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June 13th - 22nd Severe Weather Chances


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Pretty classic hook echo and the VIL shows as well - yet no warming

The 0.5° velocity scan does not show much in the way of low-level rotation, for now. Mid-level rotation is impressive, as are the 60k ft. tops. Very nice discrete supercell, which is about all one can ask for in the Plains this month.

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I'm no expert and might be missing something altogether but sure seems like NWS is asleep at the wheel ... they've warned stuff not remotely close to this regularly

what are you expecting? a tornado warning? As brett said, there is nice mid-level rotation but not much closer to the surface, and its north of the front.

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I'm no expert and might be missing something altogether but sure seems like NWS is asleep at the wheel ... they've warned stuff not remotely close to this regularly

:facepalm:

You can clearly see the RFD/outflow has cut out ahead of the storm in this image. The tornado potential is not determined on reflectivity alone. If that was the case we would have had most of D/FW under TWs last Wednesday. I would urge you not to bash professionals when you yourself said you're qualified to do so.

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From MPX:

HRRR AND LOCAL WRF SHOW

CONVECTION OVER NORTHERN MN REMAINING IN PLACE TODAY...WHICH WILL

LIKELY INHIBIT THE NORTHERN PROGRESSION OF THE WARM FRONT. AT THE

MOMENT...CURRENT THINKING BASED ON THE RAP...HRRR...AND 12Z GEM IS

THAT BY 21Z...THE FRONT WILL BE NEAR A GRANITE FALLS...TO ST.

CLOUD...TO MORA LINE. GIVEN CONVECTION OVER NRN MN...FEEL 12Z

GFS/NAM PUSH THE FRONT TOO FAR NORTH THIS AFTERNOON.

Doesn't sound good to me, with such warm 700mb temps close by. Feeling it might be another possible bust...

Anyway, how do change the thread date to extend it?

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SPC was very close to pulling a moderate risk...

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0258 PM CDT TUE JUN 19 2012

VALID 192000Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY TO THE

CNTRL HIGH PLAINS...

..UPPER MIDWEST

CONSIDERED AN UPGRADE TO A WIND-DRIVEN MODERATE RISK IN PARTS OF

CNTRL MN. A STRONGLY UNSTABLE WARM SECTOR IS PREVALENT S OF A WARM

FRONT ARCING ACROSS E-CNTRL SD TO NRN WI WITH PRIMARY SURFACE LOW

NEAR HON AND AHEAD OF A COLD FRONT EXTENDING SWWD INTO SWRN NEB.

VERY STRONG DEEP-LAYER SHEAR EXISTS WITHIN THE WARM FRONTAL ZONE.

PRIMARY CONCERN IS WITH REGARD TO WARM MID-LEVEL TEMPERATURES AS

LEAD SHORT WAVE IMPULSE IS WELL REMOVED TO THE NW ALONG THE

MT/SASKATCHEWAN BORDER...AND UPSTREAM IMPULSE IS STILL OVER THE NRN

INTERMOUNTAIN WEST. CONVERGENCE INVOF SURFACE LOW SHOULD BE

SUFFICIENT FOR TSTM DEVELOPMENT BY EARLY EVENING...BEYOND THE

ELEVATED ONGOING CONVECTION OVER NRN MN. UPSCALE GROWTH AND

CONSOLIDATING COLD POOLS WILL BE NECESSARY FOR AN MCS TO OVERCOME

OPEN WARM SECTOR INHIBITION. IF THIS INDEED OCCURS...POTENTIAL IS

CERTAINLY THERE FOR HIGHER-END COVERAGE/INTENSITY OF ALL SEVERE

TYPES.

..CNTRL HIGH PLAINS

WITH APPROACH OF THE SHORT WAVE IMPULSE OVER THE NRN INTERMOUNTAIN

WEST...ASCENT WILL STRENGTHEN AND YIELD TSTM CLUSTERS AFTER DARK.

SUFFICIENT VERTICAL SHEAR AND MUCAPE WILL EXIST FOR HAIL-PRODUCING

STORMS AND THUS HAVE EXTENDED SLIGHT RISK WWD.

..GRAMS.. 06/19/2012

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When/ If any Discrete Supercells form across western Minnesota, or Northeastern South Dakota it could get pretty interesting... Especially since there is 400-500 Effective Helicity m2/s2 and 65-70kt Bulk-Shear in place.... Although the Warm front would definitely have to move a bit farther north for anything to happen...

EDIT: Wow... Now there is 400-700 Effective Helicity in place m2/s2.. With a Supercell Composite of 36..

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When/ If any Discrete Supercells form across western Minnesota, or Northeastern South Dakota it could get pretty interesting... Especially since there is 400-500 Effective Helicity m2/s2 and 65-70kt Bulk-Shear in place.... Although the Warm front would definitely have to move a bit farther north for anything to happen...

EDIT: Wow... Now there is 400-700 Effective Helicity in place m2/s2.. With a Supercell Composite of 36..

Doesn't matter if nothing fires.

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MESOSCALE DISCUSSION 1224

NWS STORM PREDICTION CENTER NORMAN OK

0456 PM CDT TUE JUN 19 2012

AREAS AFFECTED...PARTS OF NERN NEB...ERN SD...SERN ND INTO CNTRL MN

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 192156Z - 192330Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...UNCERTAINTY LINGERS CONCERNING TIMING OF BOUNDARY LAYER

BASED WARM SECTOR DEVELOPMENT...AND INITIATION OF MORE VIGOROUS

CONVECTION WITHIN LOWER/MID TROPOSPHERIC WARM ADVECTION TO THE NORTH

OF THE WARM FRONT. HOWEVER...ONE OR MORE WATCHES LIKELY WILL BE

NEEDED BY EARLY EVENING...PERHAPS WITHIN THE NEXT HOUR OR TWO.

DISCUSSION...VERY WARM ELEVATED MIXED LAYER AIR CONTINUES TO PROVIDE

STRONG INHIBITION TO CONVECTIVE DEVELOPMENT...BOTH IN THE WARM

SECTOR OF THE DEEP EASTERN SOUTH DAKOTA CYCLONE...AND WITHIN AT

LEAST A NARROW CORRIDOR TO THE NORTH OF THE WARM FRONT EXTENDING TO

THE EAST NORTHEAST...ACROSS PARTS OF CENTRAL MINNESOTA. THE VERY

MOIST WARM SECTOR HAS BECOME MODERATE TO STRONGLY UNSTABLE BENEATH

STEEP MID-LEVEL LAPSE RATES...WITH MIXED LAYER CAPE NOW ON THE ORDER

OF 2000-3000+ J/KG. AND DEEP LAYER SHEAR IS STRONG AND FAVORABLE

FOR SUPERCELLS...WITH LOW-LEVEL HODOGRAPHS SIZABLE AND SUPPORTIVE OF

TORNADIC POTENTIAL...MAINLY ALONG THE WARM FRONT.

LOW-LEVEL CONVERGENCE APPEARS MAXIMIZED NEAR THE SURFACE LOW...FROM

HURON INTO THE WATERTOWN AREA...AND DEEPENING CONVECTION IS ALREADY

EVIDENT TO THE NORTH OF HURON. GUIDANCE IS ALSO SUGGESTIVE THAT A

WEAKNESS IN THE INHIBITION MAY EXIST ACROSS THIS

VICINITY...SOUTHWARD ALONG A PRE-FRONTAL SURFACE TROUGH INTO

NORTHEAST NEBRASKA...ALONG WHICH SHALLOWER CUMULUS DEVELOPMENT HAS

BEEN EVIDENT. MEANWHILE...AN INCREASE IN STORM DEVELOPMENT DOES

APPEAR UNDERWAY TO THE NORTH OF THE WARM FRONT...ACROSS PARTS OF

SOUTHEASTERN NORTH DAKOTA INTO WEST CENTRAL MINNESOTA...WHICH THE

LATEST HIGH RESOLUTION RAPID REFRESH SUGGESTS MAY EXPAND

CONSIDERABLY AND GROW UPSCALE THROUGH THE 00-02Z TIME FRAME.

WHILE THE EVOLUTION OF CONVECTIVE DEVELOPMENT DURING THE NEXT FEW

HOURS REMAINS A BIT UNCLEAR...THE GREATEST SEVERE WEATHER

POTENTIAL...INCLUDING THE RISK FOR TORNADOES...APPEARS TO EXIST WITH

CONVECTION NEAR THE HURON/WATERTOWN AREAS...IF AND WHEN THE CAP

FINALLY BREAKS LATE THIS AFTERNOON.

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They'd be a lot higher if this EML wasn't being such a stick in the mud.

Yeah, once I read the Watch discussion I finally came to my senses and realized duh, there is an extensive cap in place... And if there wasn't the probabilities would be much much higher..

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Looks like there's a supercell tracking over west Lake Superior in the past half hour, with strong velocities indicated. That's exciting.

Looks like a pretty good environment for elevated supercells up there with strong 0-3 km SRH and very strong deep layer shear. Low lake temps and subsequent lacking SFC instability will nullify any tornado chances though...

1kmv.gif?1340149032251

Not really much evidence that CI is imminent in the "primed zone" where tornado parameters are currently maxed out, despite CINH eroding in SE SD and parts of MN. The most favorable synoptic forcing for ascent looks to be to the north and west of the warm sector as well (approaching UL shortwave, 700 mb frontagenesis, and LL convergence). EMLs have really been event killers this year!

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Looks like there's a supercell tracking over west Lake Superior in the past half hour, with strong velocities indicated. That's exciting.

It looked pretty good before exiting land but I guess it was probably elevated?

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700mb temps

CAP is trying hard to break...

(Blue to red transition is 11C)

grearth2012-06-1919-42-44-78.png

Cap may not directly be the issue. CINH has apparently eroded for quite a few events this year where convection failed to form. I think in many of these events with warmer 700 mb temps, 0 CINH isn't enough for CI. As shallow convection (i.e. shallow CU field) encounters a warm EML, mixing of dry air parcels with moist ascending air usually kills initial convective plumes. In situations where CI occurs, subsequent plumes gradually moisten the mid-level environment and allow for eventual sustained deep convection. Many of the events this year have failed to reach this point, which suggests to me very dry EMLs are have been the issue this year more so than the cap "failing to break" (which terminologically suggests that CINH remained nonzero).

In a synoptic scale sense, i suspect this has to do with many upper level disturbances this year having neutral or positive tilt, which will generally result in upper level forcing displaced to the N and W of the warm sector (and subsequent upper level "support" in eroding EMLs).

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