Severe Storm Risk - Castle Pines North, CO

There is a Marginal Severe Storm Risk for your location. Continue reading for today's outlook from the National Weather Service's Storm Prediction Center. -------------------- National Severe Storm Outlook THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE SOUTHERN APPALACHIANS INTO THE SAVANNAH RIVER VALLEY AND OVER PARTS OF WESTERN AND CENTRAL MONTANA SUMMARY Widely scattered damaging wind gusts are likely across portions of the Southeast Sunday afternoon and early evening. Widely scattered large hail occurrences are expected across portions of western and central Montana Sunday afternoon and evening. Additional areas at risk for severe wind and hail are across parts of the Interior West, over the northern and central High Plains, and from the eastern Dakotas and western Minnesota into the Ozark Plateau and Gulf Coast states. Synopsis A prominent mid-level ridge over the central U.S. is forecast to weaken during the latter half of the period in response to the progression of two distinct short-wave troughs and associated wind maxima through the Interior West. Separate, weaker perturbations will move through the ridge axis over the northern Plains/mid-MO Valley region on Sunday, contributing to thunderstorm development in those areas. Elsewhere, a mid-level disturbance over the OH Valley Sunday morning is forecast to move into the Cumberland Plateau vicinity by afternoon, also likely serving as a focus for thunderstorm development. At the surface, a lee cyclone will persist over the northern High Plains, with that feature potentially deepening Sunday night in response to increasing height falls aloft. High pressure will build across the Great Lakes, OH Valley, and Northeast with a baroclinic zone present between those surface features from the mid-MO Valley through the Ozarks and TN Valley into the Southeast. Southern Appalachians into the Savannah River Valley Temperatures in the 90s will coincide with boundary-layer dewpoints in the 70s to yield a moderately to strongly unstable air mass (i.e., MLCAPE of 2000-3000+ J/kg) by afternoon with steepening low-level lapse rates. Aided by forcing attendant to the mid-level disturbance mentioned above, that thermodynamic environment will support an increase in thunderstorm coverage and intensity through the afternoon along and ahead of the surface front. Some increase in mid-level winds may accompany the disturbance with up to 30 kt of deep-layer shear forecast in the vicinity of the frontal zone. As such, the potential will exist for longer-lived multi-cells and line segments capable of damaging wind gusts and perhaps some large hail into evening. Ozark Plateau into the Gulf Coast States A similar thermodynamic environment to that previously described is anticipated ahead of the surface front Sunday afternoon. Generally weak forcing for ascent and vertical shear are expected to limit the potential for a more organized severe weather threat. However, the degree of instability will support briefly intense pulse-type storms capable of locally damaging wet microbursts during the afternoon and early evening hours. Northern Great Basin into the northern Rockies Increasing height falls and strengthening mid/upper-level flow will overspread the region Sunday afternoon into night ahead of a vigorous short-wave trough pivoting through the base of the Pacific Northwest upper low. The strongest instability (i.e., MLCAPE up to 1000-1500 J/kg) is forecast across portions of western into central MT with stronger capping with eastward extent. The presence of 40-50 kt of deep-layer shear will support supercells capable of mainly large hail through Sunday evening. While forecast hodographs exhibit considerable curvature/veering winds in the lowest 1-2-km AGL, stability concerns in the boundary layer may limit severe-wind-gust and tornado potential. Weaker instability is forecast from northeast NV and northern UT into central and eastern ID. However, the presence of steep lapse rates and kinematics mentioned above may yield a few severe storms capable of severe wind gusts. Northern and central High Plains Stronger forcing for ascent is expected to remain to the west and east of the region through the daylight hours, leading to uncertainty in storm coverage in the vicinity of the surface low and lee trough. The 00Z models indicate an increasing potential for at least isolated thunderstorms from mid-afternoon into evening along the lee trough. RAP-based forecast soundings show steep lapse rates and resulting MLCAPE of 1000-2000+ J/kg. The strongest deep-layer shear of 40-50 kt is forecast across eastern MT into ND with decreasing magnitudes with southward extent along the lee trough. As such, a conditional risk for supercells capable of large hail and severe wind gusts exists. While Marginal Risk wind and hail probabilities will be maintained with this forecast, an upgrade to level 2/Slight Risk is possible in subsequent updates. Eastern Dakotas and western Minnesota into the lower Missouri Valley Clusters of mainly elevated thunderstorms may be ongoing at 12Z Sunday, aided by forcing associated with the weak disturbance(s) cresting the mid-level ridge axis. A subset of the early-day storms is expected to persist into afternoon with additional storms forming on the leading edge of more persistent cloud cover, where pockets of stronger heating and boundary-layer dewpoints in the low/mid 70s will yield MLCAPE of 1500-2500 J/kg. The 00Z models suggest that storms will eventually grow upscale into an MCS that tracks south along or to the immediate cool side of the surface boundary through portions of the middle and lower MO Valley Sunday afternoon into evening. It currently appears that deep-layer shear of generally less than 30 kt and marginally steep mid-level lapse rates may limit the degree of cold pool organization and a greater/more continuous damaging-wind threat. Nonetheless, the setup appears supportive of sporadic damaging wind and severe hail occurrences.