SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0152 PM CST Wed Nov 05 2025 Valid 052000Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE PACIFIC NORTHWEST COAST AND ACROSS THE LOWER GREAT LAKES INTO PARTS OF NEW ENGLAND... ...SUMMARY... Isolated severe thunderstorms are possible through the day along the western Oregon and far northern California coastal region. Strong to locally severe gusts may accompany shallow convection that develops over parts of the Northeast. ...20z Update... The only adjustment was a northward expansion of the 2% tornado and 5% wind risk probabilities across the far southwest WA coast. Recent imagery from KLGX shows a cluster of semi-discrete cells off the far southwest WA coast with weak, but discernible, mid-level rotation. Regional VWPs continue to show ample low-level shear, and surface temperatures are warming to near/slightly above the upper-end of the ensemble envelope. These kinematic/thermodynamic conditions may support at least a low-end wind and brief tornado threat along the coast. Across the Lower Great Lakes/New England, regional VWPs are sampling 40-50 knot winds at around 2 km AGL. Forecast soundings suggests that winds at this level should reside well within the shallow CAPE profile along/just ahead of the front. This lends confidence in the potential for sporadic damaging winds, even though lightning production may be very limited. For additional details see the previous discussion below. ..Moore.. 11/05/2025 .PREV DISCUSSION... /ISSUED 1027 AM CST Wed Nov 05 2025/ ...Northeast/southern New England... A mid-level trough initially analyzed over the Great Lakes will steadily amplify southeastward and reach coastal New England tonight. A deepening cyclone will quickly move east across the Lower Great Lakes toward coastal New England tonight in tandem with a cold front. Model guidance continues to show near neutral/scant buoyancy profiles developing immediately ahead of the front. Despite this limited thermodynamic setup, strong large-scale forcing for ascent will act to augment the development of shallow convection later today through this evening. Around 40-60 kt of west-southwesterly flow within the lowest 1-2 km AGL will support a risk for downward momentum transport for a few strong, potentially damaging wind gusts (55-65 mph) during the afternoon and evening. ...Northern California and Oregon Coasts... Water-vapor imagery this morning shows a mid-level shortwave trough moving northeast across northern CA into southern OR as a larger-scale troughing is maintained along the Pacific Northwest coast. The mid-level cold pocket accompanying the trough will result in -22 to -24 deg C 500-mb temperatures atop a moist maritime airmass. Forecast soundings show upwards of a couple hundred J/kg MLCAPE with the greatest buoyancy near the coast. Widely scattered thunderstorms will episodically move inland. Very strong flow in the lowest 1-2 km will support the possibility for isolated strong to severe wind gusts. Forecast soundings do show some low-level curvature closer to the coast, with 150-250 m2/s2 effective SRH. As such, if a sustained, land-falling low-topped supercell can develop, a brief tornado could occur.
