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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Monday, July 10, 2023

SPC Jul 10, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Mon Jul 10 2023 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY INTO TONIGHT ACROSS PARTS OF WESTERN UPPER MICHIGAN...CENTRAL WISCONSIN...SOUTHERN MINNESOTA...NORTHERN IOWA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN THROUGH SOUTH CENTRAL NEBRASKA...NORTHWESTERN INTO CENTRAL KANSAS...PARTS OF SOUTHEASTERN COLORADO...EASTERN NEW MEXICO...THE OKLAHOMA AND TEXAS PANHANDLES INTO SOUTHWESTERN OKLAHOMA AND THE TEXAS SOUTH PLAINS... ...SUMMARY... Scattered strong thunderstorms and a couple of organizing storm clusters may pose a risk for severe hail and wind across parts of the Upper Midwest into Great Plains this afternoon into tonight. ...Synopsis... As a blocking mid-level high remains prominent east/northeast of the Canadian Maritimes vicinity, there appears likely to be little eastward progression of a broad, anomalously deep upstream mid-level low through this period. The center of the low may shift from southwest of Hudson Bay northeastward into Hudson Bay, mostly in response to significant perturbations pivoting around its periphery. While an associated occluding cyclone migrates northward through Hudson Bay, its notable trailing cold front is forecast to surge southward through much of the remainder of the Upper Great Lakes, Upper Midwest and northern Great Plains by daybreak Tuesday. A preceding front appears likely to stall and weaken further near the south Atlantic Seaboard through the Gulf States, while broad, weak mid-level troughing as far south as the Gulf Coast/northern Florida vicinity continues to slowly shift east of the lower Mississippi Valley and off the Atlantic Seaboard. Models indicate that the western flank of this front will become better defined during the day today across eastern Texas into the Raton Mesa vicinity. This will occur as strong heating occurs to its southwest, beneath warming elevated mixed-layer air advecting east of the southern Rockies, to the north and east of a prominent mid-level subtropical high centered near/west of southwestern Texas. To the northwest through north of this high, a series of short wave perturbations will slowly progress through one branch of westerlies offshore of the Pacific Northwest through the northern Rockies. ...Central Great Plains into Upper Midwest... A corridor of stronger pre-frontal heating is forecast to become characterized by moderate CAPE of 1500 J/kg, across southern Minnesota through much of north central Wisconsin. Models indicate similar destabilization southwestward across the middle Missouri Valley into central Nebraska, to the east of lee surface troughing. Perhaps aided by increasing forcing for ascent downstream of a short wave impulse pivoting around the southwestern periphery of the Canadian mid-level low, this instability is forecast to support increasing and intensifying thunderstorm development by late this afternoon. This may tend to occur to the south of the stronger mid/upper flow, but deep-layer shear may still be sufficient to support isolated supercell structures initially, before convection consolidates into one or two upscale growing and organizing clusters, posing a risk for severe hail and wind into this evening. Warmer mid-levels, with stronger inhibition and more subtle forcing for ascent, result in more uncertain thunderstorm initiation to the southwest of (roughly) the Cheyenne ridge into Kansas/Nebraska border area. However, there is a signal in at least some model output that a perturbation emerging from the Great Basin may support a developing cluster of storms along this corridor by early this evening. Aided by a northwesterly component to the mid-level flow across this vicinity, it is possible that this activity may develop a southeastward propagation into a more moist and potentially unstable environment beneath the strong capping across northwestern Kansas. If this occurs, the development of an MCV with strengthening rear inflow and increasing potential for strong surface gusts is possible late this evening into the overnight hours. ...Southern Great Plains... Beneath the warmer and more strongly capping mid-level environment, the higher terrain of southeastern Colorado into northeastern New Mexico may provide a focus for thunderstorm initiation. It is possible that this will be supported by a weak perturbation progressing around the northeastern periphery of the subtropical high, and modest northwesterly mid-level flow will aid propagation of a consolidating cluster of convection into Texas Panhandle vicinity. As this occurs, inflow of air characterized by moderate to large CAPE may contribute to intensification into an organizing cluster posing a risk for strong wind gusts this evening into the overnight hours. ...Montana... An environment becoming characterized by modest destabilization and shear, ahead of a lead short wave trough progressing into the northern Rockies, may become supportive of organized convection spreading across the mountains of western through south central Montana late this afternoon into tonight. It appears that this activity could become at least marginally supportive of severe hail and wind before weakening overnight. ...Southern New England... A mid-level short wave trough and weak surface low may provide support for thunderstorm development overspreading much of southern New England today. Despite generally weak low-level wind fields and instability, seasonably high moisture content may contribute to locally heavy precipitation loading and a couple of strong downbursts. ...Eastern Gulf coast vicinity/northern Florida... Modest mid-level speed maxima (on the order of 20-30+ kt) within the broadly cyclonic westerly flow may contribute to potential for locally damaging wind gusts in scattered strong thunderstorm development today. ..Kerr/Thornton.. 07/10/2023 Read more CHECK UPDATE ZOOM GRAPHIC