brettjrob Posted May 26, 2012 Share Posted May 26, 2012 RAP: Rapid Refresh, which is short for HRRR: High Resolution Rapid Refresh. Not sure if they are exactly the same though... The HRRR is a nested subdomain run at 3 km horizontal resolution inside the RAP domain. The RAP itself runs at 13 km resolution. Link to comment Share on other sites More sharing options...
Buckeye05 Posted May 26, 2012 Share Posted May 26, 2012 The more I look at the models, the more I think that if thinks come together just right, we could see a strong tornado or two, Especially in the Sioux City and Sioux Falls area. EHI values are completly maxed out there, along with some decent instability and vorticity values. Link to comment Share on other sites More sharing options...
jpeters3 Posted May 26, 2012 Share Posted May 26, 2012 The more I look at the models, the more I think that if thinks come together just right, we could see a strong tornado or two, Especially in the Sioux City and Sioux Falls area. EHI values are completly maxed out there, along with some decent instability and vorticity values. I agree. HRRR has been consistently developing convection in the region of maxed out parameters, where the environment is progged to be uninhibited. Other guidance is a bit all over the place with the location of CI, so i can see the reluctancy for SPC to put out higher probs due to said' uncertainties. I do however believe that the failure to even mention the conditional strong tornado potential, and the downgrade of tornado probs to 2% dramatically under-blows the potential seriousness of the situation (again, if say the HRRR verifies). Irresponsible move on their part, IMO. Link to comment Share on other sites More sharing options...
Ian Posted May 26, 2012 Share Posted May 26, 2012 I'm not sold on SD... probably going to chill in northeast NE. Link to comment Share on other sites More sharing options...
andyhb Posted May 26, 2012 Share Posted May 26, 2012 Any storm that does go up there will be liable to explode with 0-3 km EHIs of 10-12+ progged by the RAP, the LCLs don't look so bad in the area either... Link to comment Share on other sites More sharing options...
thewxmann Posted May 26, 2012 Share Posted May 26, 2012 I am a little confused about the 2% risk area too, especially considering this wording: ANY STORMS THAT CAN OVERCOME INHIBITION IN THESE AREAS WILL EXIST IN A KINEMATIC REGIME SUPPORTIVE OF SUPERCELLS. HAIL AND HIGH WINDS WILL BE POSSIBLE AND TORNADO POTENTIAL WILL BE ENHANCED NEAR THE WARM FRONT THAT WILL LIKELY BE SITUATED ACROSS NRN/CNTRL NEB. Link to comment Share on other sites More sharing options...
Ian Posted May 26, 2012 Share Posted May 26, 2012 RAP is actually sorta dry with dews in NE neb so maybe SD afterall. Yankton seems a logical spot to head to. Link to comment Share on other sites More sharing options...
andyhb Posted May 26, 2012 Share Posted May 26, 2012 MESOSCALE DISCUSSION 0911NWS STORM PREDICTION CENTER NORMAN OK 0348 PM CDT SAT MAY 26 2012 AREAS AFFECTED...SCNTRL AND ERN NE AND CONCERNING...SEVERE POTENTIAL...WATCH LIKELY VALID 262048Z - 262215Z PROBABILITY OF WATCH ISSUANCE...80 PERCENT SUMMARY...SEVERE THUNDERSTORM DEVELOPMENT EXPECTED NEXT 1 TO 2 HOURS AS AIR MASS CONTINUES TO DESTABILIZE AND CAPPING INVERSION WEAKENS. INDICATIONS ARE STORMS MAY DEVELOP RAPIDLY AND A WW WILL LIKELY BE REQUIRED. DISCUSSION...WITH TEMPERATURES WARMING INTO THE MID TO UPPER 90S AND DEWPOINTS HOLDING IN THE MID 60S TO LOW 70S...MLCAPE VALUES ARE AROUND 2500 TO 3500 J/KG. VERY STRONG CAPPING INVERSION HAS BEEN ACTING TO SUPPRESS SIGNIFICANT CONVECTION. WITH THE FIRST OF TWO WEAK IMPULSES MOVING INTO SRN NE...MID CLOUD DEVELOPMENT/SCATTERED WEAK RADAR ECHOS INDICATE THAT LIFTING IN THE CRITICAL AREA OF THE CAP IS OCCURRING. ALSO...WATER VAPOR IMAGERY ALONG WITH UPPER LEVEL POTENTIAL VORTICITY ANALYSIS SHOWS SECONDARY UPPER SYSTEM MOVING INTO THE SRN KS. AS THIS IMPULSE CONTINUES NORTHWARD...ADDITIONAL CONVECTIVE DEVELOPMENT SHOULD OCCUR ACROSS PORTIONS OF CENTRAL AND EASTERN NE INTO THE EVENING. ONCE INITIAL STORM DEVELOPMENT TAKES PLACE WITH UPDRAFTS TAPPING THE LOWER LEVEL INSTABILITY...STORMS SHOULD CONTINUE TO RAPIDLY INCREASE ACROSS THE AREA. DEEP LAYER SHEAR CONTINUES TO INCREASE TO 40 TO 50 KTS. A GREATER TORNADO THREAT MAY DEVELOP ALONG THE WARM FRONT SITUATED FROM SW NE TO NERN NE. ..BOTHWELL/CARBIN.. 05/26/2012 Link to comment Share on other sites More sharing options...
Ian Posted May 26, 2012 Share Posted May 26, 2012 Nice Link to comment Share on other sites More sharing options...
andyhb Posted May 26, 2012 Share Posted May 26, 2012 MESOSCALE DISCUSSION 0912NWS STORM PREDICTION CENTER NORMAN OK 0355 PM CDT SAT MAY 26 2012 AREAS AFFECTED...PORTIONS SERN WY...WRN NEB...EXTREME N-CENTRAL/NERN CO. CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 262055Z - 262300Z PROBABILITY OF WATCH ISSUANCE...60 PERCENT SUMMARY...POTENTIAL IS INCREASING FOR DEVELOPMENT OF SVR TSTMS...INCLUDING RISK OF SUPERCELLS AS WELL AS BOWING SEGMENTS. FULL SPECTRUM OF SVR IS POSSIBLE. DISCUSSION...20Z SFC MESOANALYSIS SHOWED CYCLONE BETWEEN DEN-GXY-FCL...WHICH SHOULD MOVE/REDEVELOP NNEWD OVER WY/NEB BORDER THROUGH 03Z. VERY SHARPLY DEFINED WARM FRONT WAS DRAWN FROM LOW ENEWD NEAR LBF-ODX-OFK LINE...AND WILL MOVE NWD OUT OF NERN CO AND OVER WRN/CENTRAL NEB IN STEP WITH SFC LOW. DIFFUSE/DOUBLE DRYLINE STRUCTURE WAS ANALYZED FROM FRONT SWD ACROSS ERN CO AND WRN KS...WITH MOIST AXIS EXTENDING FROM SRN SANDHILLS TO N PLATTE RIVER VALLEY OF WY. CONSIDERABLE CONFLUENCE ALSO WAS NOTED IN LATTER AREA...WHICH MAY REMAIN UNTIL MERGING WITH NWD-MOVING WARM-FRONTAL ZONE. BACKED FLOW FROM THAT AREA EWD OVER PANHANDLE AND SWRN NEB...PRIOR TO WARM FROPA...WILL MAINTAIN ENHANCED LOW-LEVEL SHEAR/HODOGRAPH SIZE IN SUPPORT OF SUPERCELL POTENTIAL FOR ANY RELATIVELY DISCRETE CONVECTION IN THAT REGIME. ELY/UPSLOPE FLOW ALSO WILL REPRESENT LOW-LEVEL ASCENT IN SERN WY CONFLUENCE ZONE. N OF WARM FRONT...VIS IMAGERY SHOWS MARKED CLEARING OVER LARAMIE COUNTY WY...SPREADING NWD ACROSS SRN PORTIONS PLATTE/GOSHEN COUNTIES...AND SPREADING NWD ACROSS APPROXIMATELY SRN 1/2 OF NEB PANHANDLE. RELATED INSOLATION WILL ACT ON SFC DEW POINTS 50S F AND STEEP MIDLEVEL LAPSE RATES TO SUPPORT ROUGHLY W-E ORIENTED CORRIDOR OF 1500-2500 J/KG MLCAPE...JUXTAPOSED WITH 50-60 KT EFFECTIVE SHEAR MAGNITUDE. AIR MASS FARTHER N...ESPECIALLY FROM DGW-TOR-AIA LINE NWD...HAS BEEN ENSHROUDED IN THICK LOW CLOUDS FOR MUCH OF TODAY...WITH SOME DISPERSAL ONLY RECENTLY NOTED IN VIS IMAGERY. THIS AREA WILL TAKE LONGER TO DESTABILIZE...THOUGH AREAS AS FAR N AS EXTREME SWRN SD AND NEWCASTLE REGION MAY BECOME FAVORABLE BEFORE DARK. CORRIDOR BETWEEN GCC AND CENTRAL BLACK HILLS WILL REPRESENT SW-NE GRADIENT WITHIN WHICH MLCAPE WILL DIMINISH MARKEDLY. AS SUCH...PERSISTENCE OF SFC-BASED EFFECTIVE INFLOW PARCELS BECOME MORE UNCERTAIN AS FAR N AS I-80. RELATED CINH ALSO WILL BE SLOW TO ERODE OVER CENTRAL/NRN SANDHILLS OF NEB...LEADING TO RELATIVELY LOWERED NEAR-TERM SVR PROBABILITIES THERE. ..EDWARDS/CARBIN.. 05/26/2012 Link to comment Share on other sites More sharing options...
Chinook Posted May 26, 2012 Share Posted May 26, 2012 "MESOSCALE DISCUSSION 0912 AREAS AFFECTED...PORTIONS SERN WY...WRN NEB...EXTREME N-CENTRAL/NERN CO. CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE SUMMARY...POTENTIAL IS INCREASING FOR DEVELOPMENT OF SVR TSTMS...INCLUDING RISK OF SUPERCELLS AS WELL AS BOWING SEGMENTS. FULL SPECTRUM OF SVR IS POSSIBLE." Interesting. This is chase territory. Unfortunately storms would be heading out to nowhereland in Wyoming at 45mph. That's too fast to do a good chase unless I could drive on US 85. Link to comment Share on other sites More sharing options...
hm8 Posted May 26, 2012 Share Posted May 26, 2012 EHI up to 10 in NE Nebraska per latest meso analysis Link to comment Share on other sites More sharing options...
Ian Posted May 26, 2012 Share Posted May 26, 2012 Would like so see something go better next hour Link to comment Share on other sites More sharing options...
Chinook Posted May 26, 2012 Share Posted May 26, 2012 I am going to post these pics from the SPC mesoanalysis. I am impressed by the EHI of 14 in Iowa. The helicity is generally maxed out at the areas of maximum 850mb warm advection, as it is in many cases, due to the thermal wind equation (describing geostrophic wind shear). I have been fascinated by the interplay of instability and shear for several years. Thunderstorms always respond to these factors : 1. Convective instability (Tparcel minus T) vs height, which is the driving force for accelerating air parcels up. 2. Wind vs. height, (the hodograph.) Seemingly the hodograph would tell you exactly how much parcels accelerate horizontally (given no other dynamic forces) 3. Forcing: line based or single cell 4. Ability of cells to break the cap and develop new updraft towers. strong cap situations play out differently than weak cap situations. Sometimes cells grow in weird directions, or go into cyclic supercell mode. 5. Cell merging 6. Water loading and reduction of updraft strength due to too much water Link to comment Share on other sites More sharing options...
Ian Posted May 26, 2012 Share Posted May 26, 2012 storm is struggling but we saw a cold air funnel way up high on the front edge. i think we;re going to go to SD.. the environment in nebraska is not so good. Link to comment Share on other sites More sharing options...
thewxmann Posted May 26, 2012 Share Posted May 26, 2012 Yesterday was a nice fluke, but it's 0Z and I'm not sure a surface-based supercell can develop anymore. Link to comment Share on other sites More sharing options...
Buckeye05 Posted May 26, 2012 Share Posted May 26, 2012 Easternmost storm should be moving into a favorable environment but it looks to be weakening. IDK whats going on.. Link to comment Share on other sites More sharing options...
andyhb Posted May 26, 2012 Share Posted May 26, 2012 Easternmost storm should be moving into a favorable environment but it looks to be weakening. IDK whats going on.. Cap. Link to comment Share on other sites More sharing options...
Superstorm93 Posted May 27, 2012 Share Posted May 27, 2012 Report of a 70 knot gust as a cell in KS collapsed... Pretty impressive. Link to comment Share on other sites More sharing options...
Ian Posted May 27, 2012 Share Posted May 27, 2012 we might bail to position for tomorrow.. doesnt look like its going to happen Link to comment Share on other sites More sharing options...
brettjrob Posted May 27, 2012 Share Posted May 27, 2012 Today's SWODY1s reminded me somewhat of those from March 18 in the southern High Plains. The environment in place was rather tremendous, but ultimately very few storms initiated (assuming this continues to be true over the next hour, in today's case). The outlook text on both days seemed not to stress the capping concerns to the extent that would be necessary to preclude higher probs... but ultimately the probs turned out well because of low/no coverage. Link to comment Share on other sites More sharing options...
Ian Posted May 27, 2012 Share Posted May 27, 2012 Cap. its mixing out after the warm front passes as well i think. Link to comment Share on other sites More sharing options...
brettjrob Posted May 27, 2012 Share Posted May 27, 2012 its mixing out after the warm front passes as well i think. Sounds like my oh-so-enjoyable trip to Yankton on 5/5, minus the cold outflow keeping the boundary from lifting. We got lucky yesterday that storms rode a narrow zone of pooled moisture just S of the front, because basically every day this year the broader warm sector mixes out something awful. Link to comment Share on other sites More sharing options...
Ian Posted May 27, 2012 Share Posted May 27, 2012 Sounds like my oh-so-enjoyable trip to Yankton on 5/5, minus the cold outflow keeping the boundary from lifting. We got lucky yesterday that storms rode a narrow zone of pooled moisture just S of the front, because basically every day this year the broader warm sector mixes out something awful. yeah sounds about right. i guess yesterday gave some undue confidence for today but by 5 p.m. or so it was apparent there was a bit of a problem. we were sitting in norfolk and after the front came through subsidence took over quickly -- lcls are gross. glad we got yesterday... not terribly impressed with tomorrow at this point. good to have things to do though, might have liked to use today to process if i had a crystal ball! the rap nailed the issues by midday it seems. Link to comment Share on other sites More sharing options...
JoMo Posted May 27, 2012 Share Posted May 27, 2012 Looks like death by EML. Probably get an MCS or something forming north of the front once the LLJ kicks in later tonight. Well, since the storms aren't doing much, you all can head over to Reed's facebook and watch his $2/chase for a 'premium' live stream idea implode in a fit of public anger. Link to comment Share on other sites More sharing options...
Superstorm93 Posted May 27, 2012 Share Posted May 27, 2012 Looks like death by EML. Probably get an MCS or something forming north of the front once the LLJ kicks in later tonight. Well, since the storms aren't doing much, you all can head over to Reed's facebook and watch his $2/chase for a 'premium' live stream idea implode in a fit of public anger. He must have come up with that all by himself. That's a great way to crash and burn especially in this 'thermonuclear' EML setup. Link to comment Share on other sites More sharing options...
Buckeye05 Posted May 27, 2012 Share Posted May 27, 2012 Anyone still for the strong tornado threat tomorrow? SPC has dropped that kind of wording now and parameters aren't exactly crazy tomorrow. Link to comment Share on other sites More sharing options...
thewxmann Posted May 27, 2012 Share Posted May 27, 2012 yeah sounds about right. i guess yesterday gave some undue confidence for today but by 5 p.m. or so it was apparent there was a bit of a problem. we were sitting in norfolk and after the front came through subsidence took over quickly -- lcls are gross. glad we got yesterday... not terribly impressed with tomorrow at this point. good to have things to do though, might have liked to use today to process if i had a crystal ball! the rap nailed the issues by midday it seems. It did? I thought it kept hinting at CI despite the moisture issues. Anyway congrats on the grab yesterday. 99% of the time setups like yesterday or today remain capped, especially with 700mb temps above 12C and the trof axis still miles and miles away. A 50% rate is pretty good. Link to comment Share on other sites More sharing options...
thewxmann Posted May 27, 2012 Share Posted May 27, 2012 Anyone still for the strong tornado threat tomorrow? SPC has dropped that kind of wording now and parameters aren't exactly crazy tomorrow. Let's just say this, with 925mb RH's progged around 50%, I'd be shocked if the moisture is half as good as today. And unidirectional wind profiles are nothing to be excited about. MN/WI might be the place where these problems might be slightly mitigated. Link to comment Share on other sites More sharing options...
tornadotony Posted May 27, 2012 Share Posted May 27, 2012 It did? I thought it kept hinting at CI despite the moisture issues. Anyway congrats on the grab yesterday. 99% of the time setups like yesterday or today remain capped, especially with 700mb temps above 12C and the trof axis still miles and miles away. A 50% rate is pretty good. Yesterday had a hell of a lot more going for it then you're giving it credit for. Yeah, 700mb T wasn't ideal, but given the rest of the atmospheric profile, it was just fine. The triple point was very well-defined yesterday and featured very strong sfc convergence, especially because a slight bulge in the dryline had developed by about 2100 UTC just south of it. Add in that the warm front was parallel to right-turning storm motions and you had a recipe for what evolved evident hours in advance. Link to comment Share on other sites More sharing options...
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