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andyhb

May 7th-9th Severe Weather Episodes

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People?  SPC didn't really play it up that much.  It was the TV folks that played it up.  SPC was maybe a tiny bit overhyped but the blame really lies with a few TV folks IMO.  

Anyway, lets not sidetrack this thread, sorry I brought it up :)

They played it up a ton... They mentioned a high-risk being possible in the 06Z D2, the only reasoning in the 06Z D2 outlook for not going High Risk was coverage concerns along the dryline... not the low-level wind field, and not the VBV sig.

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People?  SPC didn't really play it up that much.  It was the TV folks that played it up.  SPC was maybe a tiny bit overhyped but the blame really lies with a few TV folks IMO.  

Anyway, lets not sidetrack this thread, sorry I brought it up :)

 

Local met mentioned that he didn't think a PDS watch was needed, however he mentioned Jarrell TX being one of the reasons why the PDS watched was issued.  I'm not an expert on this subject, but I believe it had something to do with the way the setup/parameters from Jarrell and Tuesdays event had similarities to one another to warrant a PDS watch.  (Gravity waves ect)

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Local met mentioned that he didn't think a PDS watch was needed, however he mentioned Jarrell TX being one of the reasons why the PDS watched was issued.  I'm not an expert on this subject, but I believe it had something to do with the way the setup/parameters from Jarrell and Tuesdays event had similarities to one another to warrant a PDS watch.  (Gravity waves ect)

 

To count on that type of event occurring though to issue a PDS watch is foolhardy. Probabilities that high (90/80) are usually only issued when there is high confidence of a pretty substantial tornado outbreak with several significant tornadoes taking place across all of or some part of a watch area. The Jarrell-type event is not one that anyone in the severe weather enterprise can forecast with that high confidence before it's basically already happening (and I can say that with confidence). To add on to that, aside from the high instability (which still certainly wasn't as high as the Jarrell day), that setup really didn't look much like 5/27/1997 either (synoptically or on the mesoscale).

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00z BRO sounding isn't looking too promising as far as moisture goes with only a 60 degree dewpoint (and very little deep layer moisture). Going to have to be a quick turn-around.

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00z BRO sounding isn't looking too promising as far as moisture goes with only a 60 degree dewpoint (and very little deep layer moisture). Going to have to be a quick turn-around.

Agreed... Was just thinking this. If there is any positives to it, it is that the depth of low-level moisture is much better than it was at 12Z

post-7962-0-65425500-1462583561_thumb.pn

post-7962-0-83040500-1462583683_thumb.pn

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There definitely was mixing during the day there, so that's why you have the deeper moist layer and lower sfc Td. GFS seems to be doing alright with the moist tongue in the western Gulf, so we'll see.

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To count on that type of event occurring though to issue a PDS watch is foolhardy. Probabilities that high (90/80) are usually only issued when there is high confidence of a pretty substantial tornado outbreak with several significant tornadoes taking place across all of or some part of a watch area. The Jarrell-type event is not one that anyone in the severe weather enterprise can forecast with that high confidence before it's basically already happening (and I can say that with confidence). To add on to that, aside from the high instability (which still certainly wasn't as high as the Jarrell day), that setup really didn't look much like 5/27/1997 either (synoptically or on the mesoscale).

 

 

Think the SPC was worried more about the Gravity waves across west Texas early in the day. I believe when the met referred to Jarrell he was looking more so at the gravity waves and the potential they had.  Apparently gravity waves potentially played a role on 5/27/1997 Jarell tornado.
 

 

w5CpRnG.png

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We are already seeing 50s aND 60s dewpoints along the Gulf. Sure we'd normally like to see 60s creeping up to ok by now, but we were never anticipating upper 60s and 70s widespread so this should cone as a surprise to no one.

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Really liking Sunday/Monday (depending on timing) and possibly even both... Likely will see southwesterly flow aloft at H5, atop a moist and moderately unstable environment. VBV may be an issue, but not going to be focused on specifics like that yet. LLVL wind fields look like they'll be good for the most part. Lots will change.

Would be nice if if IA could get in on some severe WX on Sunday night/Monday but right now it looks like it will stay just to the southwest and west of us but at least some mature storms should occur here.

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lol, NAM doubles down with even better moisture for Sunday. I think there's some merit to the concerns expressed about sfc obs and soundings from today, and I doubt we actually see 65 F dew points along the dryline in any widespread fashion, but I don't think it's going to be as dire as some suggest. If we primarily see 61-63 F in W OK, then LCLs will probably be too borderline for a widespread/significant tornado threat before 00-01z, but there will be the customary window around sunset and the potential for one or two tornadoes with higher LCLs beforehand.

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lol, NAM doubles down with even better moisture for Sunday. I think there's some merit to the concerns expressed about sfc obs and soundings from today, and I doubt we actually see 65 F dew points along the dryline in any widespread fashion, but I don't think it's going to be as dire as some suggest. If we primarily see 61-63 F in W OK, then LCLs will probably be too borderline for a widespread/significant tornado threat before 00-01z, but there will be the customary window around sunset and the potential for one or two tornadoes with higher LCLs beforehand.

 

The NAM soundings are pretty insane in E TX on Monday as well (when there surely will be moisture). Great curvature in the lowest 3 km with strong speed shear above it leading to a very long hodograph.

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The NAM soundings are pretty insane in E TX on Monday as well (when there surely will be moisture).

 

Dang... I'd say so, completely uncapped... NAM also develops isolated convection in this region.00_NAM_072_32.86,-94.69_severe_ml.png

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As I think I mentioned earlier, this same type of secondary shortwave evolution like what is shown on Monday happened several times in 2013, and it didn't end well in a couple of cases.

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Dang... I'd say so, completely uncapped... NAM also develops isolated convection in this region.00_NAM_072_32.86,-94.69_severe_ml.png

 

 

 

No cap, but I'm wondering if the Sundays over-night/early morning storms will come into play somewhat.  (could also be a focus for boundary initiation.)

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00Z GFS is further east with the dryline than the NAM/4NAM... But just as potent. It would keep the threat closer to the I-35 corridor between Wichita and the Red-River. GFS shows a significant dryline bulge in C OK at 00Z, and much like the NAM shows pretty good moisture with widespread DPs of 63-66. Instability is not ultra impressive, but still more than workable given the wind-profile. VBV is subtle, and is above 500mb, so it probably is not much of an issue. The sounding below is pretty representative of the environment along much of the DL from  KICT to the TX/OK border at 7pm Sunday.00_GFS_048_35.97,-97.48_severe_ml.pngDespite that it does not necessarily matter whatsoever, curious with what the SPC will say/do with the upcoming 06Z D2 outlook given the multi-model agreement about the environment along and east of the dryline-- wherever the dryline ends up being.

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The GFS is without any doubt too far E with the dryline, as usual. It's just a matter of how much. Given the biases we observed last week, particularly Tue, I'm inclined to think the dryline ends up in the eastern TX PH at the time of initiation.

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The GFS is without any doubt too far E with the dryline, as usual. It's just a matter of how much. Given the biases we observed last week, particularly Tue, I'm inclined to think the dryline ends up in the eastern TX PH at the time of initiation.

certainly too far east nut it will not be that far west.

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Yeah I was thinking somewhere in the ELK/CLK vicinity might be a nice medium between the different models. The 00z NAM sped up a bit (as expected) and this is fairly progressive upper low by the time Sunday rolls around as it ejects out of the SW.

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People get easily stuck on the 5000 CAPE days in Oklahoma. Anything over like 1500 is gravy. CAPE 1500-2000 will not be a limiting factor as far as tornado potential goes.

Last Tuesday there were several people that only cared about the huge CAPE and claimed it would "solve" all other issues.

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It would be nice if we could iron out that issue above 500mb, but that isn't going to happen. Things still look good as long as moisture comes north to play.

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Yeah I was thinking somewhere in the ELK/CLK vicinity might be a nice medium between the different models. The 00z NAM sped up a bit (as expected) and this is fairly progressive upper low by the time Sunday rolls around as it ejects out of the SW.

 

Could very well be around Elk City. Even if it sets up more how I'm thinking in the eastern row of PH counties, the threat for mature supercells and tornadoes would be maximized in that Arnett-Hollis-Frederick-Seiling corridor, regardless.

 

People get easily stuck on the 5000 CAPE days in Oklahoma. Anything over like 1500 is gravy. CAPE 1500-2000 will not be a limiting factor as far as tornado potential goes.

Last Tuesday there were several people that only cared about the huge CAPE and claimed it would "solve" all other issues.

 

Yep. More CAPE is always helpful, and to some degree it can help compensate for borderline/weak shear (which is different than bad shear, like last Tuesday). But 2000 J/kg SBCAPE with good hodographs is all you really need, even on the Plains.

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At the very end of the run, so take it for whatever you want... But both the WRF-NMMB and WRF-ARW show a pretty significant long-track UH track from SW OK into C OK on sunday, ironically over the exact same areas.

WRF-NMMB:uh25_max.us_sc.png

WRF-ARW: 

uh25_max.us_sc.png

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The I-44 corridor (and extrapolating it SW from where it changes direction near Medicine Park, back to Tipton) is definitely one of OK's favorites. On any given severe wx day in western and central OK, chances are good that region gets something.

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swody2_severeprob.png?v=771

...THERE IS AN ENH RISK OF SVR TSTMS LATE SUNDAY AFTERNOON AND  
EVENING ACROSS WESTERN OKLAHOMA INTO PARTS OF WESTERN AND CENTRAL  
KANSAS...  
 
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SURROUNDING AREAS OF THE  
CENTRAL AND SOUTHERN PLAINS...  
 
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE PLAINS AS FAR SOUTH  
AS THE RIO GRANDE VALLEY...AND AS FAR NORTH AS THE MID MISSOURI  
VALLEY...  
   
..SUMMARY
 
 
SEVERE THUNDERSTORMS ARE POSSIBLE SUNDAY ACROSS THE CENTRAL AND  
SOUTHERN PLAINS. THIS INCLUDES THE RISK FOR A FEW SUPERCELLS  
CAPABLE OF PRODUCING VERY LARGE HAIL AND A COUPLE OF  
TORNADOES...PARTICULARLY ACROSS PARTS OF WESTERN OKLAHOMA INTO  
WESTERN AND CENTRAL KANSAS DURING THE LATE AFTERNOON AND EVENING  
HOURS.  
   
..SYNOPSIS
 
 
WITHIN THE SOUTHERN BRANCH OF SPLIT WESTERLIES EMANATING FROM THE  
MID-LATITUDE PACIFIC...MODELS INDICATE THAT A SIGNIFICANT CLOSED LOW  
WILL GRADUALLY SHIFT OR REDEVELOP EAST NORTHEASTWARD OUT OF THE  
INTERMOUNTAIN WEST INTO THE CENTRAL HIGH PLAINS DURING THIS PERIOD.  
THIS MAY OCCUR BOTH IN RESPONSE TO THE CONTINUING PROGRESSION OF A  
NUMBER OF SMALLER-SCALE PERTURBATION AROUND ITS SOUTHERN/EASTERN  
PERIPHERY...AND FORCING ASSOCIATED WITH A VIGOROUS NORTHERN BRANCH  
IMPULSE FORECAST TO DIG TOWARD THE NORTHERN U.S. ROCKIES.  
 
IN RESPONSE TO THESE DEVELOPMENTS MODELS INDICATE THAT A SURFACE  
CYCLONE WILL DEEPEN ACROSS SOUTHEAST COLORADO SUNDAY  
AFTERNOON...BEFORE SLOWLY MIGRATING INTO SOUTHWEST KANSAS SUNDAY  
NIGHT. SOUTHERLY RETURN FLOW OFF THE GULF OF MEXICO IS EXPECTED TO  
RESULT IN MORE SUBSTANTIVE MOISTENING OF THE BOUNDARY LAYER ACROSS  
THE SOUTHERN INTO CENTRAL PLAINS. SURFACE DEW POINTS MAY INITIALLY  
BE FAIRLY MODEST...BUT PROBABLY WILL INCREASE THROUGH THE LOWER TO  
MID 60S. BENEATH STEEP MID-LEVEL LAPSE RATES...PARTICULARLY ALONG  
THE LEADING EDGE OF STRONGER MID-LEVEL COOLING SPREADING EAST OF THE  
CENTRAL AND SOUTHERN ROCKIES...THIS IS EXPECTED TO CONTRIBUTE TO  
SUFFICIENT INSTABILITY TO SUPPORT THE RISK FOR SEVERE STORM  
DEVELOPMENT.  
 
MEANWHILE...FARTHER EAST...ANOTHER DEEP CLOSED LOW IS FORECAST TO  
BEGIN TO EVOLVE WITHIN THE NORTHERN BRANCH OF THE WESTERLIES...NEAR  
AND NORTH OF THE ST. LAWRENCE VALLEY. A COLD FRONT GENERALLY  
ASSOCIATED WITH THIS FEATURE IS EXPECTED TO REACH THE MID ATLANTIC  
COAST...TENNESSEE/LOWER OHIO/MID MISSISSIPPI AND MID MISSOURI  
VALLEYS BY 12Z SUNDAY. THEREAFTER...IT IS EXPECTED TO STALL AND  
BEGIN TO WEAKEN/SHIFT TO THE NORTHEAST...AS SOUTHERN BRANCH SHORT  
WAVE RIDGING GRADUALLY BUILDS ACROSS THE OHIO VALLEY.  
DESTABILIZATION NEAR THIS FRONT COULD BECOME SUPPORTIVE OF SOME RISK  
FOR SCATTERED THUNDERSTORM ACTIVITY...BUT THE RISK FOR SEVERE STORMS  
STILL APPEARS NEGLIGIBLE AT THE PRESENT TIME.  
   
..CENTRAL AND SOUTHERN PLAINS
 
 
THERE ARE A NUMBER OF FEATURES...PARTICULARLY AT SMALLER  
SCALES...THAT MODELS PROBABLY STILL DO NOT HAVE A PARTICULARLY GOOD  
HANDLE ON. AT LEAST SCATTERED THUNDERSTORM ACTIVITY MAY BE  
ONGOING...OR DEVELOP EARLY...ACROSS PARTS OF THE LOWER PLAINS IN  
RESPONSE TO LOW-LEVEL MOISTENING AND FORCING ASSOCIATED WITH  
LOW/MID-LEVEL WARM ADVECTION. HOWEVER...APPRECIABLE SEVERE WEATHER  
POTENTIAL STILL SEEMS MOST LIKELY TO BECOME FOCUSED ALONG A  
SHARPENING DRYLINE...PARTICULARLY FROM PARTS OF NORTHWEST TEXAS INTO  
PARTS OF WESTERN AND CENTRAL NEBRASKA DURING THE LATE AFTERNOON.  
 
IN RESPONSE TO THE DEEPENING SOUTHEAST COLORADO SURFACE LOW...THE  
DRYLINE MAY REMAIN STALLED...OR PERHAPS RETREAT A BIT...ACROSS PARTS  
OF WESTERN OKLAHOMA/KANSAS...INTO THE EVENING HOURS. IT STILL  
APPEARS THAT THE FIRST OF AT LEAST A COUPLE OF SMALLER IMPULSES WILL  
CONTRIBUTE TO INCREASING LARGE-SCALE FORCING FOR ASCENT ACROSS THIS  
REGION BY THE 21-00Z TIME FRAME. THIS MAY PROVIDE SUPPORT FOR  
DISCRETE SUPERCELL DEVELOPMENT ALONG A BROADLY  
CYCLONIC/SOUTHWESTERLY 50-70 KT MID-LEVEL JET ACROSS THE  
TEXAS/OKLAHOMA PANHANDLE REGION.  
 
AS A SOUTHERLY JET AT 850 MB STRENGTHENS TO 50+ KT INTO AND THROUGH  
MID TO LATE EVENING...THE INITIATION OF NEW STORM DEVELOPMENT MAY  
PERSIST IN THE PRESENCE OF WARM ADVECTION ACROSS THIS SAME REGION OF  
WESTERN OKLAHOMA INTO PARTS OF WESTERN AND CENTRAL KANSAS. AS  
SURFACE DEW POINTS CONTINUE TO INCREASE AT LEAST A BIT  
FURTHER...INCREASING RELATIVE HUMIDITY OF THE BOUNDARY LAYER COUPLED  
WITH ENLARGING LOW-LEVEL HODOGRAPHS MAY CONTRIBUTE TO INCREASING  
TORNADIC POTENTIAL...PERHAPS INCLUDING ONE OR TWO STRONG  
TORNADOES...
IN ADDITION TO THE CONTINUING RISK FOR LARGE HAIL.  
 
THIS ACTIVITY IS EXPECTED TO TEND TO DEVELOP NORTHEASTWARD  
OVERNIGHT...WITH SEVERE WEATHER POTENTIAL GRADUALLY DIMINISHING IN  
THE PRESENCE OF WANING OR WEAKER INSTABILITY.  
 
..KERR.. 05/07/2016  

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Should I drive east on hwy 14 or US-34 and hope I can see a tornado? Will the convective mode change to a squall line of all hail, everywhere, all the time? If I drive into a hailstorm, then my car gets dented. And I don't like that. I think that things may change so quickly that I would end up with hail dents. And there's a reasonable chance the hail could be tracking toward my house.

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Should I drive east on hwy 14 or US-34 and hope I can see a tornado? Will the convective mode change to a squall line of all hail, everywhere, all the time? If I drive into a hailstorm, then my car gets dented. And I don't like that. I think that things may change so quickly that I would end up with hail dents. And there's a reasonable chance the hail could be tracking toward my house.

 

I don't see why not, you're pretty close by and you'll probably see some great structure if no tornado.

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Should I drive east on hwy 14 or US-34 and hope I can see a tornado? Will the convective mode change to a squall line of all hail, everywhere, all the time? If I drive into a hailstorm, then my car gets dented. And I don't like that. I think that things may change so quickly that I would end up with hail dents. And there's a reasonable chance the hail could be tracking toward my house.

Go for it. Structure at the very least like Andy said. I'm just leaving Salina and heading west. I think there's a good probability of a tornado or two in northeastern Colorado anyway, but hail will be the main threat. Might need to get those plows out in a few spots.

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