January 28-30 Severe threat. S Plains to TN valley to SE

[brettjrob]

Their 'scale' has been at a 3 since earlier today. They mentioned in their afternoon AFD that the primary threat will be damaging straight-line winds but spinup QLCS tornadoes will also be a possibility. 

 

I hope folks are remembering to check the 3 KM CAPE values for this event. If a majority of the 500-700 J/Kg is in the lowest levels, there will be a problem. 

Oh, by the way, CUmet always tends to get doubtful on these winter events. He was calling bust on the Super Tuesday outbreak about 90 minutes before Memphis got slammed by two tornadic supercells. Whenever he starts to get doubtful or downplays an event, I usually start getting more concerned with it.

 

LOL. I don't remember what he said during the day on Super Tuesday, but he's got to be one of the most skilled severe weather forecasters I'm aware of outside SPC. There are a couple people here who I'd say have consistently shown a pessimistic bias over the years, but he's not one of them.

[CUmet]

Their 'scale' has been at a 3 since earlier today. They mentioned in their afternoon AFD that the primary threat will be damaging straight-line winds but spinup QLCS tornadoes will also be a possibility. 

 

I hope folks are remembering to check the 3 KM CAPE values for this event. If a majority of the 500-700 J/Kg is in the lowest levels, there will be a problem. 

Oh, by the way, CUmet always tends to get doubtful on these winter events. He was calling bust on the Super Tuesday outbreak about 90 minutes before Memphis got slammed by two tornadic supercells. Whenever he starts to get doubtful or downplays an event, I usually start getting more concerned with it.

I think you have me confused with thewxmann, or wxmann91 back in those days.  As I recall he was getting very concerned about convective initiation in the warm sector ahead of the front on that day, because it got pretty late before those cells did pop up.

[thewxmann]

Oh, by the way, CUmet always tends to get doubtful on these winter events. He was calling bust on the Super Tuesday outbreak about 90 minutes before Memphis got slammed by two tornadic supercells. Whenever he starts to get doubtful or downplays an event, I usually start getting more concerned with it.

 

No, CUmet's probably one of the top forecasters on this board. It wasn't me either... I was downplaying it the night before, but not the day of. 

[Stebo]

No, CUmet's probably one of the top forecasters on this board. It wasn't me either... I was downplaying it the night before, but not the day of. 

 

Heh, come on now, your bust call that day is legendary

[David Reimer]

I think you have me confused with thewxmann, or wxmann91 back in those days.  As I recall he was getting very concerned about convective initiation in the warm sector ahead of the front on that day, because it got pretty late before those cells did pop up.

 

Did I mix it up? Sorry man! I know someone was getting pretty skeptical a few hours before the event began in the afternoon. Hard to believe that was almost five years ago. I feel old

[andyhb]

Something else to watch ... support for nocturnal storms in E OK Monday night

 

That brings one rather recent event to mind, and it has been popping in the analogs as well.

[chase_stormz]

Which event was that? I can't remember..

[thewxmann]

Heh, come on now, your bust call that day is legendary

 

No use downplaying the downplaying I guess The forecast I made the night before was probably the worst call I have ever made. My, can't believe that was five years ago.

[Stebo]

No use downplaying the downplaying I guess The forecast I made the night before was probably the worst call I have ever made. My, can't believe that was five years ago.

 

First event I followed on the forum myself, double sided too, as locally at college we ended up with 20" of snow at Central Michigan. As for your call then, live and learn, you have to make mistakes to learn from them.

[andyhb]

Which event was that? I can't remember..

 

Lone Grove, OK. February 10th, 2009.

[chase_stormz]

Oh wow completely forgot about that event

[chase_stormz]

 

 

 

SPC AC 280642      DAY 2 CONVECTIVE OUTLOOK     NWS STORM PREDICTION CENTER NORMAN OK   1242 AM CST MON JAN 28 2013      VALID 291200Z - 301200Z      ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER OH/MID MS VALLEY   REGION SWWD INTO NERN TX...      ...SYNOPSIS...   A HIGHLY AMPLIFIED/PROGRESSIVE UPPER PATTERN WILL AFFECT THE U.S.   THIS PERIOD...WITH A STRONG TROUGH FORECAST TO EXIT THE ROCKIES AND   SHIFT INTO THE CENTRAL PORTION OF THE COUNTRY WITH TIME.      AS THE STRONG/SHARP TROUGH ADVANCES...A SHARPENING COLD FRONT IS   FORECAST TO SHIFT ACROSS THE PLAINS DURING THE FIRST HALF OF THE   PERIOD...AND THEN CONTINUE EWD OVERNIGHT.  BY THE END OF THE   PERIOD...THIS BOUNDARY SHOULD STRETCH FROM LOWER MI SWD TO THE   CENTRAL GULF COAST AND ON INTO THE GULF OF MEXICO.  IT IS THIS FRONT   WHICH WILL FOCUS A ZONE OF STRONG/LOCALLY SEVERE CONVECTION ACROSS   PARTS OF THE CENTRAL U.S. -- PARTICULARLY DURING THE LATE AFTERNOON   AND EVENING HOURS.      ...LOWER OH/MID MS VALLEYS SWWD INTO NERN TX...   SHOWERS AND PERHAPS A THUNDERSTORM OR TWO SHOULD BE ONGOING AT THE   START OF THE PERIOD ACROSS PARTS OF OK AND ADJACENT N TX/SRN   KS...AHEAD OF THE SHARPENING SURFACE FRONT.  CONVECTION SHOULD   REMAIN GENERALLY SUB-SEVERE HOWEVER INTO THE AFTERNOON...AS   MOISTENING/WEAK DESTABILIZATION OF THE PRE-FRONTAL AIRMASS OCCURS.      BY MID TO LATE AFTERNOON...500 J/KG MIXED-LAYER CAPE SHOULD COMBINE   WITH INCREASING ASCENT WITH THE APPROACH OF THE UPPER SYSTEM TO   RESULT IN AN INCREASE IN CONVECTIVE COVERAGE/INTENSITY ALONG/AHEAD   OF THE COLD FRONT.  WHILE STORMS FROM ROUGHLY THE MS VALLEY NEWD   INTO IL SHOULD STRUGGLE TO BECOME TRULY SURFACE-BASED THUS LIMITING   SEVERE POTENTIAL...STORMS FROM MO SWD WILL BE OCCURRING IN A   SUFFICIENTLY MOIST BOUNDARY LAYER TO PERMIT DAMAGING WIND/TORNADO   POTENTIAL.  WITH THE MAIN SURFACE LOW TO REMAIN WELL TO THE   N...MINIMAL LOW-LEVEL VEERING MAY LIMIT OVERALL TORNADO POTENTIAL.    HOWEVER...STRONG SPEED SHEAR GIVEN A RAPIDLY STRENGTHENING FLOW   FIELD WITH HEIGHT WILL SUPPORT ORGANIZED STORMS CAPABLE OF PRODUCING   DAMAGING GUSTS AND LIKELY A FEW ISOLATED TORNADOES.      THREAT SHOULD CONTINUE THROUGH THE EVENING AND INTO THE OVERNIGHT   HOURS...WITH LINEAR EVOLUTION OF THE CONVECTION EXPECTED WITH TIME.    DAMAGING WIND POTENTIAL MAY EVENTUALLY SPREAD E OF THE MS RIVER   VALLEY...THOUGH THE GREATEST THREAT SHOULD OCCUR DURING THE EVENING   WITHIN A REGION EXTENDING FROM THE ARKLATEX REGION NEWD ACROSS THE   OZARKS.      ..GOSS.. 01/28/2013   

 

Wow what a joke. 

[Stebo]

I completely disagree with the thought of only 500 J/kg MLCAPE, and the low orientation. There is a low that forms in AR on all models that becomes the predominant low going forward. TBH I have no idea what models were looked at because none of the ones I have looked at showed the Northern low remaining the dominant low.

[chase_stormz]

I completely disagree with the thought of only 500 J/kg MLCAPE, and the low orientation. There is a low that forms in AR on all models that becomes the predominant low going forward. TBH I have no idea what models were looked at because none of the ones I have looked at showed the Northern low remaining the dominant low.

 

The only thing I can think of is they expect the threat to ramp up overnight making it in the day 3 territory, but wow, what a terrible outlook that makes no sense. And the part about minimal low level veering... just wow.

[Stebo]

The only thing I can think of is they expect the threat to ramp up overnight making it in the day 3 territory, but wow, what a terrible outlook that makes no sense. And the part about minimal low level veering... just wow.

Yeah the minimal low level veering is bizarre, all models are showing good veering with height especially in the lowest 1km.

[David Reimer]

Focusing only on Texas, I'm a bit surprised to see they drew the SLGT line so far west. I guess they are being conservative with the line's development. I wouldn't be surprised to see them push that risk a good 100 miles east with later outlooks. I do agree with other posters that this outlook was conservative. Should the 12Z model suite continue to aggressive, I would anticipate a more strongly-worded discussion at 1730Z. It's all about the forecaster style. 

[chase_stormz]

Is Goss typically conservative? He didn't even go into much detail..

 

I would really be surprised if there is not a MOD risk at some point on Tues/Wed...

[JoMo]

Best CAPE/EHI of the entire event occurs this evening and overnight here. 06z NAM has actually increased values.  Models are kicking off a few storms in SE KS and NE OK around that time as well. Doug Cramer from NWS Springfield thinks the models might be under-doing CAPE. The 06z NAM has a nasty looking QLCS forming and rolling across my area Tues morning into early afternoon.

[SmokeEater]

SPC added a 2% tornado contour for OKC and Tulsa, saying a conditional tornado and wind threat may develop. Also, possibly upgrading to slight risk in later outlooks.

[JoMo]

12z NAM has increased instability for tonight again. Shows storms firing around midnightish around SE KS/NE OK. (RAP also shows this) 

 

The hodo ahead of the storms does loop. 

[Stebo]

I think today's instability projection is a good representation of how tomorrow's instability could realistically play out. The NAM is painting widespread 1000-1500 J/kg over a large area today. If that were to occur tomorrow things would go in a big way.

[Ground Scouring]

I can only assume that the SPC is awaiting more guidance from 12Z...to me the latest Day-2 outlook seems more aggressive with the TOR probabilities than the Day-3 outlook yesterday. SPC may be cautious because past experience with such a stretched low and an initial shortwave impulse usually resulted in a lower attendant tornado threat, but every case is unique...and as models have consistently shown a stronger and more consolidated secondary low with very strong deep-layer shear, I think even a moderate amount of low-level veering would be enough and that other factors will take over to favor the tornado threat. Also, given what I said last night about instability being underestimated on the models, the amount of instability would make a huge difference in boosting the 0-2-km SWEAT index and widening the low-level hodographs with increased updraft potential and height. In that case, even a moderate low-level veering with height would be compensated by the strong instability combined with deep-layer shear and other factors favoring rotation and rapid thunderstorm development. So SPC is almost certainly awaiting 12Z guidance re: the surface low and timing of convective initiation before going with a much-higher TOR risk at 1715Z. And for what it is worth, the latest discussion does not suggest that early convection will really do much to affect the quality of moisture and instability in the warm sector by the afternoon of 01/29. Reading between the lines suggest a much higher TOR risk than appears to be acknowledged by the SPC, as nothing has changed since yesterday and, if anything, has gotten more favorable for a significant TOR outbreak.

[Ground Scouring]

Adjusting for the 06Z NAM to account for added instability this afternoon and less early convection tomorrow morning would easily equate to AOA (at or above) 1,000 j/kg of SBCAPE over much of SE AR, N MS, and SW TN by 00Z 01/30. This is well within the sweet zone for a probable High Risk as I alluded to in another thread re: the first High Risk this year. This is also where the widespread, long-lasting, nocturnal TOR potential will begin to ramp up late in the afternoon of 01/29.

[tornadotony]

12z NAM more unstable Tues night thru Wed morning from the Ozarks and across the mid-south into the TN Valley.

[Ground Scouring]

12z NAM more unstable Tues night thru Wed morning from the Ozarks and across the mid-south into the TN Valley.

God, it brings near-60°F dew points up to the Chicago lakefront by 03Z 01/30 (a huge increase in the northward extent of the rich boundary layer relative to previous runs, indicating much less mixing early 01/29 and very strong WAA on a par almost with a March-type system). That is highly unusual after 00Z in any given time of year, and for winter, that is mouth-dropping. It is interesting to note that some of the really big upper Midwest events like Palm Sunday 1920 and 1965 only had near-60°F dew points as well--of course, this will not be a repeat of those events, but it really illustrates the magnitude of what we are seeing. This definitely puts 02/05/2008 in a run for its money.

[chase_stormz]

God, it brings near-60°F dew points up to the Chicago lakefront by 03Z 01/30. That is highly unusual after 00Z in any given time of year, and for winter, that is mouth-dropping.

 

I would hope they get a good forecaster to write the midday update because the potential is there. I would expect a much different outlook if the instability ramps up on the model runs.

[Ground Scouring]

God, it brings near-60°F dew points up to the Chicago lakefront by 03Z 01/30 (a huge increase in the northward extent of the rich boundary layer relative to previous runs, indicating much less mixing early 01/29 and very strong WAA on a par almost with a March-type system). That is highly unusual after 00Z in any given time of year, and for winter, that is mouth-dropping. It is interesting to note that some of the really big upper Midwest events like Palm Sunday 1920 and 1965 only had near-60°F dew points as well--of course, this will not be a repeat of those events, but it really illustrates the magnitude of what we are seeing. This definitely puts 02/05/2008 in a run for its money.

The projected 03Z radiosonde near Memphis, TN, also shows more low-level veering than on previous runs, plus much greater instability and SBCAPE in the lower column. There is also less capping at this time than previously depicted, supporting at least some--likely several--discrete supercell thunderstorms with more-than-sufficient SWEAT to really enhance hodographs, which are even larger on this 06Z run than on previous runs.

[Ground Scouring]

I take that back...the NAM actually shows dew points expanding substantially (!!!) into Fort Wayne, IN, and the Chicago lakefront several hours after 00Z. And it shows much of that moisture sticking around after midnight in the upper Midwest with upper-60s°F dew points as far north as Memphis and Jackson, TN (probably), by 03Z. The set-up would favor at least some isolated supercell thunderstorms as far north as Champaign, IL. Unbelievable...

[chase_stormz]

The projected 03Z radiosonde near Memphis, TN, also shows more low-level veering than on previous runs, plus much greater instability and SBCAPE in the lower column. There is also less capping at this time than previous depicted, supporting at least some--likely several--discrete supercell thunderstorms with more-than-sufficient SWEAT to really enhance hodographs, which are even larger on this 06Z run than on previous runs.

 

I love how 12z NAM shows secondary low development and gfs has been showing it for awhile now and yet SPC forecaster Goss completely ignores that..

[chase_stormz]

I love how 12z NAM shows secondary low development and gfs has been showing it for awhile now and yet SPC forecaster Goss completely ignores that..

 

On the 12z NAM the CAPE actually increases to 750-1000 across much of E AR into MS at 06z while 65+ dew points spread north with secondary low development. Hodos are huge. That would spell trouble. IN THE DARK.