Indystorm Posted February 18, 2017 Share Posted February 18, 2017 Models do struggle with these issues, particularly as we approach seasonal changes from what I have noticed. At least we have had consistency with a storm happening somewhere. Link to comment Share on other sites More sharing options...
Anti tornado Posted February 19, 2017 Author Share Posted February 19, 2017 Link to comment Share on other sites More sharing options...
Jrad08 Posted February 19, 2017 Share Posted February 19, 2017 Continues to look impressive.... dews around 61 with highs mid to upper 60s here. Crazy territory for February Link to comment Share on other sites More sharing options...
Anti tornado Posted February 19, 2017 Author Share Posted February 19, 2017 No idea what dewpoints are off the euro...I dont have a subscription to get ECMWF data. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 19, 2017 Share Posted February 19, 2017 9 minutes ago, Anti tornado said: No idea what dewpoints are off the euro...I dont have a subscription to get ECMWF data. Widespread mid 50s in the warm sector. Dews of 60+ are confined to areas along and south of the TN valley. Link to comment Share on other sites More sharing options...
Hoosier Posted February 19, 2017 Share Posted February 19, 2017 4 minutes ago, cyclone77 said: Widespread mid 50s in the warm sector. Dews of 60+ are confined to areas along and south of the TN valley. To add to this, the Euro still has a bit stronger of a cutoff low than the GFS, but it has been trending weaker. Link to comment Share on other sites More sharing options...
csnavywx Posted February 19, 2017 Share Posted February 19, 2017 15-20F dewpoint depressions along the CF and an occluded low doesn't excite me for severe potential. Euro basically agrees and shuts out most of the warm sector until it's further east and the flow is fully veered. Good if you like a snaky line or elevated hailers north of the warm front. Better moisture return or a later occlusion/deeper low would help. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted February 19, 2017 Share Posted February 19, 2017 SPC has a Day 6 15% for parts of Indiana. Link to comment Share on other sites More sharing options...
IWXwx Posted February 19, 2017 Share Posted February 19, 2017 SPC discounts severe chances in the Plains/Miss. Valley due to that pesky Gulf low that's been discussed here, but believes that moisture return will be sufficient for those of us farther east on Friday. .....Models and their ensembles indicate that an elevated mixed layer originating from the Great Plains will be advected into the highlighted area along with a strong consensus for marginal low-level moisture (50s degrees F boundary-layer dewpoints). Given the expected setup, sufficient confidence is attained for some severe risk to be highlighted graphically, with the expected severe hazard to be mainly damaging winds. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted February 19, 2017 Share Posted February 19, 2017 The GFS has loads of run to run spread on this aspect. Gives us something to watch at least! Link to comment Share on other sites More sharing options...
Anti tornado Posted February 19, 2017 Author Share Posted February 19, 2017 So...interesting analog popped up Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted February 19, 2017 Share Posted February 19, 2017 24 minutes ago, Anti tornado said: So...interesting analog popped up ...And the 18Z GFS got the warmer temps more north again. This is fun! Link to comment Share on other sites More sharing options...
Hoosier Posted February 19, 2017 Share Posted February 19, 2017 The GFS has trended toward a bit more of a southern low again, which is a negative. On the plus side, nice mid-level lapse rates/EML continues to be advertised. Overall severe potential looks a bit muddled to me at this point. Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2017 Share Posted February 20, 2017 5 hours ago, Anti tornado said: So...interesting analog popped up Rule #1 of analog forecasting: never use the most extreme event to evaluate the threat. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted February 20, 2017 Share Posted February 20, 2017 New SPC outlook has a large area highlighted Link to comment Share on other sites More sharing options...
Indystorm Posted February 20, 2017 Share Posted February 20, 2017 5 hours ago, HillsdaleMIWeather said: New SPC outlook has a large area highlighted Yes, and the geographical placement is a bit farther north than I would have initially expected. It seems the threat at present is for a strong squall line. But after what happened last night in northern San Antonio you never know. Link to comment Share on other sites More sharing options...
Hoosier Posted February 20, 2017 Share Posted February 20, 2017 The northern extent looks plausible to me at this point. Whatever magnitude of threat this ends up becoming, one thing about it is that there's no snow on the ground to have to melt off, so the northern extent of the real warm sector won't be contaminated in that way. Shouldn't be a situation where you have to go 200 miles south of the surface low to get into a threat. If you're anywhere along/south of the surface low track, you're pretty much fair game, at least until after it occludes. Link to comment Share on other sites More sharing options...
Indystorm Posted February 20, 2017 Share Posted February 20, 2017 11 hours ago, Hoosier said: The northern extent looks plausible to me at this point. Whatever magnitude of threat this ends up becoming, one thing about it is that there's no snow on the ground to have to melt off, so the northern extent of the real warm sector won't be contaminated in that way. Shouldn't be a situation where you have to go 200 miles south of the surface low to get into a threat. If you're anywhere along/south of the surface low track, you're pretty much fair game, at least until after it occludes. Correct. I might be in Highland In on Friday visiting relatives and coming back to the Indpls area on Sat. so we'll see what happens in our state. Link to comment Share on other sites More sharing options...
Indystorm Posted February 20, 2017 Share Posted February 20, 2017 Latest parameters from model runs have me expecting a QLCS type scenario with some possible spin ups for this Friday over much of IN and Chi-town region. Very good lapse rates and CAPE around 1000 j/kg for this time of year is surprising in addition to all these record setting temps. Link to comment Share on other sites More sharing options...
Hoosier Posted February 21, 2017 Share Posted February 21, 2017 This thing being progged as being in a steady state more or less suggests that sfc winds won't have much trouble veering. Tornado threat isn't zero but it's hard to imagine something appreciable barring significant changes. There's a decent slug of CAPE for this time of year, so hail and areas of damaging winds could occur. Link to comment Share on other sites More sharing options...
Hoosier Posted February 21, 2017 Share Posted February 21, 2017 Here's a forecast sounding near the IN/MI border at 18z Friday. There's some modest low level turning but not much. Link to comment Share on other sites More sharing options...
Stebo Posted February 21, 2017 Share Posted February 21, 2017 16 minutes ago, Hoosier said: Here's a forecast sounding near the IN/MI border at 18z Friday. There's some modest low level turning but not much. I would wait until this gets into the NAM range before looking at hodographs, GFS is notorious for overly veering surface winds. There should be some veering but not to the magnitude it is showing. Link to comment Share on other sites More sharing options...
Hoosier Posted February 21, 2017 Share Posted February 21, 2017 3 minutes ago, Stebo said: I would wait until this gets into the NAM range before looking at hodographs, GFS is notorious for overly veering surface winds. There should be some veering but not to the magnitude it is showing. Fair enough, but what's going to keep the winds more backed in the warm sector (say 180 or less)? I guess an area to watch for perhaps locally enhanced tornado prospects would be right on the warm front, assuming the thermodynamic environment is good enough. Link to comment Share on other sites More sharing options...
Stebo Posted February 21, 2017 Share Posted February 21, 2017 1 hour ago, Hoosier said: Fair enough, but what's going to keep the winds more backed in the warm sector (say 180 or less)? I guess an area to watch for perhaps locally enhanced tornado prospects would be right on the warm front, assuming the thermodynamic environment is good enough. If the system is still strengthening that could help, though I don't know if we will see 180 or less. Anything 200 or less would be fine though or at least give a tornado potential. Link to comment Share on other sites More sharing options...
Quincy Posted February 21, 2017 Share Posted February 21, 2017 There's not much that supports backing of low-level wind fields in the warm sector on Friday. The warm front has been fairly consistently progged to lift north through IN Friday morning and into MI by peak heating. While there may be a marginal tornado threat here, dew-points in the mid-50s won't cut it. Farther south, the guidance is unanimous in veering winds in the lowest km, yielding a largely unidirectional wind field. (00z EC included) Sure, given the magnitude of speed shear, it won't take much subtle backing to enlarge hodographs. The most likely convective mode will be linear with the potential for a few QLCS spin-ups, assuming dew-points can rise into at least the upper 50s. If moisture return is greater than currently progged with northward extent, watch the warm front, but that seems fairly unlikely given this setup and the time of year. While many analogs show some substantial severe events, most of these occurred in March and featured 60+ dews. A quick assessment of model progs also suggests the surface low occludes several hours before peak heating, further suggesting a veering wind profile with southward extent. This includes the 84hr NAM, FWIW. Terrain influences are not helpful and if anything, support a more of a SWrly low-level wind field than a Srly or SErly immediately west of the Appalachians. Thursday looks increasingly interesting SW of this sub-forum, but marginal low-level moisture and capping will most likely keep any threat limited across MO and surrounding areas. Link to comment Share on other sites More sharing options...
Quincy Posted February 21, 2017 Share Posted February 21, 2017 The #1 analog as of 00z is 3/13/06 and that was a busted MDT risk for the Ohio Valley. It's actually a very good analog given the synoptic setup, wind fields and low-level moisture. 18z special ILN RAOB had a 56F dew-point, FWIW: Link to comment Share on other sites More sharing options...
Hoosier Posted February 21, 2017 Share Posted February 21, 2017 Just an observation from today in regards to Friday. Dewpoints have had no trouble rising into the mid/upper 50s in a corridor as far north as Chicago, with even some 60 degree readings near St. Louis. The moisture really won't get shunted south to a major degree in the next couple days, so all this adds confidence in the model progs that are getting mid/upper 50s dewpoints even well into Michigan on Friday. Link to comment Share on other sites More sharing options...
Chargers09 Posted February 21, 2017 Share Posted February 21, 2017 On 2/20/2017 at 9:14 AM, Indystorm said: Yes, and the geographical placement is a bit farther north than I would have initially expected. It seems the threat at present is for a strong squall line. But after what happened last night in northern San Antonio you never know. True. There was only a 2% tornado risk down here on that day. All it takes is a little more low level shear and you get a situation like what happened here on Sunday. (For reference; we're up to 6 tornadoes. 2 EF2, 2 EF1, 2 EF0 and 1 major damaging wind event with estimated wind speeds between 120-140 mph. Crazy) Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted February 21, 2017 Share Posted February 21, 2017 12Z NAM sounding from near the Michigan/Indiana/Ohio border Link to comment Share on other sites More sharing options...
Anti tornado Posted February 21, 2017 Author Share Posted February 21, 2017 18z nam sounding north of cincinnati near Indiana Ohio border. Be interesting to see if they become more or less veered Link to comment Share on other sites More sharing options...
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