• SPC MD 1396
    on August 4, 2020 at 3:35 pm

    MD 1396 CONCERNING SEVERE POTENTIAL...TORNADO WATCH LIKELY FOR NORTHERN CT...SOUTHERN VT...SOUTHERN NH...MA...RI Mesoscale Discussion 1396 NWS Storm Prediction Center Norman OK 1034 AM CDT Tue Aug 04 2020 Areas affected...Northern CT...Southern VT...Southern NH...MA...RI Concerning...Severe potential...Tornado Watch likely Valid 041534Z - 041700Z Probability of Watch Issuance...95 percent SUMMARY...Conditions will become increasingly supportive of tornadoes over the next few hours. A Tornado Watch will likely be issued within the next hour. DISCUSSION...Wind fields are expected to strengthen significantly across the area over the next few hours as Tropical Storm Isaias continues northward into southern New England. A very moist and modestly buoyant air mass is already in place, and a few stronger storms have been noted over northern portions of the region in the past hour. These storms were likely a result of the strong warm-air advection in place, and were elevated above the boundary-layer as a result. Air mass along the coastal areas is already supportive of surface-based storms, with more area expected to become supportive as this higher theta-e air moves further inland. Thus far, most of the deep convective has remained within a band arc 80 to 100 miles from the center. This band is quickly moving northward, and will likely reach portions of southern New England by 17Z. Additionally, any development ahead of this band will be in a very favorable kinematic environment. Given this potential, a tornado watch will likely be issued within the next hour for much of southern New England. ..Mosier/Kerr.. 08/04/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...OKX...ALY... LAT...LON 41637196 41967335 43087297 42617015 41117066 41637196 Read more

  • SPC MD 1395
    on August 4, 2020 at 3:14 pm

    MD 1395 CONCERNING TORNADO WATCH 416... FOR MUCH OF NJ...SOUTHERN NY/HUDSON VALLEY...NEW YORK CITY...WESTERN/CENTRAL LONG ISLAND...SOUTHERN CT Mesoscale Discussion 1395 NWS Storm Prediction Center Norman OK 1013 AM CDT Tue Aug 04 2020 Areas affected...Much of NJ...Southern NY/Hudson Valley...New York City...Western/Central Long Island...Southern CT Concerning...Tornado Watch 416... Valid 041513Z - 041645Z The severe weather threat for Tornado Watch 416 continues. SUMMARY...Threat for brief tornadoes currently continues across much of NJ, with the threat then transitioning into southeast NY...NYC...and western Long Island over the next two hours. DISCUSSION...Latest surface observations and radar/satellite imagery place the center of Tropical Storm Isaias over the central DE/MD border. Over the past several hours, rain band arcing from about 80 miles northeast of the center to about 130 miles due east of the center has been responsible for numerous low-topped supercells, a few of which maintained enough strength once ashore to produce tornadoes. The deeper cells within the band offshore do not currently appear to have the same structure or intensity as these earlier storms. However, the environment remains strongly sheared, particularly at low-levels. Recent KDIX VAD data has 700-800 m2/s2 of 0-1 km SRH and weather spotters recently confirmed a tornado in Ocean County NJ. Best estimates of the motion of the band is northward/north-northeastward at 35-40 kt. This motion brings the band through much of central NJ by 1600Z and into central Long Island by 1700Z. Storm motion of storms within the band is north-northwestward around 40 to 50 kt, with right-moving supercells moving slightly slower and more northerly. ..Mosier.. 08/04/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OKX...PHI... LAT...LON 40047540 41097455 41327395 41347335 41137276 40807282 40337370 39457438 40047540 Read more

  • SPC Tornado Watch 415 Status Reports
    on August 4, 2020 at 12:28 pm

    WW 0415 Status Updates STATUS REPORT ON WW 415 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 ESE WAL TO 10 NW WAL TO 15 E NHK TO 25 WNW NHK. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1393 ..JEWELL..08/04/20 ATTN...WFO...PHI...LWX...AKQ... STATUS REPORT FOR WT 415 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS DEC001-003-005-041340- DE . DELAWARE COUNTIES INCLUDED ARE KENT NEW CASTLE SUSSEX MDC003-005-009-011-015-019-025-029-035-039-041-045-047-510- 041340- MD . MARYLAND COUNTIES INCLUDED ARE ANNE ARUNDEL BALTIMORE CALVERT CAROLINE CECIL DORCHESTER HARFORD KENT QUEEN ANNE'S SOMERSET TALBOT WICOMICO WORCESTER MARYLAND INDEPENDENT CITIES INCLUDED ARE Read more

  • SPC Tornado Watch 415
    on August 4, 2020 at 12:28 pm

    WW 415 TORNADO DE MD NJ VA CW 040625Z - 041600Z URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 415 NWS Storm Prediction Center Norman OK 225 AM EDT Tue Aug 4 2020 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Delaware Eastern Maryland Southern New Jersey Southeast Virginia Coastal Waters * Effective this Tuesday morning from 225 AM until NOON EDT. * Primary threats include... A few tornadoes possible SUMMARY...Multiple low-topped supercells associated with tropical cyclone Isaias will spread north-northeast from northeast North Carolina across the Virginia Tidewater, Chesapeake Bay, and the Delmarva region this morning. The tornado watch area is approximately along and 40 statute miles east and west of a line from 30 miles north of Dover DE to 30 miles southwest of Norfolk VA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. && OTHER WATCH INFORMATION...CONTINUE...WW 414... AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 400. Mean storm motion vector 17045. ...Grams Read more

  • SPC Aug 4, 2020 1300 UTC Day 1 Convective Outlook
    on August 4, 2020 at 12:14 pm

    SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0704 AM CDT Tue Aug 04 2020 Valid 041300Z - 051200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE NORTHEAST... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL HIGH PLAINS... ...SUMMARY... Tornadoes will be most likely through this afternoon from Delaware into southern New England, with a lingering threat for a couple tornadoes across northern New England this evening. Scattered large hail and severe wind gusts will be possible across the central High Plains from mid-afternoon to mid-evening. ...DE to New England... As T.C. Isaias rapidly shifts northeastward today, an accompanying very moist low-level environment will permit maintenance of weak buoyancy across the coastal plain of the Northeast into southern New England. Clusters and cells of shallow convection to the north and east of the circulation center will continue to pose a risk for tornadoes. The greatest risk will be where mid 70s surface dew points can become coincident with immense low-level hodograph curvature from DE to the NYC tri-state area. Most guidance is consistent in suggesting the very rich surface moisture will become pinched off across parts of southern New England later today. This suggests the overall tornado risk should decrease this evening as it spreads into northern New England. ...Central High to Northern Great Plains... A broad plume of 50s surface dew points is prevalent ahead of a lee surface trough, a low-amplitude shortwave impulse near the MT/SK border, and an MCV near the SD/MT border. The greatest buoyancy this afternoon should develop along the central High Plains portion of the lee trough amid very steep low to mid-level lapse rates, with relatively weaker mid-level lapse rates in the Dakotas. Scattered thunderstorms should initiate near the Front Range during the mid-afternoon and spread east within moderate mid-level west-northwesterlies. The setup should yield supercells initially producing large hail, some of which may be significant, from eastern CO into the NE Panhandle. Conglomerating cold pools should tend to foster multiple clusters as activity spreads towards the KS/CO border longitude. A dearth of surface-based instability with eastern extent in KS/OK suggests waning severe potential during the evening even though an elevated MCS should persist to the southeast. Farther north, scattered thunderstorms are expected as well, mainly across western to central ND in closer proximity to ascent tied to the approaching shortwave trough. Weak mid-level lapse rates should be a limiting factor and may result in only isolated coverage of severe hail and wind. Have expanded Marginal Risk northward for this threat. ..Grams/Jewell.. 08/04/2020 Read more

  • SPC Tornado Watch 416 Status Reports
    on August 4, 2020 at 11:20 am

    WW 0416 Status Updates STATUS FOR WATCH 0416 HAS NOT BEEN ISSUED YET Read more

  • SPC Tornado Watch 416
    on August 4, 2020 at 11:20 am

    WW 416 TORNADO CT NJ NY PA CW 041120Z - 042000Z URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 416 NWS Storm Prediction Center Norman OK 720 AM EDT Tue Aug 4 2020 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Southern Connecticut New Jersey Southeast New York Southeast Pennsylvania Coastal Waters * Effective this Tuesday morning and afternoon from 720 AM until 400 PM EDT. * Primary threats include... A few tornadoes likely SUMMARY...Band of persistent low-topped supercells across southeast Maryland should rapidly move north-northeast across parts of the Northeast Megalopolis into this afternoon. Additional cells are possible just ahead of this band as well. The tornado watch area is approximately along and 60 statute miles east and west of a line from 20 miles south southeast of Philadelphia PA to 25 miles north northeast of Bridgeport CT. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. && OTHER WATCH INFORMATION...CONTINUE...WW 415... AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 50 knots. A few cumulonimbi with maximum tops to 400. Mean storm motion vector 17045. ...Grams Read more