andyhb Posted November 6, 2012 Share Posted November 6, 2012 DAY 4-8 CONVECTIVE OUTLOOKNWS STORM PREDICTION CENTER NORMAN OK 0236 AM CST TUE NOV 06 2012 VALID 091200Z - 141200Z ...DISCUSSION... MODELS ARE IN GOOD AGREEMENT DEPICTING A LARGE TROUGH WHICH WILL MOVE ACROSS THE WRN STATES ON FRI/D4...WITH AN INTENSIFYING JET CORE NOSING INTO CO BY 12Z SAT. LOW PRESSURE WILL DEEPEN AHEAD OF THE COLD FRONT...EXTENDING FROM WRN MN SWWD ACROSS CNTRL NEB AND INTO WRN KS BY LATE AFTERNOON SAT. SUBSTANTIAL HEIGHT FALLS AND COOLING ALOFT WILL ACCOMPANY THIS COLD FRONT...AND STORMS WILL EASILY ERUPT ALONG IT. HEATING IS EXPECTED TO HELP DESTABILIZE THE AIR MASS FROM KS INTO NEB...WITH LOW LEVEL LAPSE RATE PLUME POSSIBLY EXTENDING AS FAR N AS SWRN MN. WITH DEWPOINTS ONLY IN THE UPPER 50S F...INSTABILITY LEVELS ARE FORECAST TO BE MARGINAL WITH AROUND 1000 J/KG MUCAPE. CAPPING SHOULD HAMPER DEVELOPMENT AWAY FROM THE FRONT DUE TO COOL BOUNDARY LAYER TEMPERATURES. ALL THIS SUGGESTS A LINEAR STORM MODE IS LIKELY. WHILE DEEP SHEAR WILL BE ORIENTED ALONG THE BOUNDARY...SUGGESTING CELLS MERGING...HODOGRAPHS WILL FAVOR EMBEDDED SUPERCELLS CAPABLE OF DAMAGING WINDS AND MARGINAL HAIL. WITH SUCH STRONG SHEAR...A FEW BOWING SEGMENTS MAY PRODUCE PARTICULARLY DAMAGING WINDS. SAT NIGHT...THE MAIN ENERGY WITH THIS TROUGH WILL EJECT NEWD INTO THE UPPER MS VALLEY...WHILE THE COLD FRONT CONTINUES TO MOVE SEWD ACROSS INTO IA...MO...AND OK. ALTHOUGH NUMEROUS STORMS ARE LIKELY TO EXTEND SWWD INTO OK SAT NIGHT...THE OVERALL THREAT WILL BE LIMITED BY MARGINAL INSTABILITY. SOME SEVERE THREAT IS EXPECTED TO PERSIST INTO SUN/D6...FROM ERN OK INTO AR...NERN TX AND NRN LA. DAMAGING WINDS WILL AGAIN BE THE MOST LIKELY THREAT WITH A SQUALL LINE...BUT VERY POOR LOW LEVEL LAPSE RATES ARE FORECAST AND INSTABILITY WILL BE MARGINAL. IN ADDITION...MODELS ARE IN RELATIVELY POOR AGREEMENT WITH THIS PORTION OF THE TROUGH WHICH WILL PRECLUDE ANY FURTHER AREAS. ..JEWELL.. 11/06/2012 Regarding the bolded part, I'm not sure exactly how low to mid 70s for boundary layer sfc temps in November (which is what the NWS is forecasting throughout the Plains on Saturday) is considered "cool". Something tells me they are running with the GFS thermos a bit (which also shows 60s dews, not just upper 50s for the corridor they highlighted, but that is somewhat less of a difference than the BL temps). The deep layer shear vectors aren't exactly all that parallel to the boundary, either, if you believe the GFS (and I'd tend to think the Euro as well). The cap depicted is not the strongest (especially over the area they outlined), and that difference in the boundary layer temps between the GFS and forecast highs could be the difference between seeing any pre-frontal convection or not. I have noticed a trend this year, that it seems that the GFS' forecasted convective inhibition was nearly always stronger than what actually verified, especially >4 days out, which usually resulted in a hindering of the setup actually, because too much convection ended up firing and suffocated any initial discrete cell. The Euro's stronger secondary surface cyclogenesis (try saying that 5 times in a row) is also something to take into account. Link to comment Share on other sites More sharing options...
brettjrob Posted November 6, 2012 Share Posted November 6, 2012 We're going to be crying Saturday evening when the 00z soundings come in from OK/KS if the ECMWF has anything to say about it. Absolutely textbook shear with 60-80 kts at H5 out of the WSW, and a 40-60 kt southerly LLJ. Surface low is 994 mb in NW KS at 00z Sun. Trouble is, it also has surface dew points in the mid 50s, resulting in < 500 J/kg SBCAPE (and needless to say, no convective initiation). The shear profiles look so good that I'd actually be excited if we could just get the 60-61 F dew points shown on the GFS to verify. If not for this week's trough scouring the Gulf, this would probably be one of the better threats of 2012. Link to comment Share on other sites More sharing options...
somethingfunny Posted November 6, 2012 Share Posted November 6, 2012 When in doubt, chase the South. Not saying it's a great setup down here in Texas, but it's usually the better spot to start your chase this time of the year. Link to comment Share on other sites More sharing options...
brettjrob Posted November 6, 2012 Share Posted November 6, 2012 Example of hodos that may be going to waste: Link to comment Share on other sites More sharing options...
OKpowdah Posted November 6, 2012 Author Share Posted November 6, 2012 This is a beautiful wind profile, just minimal CAPE. Too bad Link to comment Share on other sites More sharing options...
somethingfunny Posted November 6, 2012 Share Posted November 6, 2012 ^ Where is that? And I have a question: Why is it that high shear / low CAPE setups are so prolific in the Southeast? Sometimes I read AFDs from that region that almost sound as though low CAPE is a requirement for them to get tornadoes. Link to comment Share on other sites More sharing options...
OKpowdah Posted November 6, 2012 Author Share Posted November 6, 2012 ^ Where is that? And I have a question: Why is it that high shear / low CAPE setups are so prolific in the Southeast? Sometimes I read AFDs from that region that almost sound as though low CAPE is a requirement for them to get tornadoes. That's in north-central OK. You won't get as much of a cap present in the southeast usually, so in general, they rarely build up as much CAPE before storms are triggered, compared to the Plains where much higher CAPE can develop without a single Cb taking off. Link to comment Share on other sites More sharing options...
Buckeye05 Posted November 6, 2012 Share Posted November 6, 2012 Ugh this year. So much wasted potential. I keep hoping to see more CAPE trending with each run, but it just isn't happening. On to the next I suppose. Link to comment Share on other sites More sharing options...
David Reimer Posted November 7, 2012 Share Posted November 7, 2012 The 0Z GFS looked pretty good in Western Oklahoma and Southwest Kansas with a 1000 MB low in SW KS at 0Z Sunday. The GFS also does break out precipitation by 0Z with CAPE values between 500 and 750 J/Kg. With the low instability bias with the GFS and the good looking wind profiles, I'm still interested in a local chase on Saturday. I'll already be in Norman, so a 2.5 hour drive out west is nothing. We'll see what happens! Link to comment Share on other sites More sharing options...
andyhb Posted November 7, 2012 Share Posted November 7, 2012 The 0Z GFS looked pretty good in Western Oklahoma and Southwest Kansas with a 1000 MB low in SW KS at 0Z Sunday. The GFS also does break out precipitation by 0Z with CAPE values between 500 and 750 J/Kg. With the low instability bias with the GFS and the good looking wind profiles, I'm still interested in a local chase on Saturday. I'll already be in Norman, so a 2.5 hour drive out west is nothing. We'll see what happens! Good luck David. I was also looking at the Arklatex on the GFS/GGEM (too far for you to go out of Norman) on Sunday, as moisture return kicks into higher gear by then with 65+ sfc dews overspreading the area, although the deep layer shear vectors aren't as perpendicular as they are on Sunday, I'd tend to think a QLCS would be a more dominant storm mode, although large, looping hodographs suggest spin ups along the line if it were to form. A secondary sfc low along the front, which has been suggested from time to time, wouldn't hurt this either. Link to comment Share on other sites More sharing options...
David Reimer Posted November 7, 2012 Share Posted November 7, 2012 Good luck David. I was also looking at the Arklatex on the GFS/GGEM (too far for you to go out of Norman) on Sunday, as moisture return kicks into higher gear by then with 65+ sfc dews overspreading the area, although the deep layer shear vectors aren't as perpendicular as they are on Sunday, I'd tend to think a QLCS would be a more dominant storm mode, although large, looping hodographs suggest spin ups along the line if it were to form. A secondary sfc low along the front, which has been suggested from time to time, wouldn't hurt this either. I still live in Dallas, so If it looked good enough to chase, I would chase it. Nothing is set in stone right now and I was just speculating based on current model data. I haven't even begun thinking about serious chase plans. Link to comment Share on other sites More sharing options...
andyhb Posted November 7, 2012 Share Posted November 7, 2012 I still live in Dallas, so If it looked good enough to chase, I would chase it. Nothing is set in stone right now and I was just speculating based on current model data. I haven't even begun thinking about serious chase plans. No, I know. I was just going by the fact that you said you would already be in Norman on the 10th. Link to comment Share on other sites More sharing options...
brettjrob Posted November 7, 2012 Share Posted November 7, 2012 Saturday finally in NAM range. Moisture and instability woes look similar, but the dryline position appears a bit farther W, running from the Panhandles into W KS. Some hints at convective initiation during the afternoon, and hodographs look fairly nice. I'm not sure I've ever bothered chasing an environment with 500-1000 J/kg SBCAPE in the Plains, but if moisture return improves slightly, this might still be borderline interesting. Link to comment Share on other sites More sharing options...
OKpowdah Posted November 7, 2012 Author Share Posted November 7, 2012 Texas panhandle doesn't look half bad on the NAM Saturday evening Link to comment Share on other sites More sharing options...
prinsburg_wx Posted November 7, 2012 Share Posted November 7, 2012 Another winter storm likely late thu-sun for North Dakota. URGENT - WINTER WEATHER MESSAGENATIONAL WEATHER SERVICE BISMARCK ND 357 PM CST WED NOV 7 2012 ...MODERATE SNOW OVER NORTHWEST AND NORTH CENTRAL NORTH DAKOTA THURSDAY NIGHT AND FRIDAY... ...ANOTHER ROUND OF WINTER WEATHER OVER ALL OF WEST AND CENTRAL NORTH DAKOTA FRIDAY NIGHT THROUGH SUNDAY MORNING... .A STRONG STORM SYSTEM DEVELOPING OVER THE CENTRAL ROCKIES WILL MOVE INTO THE NORTHERN PLAINS AND SPREAD A MIX OF WINTRY WEATHER BEGINNING THURSDAY NIGHT AND CONTINUING INTO THE WEEKEND. NORTHWEST AND NORTH CENTRAL NORTH DAKOTA ARE FAVORED FOR SNOW BEGINNING THURSDAY NIGHT AND CONTINUING INTO FRIDAY. 3 TO 5 INCHES OF SNOWFALL IS POSSIBLE FROM WATFORD CITY TO WILLISTON...AND STANLEY...MINOT AND BOTTINEAU. ISOLATED HIGHER AMOUNTS ARE POSSIBLE IN THE CROSBY AREA. A WINTER WEATHER ADVISORY IS IN EFFECT FOR THIS AREA. A SECOND AND POTENTIALLY MORE SEVERE WAVE OF WINTER WEATHER IS EXPECTED TO IMPACT WESTERN AND CENTRAL NORTH DAKOTA BEGINNING FRIDAY NIGHT AND CONTINUING THROUGH SUNDAY MORNING. UP TO A FOOT SNOW IS POSSIBLE ALONG AND NORTH OF HIGHWAY 2...WHILE A MIX OF SNOW... SLEET AND FREEZING RAIN MAY OCCUR FARTHER SOUTH. A WINTER STORM WATCH IS IN EFFECT FOR ALL BUT FAR SOUTH CENTRAL NORTH DAKOTA FRIDAY NIGHT THROUGH SUNDAY MORNING. IF YOU ARE PLANNING TRAVEL LATE THIS WEEK...BE PREPARED FOR DANGEROUS WINTER DRIVING CONDITIONS. MONITOR LOCAL MEDIA AND WWW.WEATHER.GOV/BIS FOR LATER STATEMENTS AND POSSIBLE WARNINGS. NDZ001>004-009>011-017-080600- /O.CON.KBIS.WW.Y.0013.121109T0300Z-121110T0000Z/ /O.CON.KBIS.WS.A.0004.121110T0000Z-121111T1800Z/ DIVIDE-BURKE-RENVILLE-BOTTINEAU-WILLIAMS-MOUNTRAIL-WARD-MCKENZIE- INCLUDING THE CITIES OF...CROSBY...BOWBELLS...MOHALL... BOTTINEAU...WILLISTON...NEW TOWN...MINOT...WATFORD CITY 357 PM CST WED NOV 7 2012 ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 9 PM THURSDAY TO 6 PM CST FRIDAY... ...WINTER STORM WATCH REMAINS IN EFFECT FROM FRIDAY EVENING THROUGH SUNDAY MORNING... * TIMING...LATE THURSDAY EVENING NORTHWEST...SPREADING INTO NORTH CENTRAL NORTH DAKOTA OVERNIGHT INTO FRIDAY. A SECOND ROUND OF HEAVIER SNOW POSSIBLE FRIDAY NIGHT INTO SUNDAY. * MAIN IMPACT...3 TO 5 INCHES OF NEW SNOW POSSIBLE THURSDAY NIGHT AND FRIDAY. AN ADDITIONAL 6 TO 12 INCHES OF SNOW POSSIBLE FRIDAY NIGHT INTO SUNDAY. * OTHER IMPACTS...TRAVEL COULD BECOME VERY HAZARDOUS AS SNOW ACCUMULATES ON AREA ROADS. WINDS GUSTING OVER 30 MPH COULD CREATE REDUCED VISIBILITY AND DRIFTING SNOW AT TIMES. $$ NDZ005-012-013-018>023-025-031>037-040-041-043-080600- /O.CON.KBIS.WS.A.0004.121110T0000Z-121111T1800Z/ ROLETTE-MCHENRY-PIERCE-DUNN-MERCER-OLIVER-MCLEAN-SHERIDAN-WELLS- FOSTER-GOLDEN VALLEY-BILLINGS-STARK-MORTON-BURLEIGH-KIDDER- STUTSMAN-SLOPE-HETTINGER-BOWMAN- INCLUDING THE CITIES OF...ROLLA...TOWNER...RUGBY...KILLDEER... BEULAH...HAZEN...CENTER...GARRISON...MCCLUSKY...HARVEY... CARRINGTON...BEACH...MEDORA...DICKINSON...MANDAN...BISMARCK... STEELE...JAMESTOWN...MARMARTH...MOTT...BOWMAN 357 PM CST WED NOV 7 2012 /257 PM MST WED NOV 7 2012/ ...WINTER STORM WATCH REMAINS IN EFFECT FROM FRIDAY EVENING THROUGH SUNDAY MORNING... * TIMING...NORTH OF INTERSTATE 94...SNOW WILL DEVELOP WEST FRIDAY EVENING AND SPREAD EAST OVERNIGHT INTO SATURDAY. PERIODS OF SNOW MAY CONTINUE INTO SUNDAY MORNING. ALONG AND SOUTH OF INTERSTATE 94...A WINTRY MIX WILL BEGIN FRIDAY EVENING SOUTHWEST...AND SPREAD EAST INTO THE JAMES RIVER VALLEY SATURDAY MORNING. * SNOW IMPACTS...4 TO 8 INCHES OF POSSIBLE FROM BEACH TO BEULAH...THROUGH VELVA...RUGBY AND BELCOURT. 2 TO 4 INCHES OF SNOW POSSIBLE FROM MEDORA AND DICKINSON...THROUGH CENTER... WING AND HARVEY. LIGHT ACCUMULATIONS LESS THAN 2 INCHES POSSIBLE FROM BOWMAN AND MOTT...THROUGH BISMARCK AND MANDAN... STEELE AND JAMESTOWN. SNOW COVERED AND VERY SLICK ROADS. * SLEET AND FREEZING RAIN IMPACTS...LIGHT TO MODERATE SLEET AND FREEZING RAIN ACCUMULATIONS ARE POSSIBLE MAINLY ALONG AND SOUTH OF THE INTERSTATE 94 CORRIDOR. ICE COVERED AND VERY SLICK ROADS. * OTHER IMPACTS...WINDS GUSTING OVER 30 MPH COULD CREATE REDUCED VISIBILITY AND DRIFTING SNOW AT TIMES...IN AREAS IMPACTED BY HEAVIER SNOW. Link to comment Share on other sites More sharing options...
David Reimer Posted November 8, 2012 Share Posted November 8, 2012 SREF Sig. Tornado Ingredients for 6 PM Saturday. Keep in mind that the parameters were adjusted and thus, it is easier to reach a higher scale. Time will tell whether or not this decreases its accuracy. Link to comment Share on other sites More sharing options...
andyhb Posted November 8, 2012 Share Posted November 8, 2012 SREF Sig. Tornado Ingredients for 6 PM Saturday. Keep in mind that the parameters were adjusted and thus, it is easier to reach a higher scale. Time will tell whether or not this decreases its accuracy. There's no question the adjusted parameters are having an effect, although I did notice that there is a fairly strong consensus to get ML/SBCAPE over 500 J/kg and even some to get them both over 1000 J/kg around 18-00z Saturday. That, and Sunday looks a bit better this run of the GFS, with 1000-1500 J/kg becoming established across parts of Eastern TX, although concerns over the lack of a focused sfc low, linear forcing and rather shoddy mid-level lapse rates continue to be issues. Link to comment Share on other sites More sharing options...
Buckeye05 Posted November 8, 2012 Share Posted November 8, 2012 OK/TX border doesn't look to shabby. Nice hodographs. Link to comment Share on other sites More sharing options...
OKpowdah Posted November 9, 2012 Author Share Posted November 9, 2012 Well we are getting our moisture return starting today ... wouldn't mind seeing another 15-20 degree increase tomorrow too lol Link to comment Share on other sites More sharing options...
OKpowdah Posted November 9, 2012 Author Share Posted November 9, 2012 NAM has some decent ML lapse rates too. Just need a little more moisture in the boundary layer and this becomes interesting Link to comment Share on other sites More sharing options...
brettjrob Posted November 9, 2012 Share Posted November 9, 2012 Saturday is definitely a "woulda coulda shoulda" situation with great shear in place over favorable chase terrain. Oh well; it's November. Now that I've completely given up on it, I'm slightly intrigued by Sunday for north-central TX, primarily E of I-35. Chaser-friendly or not, the environment depicted on the NAM at 00z looks moderately favorable for tornadic supercells should discrete mode prevail. That's a big question mark given the frontal orientation relative to the deep-layer shear vectors, and the forecast for an ongoing squall line through the day anywhere N of the Red. Still worth keeping an eye on, as moisture will actually be in supply by then. Seems the only decent tornado events to affect the Metroplex going several years back are borderline-surprise ones. Link to comment Share on other sites More sharing options...
OKpowdah Posted November 9, 2012 Author Share Posted November 9, 2012 SPC day 2 has N-C KS up through SE NE and W IA in a 30% slight. Link to comment Share on other sites More sharing options...
andyhb Posted November 9, 2012 Share Posted November 9, 2012 Beginning to like Sunday a bit more on the GFS, mainly due to the surface trough not filling as fast as was originally projected. There are some great wind profiles coming out of Eastern TX and the Arklatex on Sunday afternoon/evening, the question is whether anything discrete will develop/be able to sustain itself and also whether there will be any junk cloud cover in the area, which I think is a pretty good possibility, the NAM's instability isn't as great as it was a couple of runs ago. Also, new D2 removed the 30% probs. Link to comment Share on other sites More sharing options...
OKpowdah Posted November 9, 2012 Author Share Posted November 9, 2012 18z NAM actually markedly increased CAPE, with less of a cap too. Sounding for 00z Saturday evening in NW OK. Not bad Link to comment Share on other sites More sharing options...
andyhb Posted November 10, 2012 Share Posted November 10, 2012 00z NAM really increased the instability fields across the Plains tomorrow, got some pretty nice looking soundings popping up across Central KS and NE, including after dark. Also went back to having a wider instability axis on Sunday as well. Another thought about Sunday is whether we see instability spread further east into LA/Southern AR later on once the LLJ really gets kicking. We saw this on Oct. 17th when instability wasn't progged to make if very far at all east of the MS River by a lot of model guidance, instead, it did and we had the overnight tornado event. And regardless of moisture problems, this trough is very impressive, has a 120+ kt H5 jet streak with it by Sunday. It's nice to see such an energetic system actually make it to the Central US out of the west, unlike essentially the last 7 months. Link to comment Share on other sites More sharing options...
David Reimer Posted November 10, 2012 Share Posted November 10, 2012 Link to comment Share on other sites More sharing options...
Ian Posted November 10, 2012 Share Posted November 10, 2012 the sig tor graphic is basically useless until an event that performs happens imo. the oct event that "busted" had a huge 50 contour for two days in a row. Link to comment Share on other sites More sharing options...
David Reimer Posted November 10, 2012 Share Posted November 10, 2012 the sig tor graphic is basically useless until an event that performs happens imo. the oct event that "busted" had a huge 50 contour for two days in a row. The October 12 event produced multiple tornadoes. I'm not using it on a large-scale, but using it as a means to determine that something indeed is worth watching. Link to comment Share on other sites More sharing options...
brettjrob Posted November 10, 2012 Share Posted November 10, 2012 the sig tor graphic is basically useless until an event that performs happens imo. the oct event that "busted" had a huge 50 contour for two days in a row. It wasn't useless before they lowered the CAPE and raised the LCL thresholds. Now, sadly, it seems to be nearly useless. If it still required 1000 J/kg MLCAPE, I bet we'd be seeing 10% at best. I'm really surprised by the amount of chatter in the chase community about tomorrow. Usually I'm one of the last to completely write something off, since I'm satisfied with decent structure even when tornado potential is nil. I will admit I have kind of a rigid mental threshold of 60 F for dew points when dealing with anything east of the High Plains. Only on a very few occasions have I seen exceptions (8 Mar 2010 in W OK being the only one coming to mind at the moment). What really bothers me is the combination of low buoyancy and a narrow instability axis with extreme deep-layer shear. Estimated storm motion on most forecast soundings tomorrow is in the ballpark of 55 kt. That gives you under two hours before an incipient updraft near the dryline/front begins leaving what little instability we'll have. Also, it sometimes seems to take supercells longer to mature when facing an environment characterized by a 100+ kt jet streak in the vicinity. All that said, this is probably the best-looking LLJ we've seen on the Plains since April 14, being out of the south at 45-55 kt. NAM soundings for areas like PTT-RSL at 00z look almost doable, if not for the cap at the bottom of the EML. I'd be rather shocked to see any red dots on the reports map tomorrow night, but there will probably be quite a few green ones on SN, and I just might be one. Link to comment Share on other sites More sharing options...
Ian Posted November 10, 2012 Share Posted November 10, 2012 The October 12 event produced multiple tornadoes. I'm not using it on a large-scale, but using it as a means to determine that something indeed is worth watching. yeah a few quick ones. but it was generally lesser than many (not necessarily here) thought it would be. there are plenty of other ways to come to those conclusions without that graphic imo. in the past the 50 contour tended to mean more than it seems to now.. so in that sense im talking some sort of calibration event. Link to comment Share on other sites More sharing options...
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