Chinook Posted July 7, 2014 Share Posted July 7, 2014 As I posted on the Lakes/Ohio Valley subforum: 11 (or 13) tornadoes in Iowa on July 6th-- no tornado or severe watch in this area! Link to comment Share on other sites More sharing options...
jcwxguy Posted July 7, 2014 Share Posted July 7, 2014 thats a failure for SPC Link to comment Share on other sites More sharing options...
andyhb Posted July 7, 2014 Share Posted July 7, 2014 Moderate risk considered in the latest D1, may include one later for winds. Looks like central/eastern NE might be in for another hit. ...CENTRAL PLAINS...CONSIDERED PROBABILITY AND CATEGORICAL UPGRADES TO SUPPORT A MDTRISK FOR WIDESPREAD DAMAGING WINDS OVER PARTS OF NEB/MO/IA.HOWEVER...EARLY AFTERNOON TOPEKA AND OMAHA RAOBS SUGGEST THATMOISTURE AND/OR CAPPING WILL CONTINUE TO POSE A CHALLENGE FOR MOREINTENSE CONVECTIVE DEVELOPMENT...AT LEAST IN THE SHORT-TERM.ADDITIONALLY...THERE APPEAR TO BE A VARIETY OF SCENARIOS IN TERMS OFSTORM EVOLUTION ACROSS THE NEB/KS AREAS THROUGH LATE AFTERNOON THATINTRODUCE GREATER UNCERTAINTY. STORMS MAY EVOLVE FROM AT LEAST TWODIFFERENT MECHANISMS THIS AFTERNOON. 1) ACTIVITY INCREASING ALONGRESIDUAL FRONTAL SEGMENT ACROSS WRN CO AND WRN KS MAY GROW UPSCALEAND POSE WIND AND LARGE HAIL HAZARDS EAST ACROSS KS/SRN NEB. 2)SHORTWAVE TROUGH DIGGING SEWD ACROSS SD MAY SUSTAIN CONVECTIVECLUSTER RECENTLY INTENSIFYING ACROSS SOUTHWEST SD. THIS CONVECTIONMAY DEVELOP INTO A RECOVERING AIRMASS ACROSS NEB INTO LATE AFTERNOONWITH INCREASINGLY STRONG MID-LEVEL WEST-NORTHWESTERLY FLOWCONTRIBUTING TO A FORWARD-PROPAGATING MCS WITH WIND AND HAILPOTENTIAL INTO EASTERN NEB/SOUTHERN IA AND NORTHERN MO INTO THE LATEEVENING. IT IS ALSO POSSIBLE THAT A COMBINATION OF SCENARIOS 1 AND 2RESULT IN HIGHER-END DAMAGING WIND THREAT ACROSS PARTS OF THE MORIVER VALLEY THROUGH LATE TONIGHT. IF THE GREATER POTENTIAL FORWIDESPREAD DAMAGING WINDS BECOME MORE OBVIOUS WITH TIME...IT REMAINSPOSSIBLE THAT A MDT RISK WILL BE ISSUED GIVEN MAGNITUDE OFINSTABILITY AND DEVELOPING SHEAR EXPECTED ACROSS NEB/IA/MO AREASTHROUGH TONIGHT. Link to comment Share on other sites More sharing options...
brettjrob Posted July 7, 2014 Share Posted July 7, 2014 Moderate risk considered in the latest D1, may include one later for winds. Looks like central/eastern NE might be in for another hit. It's uncanny how certain hotspots will emerge any given year and keep taking the brunt of the action time and time again. Granted, part of it is simply that the pattern got "hot" right around the climatological peak for NE/IA (mid-late June). Link to comment Share on other sites More sharing options...
Chinook Posted July 7, 2014 Share Posted July 7, 2014 The HRRR advertises a large, potentially dangerous MCS in Kansas and Missouri tonight Link to comment Share on other sites More sharing options...
Chinook Posted July 8, 2014 Share Posted July 8, 2014 A very large group of hail/wind producing storms is developing, in areas of very high CAPE, helicity and shear, Nebraska, Missouri, Iowa and Kansas. Here's my video capture of a lightning bolt tonight. Link to comment Share on other sites More sharing options...
nrgjeff Posted July 8, 2014 Share Posted July 8, 2014 thats a failure for SPC They have forgotten how to forecast without hi-res models. When the models choke, so does SPC. Link to comment Share on other sites More sharing options...
brettjrob Posted July 9, 2014 Share Posted July 9, 2014 They have forgotten how to forecast without hi-res models. When the models choke, so does SPC. That's a ridiculous claim, in light of the past few weeks as a whole. During the big outbreak sequence from June 16-18, the hi-res models "choked" almost from start to finish. Yet, SPC did pretty well on each of those days. How about on June 16, when they issued a PDS Tornado Watch for E NE, and virtually none of the hi-res models initiated storms anywhere near the place/time of the Stanton/Pilger/Wisner activity? I've seen no indication that over-reliance on hi-res models is an issue within the NWS, at least on a widespread basis. In the case of this past weekend, I would say the ingredients and synoptic pattern (i.e., strongly veered surface flow) were an outlier among environments producing substantial tornadoes in that region. Hi-res models had little to do with it. Whether a watch should have been issued more quickly once tornadoes developed is at least a legitimate discussion to have, but you're jumping to unreasonable conclusions. Link to comment Share on other sites More sharing options...
Chinook Posted July 9, 2014 Share Posted July 9, 2014 Once again, a threat for severe storms in central Nebraska and central Kansas. There are currently some hail-bearing supercells in Nebraska (GRLevel3 hail estimation says 3.75" hail on one storm, Loup City Nebraska) New watch issued for high plains ----- SEVERE THUNDERSTORM WATCH NUMBER 408 445 PM MDT WED JUL 9 2014 THE NWS STORM PREDICTION CENTER HAS ISSUED A * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF NORTHEAST COLORADO NORTHWEST KANSAS WESTERN...CENTRAL...AND NORTHERN NEBRASKA --- Here's the storm I was talking about -- about maxed out on reflectivity and VIL, probably 2-3" hail, some low-altitude rotation Link to comment Share on other sites More sharing options...
nwohweather Posted July 10, 2014 Share Posted July 10, 2014 Lol at that Day 2 Slight Risk. It's probably the smallest area I've ever seen Link to comment Share on other sites More sharing options...
nrgjeff Posted July 10, 2014 Share Posted July 10, 2014 Yes I believe they did an excellent job middle to late June. SPC made some great catches. June 16 SPC issued excellent non-model based discussions, using fundamentals. However the season as a whole, including a late May and early June slump, has shown too much reliance on high-res models. That's a ridiculous claim, in light of the past few weeks as a whole. During the big outbreak sequence from June 16-18, the hi-res models "choked" almost from start to finish. Yet, SPC did pretty well on each of those days. How about on June 16, when they issued a PDS Tornado Watch for E NE, and virtually none of the hi-res models initiated storms anywhere near the place/time of the Stanton/Pilger/Wisner activity? I've seen no indication that over-reliance on hi-res models is an issue within the NWS, at least on a widespread basis. In the case of this past weekend, I would say the ingredients and synoptic pattern (i.e., strongly veered surface flow) were an outlier among environments producing substantial tornadoes in that region. Hi-res models had little to do with it. Whether a watch should have been issued more quickly once tornadoes developed is at least a legitimate discussion to have, but you're jumping to unreasonable conclusions. I'm not an NWS basher. I'm a fan and believe the warning system saves countless lives. Just making an observation, and offering a chance to learn, during this squirrelly 2014 severe season. Link to comment Share on other sites More sharing options...
Quincy Posted July 20, 2014 Share Posted July 20, 2014 No excitement over the Day 2 moderate? Looks like a very unstable air-mass with decent speed shear. Models showing a heck of a lot of directional shear along the warm front in SE North Dakota early Monday evening. Link to comment Share on other sites More sharing options...
Jim Marusak Posted July 20, 2014 Share Posted July 20, 2014 No excitement over the Day 2 moderate? Looks like a very unstable air-mass with decent speed shear. Models showing a heck of a lot of directional shear along the warm front in SE North Dakota early Monday evening. some of the hesitance, imho, might be because of the big lid between all that low level moisture and the extreme instability (3500+ j/kg, li's near -8, TT near 55) shown on the NAM and GFS. the Canadian Regional also is showing more than a bit of hesitance in trying to tap all that instability. but that being said, shrink/weaken that lid, given everything else available, and moderate risk might be the least of our worries in MN/WI/e ND/e SD. would like to see the soundings at 12 and 18Z tomorrow as well as 00Z Tuesday in ABR, MPX, BIS, and INL to see what we'll be dealing with in the lid. Link to comment Share on other sites More sharing options...
Chinook Posted July 20, 2014 Share Posted July 20, 2014 As was mentioned in the Lakes/Ohio Valley Subforum, The GFS had 85 dew points predicted in Iowa, back a few days ago, (valid for tomorrow.) I posted a ridiculous 9000 J/kg forecast sounding (from the Dupage web site). Now it looks fairly accurate to say that Sioux City/Sioux Falls should have 7000-8000 J/kg CAPE later tomorrow, with dew points around 77. I think the moderate risk may be overdone, despite the huge cape and 40 kts of 0-6km shear in South Dakota. I am always wary of the times when the models forecast huge CAPE. The NAM/SREF suggest several thunderstorms initiating in eastern North Dakota, continuing to Minnesota. Link to comment Share on other sites More sharing options...
andyhb Posted July 20, 2014 Share Posted July 20, 2014 As was mentioned in the Lakes/Ohio Valley Subforum, The GFS had 85 dew points predicted in Iowa, back a few days ago, (valid for tomorrow.) I posted a ridiculous 9000 J/kg forecast sounding (from the Dupage web site). Now it looks fairly accurate to say that Sioux City/Sioux Falls should have 7000-8000 J/kg CAPE later tomorrow, with dew points around 77. I think the moderate risk may be overdone, despite the huge cape and 40 kts of 0-6km shear in South Dakota. I am always wary of the times when the models forecast huge CAPE. The NAM/SREF suggest several thunderstorms initiating in eastern North Dakota, continuing to Minnesota. The moderate risk isn't focused in SD tomorrow, for starters. SPC is definitely aware of models overestimating dewpoints. There will still be >3000 J/kg CAPE in the warm sector tomorrow, which is more than enough for a higher end MCS especially if a cold pool develops. The NAM, as I've said many times this Spring/Summer, has been terrible at convective forecasting (and generally everything else). With regards to capping, SPC must be at least reasonably confident in it breaking if they are issuing a D2 moderate, which are rather rare in July. It really doesn't look that strong in most of the forecast soundings I looked at. Link to comment Share on other sites More sharing options...
Jim Marusak Posted July 21, 2014 Share Posted July 21, 2014 anyone know if the TTAA's and PPBB's are out yet for INL? EC-Ontario just put up a tornado watch from the Lake of the Woods and Red Lake to Lake Nipigon, not quite including T-bay or Superior-West. And with it being the time for the soundings, they must have seen something in the 00Z that caused them to put up a Tornado watch now, especially since Downsview is quite tight in putting out tornado watches in general. edited lines below well, now I know why. courtesy the University of Wyoming, here's this evening's sounding from 72747/INL. http://weather.uwyo.edu/upperair/bimages/2014072100.72747.skewt.parc.gif Link to comment Share on other sites More sharing options...
Minnesota Meso Posted July 21, 2014 Share Posted July 21, 2014 Concerning Monday 7/21/2014. Looking at the forecast sounding for tomorrow night for MSP I see a nice temp inversion from H85 to H8 and temps at 700mb at or very close to 14° C. This could be hard to break. Best guess at this time is that the severe threat should be north of the TC metro and affect the area north of a line from Montevideo to St Cloud to far Nw WI. I'm getting somewhat concerned about the BWCA area. Of course this is based off the NAM 0z/07/21 run. Here is the 12° C line at the same time. Link to comment Share on other sites More sharing options...
Jim Marusak Posted July 21, 2014 Share Posted July 21, 2014 the trend continues for capping issues in southern MN on the 06z nam. but further north, esp north of St Cloud, Aberdeen, and the twin cities. but that being said, if you could bust the lids, according to the soundings, you're pretty much expecting anything and everything just from the pure energy available. i'll post a few of the soundings for perspective. BIS at 4pm GFK at 6pm AXN at 7pm FAR at 7pm INL at 7pm STC at 7pm RWF at 7pm and the twin cities/MSP at 7pm Link to comment Share on other sites More sharing options...
MCS_hunter Posted July 21, 2014 Share Posted July 21, 2014 Saw the northward shift in the mod risk coming yesterday. Even yesterday's 12z runs gave a clue about it so I'm not sure why spc had the mod risk so far south to begin with. Link to comment Share on other sites More sharing options...
bdgwx Posted July 21, 2014 Share Posted July 21, 2014 Saw the northward shift in the mod risk coming yesterday. Even yesterday's 12z runs gave a clue about it so I'm not sure why spc had the mod risk so far south to begin with. I'm with you. I didn't look at the 12Z closely, but by the 18Z runs the threat was definitely more north and west. Obviously the SPC wouldn't have had time to use that run in its decision making process. Right now though the moderate risk area matches up pretty well with the storm scale modeling. The 4km NAM nest is showing a few discrete UH tracks whereas the HRW flavors are showing UH tracks for MCVs only. The MCS and associated wind appears to be the dominant threat from all three. The updraft velocity products from the HRW flavors are showing a pretty potent MCS. Link to comment Share on other sites More sharing options...
Chinook Posted July 21, 2014 Share Posted July 21, 2014 The 15z HRRR starts out some storms in southwest ND, and continues that group towards the Boundary Waters Canoe Area. edit: and the tornado watch is already up, with a few storms in southwest North Dakota -- TORNADO WATCH NUMBER 426 NWS STORM PREDICTION CENTER NORMAN OK 110 PM CDT MON JUL 21 2014 THE NWS STORM PREDICTION CENTER HAS ISSUED A * TORNADO WATCH FOR PORTIONS OF WESTERN AND CENTRAL NORTH DAKOTA DISCUSSION...THUNDERSTORMS ARE INTENSIFYING OVER WESTERN ND. THIS ACTIVITY WILL CONTINUE TO GROW AND BUILD EASTWARD ... Link to comment Share on other sites More sharing options...
andyhb Posted July 21, 2014 Share Posted July 21, 2014 That cluster organizing near Dickinson has significant I-94 MCS written all over it. Mid 70s dewpoints with extreme instability (4000-5000 J/kg MLCAPE, >5000 J/kg MUCAPE) out ahead of it with large DCAPE values >1000 J/kg, steep mid level lapse rates of 8-9˚C/km and CB sig svr up to 100 in eastern ND per mesoanalysis. There appears to be a s/w trough advancing eastward from MT/WY that should enhance deep layer shear somewhat as well. Backing surface winds might enhance the tornado potential. Link to comment Share on other sites More sharing options...
andyhb Posted July 21, 2014 Share Posted July 21, 2014 Right on cue... MESOSCALE DISCUSSION 1420NWS STORM PREDICTION CENTER NORMAN OK0320 PM CDT MON JUL 21 2014AREAS AFFECTED...PORTIONS OF NDCONCERNING...TORNADO WATCH 426...VALID 212020Z - 212115ZTHE SEVERE WEATHER THREAT FOR TORNADO WATCH 426 CONTINUES.SUMMARY...LARGE HAIL/SOME TORNADO RISK IS EXPECTED TO CONTINUE THISAFTERNOON. HOWEVER...THE POTENTIAL FOR WIDESPREAD/INTENSE DAMAGINGWINDS IS OTHERWISE EXPECTED TO STEADILY INCREASE THROUGH LATEAFTERNOON ACROSS ND. TORNADO WATCH 426 CONTINUES UNTIL 00Z.DISCUSSION...EARLIER SEMI-DISCRETE STORMS ACROSS WEST/SOUTHWEST NDHAVE QUICKLY CONGEALED INTO A LOOSELY ORGANIZED LINEAR COMPLEX AS OF20Z...WITH A SOUTH-END SUPERCELL NOTED TO BE NEARING THE I-94VICINITY AROUND/JUST EAST OF DICKINSON. A LARGE HAIL/TORNADO RISK ISPOSSIBLE WITH THIS STORM...AND/OR OTHER GRADUALLY INCREASINGDEVELOPMENT ACROSS NORTH-CENTRAL ND...ESPECIALLY IN VICINITY OF ASURFACE BOUNDARY THAT ANGLES GENERALLY SOUTHWEST-NORTHEAST ACROSSND.HOWEVER...THE DEVELOPMENT/MATURATION OF A SPATIALLY EXPANDINGQUASI-LINEAR MESOSCALE CONVECTIVE SYSTEM WILL LIKELY BE THEPREVALENT SCENARIO. AS THIS SYSTEM CONTINUES TO GROW UPSCALE ANDACCELERATE EAST-NORTHEASTWARD...WIDESPREAD/POTENTIALLY INTENSEDAMAGING WINDS SHOULD BECOME AN INCREASING CONCERN BY LATE AFTERNOONACROSS CENTRAL ND. THIS MCS WILL THRIVE WITHIN AN ENVIRONMENT THATIS CHARACTERIZED BY STRONG TO EXTREME INSTABILITY...WITH 18ZOBSERVED REGIONAL SOUNDINGS/SPC OBJECTIVE ANALYSIS SUPPORTIVE OF2500-5000 J/KG MLCAPE ACROSS CENTRAL/EASTERN ND...GUYER.. 07/21/2014 Link to comment Share on other sites More sharing options...
bdgwx Posted July 21, 2014 Share Posted July 21, 2014 18Z special sounding from BIS is showing plenty of instability, but the wind shear is on the lower end of the severe thresholds. I'm sure wind fields will increase throughout the evening though. And, of course, there is more instability the further east you go from BIS. Link to comment Share on other sites More sharing options...
Jim Marusak Posted July 21, 2014 Share Posted July 21, 2014 18Z special sounding from BIS is showing plenty of instability, but the wind shear is on the lower end of the severe thresholds. I'm sure wind fields will increase throughout the evening though. And, of course, there is more instability the further east you go from BIS. yea, shear is marginal. but with that much cape in the parcel, that alone can take what shear is available and turn it into major problems. and with the lids as they appear on the full set of 18z supplemental soundings (BIS, INL, ABR, and MPX), they pretty much are going with what some in here pictured yesterday as well as most of the models, with the weaker lid near/north of STC/DIK than to the south. that being said, if you can break the lid down here in the twin cities or in the US 212 corridor, we are screwed. Link to comment Share on other sites More sharing options...
Chinook Posted July 21, 2014 Share Posted July 21, 2014 Bismarck radar is now showing some higher base velocities near New Salem ND. I think they will have more 60-70mph wind reports there in the next half hour. Link to comment Share on other sites More sharing options...
andyhb Posted July 21, 2014 Share Posted July 21, 2014 Going strong now moving east at 45-50 mph, have some impressive velocities aloft from Bismarck (70-80+ kts) and also several 70+ mph wind reports in the past couple hours. Seeing some upper 70s, even 80 degree dewpoints in E ND and NE SD per latest obs. DCAPE has increased into the 1300-1500 J/kg range ahead of it, in addition to SB/MLCAPE hovering at 4500-6500 J/kg. Link to comment Share on other sites More sharing options...
bdgwx Posted July 21, 2014 Share Posted July 21, 2014 This was awhile ago, but L3 radar data had a couple of 95 kt bins in the bookend vortex at 1 km. I'd imagine there were some pretty strong gusts there, but I haven't seen any reports. Link to comment Share on other sites More sharing options...
Chinook Posted July 22, 2014 Share Posted July 22, 2014 It certainly seems like a textbook case derecho at this point (if it keeps producing wind reports). It seems to have formed and intensified in a relative minimum of 0-6km shear though. Link to comment Share on other sites More sharing options...
MCS_hunter Posted July 22, 2014 Share Posted July 22, 2014 Storms beginning to develop in northern SD now. Link to comment Share on other sites More sharing options...
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