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Mesoscale Discussion 1649 NWS Storm Prediction Center Norman OK 0356 PM CDT Thu Jul 20 2023 Areas affected...Parts of western NY...western PA...and far eastern OH Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 202056Z - 202230Z Probability of Watch Issuance...95 percent SUMMARY...The risk of severe winds will increase in the next few hours as an organized MCS overspreads the area from the west. A watch issuance is likely for parts of the area in the next hour or so. DISCUSSION...Recent radar data from KDTX depicts a well-organized bowing MCS tracking eastward at around 40 kt in Ontario -- where a recent 63-kt gust was measured. Ahead of the MCS, antecedent diurnal heating of a relatively moist air mass (generally lower/middle 60s dewpoints) has contributed to weak/moderate surface-based instability -- with the greater instability confined to western PA and eastern OH (see 20Z observed PIT and 19Z BUF soundings). 40-50 kt midlevel winds should support continued convective organization as it crosses Lake Erie and approaches western NY, eastern OH, and western PA -- with a risk of severe winds during the next few hours. While there is some uncertainty on how intense the northern portion of the line will be given less instability farther north, the well-established cold pool and favorable deep-layer shear will still pose a risk of severe outflow winds. A watch will likely be issued in the next hour or so. ..Weinman/Hart.. 07/20/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BGM...BUF...CTP...PBZ...CLE... https://www.spc.noaa.gov/products/md/md1649.html

Good afternoon discussion from LWX on tonight's threat .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A broken cumulus deck has started to pan out across the area early this afternoon, with high level cirrus clouds overhead. Moisture out ahead of an approaching front coupled with increasing instability further east has generated a few strong to even severe thunderstorms early this afternoon across portions of PA/MD, mainly across PHI`s area. Lingering slight chance PoPs exist further east throughout the afternoon but widespread scattered showers/thunderstorms are not expected through the remainder of the afternoon and evening. By tonight, a cold front will continue to traverse closer to the region from the Ohio Valley. Climatologically speaking, this event does not fit quite into the usual category, especially for the middle of July. Nonetheless, CAMs and other guidance has continued to suggest a strong line of showers and thunderstorms overnight and into Friday morning across a good portion of the forecast area. A general timeline for the feature path would be 6-8z across the far western areas and not leaving the eastern segments of the CWA until after 12-14z Friday morning. Latest guidance suite has slowed the progression down an hour or so for the life cycle but overall intensity has generally stayed the same. There still remains uncertainties with this event with respect to intensity especially. Convection ahead of the frontal passage may inhibit further development across certain areas which would limit overall impacts. Should the CI remain light/brief then hazards will be more widespread across portions of the area. There continues to be a multi-hazard possibility for the overnight hours. Strong to severe thunderstorms will be possible, especially along and east of the Blue Ridge Mountains and along and north of I- 66. One caveat to mention would be across NE MD early Friday morning, where the shear profiles and instability look to be greatest. Damaging winds and an isolated/tornado or waterspout are possible across those areas especially. Lapse rates do not look as favorable during this time across those area, thus hail threat looks to be limited but certainly non-zero. Also, isolated instances of flooding due to training storms is possible across areas east of US- 15, where especially the urban corridors have lower FFG values. We will continue to monitor the trends of this system as it continues to dive into the Mid-Atlantic and Northeast states later today and into early Friday morning. Highs will top out in the upper 80s to low 90s across the lower elevations, with mid to upper 70s for the mountains.

16z HRRR is much more stormy for the region starting around midnight and continuing through sunrise

14z HRRR actually looks pretty good tbh ETA - 15z looks about the same

Decent MUCAPE and shear most likely... lapse rates aren't too bad either

12z NAM Nest and 15z RAP favor MD and PA for whatever is left of the MCS/line... comes in between 11pm and 4am or so looks like

Not sure if we are watching the same area... but SPC upgraded parts of the Ohio Valley to a ENH risk for large hail and damaging winds... and SLGT was moved further east into PA

SPC mentioned us Thursday into Friday on the Day 4-8 OTLK... LWX AFD also mentions it LONG TERM /THURSDAY THROUGH SUNDAY/... Shower and thunderstorm chances round out the workweek with drier and slightly cooler conditions expected for the weekend. Synoptically, not much change in the overall pattern. The upper level ridge remains in the west while the mean upper level trough builds east from the Great Lakes. With west to northwest flow aloft, multiple shortwave disturbances and a front will be able to track across the region. Timing and placement of these systems still remains uncertain with a focus on western portions of the forecast area. Even with that said, 12z guidance shows some alignment for the highest probability of convection Thursday into Friday as shortwave energy dives south and the resultant cold front crosses the region. 12z deterministic/ensemble guidance shows increasing instability and shear during this time leading to the potential for strong to severe storms. Currently SPC makes a mention of this potential threat in there Day 5/6 discussion, but no areas have been highlighted at this time. Primary threats with these storms would be damaging winds, large hail, and isolated instances of flooding. WPC currently has the area highlighted in a marginal risk for excessive rainfall during the Day4/5 (Thursday-Friday) timeframe.

Lots of flooding down in Lynchburg with heavy rain and storms... we'll see if that makes it up here in a few hours

Thundering here now a good bit

Interesting NW complex movement out of Prince Willam

Rain picking up here... and def see redevelopment SW of CHO

I dunno... i see redevelopment down by CHO

Yikes if you are on i40 right now in NM BULLETIN - EAS ACTIVATION REQUESTED Severe Thunderstorm Warning National Weather Service Albuquerque NM 629 PM MDT Sat Jul 15 2023 The National Weather Service in Albuquerque has issued a * Severe Thunderstorm Warning for... Central San Miguel County in northeastern New Mexico... Western Quay County in east central New Mexico... Northeastern Guadalupe County in east central New Mexico... * Until 730 PM MDT. * At 628 PM MDT, severe thunderstorms were located along a line extending from 11 miles southeast of Watrous to 8 miles west of Variadero, moving south at 15 mph. THESE ARE DESTRUCTIVE STORMS APPROACHING I-40 FROM THE NORTH. HAZARD...Three inch hail and 70 mph wind gusts. SOURCE...Radar indicated. IMPACT...People and animals outdoors will be severely injured. Expect shattered windows, extensive damage to roofs, siding, and vehicles. * Locations impacted include... Santa Rosa, Montoya, Colonias, Variadero, Maes, Newkirk, Santa Rosa Lake State Park, Cuervo, Trujillo and Trementina. This includes the following highways... Interstate 40 between Mile Markers 265 and 314. State Road 104 between Mile Markers 15 and 73. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. These are dangerous storms. Prepare immediately for large destructive hail capable of producing significant damage. People outside should move to shelter inside a strong building, and stay away from windows. Heavy rains from severe thunderstorms can produce sudden and dangerous flows in arroyos, ditches and over low water crossings. Do not attempt to drive through areas where water covers the roadway. && LAT...LON 3493 10484 3490 10431 3511 10402 3563 10441 3578 10460 3567 10497 TIME...MOT...LOC 0028Z 338DEG 11KT 3565 10488 3541 10462 TORNADO...POSSIBLE THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...3.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...70 MPH

BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Baltimore MD/Washington DC 831 PM EDT Sat Jul 15 2023 The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for... Northwestern Washington County in north central Maryland... Eastern Allegany County in western Maryland... Northern Morgan County in the Panhandle of West Virginia... Northwestern Berkeley County in the Panhandle of West Virginia... * Until 915 PM EDT. * At 831 PM EDT, severe thunderstorms were located along a line extending from near Paw Paw to near Martinsburg, moving northeast at 45 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... Hancock, Berkeley Springs, Great Cacapon, Clear Spring, Pecktonville, Big Pool, Johnsons Mill, Cherry Run, Tomahawk, Johnsontown, Lineburg, Valley View, Spohrs Crossroads, Spruce Pine Hollow, Highland Ridge, Smith Crossroads, Berryville, New Hope, Sleepy Creek and Shady Grove. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Large hail and damaging winds and continuous cloud to ground lightning is 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.

Preliminary Local Storm Report National Weather Service Baltimore MD/Washington DC 825 PM EDT Sat Jul 15 2023 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 0822 PM Hail La Plata 38.53N 76.97W 07/15/2023 M1.00 inch Charles MD Law Enforcement && Event Number LWX2301401

BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Baltimore MD/Washington DC 815 PM EDT Sat Jul 15 2023 The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for... Southwestern Prince Georges County in central Maryland... Central Charles County in southern Maryland... * Until 900 PM EDT. * At 815 PM EDT, a severe thunderstorm was located over Port Tobacco River, moving north at 20 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... Port Tobacco River, Accokeek, Bryans Road, Pomfret, Port Tobacco Village, Port Tobacco, Faulkner and Ripley.

BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Baltimore MD/Washington DC 807 PM EDT Sat Jul 15 2023 The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for... Southeastern Prince Georges County in central Maryland... Northeastern Charles County in southern Maryland... * Until 845 PM EDT. * At 806 PM EDT, a severe thunderstorm was located near La Plata, moving north at 20 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... Waldorf, La Plata, Saint Charles, Accokeek, Brandywine, Baden, Bryantown, Port Tobacco Village, Northwood, Dentsville, White Plains and Bel Alton. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Large hail and damaging winds and continuous cloud to ground lightning is occurring with this storm. 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 this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways.

BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Baltimore MD/Washington DC 756 PM EDT Sat Jul 15 2023 The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for... Western Washington County in north central Maryland... Allegany County in western Maryland... Northeastern Garrett County in western Maryland... Northwestern Morgan County in the Panhandle of West Virginia... Northeastern Mineral County in eastern West Virginia... North central Hampshire County in eastern West Virginia... * Until 900 PM EDT. * At 756 PM EDT, severe thunderstorms were located along a line extending from near Frostburg to near Romney, moving northeast at 20 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... Cumberland, Frostburg, Bel Air, Paw Paw, La Vale, Fort Ashby, Ridgeley, Cresaptown, Potomac Park, Wiley Ford, Eckhart Mines, Mount Savage, Rawlings, Ellerslie, Springfield, Corriganville, Midland, Midlothian, Green Spring and Flintstone. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Large hail and damaging winds and continuous cloud to ground lightning is 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.

Storms starting to fire in S MD now as well, especially near La Plata

Wonder how much of that line of heavy to severe storms SW of us reaches us in the metro over the next hour or so

Huh... was not expecting this... but I guess it's warranted Flood Watch National Weather Service Baltimore MD/Washington DC 638 PM EDT Sat Jul 15 2023 DCZ001-MDZ003>006-008-011-013-014-016-503>508-VAZ028-030-031-036>040- 050-051-053>057-501-502-505>508-526-527-WVZ051>053-160645- /O.NEW.KLWX.FA.A.0003.230715T2238Z-230716T0800Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ District of Columbia-Washington-Frederick MD-Carroll-Northern Baltimore-Cecil-Southern Baltimore-Prince Georges-Anne Arundel- Charles-Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Northwest Harford- Southeast Harford-Frederick VA-Warren-Clarke-Nelson-Albemarle-Greene- Madison-Rappahannock-Orange-Culpeper-Fairfax-Arlington/Falls Church/Alexandria-Stafford-Spotsylvania-King George-Northern Fauquier-Southern Fauquier-Western Loudoun-Eastern Loudoun-Northern Virginia Blue Ridge-Central Virginia Blue Ridge-Northwest Prince William-Central and Southeast Prince William/Manassas/Manassas Park- Morgan-Berkeley-Jefferson- Including the cities of College Park, South Gate, Bethesda, Falls Church, Annapolis, Purcellville, Franconia, Ashburn, Woodbridge, Charles Town, Dahlgren, McLean, Hagerstown, Montclair, Ellicott City, Odenton, Leesburg, Suitland-Silver Hill, Clinton, Glen Burnie, Falmouth, Shepherdstown, Aberdeen, Lovingston, Winchester, Herndon, Severn, Turnbull, Alexandria, Camp Springs, Eldersburg, Annandale, Chantilly, Haymarket, Madison, Lake Ridge, Germantown, Bowie, Manassas, Lisbon, Washington, Rockville, Warrenton, Reisterstown, Cockeysville, Waldorf, Arlington, Sterling, Wintergreen, Gordonsville, Front Royal, Berryville, Fredericksburg, Laurel, Paw Paw, Westminster, Dale City, Charlottesville, Baltimore, Severna Park, Big Meadows, Orange, Gaithersburg, Greenbelt, Ballenger Creek, Columbia, Martinsburg, Centreville, Elkton, Frederick, Silver Spring, Jarrettsville, Stanardsville, Reston, Damascus, Arnold, St. Charles, and Culpeper 638 PM EDT Sat Jul 15 2023 ...FLOOD WATCH IN EFFECT UNTIL 4 AM EDT SUNDAY... * WHAT...Flash flooding caused by excessive rainfall is possible. * WHERE...Portions of DC, Maryland, Virginia and panhandle West Virginia, including the following areas: in DC, District of Columbia. In Maryland, Anne Arundel, Carroll, Cecil, Central and Southeast Howard, Central and Southeast Montgomery, Charles, Frederick MD, Northern Baltimore, Northwest Harford, Northwest Howard, Northwest Montgomery, Prince Georges, Southeast Harford, Southern Baltimore and Washington. In Virginia, Albemarle, Arlington/Falls Church/Alexandria, Central Virginia Blue Ridge, Central and Southeast Prince William/Manassas/Manassas Park, Clarke, Culpeper, Eastern Loudoun, Fairfax, Frederick VA, Greene, King George, Madison, Nelson, Northern Fauquier, Northern Virginia Blue Ridge, Northwest Prince William, Orange, Rappahannock, Southern Fauquier, Spotsylvania, Stafford, Warren and Western Loudoun. In panhandle West Virginia, Berkeley, Jefferson and Morgan. * WHEN...Until 4 AM EDT Sunday. * IMPACTS...Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Flooding may occur in poor drainage and urban areas. * ADDITIONAL DETAILS... - A seasonably moist airmass with ample moisture content ahead of an approaching frontal boundary will result in numerous showers and thunderstorms. These showers and thunderstorms will be capable of producing heavy rainfall with totals on the order of 1 to 3 inches with locally higher amounts where thunderstorms may train. These totals may result in flash flooding, particularly in urban areas and those that have observed recent heavy rainfall. - Please visit www.weather.gov/safety/flood for flood safety and preparedness information

Probably going to be sub-severe, but decent storms in WV headed eastward

Mesoscale Discussion 1565 NWS Storm Prediction Center Norman OK 0250 PM CDT Sat Jul 15 2023 Areas affected...Portions of far northwestern NC...southwestern into central/northern VA...the eastern WV Panhandle...MD...DC...south- central into southeastern PA...northern DE...and NJ Concerning...Severe potential...Watch unlikely Valid 151950Z - 152215Z Probability of Watch Issuance...20 percent SUMMARY...An isolated threat for hail and damaging winds should gradually increase this afternoon. While watch issuance is unlikely in the short term (next 1-2 hours), trends will be closely monitored. DISCUSSION...Isolated to widely scattered thunderstorms have developed this afternoon along and just east of the Blue Ridge Mountains extending from far northwestern NC into southwestern and central VA. A separate area of convection is ongoing across parts of southeastern PA into northern DE and NJ. This activity is likely being aided by modest large-scale ascent preceding a shortwave trough moving eastward over the OH/TN Valleys. A very moist low-level airmass, with surface dewpoints generally in the low to mid 70s, is present along and east of the ongoing convection. Ample daytime heating has eroded remaining MLCIN, and moderate to locally strong instability has developed in response. Although low-level winds remain weak per recent VWPs from KFCX/KLWX, modest strengthening of mid-level southwesterlies to around 30-35 kt has been noted with the approach of the shortwave trough. Similar values of deep-layer shear should foster modest updraft organization. Multicells should be the primary convective mode. But, marginal supercell structures may also occur, posing an isolated hail and damaging wind threat. At this point, overall convective coverage should tend to remain fairly isolated. Poor mid-level lapse rates should also temper updraft intensity/acceleration to some extent. A loosely organized cluster of thunderstorms over WV may also move into parts of western MD/VA over the next couple of hours with an isolated strong to damaging wind threat. While watch issuance appears unlikely in the short term, trends will be closely monitored. ..Gleason/Bunting.. 07/15/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...CTP...LWX...RNK.. https://www.spc.noaa.gov/products/md/md1565.html

MRGL risk was nudged east on the 1630z OTLK to now include i95 corridor for damaging wind gusts