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6/20-21 Severe Weather Threat for the Northern Plains


AgeeWx

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As the topic description alludes to, SPC has hatched an area on both the Day 2 and Day 3 outlook for parts of the Northern Plains. The tornado threat (everyone's favorite topic) does not appear to be large but the threat for damaging winds and large hail appear to be favored with the set-up. Model agreement has not been the best regarding convective mode but the instability will be there with forecasted dewpoints in the mid to upper 60's as far north as the border.

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As my colleague and office mate ZackH, alluded to, Saturday seems to be carry the most substantial risk for severe weather as the closed H5 circulation spins over the inter-mountain west and ejects small disturbances over the Northern Plains throughout the forecast period.

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As my colleague and office mate ZackH, alluded to, Saturday seems to be carry the most substantial risk for severe weather as the closed H5 circulation spins over the inter-mountain west and ejects small disturbances over the Northern Plains throughout the forecast period.

 

Southern/Central ND looks absolutely primed on Saturday according to the GFS. Then a big MCS on Saturday night travelling north/northeast along with the ejecting low.

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And as well, we are looking at some pretty good elevated convection at night thursday night and friday night, as far east as the twin cities. The multi-day outbreak scenario is definitely there. But the 18Z nam is getting more progressive in ejecting the 500hPa low out of the BC interior elongating it with sending one piece into the prairies and the other into northern NV at 00z saturday.

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For what its worth, which I know is not much (its still fun to look at though), here's the Sig Tor Ingredients from the SREF for 00z Friday:

 

SREF_prob_combined_sigtor__f033.gif

 

Its hard to get too excited about the SREF, however, because it is basically just an ensemble version of the NAM and it seems like most everyone is throwing the NAM out.  The NAM doesn't look like much for Saturday, but again... its the NAM which has been a major outlier thus far.

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18z runs make both Thurs and Sat look more meh... we will see if that trend continues on the 00z runs.

 

I'm not sure Saturday looked any less potent (considering I am basically ignoring the NAM at this range), assuming we do get a more organized speed max overlapping the warm sector, there should be at least decent potential there.

 

If the main vort max slows anymore and takes a more southern track, then Sunday may become the more impressive day on the weekend again.

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D3.

 

DAY 3 CONVECTIVE OUTLOOK     NWS STORM PREDICTION CENTER NORMAN OK   0230 AM CDT THU JUN 20 2013   VALID 221200Z - 231200Z   ...THERE IS A SLGT RISK OF SVR TSTMS FOR THE NRN PLAINS AND UPPER MS   VALLEY...   ...SYNOPSIS...   THE ECMWF/UKMET/CMC SUGGEST A VIGOROUS SHORTWAVE IMPULSE EMBEDDED   WITHIN THE PERSISTENT UPPER-LEVEL TROUGH OVER THE NORTHWEST WILL   EJECT E/NEWD INTO THE NRN HIGH PLAINS BY EARLY SUN. NAM/GFS APPEAR   FASTER AND LESS AMPLIFIED...WHICH LACKS RUN-TO-RUN CONTINUITY   COMPARED TO THE ECMWF. FOLLOWING THE NON-NCEP GUIDANCE...SURFACE   THERMAL LOW SHOULD REMAIN CENTERED NERN CO...WITH A SSW/NNE-ORIENTED   QUASI-STATIONARY FRONT TOWARDS THE RED RIVER OF THE NORTH. A   W/E-ORIENTED COMPOSITE WARM FRONT/OUTFLOW SHOULD EXTEND E OF THIS   FRONT...LIKELY MODULATED BY MCS/S ON D1/D2.   ...NRN PLAINS...UPPER MS VALLEY...   CONVECTIVE SCENARIO FOR D3 IS MUDDLED BY THE LIKELIHOOD OF MCS/S IN   PRECEDING DAYS AS WELL AS OUTLYING DEPICTIONS FROM DETERMINISTIC   NCEP GUIDANCE. AS SUCH...DETAILS ARE UNCLEAR BUT THE PROBABLE   EJECTION OF THE SHORTWAVE IMPULSE INTO THE NRN HIGH PLAINS INCREASES   CONCERN FOR A POTENTIAL SIGNIFICANT SEVERE EVENT IN PARTS OF THE   UPPER MIDWEST.   THE PLAINS LLJ SHOULD REMAIN STRONG /EVEN THROUGH THE DIURNAL   HEATING CYCLE/ YIELDING CONTINUED WAA ALONG AND N OF THE COMPOSITE   WARM FRONT/OUTFLOW IN THE NRN UPPER MS VALLEY/GREAT LAKES. BENEATH   CAPPING...60S SURFACE DEW POINTS SHOULD BE MAINTAINED AND DAYTIME   HEATING IN THE WAKE OF MORNING CONVECTION MAY YIELD A STRONG TO   EXTREMELY UNSTABLE AIR MASS. AS LARGE-SCALE ASCENT INCREASES SAT   EVENING...CONVECTION SHOULD FIRE ALONG THE QUASI-STATIONARY FRONT.   WITH STRENGTHENING WIND PROFILES...SUPERCELLS PRIMARILY PRODUCING    LARGE HAIL /SOME SIGNIFICANT/ ALONG WITH A FEW TORNADOES MAY OCCUR.   WITH THE DEEP-LAYER FLOW GENERALLY PARALLEL TO THE BOUNDARY AND THE   BULK OF STRONGER WINDS OCCURRING IN THE LOW/MID-LEVELS...CONVECTION   SHOULD QUICKLY GROW UPSCALE WITH RISKS FOR SEVERE WIND/HAIL.   ..GRAMS.. 06/20/2013
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Saturday's setup over E SD has been advertised as pretty solid on the GFS for a few days, but the NAM insists on driving the boundary farther S into NE. Euro is more in the GFS camp. That's the day that impresses me most out of this three-day stretch (Thu-Sat).

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In the short term, no watches/warnings in the Dakotas. I think the area near the warm front (ND/SD border) may be an area to watch for supercells and tornadoes today, especially if helicity increases. Wind directional shear (700mb is south, 500mb is west) is already quite large in South Dakota. I've rarely seen 700mb and 500mb be so different in wind direction at a spot.

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SPC mesoanalysis forecasting an uptick in SRH throughout the afternoon in Eastern North Dakota. Not that current trends would lead anyone to believe that discrete convection is imminent.

You may be right.  The 4km NAM suggests mainly linear development. (12z 4km-NAM)

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Pretty decent looking supercell in Emmons County, ND.

 

It has a good environment too, fixed/effective layer STP of 3-4, 0-3 km EHI of 5-6, SCP up to 16+, sfc winds are backed southeasterly with adequate LCLs and a pool of 70-72 degree dewpoints.

 

TW for the eastern cell along I-94.

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Confirmed tornado now with that cell.

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTHWESTERN BARNES COUNTYUNTIL 645 PM CDT...AT 620 PM CDT...A CONFIRMED TORNADO WAS LOCATED NEAR ROGERS...ANDMOVING EAST AT 20 MPH.HAZARD...TORNADO.SOURCE...WEATHER SPOTTERS CONFIRMED TORNADO.IMPACT...SPORADIC DAMAGE TO MOBILE HOMES...ROOFS AND VEHICLES.THIS TORNADIC STORM WILL BE NEAR...  BALD HILL DAM AROUND 635 PM CDT.
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Confirmed tornado now with that cell.

 

I know who the spotter was and lets just say I'm skeptical.  I know plenty of other chasers on that storm who saw nothing... but we will see.

 

We had a surprising chase though with the storm NE of that storm... got in the middle of a microburst that moved our car.  We also saw a grain silo it destroyed.  Some great HP structure and golf ball size hail.

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so, the question is, how do you draw the upcoming box that should be out soon to replace the current one? roughly?

 

i'm thinking something in the order of  GFK > DLH > ONA > RWF > HON > JMS as your corner points. but I am open to suggestions on how to modify that.

 

 

edit:

 

I guess we know now.... 

 

http://www.spc.noaa.gov/products/watch/ww0332.html

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Just a tad windy....

BULLETIN - EAS ACTIVATION REQUESTED  SEVERE THUNDERSTORM WARNING  NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN  137 AM CDT FRI JUN 21 2013    THE NATIONAL WEATHER SERVICE IN THE TWIN CITIES HAS ISSUED A    * SEVERE THUNDERSTORM WARNING FOR...    CHIPPEWA COUNTY IN WEST CENTRAL MINNESOTA...    NORTHWESTERN KANDIYOHI COUNTY IN CENTRAL MINNESOTA...    WESTERN STEARNS COUNTY IN CENTRAL MINNESOTA...    EASTERN SWIFT COUNTY IN WEST CENTRAL MINNESOTA...    * UNTIL 230 AM CDT    * AT 133 AM CDT...SEVERE THUNDERSTORMS WERE LOCATED ALONG A LINE    EXTENDING FROM 7 MILES SOUTHEAST OF GLENWOOD TO 6 MILES SOUTH OF    BENSON TO APPLETON TO 9 MILES WEST OF MADISON...AND MOVING    SOUTHEAST AT 30 MPH.      THESE ARE VERY DANGEROUS STORMS.      HAZARD...QUARTER SIZE HAIL AND 90 MPH WIND GUSTS.      SOURCE...RADAR INDICATED.      IMPACT...YOU ARE IN A LIFE THREATENING SITUATION. MOBILE HOMES WILL             BE HEAVILY DAMAGED OR DESTROYED. HOMES AND BUSINESSES WILL             HAVE SUBSTANTIAL ROOF AND WINDOW DAMAGE. FLYING DEBRIS             WILL BE DEADLY TO PEOPLE AND ANIMALS. EXPECT EXTENSIVE             TREE DAMAGE AND POWER OUTAGES.    * LOCATIONS IMPACTED INCLUDE...    MONTEVIDEO...WILLMAR...PAYNESVILLE...BIG BEND CITY...DE GRAFF...    MILAN...PADUA...MURDOCK...BROOTEN...SUNBURG...ELROSA...KERKHOVEN...    WATSON...BELGRADE...SPRING HILL...GEORGEVILLE...PENNOCK...GLUEK...    LAKE HENRY AND RAYMOND.    PRECAUTIONARY/PREPAREDNESS ACTIONS...    THIS IS AN EXTREMELY DANGEROUS SITUATION WITH TORNADO LIKE WIND  SPEEDS EXPECTED. MOBILE HOMES AND HIGH PROFILE VEHICLES ARE  ESPECIALLY SUSCEPTIBLE TO WINDS OF THIS MAGNITUDE AND MAY BE  OVERTURNED. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE  LOWEST FLOOR OF A BUILDING. THESE STORMS HAVE THE POTENTIAL TO CAUSE  SERIOUS INJURY AND SIGNIFICANT PROPERTY DAMAGE
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well, my neighborhood in st paul got lucky no big damage here other than one branch measuring 2 3/4" diameter, most were 1/2" or less. but power last i knew was out in the west end in minnetonka, and there was some lightning/wind damage over in the west end and highland park areas of stp as well as over near stillwater and in i think maplewood.

 

just now have to want and see about the new MCS headed our way from just east of RAP. latest storm report with those cells has baseball-sized and tennisball-sized hail in western Jackson County in SD.

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This was one of the craziest non-tornado chases I've ever had.  Got some incredible timelapse video and some cool footage in the middle of a probable microburst.  The video doesn't quite do it justice as the wind was slightly actually moving our car.  Also including a couple of damage pics.

 

http://www.youtube.com/watch?v=eR2SNvoB08A

 

 

1016083_857587526072_1091772951_n.jpg

 

1017646_857587311502_335656250_n.jpg

 

1014378_857587371382_1157117266_n.jpg

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