Severe Storm Risk - Watertown, CT

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 ACROSS PARTS OF SOUTHERN MINNESOTA INTO IOWA...NORTHERN WISCONSIN INTO THE UPPER PENINSULA OF MICHIGAN...AND THE MID-ATLANTIC SUMMARY Isolated to scattered severe thunderstorms are possible across parts of the Upper Midwest/Great Lakes this afternoon and evening, with large to very large hail and severe winds the main threats. Thunderstorms capable of scattered damaging winds may also occur over portions of the Mid-Atlantic. Upper Midwest/Great Lakes Thunderstorms are ongoing along/ahead of a cold front late this morning from the MN Arrowhead southwestward into southern MN/northern IA. While there are still uncertainties regarding convective evolution this afternoon and evening, it appears increasingly probable that two mesoscale corridors of greater severe potential will exist: one across southern MN into IA, and another across northern WI into the U.P of MI. In general, the severe risk today will be aided by a mid/upper-level trough advancing east-southeastward across these regions in tandem with a 35-50 kt west-northwesterly mid-level jet. Thunderstorms are expected to further increase in coverage and intensity along the eastward-advancing cold front this afternoon across parts of northern WI into the western U.P of MI. While latest NAM/RAP forecast soundings across this area suggest low-level moisture remains fairly shallow/limited, mostly clear conditions are noted on recent visible satellite imagery. Resultant moderate instability and gradually strengthening deep-layer shear with the approach of the mid/upper-level trough will aid in thunderstorm organization. Small clusters/bowing line segments will probably be the dominant mode given the linear forcing of the cold front, with enhanced low/mid-level flow aiding the risk for scattered severe/damaging winds. A Slight Risk has been added for parts of northern WI into the U.P of MI given increased confidence in this scenario occurring. Farther south, generally elevated convection is ongoing across southern MN into northern IA. The 12Z observed sounding from MPX showed fairly steep low/mid-level lapse rates in the 850-530 mb layer, which along with 35-40 kt of effective bulk shear and around 2000 J/kg of MUCAPE may continue to support a threat for severe hail with this activity in the short term. Even though cloud cover remains prevalent across these areas late this morning, a corridor of moderate to locally strong instability is still forecast to develop this afternoon across parts of eastern NE into IA ahead of the cold front. Current expectations are for multiple surface-based supercells and/or bowing clusters to develop along/ahead of the front in southern MN, and then spread southeastward across IA through the late afternoon/early evening. A threat for both large hail and damaging winds should exist with this activity, and a Slight Risk has been introduced where confidence is greater that robust convection will occur. 2+ inch diameter hail and perhaps a tornado also appear possible with any surface-based supercell, even though low-level flow will not be overly strong. Ohio Valley into the Mid-Atlantic Between upper troughing over central Canada/the Upper Midwest and upper ridging over the western Atlantic, around 20-30 kt of southwesterly mid-level flow will exist today from the OH Valley into the Mid-Atlantic and Northeast. Greater destabilization and steepening of low-level lapse rates are anticipated this afternoon across the Mid-Atlantic, where recent visible satellite imagery shows generally clear skies. Loosely organized cells/clusters that initially develop across the higher terrain of the central Appalachians should spread into the Mid-Atlantic coastal plain through the afternoon/evening, while posing a threat for scattered damaging winds up to 50-60 mph and perhaps marginally severe hail. Across the OH Valley, somewhat weaker mid-level flow may tend to limit updraft organization. Still, some potential for clustering and isolated damaging winds may exist downstream of ongoing convection where greater destabilization can ocur. Have therefore expanded the Marginal Risk across much of the OH Valley to account for this possibility. Southern/Central Plains into the Ozarks Elevated thunderstorms posing an isolated hail threat in southeast KS late this morning should further diminish into the early afternoon as a southwesterly low-level jet gradually weakens. To the south and east of this activity, a hot and unstable airmass will exist this afternoon across OK into parts of southern MO and AR. Although details regarding convective evolution remain unclear, it is possible that robust thunderstorms develop/continue on the outflow from this morning's activity, or near multiple MCVs present from earlier convection. Isolated strong to severe winds appear possible, even though deep-layer shear should remain weak. The Marginal Risk has been expanded eastward and connected to the risk area in the OH Valley. Other isolated thunderstorms posing some severe wind threat may develop this afternoon farther west across eastern NM into the OK/TX Panhandles. Arizona Modest east-southeasterly mid-level flow will persist today over AZ to the south of a mid/upper-level anticyclone centered over the Four Corners. Widely scattered convection should develop over the Mogollon Rim and the higher terrain in southeast AZ this afternoon, and gradually spread into the lower deserts this evening. Given the very well-mixed boundary layer and weak to locally moderate instability expected to be in place ahead of these thunderstorms, have maintained low severe wind probabilities. Northern Nebraska/Southern South Dakota Elevated thunderstorms may develop across parts of northern NE and southern SD late tonight/early Saturday morning as isentropic ascent increases in tandem with modest strengthening of a southerly low-level jet. Low-level moistening beneath steepening mid-level lapse rates should support sufficient MUCAPE for robust updrafts, although confidence in overall coverage remains low due to weak/nebulous large-scale ascent. Regardless, strong shear in the cloud-bearing layer across this area should promote organized convection capable of producing isolated severe hail.