snowlover2 Posted July 17, 2020 Share Posted July 17, 2020 SPC has expanded the moderate risk area into northwest WI and the enhanced across the rest of north WI into the UP of MI. They even say in the disco that a derecho appears possible. Quote Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Fri Jul 17 2020 Valid 171630Z - 181200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH TONIGHT ACROSS PARTS OF THE NORTHERN PLAINS AND UPPER MIDWEST... ...SUMMARY... A significant severe weather event is possible this evening and tonight over parts of North Dakota, northern Minnesota, and northwest Wisconsin. Widespread damaging winds are possible. ...ND to WI/Upper MI... Morning water vapor loop shows fast westerly flow across the northern tier of states, with an embedded low-amplitude shortwave trough over eastern MT. Southerly low-level winds are present across the Dakotas, with local VADs showing 20-30 knots at 1-2km. These winds are helping to transport 70s surface dewpoints northward, yielding an axis of MLCAPE exceeding 4000 J/kg later today from central ND into western MN. Thunderstorms are expected to form early this afternoon as forcing overspreads the returning moisture, with a few supercells capable of large hail, damaging winds, or perhaps a tornado over western/central ND. All guidance lends confidence that these storms will congeal into one or more bowing structures by this evening over eastern ND. Storms will track rapidly eastward at 40-50 knots across parts of MN and into northern WI and upper MI overnight. Given the very favorable thermodynamic profiles in place, the strong westerly flow aloft, and the consistent model guidance, it appears possible that a derecho will occur this evening and tonight from ND to WI - with the threat of a corridor of widespread and significant damaging winds. Have expanded the MDT/ENH risks eastward into parts of WI/Upper MI where the bowing complex appears most likely to track late tonight. Have also expanded the ENH southward into more of central MN due to uncertainty of how far south the MCS might develop. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted July 17, 2020 Share Posted July 17, 2020 Miss north FTL. Just get to bake tomorrow and Sunday. Link to comment Share on other sites More sharing options...
madwx Posted July 17, 2020 Share Posted July 17, 2020 Just now, CheeselandSkies said: Miss north FTL. Saturday night is gonna be a dead on hit. Like the Summer nighttime MCS of yore. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted July 17, 2020 Share Posted July 17, 2020 Just now, madwx said: Saturday night is gonna be a dead on hit. Like the Summer nighttime MCS of yore. We shall see... Link to comment Share on other sites More sharing options...
crossbowftw3 Posted July 17, 2020 Share Posted July 17, 2020 Rather concerning wording at 1630- 7000 SBCAPE pooling in ND already https://www.spc.noaa.gov/products/outlook/day1otlk.html Link to comment Share on other sites More sharing options...
madwx Posted July 17, 2020 Share Posted July 17, 2020 I'm ready for the 2 straight hours of strobe like lightning 2 Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 17, 2020 Share Posted July 17, 2020 Solid support for a weakening MCS to move in very early Sunday morning around here. However, I'm not sold on anything more than a marginal worthy severe threat. Link to comment Share on other sites More sharing options...
Baum Posted July 17, 2020 Share Posted July 17, 2020 ^ ugh. a thundershower around breakfast and than clouds to spoil the heat. Hoping this thing is racing so it maintains some intensity and than clears MBY. 1 1 Link to comment Share on other sites More sharing options...
snowlover2 Posted July 17, 2020 Author Share Posted July 17, 2020 No real change on the updated day 2 but they do mention that an enhanced area will likely be needed. Quote Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1239 PM CDT Fri Jul 17 2020 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE UPPER MIDWEST AND GREAT LAKES REGION... ...SUMMARY... Scattered severe storms should occur Saturday across portions of the Upper Midwest and Great Lakes vicinity. Damaging winds and large hail appear to be the main hazards with these storms, some of which could be significant. A few tornadoes are also possible. ...Upper Midwest through Great Lakes areas... An MCS will likely be ongoing over a portion of the Great Lakes region, most likely from upper MI into WI, with trailing outflow boundary extending farther southwest into southern MN. Meanwhile, farther upstream, a progressive shortwave trough will reside over the northern Plains with accompanying cold front likely extending from eastern ND southwestward through western SD. This front will continue east and likely extend from northern MN through eastern SD, central NE into northeast CO by early afternoon. The atmosphere in vicinity of and south of the outflow boundary and east of the cold front will likely once again become very unstable with 3000-4000 J/kg MLCAPE supported by rich low-level moisture and steep lapse rates. Initial thunderstorms will most likely develop near intersection of the cold front and remnant outflow boundary from southeast SD into southwest MN. This region will reside within belt of stronger mid-level winds supporting 35-40 kt effective bulk shear. Discrete supercells will be likely with a threat for large to very large hail and a few tornadoes possible as well. Eventually storms should evolve into an organized MCS with an increasing threat for damaging wind, some of which could be significant. Considerable uncertainty still exists regarding where tonight's MCS and outflow boundary will have the most impact on Saturday's pre-storm environment. Will therefore leave as SLGT risk for now. However, an upgrade to enhanced will probably be needed for a portion of this region in upcoming day 1 outlooks. ..Dial.. 07/17/2020 Link to comment Share on other sites More sharing options...
RyanDe680 Posted July 17, 2020 Share Posted July 17, 2020 Borderline meh for the metro 1 Link to comment Share on other sites More sharing options...
Hoosier Posted July 17, 2020 Share Posted July 17, 2020 8 minutes ago, RyanDe680 said: Borderline meh for the metro I'd agree with that at this point. Timing not great (could be even worse I guess) and also some indications of any heavier activity missing to the west. Link to comment Share on other sites More sharing options...
madwx Posted July 17, 2020 Share Posted July 17, 2020 this mornings 3km NAM has a good handle on the current storms, just about an hour or 2 late with the development 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted July 17, 2020 Share Posted July 17, 2020 3 hours ago, madwx said: I'm ready for the 2 straight hours of strobe like lightning Bring it. If that timing is right, I'll be going to work in the trailing stratiform precip region, which if any luck will have some lightning I can catch on-air with our skycams. Link to comment Share on other sites More sharing options...
Hoosier Posted July 17, 2020 Share Posted July 17, 2020 18Z HRRR was pretty far north with Sat-early Sun. Link to comment Share on other sites More sharing options...
snowlover2 Posted July 17, 2020 Author Share Posted July 17, 2020 Got the very rare PDS T-storm watch for a good chunk of MN. Quote URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 380 NWS Storm Prediction Center Norman OK 535 PM CDT Fri Jul 17 2020 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northern and central Minnesota Southeast North Dakota Northern South Dakota * Effective this Friday afternoon and Saturday morning from 535 PM until 100 AM CDT. ...THIS IS A PARTICULARLY DANGEROUS SITUATION... * Primary threats include... Widespread damaging winds expected with scattered significant gusts to 90 mph likely Scattered large hail and isolated very large hail events to 2.5 inches in diameter possible A couple tornadoes possible SUMMARY...An intense linear-type complex of storms is expected to evolve into a derecho this evening and produce widespread/significant damaging winds as it accelerates east-southeastward across the region. Isolated large hail is also possible, and a tornado risk cannot be ruled out, particularly near the warm front. The severe thunderstorm watch area is approximately along and 85 statute miles north and south of a line from 85 miles north of Mobridge SD to 45 miles east of Brainerd MN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. 2 Link to comment Share on other sites More sharing options...
purduewx80 Posted July 17, 2020 Share Posted July 17, 2020 4 hours ago, Hoosier said: I'd agree with that at this point. Timing not great (could be even worse I guess) and also some indications of any heavier activity missing to the west. I dunno, most guidance suggests whatever is left moves through Chicago/N IN Sunday morning...pretty much the least favorable time for severe wx, climatologically. Link to comment Share on other sites More sharing options...
Hoosier Posted July 17, 2020 Share Posted July 17, 2020 2 minutes ago, purduewx80 said: I dunno, most guidance suggests whatever is left moves through Chicago/N IN Sunday morning...pretty much the least favorable time for severe wx, climatologically. Guess it depends. If it can get in at like 4 am, I'd consider that marginally better than 7 am. Link to comment Share on other sites More sharing options...
purduewx80 Posted July 17, 2020 Share Posted July 17, 2020 Just now, Hoosier said: Guess it depends. If it can get in at like 4 am, I'd consider that marginally better than 7 am. agreed. as others have pointed out, there are positives to MCS maintenance that time of night. Link to comment Share on other sites More sharing options...
OrdIowPitMsp Posted July 18, 2020 Share Posted July 18, 2020 Gust of 73mph 2mi N of Holt MN. The sound of chainsaws will be widespread across the northland come tomorrow 4 Link to comment Share on other sites More sharing options...
A-L-E-K Posted July 18, 2020 Share Posted July 18, 2020 Heck of a right blinker 2 Link to comment Share on other sites More sharing options...
Hoosier Posted July 18, 2020 Share Posted July 18, 2020 Wild divergence between the 3 km and 12 km NAM tomorrow night. 1 Link to comment Share on other sites More sharing options...
madwx Posted July 18, 2020 Share Posted July 18, 2020 suffice to say the HRRR was wrong about the path of the MCS tonight 2 1 Link to comment Share on other sites More sharing options...
wisconsinwx Posted July 18, 2020 Share Posted July 18, 2020 4 hours ago, madwx said: suffice to say the HRRR was wrong about the path of the MCS tonight More southward building than even I thought. Link to comment Share on other sites More sharing options...
A-L-E-K Posted July 18, 2020 Share Posted July 18, 2020 strong llj really helping to sustain what remains of overnight MCS into N. IA right now but it should crap the bed here as the jet fades Link to comment Share on other sites More sharing options...
Powerball Posted July 18, 2020 Share Posted July 18, 2020 Thread should probably be extended to include the 19th, for the Eastern GL and OH Valley. I wouldn't be surprised if the slight risk area gets expanded back NW to Detroit and Toledo, although it is contingent on how tonight's activity evolves. SPC AC 180558 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Sat Jul 18 2020 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN OH INTO NORTHWESTERN PA AND WESTERN NY... ...SUMMARY... Isolated strong to severe thunderstorms may occur Sunday from portions of the Great Lakes/Ohio Valley regions into the mid Mississippi Valley and parts of the Plains. Damaging winds and large hail should be the main threats. ...Great Lakes into the Ohio Valley and Western New York... An MCS may be ongoing at the start of the period Sunday morning across parts of Lower MI, with additional convection possible farther south into northern IL/IN. This MCS should decay quickly across Lower MI and vicinity as it encounters substantial convective inhibition with eastward extent across the Great Lakes region. Depending on its organization, it may still pose an isolated threat for damaging winds before it weakens/dissipates. In the wake of this morning activity, an upper trough is forecast to move east-northeastward from the Upper Midwest/Great Lakes into Ontario and Quebec through the period. A surface low should likewise develop northeastward across Ontario/Quebec through the day. A cold front trailing southwestward from this low across the Great Lakes/Upper Midwest should shift east-southeastward. Diurnal heating of a rather moist low-level airmass will likely foster moderate to potentially strong instability ahead of the front by Sunday afternoon. The stronger large-scale ascent associated with the upper trough should remain in Canada. Regardless, low to mid-level westerly flow is forecast to strengthen through the day across parts of the OH Valley into western PA/NY. A corresponding modest increase in effective bulk shear to around 25-35 kt will probably be sufficient for storm organization. Current expectations are for scattered storms to develop along/ahead of the front Sunday afternoon across northern IN/OH. Additional convection may advance eastward from southern Ontario across Lakes Erie/Ontario, and into northwestern PA and western NY by early Sunday evening. Clusters/small bows should the main storm mode. With steepened low-level lapse rates and enhanced low/mid-level flow across these areas, at least isolated damaging wind gusts may occur. Isolated instances of marginally severe hail also appear possible. Confidence has increased enough regarding this scenario to include 15% severe wind probabilities and a corresponding Slight Risk from northern OH into western NY. Storms should gradually weaken Sunday evening farther east into central PA/NY as they encounter less instability. Link to comment Share on other sites More sharing options...
wisconsinwx Posted July 18, 2020 Share Posted July 18, 2020 43 minutes ago, A-L-E-K said: strong llj really helping to sustain what remains of overnight MCS into N. IA right now but it should crap the bed here as the jet fades We’ll see, definite signs the last half hour of disorganization but still tons of lightning with the MCS. Link to comment Share on other sites More sharing options...
OrdIowPitMsp Posted July 18, 2020 Share Posted July 18, 2020 Storms rolled through here around 3am while weakening. MSP managed a 55MPH gust. Widespread 2-3" rain totals up north where they really needed it. Link to comment Share on other sites More sharing options...
A-L-E-K Posted July 18, 2020 Share Posted July 18, 2020 Still hanging Link to comment Share on other sites More sharing options...
A-L-E-K Posted July 18, 2020 Share Posted July 18, 2020 Rapidly destabilizing downstream now Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 18, 2020 Share Posted July 18, 2020 23 minutes ago, A-L-E-K said: Still hanging Struggling to maintain, with shear lacking and best flow north. This is probably the best it'll get. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now