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May 4th - 16th Severe Weather Thread


andyhb

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Yeah, but that generally means nothing regarding May, last year had a very widespread outbreak in Mid April and then two more massive outbreaks in Late April and Late May...

I was just making a simple comparison... (That year had a big April Outbreak, this year had a Big April Outbreak, that year didn't have any May Outbreak, this year hasn't a Big May Outbreak so far...)

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Last year was quiet too until all hell broke loose from the 20th through the 25th...

Although for general severe across the country, mid May 2008 was quite active (I'm sure JoMo knows what I'm referring to), this one for the next week and a half (or more) looks to have very little period across the CONUS...

May 2008 was a pretty Active Month, at least by a weekly basis... Considering we had an Early May Outbreak which produced 62-Tornadoes, A Mid-May Outbreak which produced 147 Tornadoes, and a Late-May Outbreak which produced 234 Tornadoes, and then we had another Mid/ Early June Outbreak which produced 136 Tornadoes...

Without a doubt, May 2008 was a fairly active La Nina month that favored areas east of the Plains until the last week. By contrast, this month is going to be very quiet everywhere for the next week or two, at least.

From a chaser's point of view, though, May 2008 was fairly worthless up until the 22nd. A few brave souls willing to battle the Ozarks and Ouachitas saw some of the impressive dryline supercells on 10 May (JoMo will remember that one), but that was about it. For traditional Chase Alley, the pattern was disgusting up until the last week, so that's the comparison I was trying to make.

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I was just making a simple comparison... (That year had a big April Outbreak, this year had a Big April Outbreak, that year didn't have any May Outbreak, this year hasn't a Big May Outbreak so far...)

No, I realize that.

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Last May was awful for the first 14-21 days. Watch the PBS documentary on last yr and watch NWS guys note its historical low. People were just still into April 27 they did not notice as much maybe. You can count "potential" which was still few and far between but then by that metric this May is way better than last May so far. Some of the same issues too--blocky pattern (rex block for like half of last may).. even when things got better there was an EC trough limiting moisture return.

Can't focus too much on a few day period of quiet.. sure if it stretches to two weeks it's not necessarily "normal" for May. But there really is no daily avg for tornadoes even if May/June are pretty close to having a CONUS tornado 8 of 10 or 9 of 10 days on avg.

These things tend to balance themselves out. An EC ridge is usually assured by Memorial Day weekend. Something will crop up by then if not before. The 22-23 is probably ripe as I'll be on a plane back from Tokyo before heading to the Plains.

My guess is this yr ends up about avg -- and after last yr anything will seem "quiet" overall.

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Last May was awful for the first 14-21 days. Watch the PBS documentary on last yr and watch NWS guys note its historical low. People were just still into April 27 they did not notice as much maybe. You can count "potential" which was still few and far between but then by that metric this May is way better than last May so far. Some of the same issues too--blocky pattern (rex block for like half of last may).. even when things got better there was an EC trough limiting moisture return.

Can't focus too much on a few day period of quiet.. sure if it stretches to two weeks it's not necessarily "normal" for May. But there really is no daily avg for tornadoes even if May/June are pretty close to having a CONUS tornado 8 of 10 or 9 of 10 days on avg.

These things tend to balance themselves out. An EC ridge is usually assured by Memorial Day weekend. Something will crop up by then if not before. The 22-23 is probably ripe as I'll be on a plane back from Tokyo before heading to the Plains.

My guess is this yr ends up about avg -- and after last yr anything will seem "quiet" overall.

2004 was very similar. Very quiet up until about May 19th, then gangbusters.

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SPC upped tor chance to 5% in southwest TX.

Cold front making its way, now over north central Texas. We'll be waiting southwest of Abilene.

Good luck! That region of TX has pulled out a few nice surprises so far this year, so I have a good feeling about your chances of seeing something worthwhile.

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MESOSCALE DISCUSSION 0743

NWS STORM PREDICTION CENTER NORMAN OK

1240 PM CDT MON MAY 07 2012

AREAS AFFECTED...PARTS OF THE PECOS VALLEY/EDWARDS PLATEAU REGION OF

SOUTHWEST TX

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 071740Z - 071915Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...STRONG/SEVERE STORM DEVELOPMENT IS EXPECTED TO INCREASE

ACROSS THE REGION DURING THE NEXT FEW HOURS.

DISCUSSION...MID/UPPER FORCING FOR UPWARD VERTICAL MOTION SPREADING

NORTHEASTWARD ACROSS SOUTHWEST TEXAS MAY BE CONTRIBUTING TO RECENT

STORM DEVELOPMENT TO THE WEST OF SAN ANGELO. THIS APPEARS TO BE

NEAR THE INTERSECTION OF A SLOWLY SOUTHWARD ADVANCING COLD

FRONT...AND THE DRY LINE...WHERE THE MOIST BOUNDARY LAYER IS

BECOMING STRONGLY UNSTABLE WITH INSOLATION BENEATH VERY STEEP

MID-LEVEL LAPSE RATES. ONGOING CONVECTION MAY NOT YET BE SURFACE

BASED...BUT A ZONE OF PERSISTENT LOW-LEVEL CONVERGENCE NEAR/

SOUTHWEST THROUGH SOUTH OF SAN ANGELO COULD BECOME THE FOCUS FOR

ADDITIONAL INTENSIFYING STORM DEVELOPMENT THROUGH 20-22Z. ONCE THIS

OCCURS...THOUGH LOW-LEVEL FLOW/SHEAR IS WEAK...DEEP LAYER SHEAR WILL

BE SUFFICIENT FOR SUPERCELLS CAPABLE OF PRODUCING AT LEAST LARGE

HAIL INITIALLY.

..KERR.. 05/07/2012

ATTN...WFO...EWX...SJT...MAF...

post-32-0-98289600-1336413012_thumb.gif

post-32-0-69301000-1336413025_thumb.jpg

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^^ Watch issued.

Deep layer shear weak, under 30 knots, but 3500 to 4000 J/Kg MLCAPE per SPC mesoanalysis, and a clear boundary on SJT radar approaching freshly severe warned cells from the Northeast, maybe they'll there'll be some local excitement around San Angelo today.

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some others with wxbug out this week ended up in ohio.. why they'd go there is beyond me. i guess maybe they were in ill y-day? s tx can be an interesting play at times.. at least there are storms.

accuwx is calling for a summer of death ridge. hopefully that's not met summer.

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some others with wxbug out this week ended up in ohio.. why they'd go there is beyond me. i guess maybe they were in ill y-day? s tx can be an interesting play at times.. at least there are storms.

accuwx is calling for a summer of death ridge. hopefully that's not met summer.

Not anything like last year, I'd almost be willing to bet. The upper air pattern is polar opposite of what we down here were experiencing at this time last year. Further W into the Great Basin...perhaps.

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Not anything like last year, I'd almost be willing to bet. The upper air pattern is polar opposite of what we down here were experiencing at this time last year. Further W into the Great Basin...perhaps.

more focused on the rockies to high plains. ring of fire from Minn to the mid-Atlantic. "less rainy than spring" in your area. i can't remember the last time they got a seasonal forecast right tho... ;)

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Disorganized MCS now south of San Angelo, outflow dominant. Heading to Iraan / Fort Stockton.

Good luck man, looks like S Texas will be the place to be the next couple to three days.

I had chosen Eldorado for a forecast point today for severe hail. Agreed, it looked like an outflow dominant day with the very low LCLs and high CAPE/low shear environment. If you include surface - 8 km shear, there could be marginal supercells....but it doesn't look like that is being realized yet. Happy chasing today, hope you you see something worthwhile.

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2004 was very similar. Very quiet up until about May 19th, then gangbusters.

5/12/04 was a good day, Attica and Harper, KS tornadoes (and a host of others).

Also, found this on another board, thought it was a fairly good description of what this next week and however many more days is basically saying to chasers (and it's a pretty good meme to boot, one may recall a quote from a certain movie regarding a particular extremity of a deity)...

c2f5x.jpg

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
540 PM CDT MON MAY 07 2012
..TIME...   ...EVENT...	  ...CITY LOCATION...	 ...LAT.LON...
..DATE...   ....MAG....	  ..COUNTY LOCATION..ST.. ...SOURCE....
	    ..REMARKS..
0529 PM	 TORNADO		  4 SE CASTELL		    30.67N  98.91W
05/07/2012				   LLANO			  TX   LAW ENFORCEMENT
	    TORNADO REPORT BY THE SHERIFF ON COUNTY ROAD 105.

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But we got wxmann for that :P

Come to the dark side :P

I'd say it's probably the latter, considering the Leap Day and 3/2 systems were the only ones it seems to have really shunted the ridge at all over the past several months. The 4/14 system, for example, had a very intense jet max (90-100+ kts at H5, 120+ at H3/H25), but the stubbornness of the ridge probably prevented it from realizing its true potential (although we still ended up with one of the bigger Plains outbreaks in awhile) and also helped to screw up the setup across the GL/Upper MS Valley the next day...

I would think that too, but 2007 also had an anomalously strong SE ridge and we still got big events (3/28, 4/21(?), 5/4-5, etc). So the ridge can't be the only answer. Something about the stuff that's coming ashore from the Pacific...

Last May was awful for the first 14-21 days. Watch the PBS documentary on last yr and watch NWS guys note its historical low. People were just still into April 27 they did not notice as much maybe. You can count "potential" which was still few and far between but then by that metric this May is way better than last May so far. Some of the same issues too--blocky pattern (rex block for like half of last may).. even when things got better there was an EC trough limiting moisture return.

Can't focus too much on a few day period of quiet.. sure if it stretches to two weeks it's not necessarily "normal" for May. But there really is no daily avg for tornadoes even if May/June are pretty close to having a CONUS tornado 8 of 10 or 9 of 10 days on avg.

These things tend to balance themselves out. An EC ridge is usually assured by Memorial Day weekend. Something will crop up by then if not before. The 22-23 is probably ripe as I'll be on a plane back from Tokyo before heading to the Plains.

My guess is this yr ends up about avg -- and after last yr anything will seem "quiet" overall.

This is mostly true, and nature tends to balance itself out over both medium and long timescales. And I think we will still get severe weather events before July. But over the last couple of decades, post-Nina or 2nd year Nina springs have generally had lackluster Mays (see 2009, 2006, 2000 to an extent), and the balance argument would favor a below-average spring after 2011. And if the ridge has been the problem, the approach of summer is not going to help. So I wouldn't be surprised if this was the start of a lengthy down period. On the other hand, who knows... things can switch on a dime just like they did last year. But if I were a betting man...

May 22-23 has been extremely ripe for tornadoes in the past decade (Joplin, Bowdle, Hallam, Quinter). I wouldn't be surprised if something happened then.

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I would think that too, but 2007 also had an anomalously strong SE ridge and we still got big events (3/28, 4/21(?), 5/4-5, etc). So the ridge can't be the only answer. Something about the stuff that's coming ashore from the Pacific...

5/4-5 and 3/28 that year were similar to the setup from 3/17-18 this year (deep meridional troughs with similar orientation). As such, they were probably close to subjectively "busting" as this year's event did, just did not have quite the vort max, sfc setup and shortwave structure that either of those two events that ended as significant outbreaks did (plus the outflow boundary from the slow moving convection which screwed up tornadic potential on the 18th).

So I wouldn't be surprised if this was the start of a lengthy down period.

Well, that's certainly not what chasers want to hear... :bag:

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Come to the dark side :P

I would think that too, but 2007 also had an anomalously strong SE ridge and we still got big events (3/28, 4/21(?), 5/4-5, etc). So the ridge can't be the only answer. Something about the stuff that's coming ashore from the Pacific...

This is mostly true, and nature tends to balance itself out over both medium and long timescales. And I think we will still get severe weather events before July. But over the last couple of decades, post-Nina or 2nd year Nina springs have generally had lackluster Mays (see 2009, 2006, 2000 to an extent), and the balance argument would favor a below-average spring after 2011. And if the ridge has been the problem, the approach of summer is not going to help. So I wouldn't be surprised if this was the start of a lengthy down period. On the other hand, who knows... things can switch on a dime just like they did last year. But if I were a betting man...

May 22-23 has been extremely ripe for tornadoes in the past decade (Joplin, Bowdle, Hallam, Quinter). I wouldn't be surprised if something happened then.

It's not a good sign to have a jet so flipping weak like progged for the next two weeks this early in May. It only gets weaker from here, folks.

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