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An attendant threat for severe weather once again presents itself across portions of the Northern Plains today, with a large area from NE MT to central MN and much of central NE outlined by the SPC for a slight risk of severe weather.  Despite ongoing convection across eastern portions of the region, a mid-level disturbance should move east into western portions of the outlook area, as a surface low currently centered over WC SD, with an ancillary, albeit weak surface boundary, works its way towards central SD this evening.

The atmosphere is expected to become unstable across parts of the region by late this afternoon, with convection possibly developing across parts of central and north central SD and eastern ND between 19z and 21z, moving ESE throughout the evening.  Available instability, ample precipitable water values (high moisture content) and favorable deep layer shear profiles (both were evident per 12z BIS and ABR soundings) will support the risk for damaging winds, large hail (>1.00″), heavy rainfall, and potentially even a few tornadoes within the deepest convection.  The greatest tornado threat appears to be juxtaposed with the best shear in the vicinity (ESE) of the triple point, as the warm sector wraps into the low pressure system.  Additionally, any storms that can become rooted in the boundary layer near the weak surface convergence will also have the potential to be tornadic.

Be sure to check back with ChaserTV for the availability of any live streamer feeds that may come available later today; remember that you can also follow us on Twitter and Facebook for breaking weather updates too.

JLR

The Northern Plains will once again become active today, with a more appreciable threat for severe weather across a broader area from the eastern Dakotas into the northwestern Great Lakes region.  A shortwave centered over the Prairie Provinces of west central Canada will progress eastward towards the central Canadian Shield.  H25 flow of ~ 100 kts will exist coterminously with strong westerly H5 flow of ~ 60 kts as a vort max approaches southeastern MB late this afternoon.

A concomitant surface low will move into WC ON by early afternoon, with an ancillary cold front extending from near YHD to ABR by 18z.  SW H85 flow of 30-40 kts will continue to anneal throughout the afternoon, as strong WAA in advance of the CF engenders SBCAPE values on the order of 2000 – 3000 J/KG, with LI values progged to be < -6C across the region and SFC-500 mb shear values AOA 55 kts across a broad swath from NC MN to SW ON.   While 700 mb temps of 10C – 12C will be found across the region, CIN should erode in advance of the front in association with strong forcing.  This strong forcing coupled with adequate low level moisture, instability and low level WAA courtesty of a strengthening SW H85 flow will provide the impetus for the development of deep convection.

Ample speed shear, with a 20 kt increase between 850mb and 250 mb per KDLH forecast SKEW-T via RUC guidance (the 12z observed sounding at INL is posted below), and suitable directional shear engender the threat for rotating updrafts and perhaps some discrete activity early in the evolution of this event.  While tornado potential exists courtesy of these favorable shear profiles, there is also an attendant threat for damaging winds, with mean downdraft CAPE >=1000 J/KG present across much of the area per SREF, and large hail.  Ongoing, elevated convection relatively along and north of I-94 should begin to clear the area through 17z, allowing for atmospheric recovery in the wake of diurnal heating.  Current thinking is that convection will re-initiate by late afternoon ahead of the front, with discrete supercells likely early in the evolution of the event, before transitioning more to a linear mode and moving ESE across the region.  The impact of this morning’s convection as it pertains to remnant OFBs will have to be watched, as any such boundaries will likely enhance tornado potential later this afternoon, should the atmosphere be able to recover across the risk area.

As always, be sure to check back with ChaserTV to see if any live severe weather streams are available from this area.  Additionally, you can follow us on both Facebook and Twitter for the latest breaking severe weather news and updates of noteworthiness.

JLR

The main trough responsible for yesterday’s severe weather episode over the Northern Plains, along with the extensive flooding ongoing across the Upper Mississippi River Valley, will continue to move eastward from its current position over the Western Great Lake/Superior Upland region into the Canadian provinces of Ontario and Quebec later this evening.  A rather respectable H25 jet streak of 120 kts will begin to exit stage right at the base of the trough.

The current mid level wave centered over the Upper Midwest will continue to gyrate eastward towards lower Michigan this afternoon, with stellar H5 winds of 60kts, coupled with stout WSW H85 flow of 40 kts.  This mid level wave, coupled with the attendant surface boundaries, should provide a favorable environment for severe weather this afternoon, mainly in the form of damaging winds, though a tornado or two can not be ruled out.  Commodious instability should germinate this afternoon across the region (RUC and NAM guidance suggests SBCAPE values AOA 2500 J/KG across the region by 22z) as WAA in advance of the shortwave, coupled with decent forcing and ample SFC-500 mb shear profiles of 40-50 kts will promote an environment opulent for severe thunderstorms by this afternoon.

Current RUC and HIRESW forecast soundings are adumbrating largely unidirectional wind profiles across the region (see DTW 22z SkewT below), suggesting a preponderant risk for damaging winds as the primary hazard.  The greatest risk for severe weather will exist across the eastern Corn Belt region and into the eastern Great Lakes region today.

Please tune in to ChaserTV later today to see if any streamers are live in the field with severe weather as it unfolds; be sure to follow us on Twitter and Facebook for the latest severe weather updates too.

JLR

A more appreciable severe weather event is likely over portions of the Northern Plains for late this afternoon and evening, particularly for portions of E SD, SW MN and far NW IA, though an MCS is likely to propagate across roughly the same areas that experienced some severe weather in the Upper Mississippi Valley later tonight, with an enhanced threat for wind damage and heavy rainfall.  A trough currently situated over the eastern Rockies will continue to gyrate eastward into the Dakotas this afternoon.  DPVA and low level WAA associated with the approaching trough should provide the impetus for the ontogenesis of severe weather across that region this afternoon, with an H5 jet maxima of 60 kts approaching the region from the SW, coupled with S-SE H85 flow increasing to 30 kts by 00z.

An attendant surface boundary extending eastward from the surface low is expected to be juxtaposed abutting the I-90 corridor region, or perhaps a soupcon to the south, with ample deep layer shear profiles, especially INVO the triple point.  While latest model guidance suggests that 700 mb temps will be AOA 10C across much of the region, CIN should canker away by late this afternoon.  SBCAPE could easily be AOA 3000 J/KG, along with LI < -8C, so if these shear and instability parameters do indeed metamorphose, E/SE SD, far NW IA and even far SW MN could see an enhanced threat for tornadoes, damaging winds and possibly hail > 1.00″ today.  Current thinking suggests that convection should inaugurate within a PIR to MBG corridor by 22z, with discrete, tornadic supercells a threat early in the evolution if the event, before congealing into a more linear structure and traversing ESE throughout the evening.

As always, be sure to check back here at ChaserTV to see if any live streamers active throughout the region.  You can  also follow us on Facebook or Twitter for the latest breaking weather updates.

JLR