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midatlanticweather

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    2026 Mid-Atlantic Severe Storm General Discussion

    in Mid Atlantic

    Posted

    2 minutes ago, H2O said:

    It will clear off at 12:52pm and be sunny for exactly one hour and 22 min. That will give enough time for one cell to form near Winchester to miss east coast npz and give a severe warning to leesburgtownville up to Frederick. Then a dc split will happen with one red box over laurel for broad rotation on radar 

    Well here in Purcellville we may get a warning... and have it dropped as downslope of the Blue Ridge/Mount Weather (probably some Government experiment, but keep that a secret) splits it and then reforms exactly like you said!

     

    • Like 2

    2026 Mid-Atlantic Severe Storm General Discussion

    in Mid Atlantic

    Posted 

    Severe Thunderstorm Warning  NWS Baltimore MD/Washington DC 246 PM EDT Thu Aug 6 2026

The NWS in Sterling Virginia has issued a

* Severe Thunderstorm Warning for... West central Montgomery County in central Maryland... East central Loudoun County in northern Virginia... North central Fairfax County in northern Virginia...

* Until 330 PM EDT.

* At 246 PM EDT, a severe thunderstorm was located over Oatlands, or near Broadlands, moving northeast at 15 mph.

HAZARD...60 mph wind gusts.

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... Reston, Leesburg, Broadlands, Lansdowne, Lowes Island, Brambleton, Poolesville, Ashburn, Sterling, Great Falls, Countryside, Belmont, Gleedsville, Beallsville, and Sterling Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

TIME...MOT...LOC 1846Z 241DEG 13KT 3904 7757

KJP

WIND...60 MPH - Radar indicated
HAIL...<0.75" - Radar indicated

    August 2026 Medium/ Long Range

    in Mid Atlantic

    Posted

    Been watching the models and CPC now jumping on the near to slightly below normal in the long range. Like that.. let's see how it pans out. Not of a war going on but it does seem to favor us in cooler than average after the middle of next week.

    2026 Mid-Atlantic Severe Storm General Discussion

    in Mid Atlantic

    Posted

    MD 1691 graphic

     Mesoscale Discussion 1691
   NWS Storm Prediction Center Norman OK
   1253 PM CDT Tue Jul 21 2026

   Areas affected...portions of the Mid-Atlantic

   Concerning...Severe potential...Watch likely 

   Valid 211753Z - 211930Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Multiple rounds of numerous, strong to severe
   thunderstorms will bring a risk for primarily damaging wind gusts to
   portions of the Mid-Atlantic through this evening, with a couple of
   brief tornadoes and isolated large hail also possible.

   DISCUSSION...Scattered thunderstorms have developed along the Blue
   Ridge as of 1750 UTC ahead of a mid-level shortwave trough that is
   progressing eastward across the upper Ohio Valley. Expectation is
   for this activity to spread eastward this afternoon with additional
   thunderstorms likely to progress into the region from the northwest
   this evening. Filtered heating of the downstream environment has
   resulted in temperatures warming into the upper 80s/near 90 F. With
   dewpoints in the low/mid 70s, this is supporting moderately strong
   buoyancy across the region. While effective shear of 35-45+ kts will
   favor storm organization, widespread thunderstorm development and
   cold pool consolidation are anticipated to yield a
   multicellular/outflow-dominant storm mode, with damaging to severe
   wind gusts the primary risk. A couple of brief tornadoes and
   isolated large hail will also be possible.

   Additionally, guidance suggests that air mass recovery will occur in
   the wake of these initial storms, which may allow the severe threat
   to persist into this evening as additional convection progresses
   southeastward into the region. Given this severe potential, watch
   issuance will likely be needed in the next hour or two.

   ..Chalmers/Mosier.. 07/21/2026

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

   ATTN...WFO...PHI...AKQ...LWX...RNK...

   LAT...LON   37348031 38057950 39047840 39467763 39467704 39397660
               39147596 38857550 38557536 38147544 37417580 37067629
               36927689 36917711 36747834 36737931 36818019 37078049
               37218043 37348031 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
    • Like 1

    2026 Mid-Atlantic Severe Storm General Discussion

    in Mid Atlantic

    Posted

    15 minutes ago, high risk said:

    What the heck is that random lightning strike near Damascus???image.thumb.png.a063b1c2fb806bb9d738a6e4e5aafc84.png

    Strike out of the blue (well haze today) I got one around July 4th that lit up the outside even with the sunshine. A year ago one struck behind the neighbor's house and fired the well pump. That one there is furthest one I have seen from the main cell, maybe a storm is trying to form there

    2026 Mid-Atlantic Severe Storm General Discussion

    in Mid Atlantic

    Posted

    16 minutes ago, WxUSAF said:

    Why has the NAM just looked like shit for any shower/storm day we’ve had this year from any range >6 hours??

    I asked Chat GPT - Here is what it thinks (LOL) Waste of time, but I could not resist! :D

    -------------------------
     

    I've noticed the same thing this warm season, especially across the Mid-Atlantic. The NAM (both 12 km and 3 km Nest) has had a habit of looking terrible beyond about 6–12 hours for convective days, then suddenly "finding" storms in the final few runs. A few reasons:

    1. It's heavily driven by its own physics

      • The NAM tends to overmix the boundary layer during the day.

      • That lowers dewpoints too much.

      • CAPE gets underdone and convective initiation is delayed or suppressed.

    2. Small errors explode in summertime

      • July convection in Virginia often depends on:

        • a leftover outflow boundary

        • a weak differential heating zone

        • a tiny vorticity maximum

        • terrain circulations along the Blue Ridge

      • If the model is off by 20 miles or an hour on any of those, the entire simulated radar looks different.

    3. Data assimilation doesn't capture morning boundaries well
      Once radar, satellite, surface observations, and morning soundings are ingested, the 6–12 hour forecasts improve dramatically because the model finally "knows" where the atmosphere actually is.

    4. The FV3-based CAMs have generally been outperforming it
      This year I've found:

      • RRFS

      • HRRR

      • WoFS (short range)

      • even the HRDPS at times

      have handled scattered convection better than the NAM Nest.

    5. The pattern we've been in is especially unfriendly
      We've had a lot of:

      • weak northwest flow

      • pulse convection

      • little synoptic forcing

      • abundant moisture

      That's almost the worst-case scenario for deterministic CAMs. The difference between "nothing" and "10 storms" can literally be one county's outflow boundary.

    For Loudoun County specifically

    The NAM has repeatedly shown this sequence:

    • 24–36 hr: mostly dry

    • 18 hr: isolated showers

    • 12 hr: scattered storms

    • 6 hr: widespread afternoon convection

    • Reality: the 6-hour run ends up being closest.

    For your forecasting, I'd probably trust the NAM mainly for:

    • temperature trends

    • dewpoint trends

    • low-level winds

    • large-scale forcing

    ...and lean much more on the HRRR/RRFS for actual storm placement once you're inside about 18 hours.

    The other thing I've noticed this summer is that the ECMWF AI (AIFS) has often had a better "feel" for whether the day would end up active than the NAM did 24–48 hours out. It obviously can't tell you exactly where a cell will pop, but its broader convective signal has been surprisingly consistent.

    2026 Mid-Atlantic Severe Storm General Discussion

    in Mid Atlantic

    Posted

    Slight risk Saturday. Guess it depends how much clearing we get and heating ahead of the energy and way too many unknowns. 
     

    ZCZC SPCSWODY3 ALL

    ACUS03 KWNS 160734

    SPC AC 160734

    Day 3 Convective Outlook

    NWS Storm Prediction Center Norman OK

    0234 AM CDT Thu Jul 16 2026

    Valid 181200Z - 191200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE OHIO VALLEY INTO THE MID-ATLANTIC...

    ...SUMMARY...

    Severe thunderstorms will be possible across portions of the Ohio Valley during the late afternoon and evening hours before moving southeast toward the Mid-Atlantic overnight. Additional strong-to-severe thunderstorms will be possible during the afternoon across portions of the Mid-Atlantic.

    ... Synopsis ...

    The CONUS-wide mid-level ridge centered over the north-central Plains for much of the past week will have retrograded west by Saturday and be located across the US and Canadian Rockies. Strong mid-level westerlies will persist on the ridge's northwest, north, and northeast periphery. Embedded within the westerlies, a series of short-wave troughs and smaller-scale vorticity/speed maxima will move across the Great Lakes and Northeast.

    At the start of the forecast period, the main short-wave trough will be located across central Ontario, with its associated jet streak located across the Upper Midwest. This feature will dig southeast on Saturday, ending up in the vicinity of northern New England by Sunday morning. Ahead of this main wave, the 20260716/00 UTC guidance suite shows multiple speed/vorticity maxima moving through the west-northwesterly flow, each of which will be capable of aiding the development of scattered elevated thunderstorms.

    At the surface, a weak surface low should develop Saturday morning across southern Ontario/the northern Great Lakes. This low will slowly deepen during the day as it digs southeast, reaching upstate New York by evening. Ahead of the surface low, southwesterly low-level flow will transport a very moist airmass northeast into the Lower Great lakes, with 70F surface dewpoints possible as far northeast as western New York.

    To the southwest of the surface low, a surface cold front will serve as an initiating boundary for thunderstorms during the afternoon. An unstable and strongly sheared airmass will be in place by later afternoon across Ohio northeast into western New York. As thunderstorms initiate along the front, large hail will be possible before thunderstorm outflows eventually congeal into one or more linear clusters posing a threat for damaging winds. This line of storms will push south and east during the evening and overnight with a continued threat of strong, damaging thunderstorm winds.

    Farther southeast across the Mid-Atlantic, most model guidance indicates the development of a surface trough to the east of the Appalachians during the late afternoon. To the east of this trough axis, temperatures will warm into the 90Fs, although there is some uncertainty how far north the hot boundary layer will extend. Given the presence of this surface trough and strong diurnal heating, several clusters of thunderstorms will be possible during the afternoon, especially if any of the previously discussed vorticity/speed maxima can interact with the low-level trough. Strong, damaging winds will be possible with any thunderstorm complex during the afternoon. Additional severe potential will also exist overnight as the remnants of the convection along the cold front approaches the region. Gusty thunderstorm winds will be the likely threat with these storms.

    ..Marsh.. 07/16/2026


    image.thumb.png.654e042c09ec3ab073869936175a9edc.png

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