe we will, and that the storms
moving out of central WV into our region by early-mid afternoon
do have a decent chance to maintain or redevelop on our side of
the Allegheny Front. Assuming this does happen, the available
shear/instability support both multicell structures, as well as
discrete supercell structures. All hazards will be possible,
including tornadoes with any storms this afternoon. The
environment in place will make damaging winds possible with any
storms that form. However, that threat would likely be maximized
in scenarios that produce a more linear convective mode, with a
QLCS or smaller bowing segments. A more cellular mode would
likely lead to supercells, a greater threat for both severe hail
and tornadoes, and lesser areal coverage of damaging winds
compared to a linear mode. Storms spread east through the
afternoon and towards the I-95 corridor by this evening. The
eastward extent is also in question, and will likely depend on
what from convection takes.

The Storm Prediction Center maintained the SLGT risk for severe
today, but did expand their 5% tornado probability outline for
most of the area, and maintained the CIG1 hatching area
(suggesting a reasonable maximum tornado intensity of EF-2, if a
tornado were to occur). That hatched area with 5% probs is an
indication of the level of uncertainty still in the forecast,
but also the high-end nature if things do tailor towards the
worst-case scenario. They also have a 5 percent hail contour,
and a 30% wind contour (which is driving the SLGT risk
category). There is no CIG 1 hatching for wind, but hurricane
force gusts (74+ mph) are needed to justify wind hatching. It
wouldn`t be a shock to see some 60-70 mph gusts in any bowing
segments.

The main line of showers that will accompany the actual cold
front itself will largely fizzle into showers with a shift in
synoptic winds in its wake. This is because it comes through
overnight, with no instability left to work with.


A brief summary of the main takeaways follows below:

-Forecast uncertainty is very high tomorrow. Plausible scenarios
 range from no severe thunderstorms at all, to a very impactful
 severe thunderstorm event.

-Any storms that do form this afternoon will likely turn
 severe, posing at least a threat for damaging winds, and
 potentially large hail and tornadoes too (if the storm mode is
 supercellular).

-The timing of the most intense storms is expected to be in the
 afternoon and evening hours, with the strongest storms (if
 they occur at all) expected to move through the I-95 corridor
 between roughly 3 and 8 PM.

-A squall line will likely approach from the Ohio Valley and
 track toward the Alleghenies tomorrow evening, but will likely
 be weakening as it does so. Any severe threat with this line
 will likely stay confined to along/west of the Allegheny Front.