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July 5th and beyond Severe Weather thread


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baro, I plan on chasing Friday night. I'm thinking about heading to the Killarney/Boissevain area in southwestern Manitoba. It's SSW of Brandon, near the ND border. Can't leave until after 6, so that's the best option right now. Would that be a good enough spot to see some supercells or is further east a better option?

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baro, I plan on chasing Friday night. I'm thinking about heading to the Killarney/Boissevain area in southwestern Manitoba. It's SSW of Brandon, near the ND border. Can't leave until after 6, so that's the best option right now. Would that be a good enough spot to see some supercells or is further east a better option?

The farther W the better, but you are in a tough situation there. The main corridor of instability is well off in western NODAK, and initiation will be along the frontal boundary in eastern MT. Given the amount of low level turning and relatively weak mid level flow, supercell storm motions are going to be incredibly slow. The farther W the better, I am just not sure you will get there in time if you can't leave until after 6.

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The farther W the better, but you are in a tough situation there. The main corridor of instability is well off in western NODAK, and initiation will be along the frontal boundary in eastern MT. Given the amount of low level turning and relatively weak mid level flow, supercell storm motions are going to be incredibly slow. The farther W the better, I am just not sure you will get there in time if you can't leave until after 6.

I guess it will be tough to get any legit supercell activity that far east so early. I am heading out with a lightning photographer, though. Not sure if heading out for a pure MCS would be worth it, though.

Thanks for your response!

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I think Saturday still has a decent severe weather threat. The tornado threat has rapidly decreased, though. Even if it's just some hail and strong winds, that's fine by me. Haven't had much to be excited about up here since 07. For that reason, I'll take whatever I can get :lmao:

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I'm wondering how long the storms will stay discrete (with regards to Derek's storm chasing plans)

Edit: And I agree with baro that the models seemed to have waned off for Saturday.

Yeah good question. The frontal boundary is rather interesting, and it is really more of a dryline than a cold front. Soundings behind the windshift/dryline feature are deeply well mixed (with the possibility the windshift stalls during the later afternoon and even possibly mixes back westward like normal drylines), and it seems possible, if initiation occurs as early as some guidance suggests, that supercells will be able to last into the early evening before the low level jet really ramps up into the western ND plains. This may be a case where the slow moving deep cyclone in CA is partially a good thing as the cold front doesn't necessarily overtake the dryline/baroclinic trof early on.

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Yeah good question. The frontal boundary is rather interesting, and it is really more of a dryline than a cold front. Soundings behind the windshift/dryline feature are deeply well mixed (with the possibility the windshift stalls during the later afternoon and even possibly mixes back westward like normal drylines), and it seems possible, if initiation occurs as early as some guidance suggests, that supercells will be able to last into the early evening before the low level jet really ramps up into the western ND plains. This may be a case where the slow moving deep cyclone in CA is partially a good thing as the cold front doesn't necessarily overtake the dryline/baroclinic trof early on.

So, you think I'll at least get in on some MCS action in SW MB? Would be fine by me!

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Looking at the instability/shear profiles, I would not be shocked if we saw a localized tornado outbreak in ND on Friday. Will depend on how messy the warm sector is (NAM/SREF indicating very messy and thus a lowered potential).

I agree, it is one of the most impressive setups I have seen in quite a long time in western ND. Of course the beefy mid level warm air advection/insane precipitable waters is a major cause for concern in terms of cloud debris/ongoing DMC with elevated junk pushing in from MT.

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day2probotlk_0600_any.gif

SPC AC 070600

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0100 AM CDT THU JUL 07 2011

VALID 081200Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NORTHERN/CENTRAL

PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MID-ATLANTIC

REGION...

...NORTHERN/CENTRAL PLAINS...

A POTENT UPPER TROUGH/ASSOCIATED SPEED MAX WILL SPREAD EASTWARD FROM

THE NORTHERN/CANADIAN ROCKIES TO THE NORTHERN PLAINS/CANADIAN

PRAIRIES ON FRIDAY. SURFACE CYCLOGENESIS WILL OCCUR ACROSS THE

NORTHERN HIGH PLAINS WITH A SHARPENING NORTH-SOUTH LEE TROUGH

EXTENDING SOUTHWARD INTO THE CENTRAL HIGH PLAINS. THIS SURFACE

TROUGH WILL EVENTUALLY BE OVERTAKEN BY AN EASTWARD ACCELERATING COLD

FRONT ACROSS THE NORTHERN HIGH PLAINS. NEAR/EAST OF THE SURFACE

TROUGH/COLD FRONT...AND SOUTH OF A

NORTHWARD-SHIFTING/NORTHWEST-SOUTHEAST ORIENTED WARM FRONT ACROSS

THE DAKOTAS/UPPER MIDWEST...A MOIST AIRMASS WILL BE IN PLACE ACROSS

FAR EASTERN MT AND THE DAKOTAS/NEB...WITH LOWER/MIDDLE 60S F SURFACE

DEWPOINTS LIKELY TO BE PREVALENT IN THESE AREAS BY FRIDAY AFTERNOON.

AIDED BY APPRECIABLE LARGE SCALE FORCING FOR ASCENT...TSTMS SHOULD

INCREASE IN COVERAGE/VIGOR RELATIVELY EARLY IN THE

DAY/AFTERNOON...AND CERTAINLY BY MID/LATE AFTERNOON AND INTO THE

EVENING ACROSS EASTERN MT TO THE WESTERN DAKOTAS. A BIT

LATER...OTHER HIGHER BASED SEVERE TSTM DEVELOPMENT SHOULD OCCUR

SOUTHWARD INTO THE CENTRAL HIGH PLAINS IN VICINITY OF THE LEE

TROUGH. ESPECIALLY FROM FAR EASTERN MT TO THE WESTERN/CENTRAL

DAKOTAS...AMPLE VERTICAL SHEAR /40-45 KT EFFECTIVE BULK SHEAR/

COINCIDENT WITH A MOIST/MODERATELY UNSTABLE AIRMASS WILL SUPPORT

SUPERCELLS CAPABLE OF LARGE HAIL WITH A TORNADO RISK AS WELL.

ESPECIALLY AS THE COLD FRONT OVERTAKES THE SURFACE TROUGH DURING THE

EVENING/OVERNIGHT...STORMS SHOULD CONSOLIDATE/SPREAD EASTWARD

THROUGH THE EVENING/OVERNIGHT WITH A RISK OF DAMAGING WINDS/HAIL

CONTINUING ACROSS THE DAKOTAS.

...EASTERN GREAT BASIN TO SOUTHERN MT...

ISOLATED STRONG/SEVERE TSTMS WILL BE POSSIBLE WITHIN A RELATIVELY

MOIST/MODESTLY SHEARED PRE-COLD FRONTAL REGIME ACROSS THE EASTERN

GREAT BASIN. OTHER STRONG HIGH-BASED STORMS MAY POSSIBLE NEAR THE

HIGHER TERRAIN OF SOUTHERN MT/PERHAPS NORTHERN WY WITHIN A

POST-FRONTAL REGIME. IN EITHER CASE...DOWNBURSTS AND/OR HAIL MAY BE

POSSIBLE ON AN ISOLATED BASIS.

...MID-ATLANTIC/SOUTHEAST STATES AND CAROLINAS...

THE EXACT DEGREE/SPATIAL LOCATION OF STRONGEST DIURNAL

DESTABILIZATION IS STILL UNCERTAIN FOR FRIDAY. HOWEVER...A

MOIST/POTENTIALLY UNSTABLE AIRMASS IN THE PRESENCE OF INCREASINGLY

CYCLONIC/STRONGER MID-HIGH LEVEL FLOW OVER THE MID-ATLANTIC

REGION/DELMARVA SHOULD CONTRIBUTE TO SCATTERED STRONG/SEVERE TSTMS

FRIDAY AFTERNOON/EARLY EVENING...ESPECIALLY INCLUDING PORTIONS OF

VA/NC/DELMARVA. WITH THE POTENTIAL FOR RELATIVELY WELL-SUSTAINED

MULTICELLS...THE STRONGEST STORMS WILL BE CAPABLE OF DOWNBURSTS/WIND

DAMAGE AS WELL AS MARGINALLY SEVERE HAIL.

..GUYER.. 07/07/2011

I'm beginning to think that the amount of forcing may be able to overcome that messiness in the warm sector.

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I'm beginning to think that the amount of forcing may be able to overcome that messiness in the warm sector.

The problem might be too much forcing causing storms to go up much too early. In general the best outbreaks have a moderate cap that breaks later in the afternoon early evening. If things get messy and storms go up across the warm sector early afternoon they'll congeal or cloud debris will essentially limit peak heating meaning less energy. Potential is certainly there and a slightly warmer layer in the 850-700mb area could do wonders to suppress convection until later in the afternoon. As far as the mcs though it should be just fine later in the evening. This sure could be a wasted potential for a decent tornado outbreak, like we saw about a month and a half or so ago in OK and KS (not sure about date) when a moderate went to waste when storms went up early and the warm sector was worked over.

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The problem might be too much forcing causing storms to go up much too early. In general the best outbreaks have a moderate cap that breaks later in the afternoon early evening. If things get messy and storms go up across the warm sector early afternoon they'll congeal or cloud debris will essentially limit peak heating meaning less energy. Potential is certainly there and a slightly warmer layer in the 850-700mb area could do wonders to suppress convection until later in the afternoon. As far as the mcs though it should be just fine later in the evening. This sure could be a wasted potential for a decent tornado outbreak, like we saw about a month and a half or so ago in OK and KS (not sure about date) when a moderate went to waste when storms went up early and the warm sector was worked over.

I believe that was May 11th...and yes that was a frustrating day.

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The problem might be too much forcing causing storms to go up much too early. In general the best outbreaks have a moderate cap that breaks later in the afternoon early evening. If things get messy and storms go up across the warm sector early afternoon they'll congeal or cloud debris will essentially limit peak heating meaning less energy. Potential is certainly there and a slightly warmer layer in the 850-700mb area could do wonders to suppress convection until later in the afternoon. As far as the mcs though it should be just fine later in the evening. This sure could be a wasted potential for a decent tornado outbreak, like we saw about a month and a half or so ago in OK and KS (not sure about date) when a moderate went to waste when storms went up early and the warm sector was worked over.

Yeah, I would certainly agree with the MCS potential. Could be a significant damaging wind event for the central/eastern Dakotas after dark. Looking forward to some nice action up here, too.

Saturday's severe potential continues to diminish. Sure, there will be elevated strong to severe storms everywhere in the morning but that's going to harm our potential come the afternoon hours.

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Tomorrow still looks highly interesting with quite a bit of potential. Guidance keeps coming in on the stronger side of the solutions from a couple days ago, GFS bombing this thing out sub 990. Limiting factors may be garbage convection early on with limited CAPE alluded to by Cmich and TornadoTony as well as some really moist profiles. Shear profiles, on the other hand, are superb. Lot of potential but it is turning into what may not be a terribly great chase event with ample cloudcover likely and possibly some darn near HP type supercells and messy convection by later afternoon.

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Tomorrow still looks highly interesting with quite a bit of potential. Guidance keeps coming in on the stronger side of the solutions from a couple days ago, GFS bombing this thing out sub 990. Limiting factors may be garbage convection early on with limited CAPE alluded to by Cmich and TornadoTony as well as some really moist profiles. Shear profiles, on the other hand, are superb. Lot of potential but it is turning into what may not be a terribly great chase event with ample cloudcover likely and possibly some darn near HP type supercells and messy convection by later afternoon.

Yeah I'm really thinking the western 1/3 to 1/2 of ND might be in for quite a substantial event tomorrow.

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I've noticed the models aren't showing a ton of instability tomorrow night. Is this a case where the dynamics will just end up winning out? Rare to get a high shear/lower instability day in July up here!

My gut says you're too far north for substantial severe.

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What do you think of the potential caveats for tomorrow? I am a bit worried about what looks like ample cloud cover as well as the very moist profiles which will be difficult to mix cloud layers out if any develops in the lower levels.

The caveats are more numerous than we realize I think given the models' poor handling of the convection and convective feedback issues. There doesn't look like there will be much capping and I think that the models are trying to signal early initiation. The NAM would support sig severe by 18z but for some reason has mixed-out low levels leading to LCLs around 1250m. I don't buy that but I don't think anything can honestly be ruled out at this point. The main underscore here is that the synoptic setup would be favorable for a tornado outbreak and that the mesoscale features need to be closely monitored.

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