Ed Lizard Posted November 4, 2011 Share Posted November 4, 2011 I get a feeling, from what was a fairly ordinary FB post, NWS OUN's afternoon AFD will be worth reading. Link to comment Share on other sites More sharing options...
David Reimer Posted November 4, 2011 Author Share Posted November 4, 2011 I get a feeling, from what was a fairly ordinary FB post, NWS OUN's afternoon AFD will be worth reading. As usual, it was completely useless. Fresh off the 15Z SREF... Link to comment Share on other sites More sharing options...
andyhb Posted November 4, 2011 Share Posted November 4, 2011 As usual, it was completely useless. Fresh off the 15Z SREF... Definitely liking the look of that, and still 78 hrs. out, which is rather impressive for the SREF. Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 4, 2011 Share Posted November 4, 2011 FWD hedging for the expected reasons on initiation and storm mode Monday afternoon, all depending on whether overnight/morning activity breaks up and allows some Sun, but seems pretty convinced on a solid line with the actual front. Link to comment Share on other sites More sharing options...
BeauDodson Posted November 4, 2011 Share Posted November 4, 2011 Seems like instability is going to be the big question as we head into this event - Paducah was very bullish in their hazardous weather outlook (mentioning tornadoes and significant severe). A bit surprised this far out. MARS has been hitting the event (also noted the 15th on the MARS) Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 4, 2011 Share Posted November 4, 2011 Internet not helping me much re "MARS". I can see it is some kind of analog finder. Is this related to the SPC web site sounding analogs? Link to comment Share on other sites More sharing options...
David Reimer Posted November 5, 2011 Author Share Posted November 5, 2011 Link to comment Share on other sites More sharing options...
Srain Posted November 5, 2011 Share Posted November 5, 2011 The NAM/WRF and the GFS raise an eyebrow. Looking forward to see what the SPC has to say this evening... Link to comment Share on other sites More sharing options...
andyhb Posted November 5, 2011 Share Posted November 5, 2011 The NAM/WRF and the GFS raise an eyebrow. Looking forward to see what the SPC has to say this evening... I'd probably guess a day 3 slight risk with maybe a 30% area somewhere around Wichita Falls, maybe Lawton, south to around Abilene. Maybe a hatched area as well depending on the Euro's verbatim. Although the potential presence of clouds/rain may limit their outlook, like it did with the Day 4-8. Link to comment Share on other sites More sharing options...
Srain Posted November 5, 2011 Share Posted November 5, 2011 I'd probably guess a day 3 slight risk with maybe a 30% area somewhere around Wichita Falls, maybe Lawton, south to around Abilene. Maybe a hatched area as well depending on the Euro's verbatim. Although the potential presence of clouds/rain may limit their outlook, like it did with the Day 4-8. I tend to agree, Maybe as far NE as OKC. We will see. Guidance has struggled with this event and we often see that in early November. I am a bit concerned for points N and E as well. Perhaps this event will attract those that follow severe events from other sub forums or have been rather quiet... Link to comment Share on other sites More sharing options...
brettjrob Posted November 5, 2011 Share Posted November 5, 2011 Wow, the SREF today has been nothing if not consistent. I thought that was an accidental re-post of the 15z at first. I'm still skeptical for a couple reasons. I hadn't taken a close look at model soundings until now, but delving into those from the 00z NAM, there's more of a skinny-CAPE look than I was expecting. With EL's unseasonably high, yet SBCAPE still mainly in the 1500 J/kg range, mid-lapse rates and parcel accelerations don't exactly look impressive. LI's look to be around -4 to -5 C, which is fairly marginal for the Plains. Low-level shear is somewhat anemic at 21z, then really takes off at 00z, but will surface-based activity still be ongoing then with the sun now setting around 23z? With those gripes out of the way, I still think this is the most impressive November setup in the southern Plains (W of I-35) in several years. The last one I can remember was in 2008, and it failed to produce tornadoes mainly due to moisture return that was significantly poorer than Monday's. If the NAM is largely correct in leaving the Red River Valley portion of the warm sector uncontaminated up to the time of afternoon surface-based initiation, there should be a window of opportunity (mainly 3-6pm) for tornadic supercells. If the GFS is correct with its convective vomit early in the day, which it's consistently shown for numerous runs, this thread will be moot. I'm guessing 15% on the SWODY3, with maybe 30% hatched probabilities by tomorrow night should the NAM/SREF hold their ground. Link to comment Share on other sites More sharing options...
andyhb Posted November 5, 2011 Share Posted November 5, 2011 I tend to agree, Maybe as far NE as OKC. We will see. Guidance has struggled with this event and we often see that in early November. I am a bit concerned for points N and E as well. Perhaps this event will attract those that follow severe events from other sub forums or have been rather quiet... If the pattern that plays out over the next couple of weeks looks anything like the 18z GFS run, we will be seeing some substantial activity in these threads for the month of November... Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 5, 2011 Share Posted November 5, 2011 Long and skinny CAPES on the model sounding where the LFC would be thousands of feet lower and the CAPE would be much higher if the actual surface temps were just a couple of degrees warmer than forecast, would seem to me, big bust/big action potential. Picture the sounding if Ardmore is just a three or four degrees warmer than forecast ... Link to comment Share on other sites More sharing options...
andyhb Posted November 5, 2011 Share Posted November 5, 2011 Picture the sounding if Ardmore is just a three or four degrees warmer than forecast ... Trouble... Link to comment Share on other sites More sharing options...
baroclinic_instability Posted November 5, 2011 Share Posted November 5, 2011 Wow, the SREF today has been nothing if not consistent. I thought that was an accidental re-post of the 15z at first. I'm still skeptical for a couple reasons. I hadn't taken a close look at model soundings until now, but delving into those from the 00z NAM, there's more of a skinny-CAPE look than I was expecting. With EL's unseasonably high, yet SBCAPE still mainly in the 1500 J/kg range, mid-lapse rates and parcel accelerations don't exactly look impressive. LI's look to be around -4 to -5 C, which is fairly marginal for the Plains. Low-level shear is somewhat anemic at 21z, then really takes off at 00z, but will surface-based activity still be ongoing then with the sun now setting around 23z? With those gripes out of the way, I still think this is the most impressive November setup in the southern Plains (W of I-35) in several years. The last one I can remember was in 2008, and it failed to produce tornadoes mainly due to moisture return that was significantly poorer than Monday's. If the NAM is largely correct in leaving the Red River Valley portion of the warm sector uncontaminated up to the time of afternoon surface-based initiation, there should be a window of opportunity (mainly 3-6pm) for tornadic supercells. If the GFS is correct with its convective vomit early in the day, which it's consistently shown for numerous runs, this thread will be moot. I'm guessing 15% on the SWODY3, with maybe 30% hatched probabilities by tomorrow night should the NAM/SREF hold their ground. I tend to agree here, while the setup looks great initially on paper, seems quite a few things may keep it as a marginal threat at most. The guidance has been pretty consistent in the trough ejecting as a somewhat positive tilt wave with a narrow leading edge anomaly. Quite a bit of trailing energy...the orientation of the wave would suggest quite a bit of activity underneath the right entrance region of the jet and over the relatively sharp low level WAA regime. Seems there will be quiet a strong mesoscale front/jet coupling in the low levels/upper levels with a pretty good chance of rain/elevated thunder. I am leaning more towards a GFS type solution than the NAM...I just don't see why it is so dry early on. Throw in what will likely be a relatively dense plume of lee cirrus/WAA cirrus ahead of the trough with short heating, I would have to think SPC will stick with more marginal probs. And regarding the skinny CAPE...that is something to consider with SREF tor probs as they will not account for the CAPE distribution. Link to comment Share on other sites More sharing options...
David Reimer Posted November 5, 2011 Author Share Posted November 5, 2011 I tend to agree here, while the setup looks great initially on paper, seems quite a few things may keep it as a marginal threat at most. The guidance has been pretty consistent in the trough ejecting as a somewhat positive tilt wave with a narrow leading edge anomaly. Quite a bit of trailing energy...the orientation of the wave would suggest quite a bit of activity underneath the right entrance region of the jet and over the relatively sharp low level WAA regime. Seems there will be quiet a strong mesoscale front/jet coupling in the low levels/upper levels with a pretty good chance of rain/elevated thunder. I am leaning more towards a GFS type solution than the NAM...I just don't see why it is so dry early on. Throw in what will likely be a relatively dense plume of lee cirrus/WAA cirrus ahead of the trough with short heating, I would have to think SPC will stick with more marginal probs. And regarding the skinny CAPE...that is something to consider with SREF tor probs as they will not account for the CAPE distribution. I agree with you both. While there is potential with this event, it will likely be focused in a localized area, aided by mesoscale factors that we won't even know will exist until Sunday Night or Monday Morning. There are several complicating factors, including the quality of moisture return and how fast the morning convection will clear out. I'm not diving into the specifics with this setup yet and I doubt that SPC will place more then a standard risk of severe weather (15%) across the area with tonight's outlook. If model data begins to agree on a solution that would favor a more concentrated area of severe weather, they may go higher with the probs on the Day 2 outlook. We'll see what can come of the instability axis once we get a squall line going along the cold front, as that could be a decent wind producer. Link to comment Share on other sites More sharing options...
brettjrob Posted November 5, 2011 Share Posted November 5, 2011 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0149 AM CDT SAT NOV 05 2011 VALID 071200Z - 081200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF OK AND TX.... .SYNOPSIS IMPRESSIVE SHORTWAVE TROUGH WILL PROGRESS EWD FROM AZ/UT INTO THE ERN NM/TX PANHANDLE AND BE THE PRIMARY FACTOR FOR SEVERE CONVECTION THIS PERIOD. WHILE LATEST DETERMINISTIC MODELS ARE IN REASONABLE AGREEMENT ON OVERALL PATTERN...00Z NAM/ECMWF CYCLOGENESIS IS SLOWER...AS IS THE EWD MOTION OF THE DEVELOPING LOW...AS COMPARED TO THE 00Z GFS. LATEST NAM/ECMWF ARE PREFERRED GIVEN THAT THE STRONGER FORCING/JET MAX WILL BE LOCATED ON THE SRN BASE OF THE TROUGH UNTIL THE END OF THE PERIOD. THEREFORE BY LATE MONDAY AFTERNOON...AT THE SURFACE...EXPECT WEAKENING FRONT TO EXTEND FROM NEAR CNU SWWD TO A WEAK SURFACE LOW NEAR CDS...WITH A DRYLINE STRETCHING SWD FROM THE LOW ACROSS WRN TX. SURFACE LOW/FRONT/DRYLINE SHOULD EDGE ONLY SLOWLY EWD OVERNIGHT. ..TX/OK STRONG UPPER LEVEL DIFFLUENCE....BETWEEN THE POLAR AND SUBTROPICAL JETS...IS EXPECTED TO RESULT IN CONSIDERABLE CLOUDS AND CONVECTION ACROSS THE REGION MUCH OF THE DAY...LIMITING HEATING AND CONSEQUENT SURFACE INSTABILITY. HOWEVER...AS THE STRONGER DIFFLUENCE SHIFTS EWD...PCPN/CLOUDS MAY DECREASE SUFFICIENTLY FOR TEMPERATURES TO WARM INTO THE 70S...ESPECIALLY ACROSS SWRN OK AND NWRN TX. THESE READINGS COMBINED WITH 60-65 DEGREE DEWPOINTS AND STEEP MID/HIGH LEVEL LAPSE RATES WOULD YIELD MLCAPES AROUND 1500 J/KG. THIS INSTABILITY PLUS VEERING AND STRENGTHENING WIND PROFILES WITH HEIGHT...YIELDING 50-60 KT OF DEEP LAYER SHEAR...WOULD BE FAVORABLE FOR SUPERCELLS. WHILE LARGE HAIL WOULD BE THE MAIN THREAT...THE MOIST BOUNDARY LAYER AND 20-30 KT OF LOW LEVEL SHEAR ALSO FAVOR TORNADOES. ATTM...THE GREATEST THREAT FOR THE MORE INTENSE STORMS APPEARS TO EXIST ACROSS SWRN OK/NWRN TX AND IS DEPICTED BY THE 30% SEVERE PROBABILITY LINE ON THE PROBABILITY GRAPHIC. WHILE THE SEVERE THREAT SHOULD PERSIST INTO THE EVENING AS THE STORMS SPREAD NEWD INTO CENTRAL OK/NRN TX...WEAKER INSTABILITY/LAPSE RATES SUGGESTS THE STORMS WILL NOT BE AS INTENSE OR AS NUMEROUS AS THE STORMS THAT DEVELOP EARLIER IN THE AFTERNOON. ..IMY.. 11/05/2011 Link to comment Share on other sites More sharing options...
andyhb Posted November 5, 2011 Share Posted November 5, 2011 I'd probably guess a day 3 slight risk with maybe a 30% area somewhere around Wichita Falls, maybe Lawton, south to around Abilene. Maybe a hatched area as well depending on the Euro's verbatim. Although the potential presence of clouds/rain may limit their outlook, like it did with the Day 4-8. Damn, I guess I do know what I'm talking about. Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 5, 2011 Share Posted November 5, 2011 0z ECMWF shows good moisture return, with 60+ dp's into S. Kansas by Monday evening. The warm sector is filled with clouds with some showery activity from time to time. There is also pre-18z widespread/heavy development along and north of a Post to Ardmore line. Link to comment Share on other sites More sharing options...
andyhb Posted November 5, 2011 Share Posted November 5, 2011 New Day 4-8: DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0304 AM CDT SAT NOV 05 2011 VALID 081200Z - 131200Z TUE/D4... DETERMINISTIC AND MEDIUM RANGE ENSEMBLES ARE IN GENERAL AGREEMENT OF UPPER LOW TRACKING FROM THE TX PANHANDLE AREA NEWD INTO IA... THOUGH AT VARIOUS SPEEDS AND INTENSITY. THE FORCING...SHEAR AND INSTABILITY APPEAR FAVORABLE FOR SEVERE...ESPECIALLY AS THE UPPER TROUGH BECOMES NEGATIVELY TILTED LATER IN THE PERIOD. THE BEST THREAT FOR SEVERE WEATHER WILL BE IN THE MID MS VALLEY WHERE THE BEST COMBINATION OF STRONGER FORCING AND INSTABILITY ARE FORECAST TO OCCUR. MODELS ARE HIGHLY SUGGESTIVE OF A FAST MOVING THUNDERSTORM LINE...WITH WIND DAMAGE THE MAIN THREAT. NORTH OF THE OUTLOOK AREA...FORCING AND WIND FIELDS WILL BE VERY STRONG AND FAVORABLE FOR SEVERE WEATHER...BUT UNCERTAINTY ON INSTABILITY PREVENTED THE RISK AREA FROM BEING EXTENDED FARTHER NWD. SOUTH OF THE OUTLOOK AREA IN ERN TX/FAR SRN AR AND LA...STORMS ARE LIKELY AS FRONT/TROUGH SHIFTS EWD. HOWEVER... SEVERE THREAT EXPECTED TO BE MORE ISOLATED AS MAIN FORCING PASSES WELL NORTH OF AREA WITH LITTLE IN THE WAY OF HEIGHT CHANGES. WED/D5...UPPER WAVE AND SURFACE LOW PRESSURE ARE FORECAST TO LIFT NEWD INTO THE OH VALLEY/GREAT LAKES REGION. WHILE A LOW END SEVERE WIND THREAT MAY STILL EXIST IN THE MORNING...GIVEN THE STRONG FORCING/WIND FIELDS...MOST OF THE CONVECTION IS EXPECTED TO SHIFT NEWD INTO AN AREA WHERE NO APPRECIABLE INSTABILITY IS FORECAST. THU/D6 - SAT/D8... UPPER TROUGH OVER THE MS VALLEY IS PROGGED TO AMPLIFY AND SHIFT EWD THROUGH THE PERIOD...WHILE ANOTHER TROUGH MOVES ONTO THE WEST COAST FRI. BOTH SYSTEMS WILL BE ACCOMPANIED BY PCPN AND PERHAPS THUNDERSTORMS...ESPECIALLY IN THE ERN CONUS...BUT VERY WEAK INSTABILITY SHOULD LIMIT THE SEVERE THREAT. Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 5, 2011 Share Posted November 5, 2011 3 hour NAM frpm PSU e-Wall not giving me a big feel for widespread severe. Widespread thunder, yes. Childress looks to clear out in the afternoon, with storms developing just West at 6 pm local Monday. 60 hours out, not saying verbatim, but maybe localized severe somewhere NW TX/SW OK. Link to comment Share on other sites More sharing options...
tornadotony Posted November 5, 2011 Share Posted November 5, 2011 3 hour NAM frpm PSU e-Wall not giving me a big feel for widespread severe. Widespread thunder, yes. Childress looks to clear out in the afternoon, with storms developing just West at 6 pm local Monday. 60 hours out, not saying verbatim, but maybe localized severe somewhere NW TX/SW OK. With that kind of kinematic profile, that CAPE would support decent severe. Additionally, I'd be beyond weary of even looking at the NAM at this range with much seriousness. Link to comment Share on other sites More sharing options...
David Reimer Posted November 5, 2011 Author Share Posted November 5, 2011 With that kind of kinematic profile, that CAPE would support decent severe. Additionally, I'd be beyond weary of even looking at the NAM at this range with much seriousness. I agree with you on how we must keep in mind this is still 48+ hours out, however, I am noticing a concerning trend with the past few runs of the NAM. It looks like it's being a bit slower with the system as a whole compared to the GFS. That's not surprising as the GFS is usually a tad too fast, but if the NAM's solution plays out the dryline will remain further west with the low level jet displaced off to the east. Not to mention that the NAM is also maintaining precipitation in the warm sector until 3-4 PM in the afternoon. That's just not going to work once we have sunset at 5:30 in the afternoon on Monday out there. We're still a few days out, but those two trends are concerning to me. Link to comment Share on other sites More sharing options...
David Reimer Posted November 5, 2011 Author Share Posted November 5, 2011 One positive thing the 12Z NAM is showing would be the low level CAPE values. Please note that this is at 9 PM on Monday, although the values are about the same at 6 PM as well. Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 5, 2011 Share Posted November 5, 2011 Additionally, I'd be beyond weary of even looking at the NAM at this range with much seriousness. This... The new NAM has not done well in it's medium and long range since becoming OP. Link to comment Share on other sites More sharing options...
scoresman Posted November 5, 2011 Share Posted November 5, 2011 The only day I can get out is Tuesday.. Looking like it might be one big squall line across AR/MO but im holding out hope. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 5, 2011 Share Posted November 5, 2011 Significant Tornado Parameter spiking in NE Texas Panahndle/SW Oklahoma Monday evening. Link to comment Share on other sites More sharing options...
David Reimer Posted November 5, 2011 Author Share Posted November 5, 2011 15Z SREF Link to comment Share on other sites More sharing options...
andyhb Posted November 5, 2011 Share Posted November 5, 2011 18z NAM showing some rather beefy EHI values in North Central TX/SW OK... GFS has the threat a bit further to the east, but is in general in decent agreement with the NAM, perhaps with a bit less instability, but stronger LL jet. Link to comment Share on other sites More sharing options...
David Reimer Posted November 6, 2011 Author Share Posted November 6, 2011 21Z SREF for 6 PM on Monday Link to comment Share on other sites More sharing options...
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