andyhb Posted April 23, 2014 Author Share Posted April 23, 2014 I don't really see any differences in the 500 mb vertical velocity field (a flag for erroneous convective feedback) between the 12z and 18z GFS runs, at least prior to 18z Saturday. The convection the 12z GFS absolutely blew up like a nuke was around 00z Sunday, not 18z Saturday. The 18z GFS has nothing of this sort. Link to comment Share on other sites More sharing options...
heavy_wx Posted April 23, 2014 Share Posted April 23, 2014 The convection the 12z GFS absolutely blew up like a nuke was around 00z Sunday, not 18z Saturday. The 18z GFS has nothing of this sort. Right, but that wouldn't affect the model's environment before initiation Saturday. Link to comment Share on other sites More sharing options...
andyhb Posted April 23, 2014 Author Share Posted April 23, 2014 Saturday this run is driven by the ridge out ahead being less amplified due to the NE ULL not being nearly as well developed as it was in the previous runs. This allows a more progressive solution and thus the dryline lighting up. Link to comment Share on other sites More sharing options...
Ground Scouring Posted April 23, 2014 Share Posted April 23, 2014 Just for knowledge: When was the last time we saw a significant outbreak with such a broad-based trough (basically covering most of the CONUS) as the 18Z GFS shows by 00Z Monday? 04/27/2011 was obviously one, as was 04/03/1974…not that those are analogous at all to this setting, other than in terms of a general progressive trend. Most of the CIPS analogs had a more amplified trough than what the GFS shows Monday. My climatological knowledge of cases needs improvement, I will admit. Link to comment Share on other sites More sharing options...
Superstorm93 Posted April 23, 2014 Share Posted April 23, 2014 The convection the 12z GFS absolutely blew up like a nuke was around 00z Sunday, not 18z Saturday. The 18z GFS has nothing of this sort. That's actually extremely interesting to see... Link to comment Share on other sites More sharing options...
Superstorm93 Posted April 23, 2014 Share Posted April 23, 2014 I wish I knew what these meant. Any website suggestions on interpreting these graphs? Here are some links on hodographs (bottom image) http://www.crh.noaa.gov/images/lmk/Hodographs_Wind-Shear.pdf http://www.meteor.iastate.edu/classes/mt417/powerpoint/417_wk7.pdf http://www.weathercharts.org/hodograph.ppt https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=0CGEQFjAF&url=http%3A%2F%2Fnetfam.fmi.fi%2FStorm05%2Fhodographs.ppt&ei=1VdYU4j2JsevyASp14LQBw&usg=AFQjCNHBGFtccKKqXzZF7GGcCpYImdc9Gg&sig2=Gp6KD8xwaCg7JpNQEjqH8A&bvm=bv.65397613,d.aWw Link to comment Share on other sites More sharing options...
chase_stormz Posted April 23, 2014 Share Posted April 23, 2014 Of course Sunday is looking like the weakest threat which is the only day I can chase.. Link to comment Share on other sites More sharing options...
olafminesaw Posted April 23, 2014 Share Posted April 23, 2014 Here are some links on hodographs (bottom image) http://www.meteor.iastate.edu/classes/mt417/powerpoint/417_wk7.pdf http://netfam.fmi.fi/Storm05/hodographs.ppt The second link doesn't work. Link to comment Share on other sites More sharing options...
soonertrey Posted April 24, 2014 Share Posted April 24, 2014 Of course Sunday is looking like the weakest threat which is the only day I can chase.. Same here. But I wouldn't give up on Sunday just yet though. There is still a lot of model variability and a lot can change between now and then. Link to comment Share on other sites More sharing options...
jdrenken Posted April 24, 2014 Share Posted April 24, 2014 Still looking at late 25APR14 or early 26APR14 for sampling. Link to comment Share on other sites More sharing options...
NTXYankee Posted April 24, 2014 Share Posted April 24, 2014 12z euro looked nice with the slower solution, but it blows the dryline past I-35 around 18Z. Still hanging on to hope that models are moving it too fast like SPC and FWD mentioned this morning. Tornado aspect I could do without, a good storm would be nice though. Link to comment Share on other sites More sharing options...
FHSC Sam Posted April 24, 2014 Share Posted April 24, 2014 Gonna see if the GFS continues trending better conditions for Saturday, and same for NAM, although NAM hasn't been as good. Waiting for the 0z runs... Link to comment Share on other sites More sharing options...
Minnesota Meso Posted April 24, 2014 Share Posted April 24, 2014 There has been some mention of analogs, I agree that could be a key element in what may happen. I think tomorrows suite of models runs should start to converging on a better solution. The models have historically had a difficult time at the H5 level depicting the proper storm tracks when they want to close it off and linger it a few days like they show with this system when it get to the Great Lakes area. Chasers should not count Saturday out as they may have a very short time to pull the trigger. Link to comment Share on other sites More sharing options...
AgeeWx Posted April 24, 2014 Share Posted April 24, 2014 00Z GFS continuing the trend with a broader, negatively tilted trough. SFC low continues deepening throughout the day over NE CO. At least it's not a step backwards. Link to comment Share on other sites More sharing options...
andyhb Posted April 24, 2014 Author Share Posted April 24, 2014 00z GFS is still a hell of a setup on the dryline on Saturday, Monday still looking bad as per usual it seems. Link to comment Share on other sites More sharing options...
Indystorm Posted April 24, 2014 Share Posted April 24, 2014 And James Spann is reporting that Birmingham NWS radio is down for most of the upcoming week. Not good for Dixie in the Monday period after this system progresses eastward from the plains. Link to comment Share on other sites More sharing options...
natecast Posted April 24, 2014 Share Posted April 24, 2014 00z GFS is still a hell of a setup on the dryline on Saturday, Monday still looking bad as per usual it seems. Man, that trough orientation being shown on the latest GFS for Saturday evening across W/C KS & W OK resembles some pretty big outbreaks of the past. The timing of storm initiation would put storms maturing near sunset with one hell of a LLJ ramping up. The tornado threat could last well into the night across the region as well. Now time to wait for the Euro. Link to comment Share on other sites More sharing options...
MCS_hunter Posted April 24, 2014 Share Posted April 24, 2014 I'm kinda novice to severe weather forecasting but, is anyone else worried about the cap building into southern-central Kansas after 00Z on Sunday on the 00Z GFS? Link to comment Share on other sites More sharing options...
AgeeWx Posted April 24, 2014 Share Posted April 24, 2014 Man, some of the point forecast soundings along I-70 are something else. As Thundersnow12 previously noted, the secondary moisture surge as the SFC low deepens could make for a late show in South Central KS Saturday night. Link to comment Share on other sites More sharing options...
thewxmann Posted April 24, 2014 Share Posted April 24, 2014 One concern I do have about Saturday daytime is the moisture return. Latest GFS not as robust with it as previous runs, though I don't know what the Euro shows. With temperatures well into the 80's during the day, Td's around and lower than 65F not going to cut it for tornadic activity. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted April 24, 2014 Share Posted April 24, 2014 For Saturday night, I think the GFS is to slow with storm initiation. At hour 66 it has a strong vort max at H5 just sw of the 4 corners area. Between h66 and h72 it phases with a northern stream, and the vort max moves strongly north. After phasing its drops strongly south between h72 and h78. That whole 12hour period looks rather strange to me. The jump to the north allows the surface low to set up a bit further north than what I would like to see. I doubt the Euro or GEM will show that 12 hour phasing event. IE, the GFS is about 4-6 hours to slow. Edit: Lets put it this way, I think the Euro will show that same vort max at h66 but it won't phase with the northern energy until the vort max over the 4 corners area goes negatively titled as it runs into the ridge, at which time we will see the phase, providing for explosive development Sat evening. Link to comment Share on other sites More sharing options...
nwburbschaser Posted April 24, 2014 Share Posted April 24, 2014 One concern I do have about Saturday daytime is the moisture return. Latest GFS not as robust with it as previous runs, though I don't know what the Euro shows. With temperatures well into the 80's during the day, Td's around and lower than 65F not going to cut it for tornadic activity. If you look back for a few runs then you can really see that moisture has been trending downward. The GFS may just be coming back to a more realistic forecast and it will level out, but it's definitely something to watch. Link to comment Share on other sites More sharing options...
Chicago Storm Posted April 24, 2014 Share Posted April 24, 2014 One concern I do have about Saturday daytime is the moisture return. Latest GFS not as robust with it as previous runs, though I don't know what the Euro shows. With temperatures well into the 80's during the day, Td's around and lower than 65F not going to cut it for tornadic activity. The ECMWF has <65F DP's, with highs in the low to mid-90s. Link to comment Share on other sites More sharing options...
JoMo Posted April 24, 2014 Share Posted April 24, 2014 I'm kinda novice to severe weather forecasting but, is anyone else worried about the cap building into southern-central Kansas after 00Z on Sunday on the 00Z GFS? yeah CIN increases rapidly. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 24, 2014 Share Posted April 24, 2014 I'll be out there Sunday somewhere probably in Kansas. The 12z Euro indicated surface cape up close to 3000j/kg near the dry line by early afternoon. Definitely looking like an early initiation type of day. Incoming mid-level jet and associated vorticity max should make for a nice string of tightly packed sups all along the surging dry line early on. From a chasing standpoint not exactly ideal, but definitely worthy of a chase. Deep moisture will be firmly in place by Sunday to be sure. Link to comment Share on other sites More sharing options...
thewxmann Posted April 24, 2014 Share Posted April 24, 2014 The ECMWF has <65F DP's, with highs in the low to mid-90s. Wow. That moisture is really going to mix out like a rock if the insolation is strong enough to heat the boundary layer to the 90s. Actually a big clue I noticed tonight: note the anticyclonic flow in the eastern GOM (again) prior and during the ejection of the trough. Moisture quality is going to be much better than it is tonight, but still not ideal because of this. The richer moisture is still confined to the Gulf Coast just 24h before the event. <65F and 90F -- a 25F T/Td spread -- is marginal to say the least for any tornado, much less a significant tornado. Something to watch. The EML really cranks up after dark as well as the LLJ veers and advects hotter 850mb air over the warm sector. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 24, 2014 Share Posted April 24, 2014 I think west-central and northwest OK are looking pretty good for Sat. Euro and GFS both show moisture/CAPE quickly bulging north-northwest through that area by early evening. Euro has consistently induced precip in those areas as well. Shear profiles are very nice. The Woodward OK area is looking very nice to me at this point... Link to comment Share on other sites More sharing options...
Minnesota Meso Posted April 24, 2014 Share Posted April 24, 2014 yeah CIN increases rapidly. I think all that CIN builds up because of what the gfs does between hour 66 and 72 at the H5 level. Link to comment Share on other sites More sharing options...
brettjrob Posted April 24, 2014 Share Posted April 24, 2014 Wow. That moisture is really going to mix out like a rock if the insolation is strong enough to heat the boundary layer to the 90s. Actually a big clue I noticed tonight: note the anticyclonic flow in the eastern GOM (again) prior and during the ejection of the trough. Moisture quality is going to be much better than it is tonight, but still not ideal because of this. The richer moisture is still confined to the Gulf Coast just 24h before the event. <65F and 90F -- a 25F T/Td spread -- is marginal to say the least for any tornado, much less a significant tornado. Something to watch. The EML really cranks up after dark as well as the LLJ veers and advects hotter 850mb air over the warm sector. I'm getting onboard with your pessimism for Saturday regardless of initiation, especially after witnessing moisture today ahead of the dryline. The drought is absolutely killing us, and as usual, dew points will likely verify even lower than any of the current progs on Saturday afternoon. Weird things happen though. Arnett (5/4/07) and Rozel (5/18/13) are good examples where "skinny" but intense tornadoes have occurred in this part of the High Plains with large T-Td spreads but an otherwise favorable setup. As far as a widespread tornado event with multiple cyclic storms, I'd be pretty surprised. Reminds me a bit of the HIGH risk bust on 6/5/08. It's weird to think about LCL issues with theta-e and CAPE are through the roof, and dew points are well above 60 F, but temperatures of 90 F will do that to you. Link to comment Share on other sites More sharing options...
chase_stormz Posted April 24, 2014 Share Posted April 24, 2014 I'm getting onboard with your pessimism for Saturday regardless of initiation, especially after witnessing moisture today ahead of the dryline. The drought is absolutely killing us, and as usual, dew points will likely verify even lower than any of the current progs on Saturday afternoon. Weird things happen though. Arnett (5/4/07) and Rozel (5/18/13) are good examples where "skinny" but intense tornadoes have occurred in this part of the High Plains with large T-Td spreads but an otherwise favorable setup. As far as a widespread tornado event with multiple cyclic storms, I'd be pretty surprised. Reminds me a bit of the HIGH risk bust on 6/5/08. It's weird to think about LCL issues with theta-e and CAPE are through the roof, and dew points are well above 60 F, but temperatures of 90 F will do that to you. What are your thoughts on Sunday? Link to comment Share on other sites More sharing options...
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