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May 23-31 Severe Threats


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Not sure if this is thread-worthy yet, but interesting Day 4-8 SPC outlook this morning hinting at a return to an active severe pattern in parts of the subforum starting next week and possibly into at least the first part of Memorial Day weekend:

 

http://www.spc.noaa.gov/products/exper/day4-8/

 

DAY 4-8 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0400 AM CDT FRI MAY 20 2016

   VALID 231200Z - 281200Z

   ...DISCUSSION...
   AN INCREASINGLY SEVERE-CONDUCIVE PATTERN IS EXPECTED THROUGH EARLY
   NEXT WEEK...ESPECIALLY ACROSS PARTS OF THE CENTRAL/SOUTHERN PLAINS
   TO THE MO VALLEY/MIDWEST. THIS WILL GENERALLY BE ATTRIBUTABLE TO
   SEMI-PERSISTENT TROUGHING WEST OF THE ROCKIES AND
   NORTHWARD-DEVELOPING LOW-LEVEL MOISTURE...WITH A PARTICULARLY
   MOISTURE-RICH/STRONGLY UNSTABLE AIR MASS EXPECTED ACROSS THE
   SOUTH-CENTRAL PLAINS IN THE ABSENCE OF LOCALIZED CONVECTIVE
   OVERTURNING.

   CURRENT INDICATIONS ARE THAT AT LEAST CATEGORICAL SLIGHT RISKS ARE
   PLAUSIBLE EACH DAY THROUGH AT LEAST THE MIDDLE PART OF THE WEEK /DAY
   7 THURSDAY/. IT SHOULD ALSO BE NOTED THAT GRAPHICAL RISK ADJUSTMENTS
   WILL UNDOUBTEDLY BE NEEDED AS MESOSCALE DETAILS ARE RESOLVED.


   DAY 4/MONDAY...WHILE RESIDUAL DAY 3 CONVECTION AHEAD OF A COLD FRONT
   CASTS SOME UNCERTAINTY...SEVERE THUNDERSTORMS COULD OCCUR AS FAR
   NORTH AS MN/IA.
A SOMEWHAT MORE CERTAIN SEVERE RISK IS EXPECTED
   ACROSS THE SOUTH-CENTRAL PLAINS INCLUDING PARTS OF KS/OK INTO
   NORTH/WEST TX NEAR THE DRYLINE.

   DAY 5 TUESDAY...INCREASING/NORTHWARD RETURNING LOW-LEVEL MOISTURE
   AHEAD OF A COLD FRONT/DRYLINE...IN CONJUNCTION WITH A
   LOWER-AMPLITUDE TROUGH OVER THE CENTRAL PLAINS...SHOULD LEAD TO
   SEVERE THUNDERSTORMS RISKS ACROSS PARTS OF THE CENTRAL/SOUTHERN
   PLAINS TO LOWER/MIDDLE MO VALLEY.


   DAY 6/WEDNESDAY...AS THE DEAMPLIFYING TROUGH OVERSPREADS THE UPPER
   MIDWEST/GREAT LAKES...SEVERE THUNDERSTORMS COULD OCCUR ACROSS PARTS
   OF WI/IL/MI AND MIDDLE MS VALLEY/OZARKS... SOUTHWESTWARD TO NEAR THE
   SOUTHERN PLAINS DRYLINE VICINITY WHERE THE SEVERE RISK MAY BE MORE
   ISOLATED/CONDITIONAL WITHIN A VERY UNSTABLE ENVIRONMENT.
WHILE
   SEVERE THUNDERSTORMS CAN BE EXPECTED ON WEDNESDAY...THE POSSIBILITY
   OF EARLY-DAY CONVECTION ACROSS THE MIDWEST AND RELATED MESOSCALE
   UNCERTAINTIES CURRENTLY PRECLUDES A GRAPHICALLY DEPICTED SEVERE
   RISK.

   DAY 7/THURSDAY...WHILE CONFIDENCE IN SPATIAL DETAILS IS NOT OVERLY
   HIGH...EARLY INDICATIONS ARE THAT A NORTHEASTWARD-EJECTING SOUTHERN
   STREAM TROUGH IN CONJUNCTION WITH STRENGTHENING WESTERLIES ALOFT
   WILL OVERSPREAD A VERY MOIST/UNSTABLE WARM SECTOR ACROSS THE
   SOUTH-CENTRAL PLAINS TO MO VALLEY/MIDWEST.


   ..GUYER.. 05/20/2016
 

 

 

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definitely the best airmass of 2016 coming for those of use further NE

naso excited about severe but general thunder prospects go way up

Agreed, nothing in the progs screams anything major but wouldn't be surprised to see a few slight risk type days mixed in. At this point, either Wednesday or Thursday look to be potential days and then possibly Friday or Saturday. Obviously lots of timing differences to iron out, but nice to finally have storm chances on the horizon and if the mesoscale details work out possibly even some severe prospects.
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D3 includes some of Illinois, Iowa, and Missouri in the SLGT risk, along with a big MRGL risk that covers most of Illinois, Minnesota, and Wisconsin. SPC has hatched over the plains. 

 

 

 

...CENTRAL PLAINS/CORN BELT/MIDWEST...
MCS/RESIDUAL CONVECTION-RELATED DETAILS ARE NOT PARTICULARLY
CERTAIN...BUT WITH AID OF WARM ADVECTION...IT IS POSSIBLE THAT AN
MCS MAY BE ONGOING SOMEWHERE ACROSS EASTERN PORTIONS OF KS/NEB INTO
IA/MO TUESDAY MORNING. IF THIS IS THE CASE...THESE STORMS COULD
LINGER/FORWARD PROPAGATE EAST-SOUTHEASTWARD ACROSS ADDITIONAL
PORTIONS OF IA/MO/WESTERN IL WITHIN A DIURNALLY DESTABILIZING AIR
MASS. ANOTHER ROUND OF CONVECTION COULD MOVE INTO PARTS OF THIS
REGION /IA-MO-IL/ LATE TUESDAY NIGHT/EARLY WEDNESDAY.

OTHERWISE...WHILE SPATIAL/TIMING-RELATED VARIABILITY EXISTS AMONGST
AVAILABLE GUIDANCE...A LOW-AMPLITUDE SHORTWAVE TROUGH SHOULD EMERGE
FROM THE CENTRAL ROCKIES AND MOVE ACROSS NEB AND THE MIDDLE MO
VALLEY TUESDAY AFTERNOON/NIGHT. THIS WAVE SHOULD CONTRIBUTE TO DEEP
CONVECTIVE DEVELOPMENT WITHIN A MODERATE TO STRONGLY UNSTABLE
BOUNDARY LAYER ACROSS NEB/NORTHERN KS NEAR/NORTH OF A FRONT AND
NORTH/NORTHEAST OF A CENTRAL HIGH PLAINS SURFACE LOW...WITH AID OF
LOW-LEVEL UPSLOPE TRAJECTORIES ACROSS WESTERN NEB/NORTHWEST KS. A
STRONGLY SHEARED ENVIRONMENT COULD SUPPORT SUPERCELLS CAPABLE OF
VERY LARGE HAIL AND A FEW TORNADOES...WITH STORMS EVENTUALLY GROWING
UPSCALE/POTENTIALLY CAPABLE OF DAMAGING WINDS AS THEY PROGRESS
EAST-NORTHEASTWARD TOWARD/ACROSS THE MIDDLE MO VALLEY.

post-13724-0-50998500-1463903874_thumb.g

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The 12Z NAM has 5000 CAPE in lower MI Thursday night

Yeah, not gonna happen.

 

 

Interestingly it has dewpoints in the low 70s, which is very similar to the GFS...maybe a tick higher.  The bigger difference is temps as the NAM is considerably warmer than the GFS.  If those dewpoints come to fruition then it's possible that CAPE could be near NAM levels.

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Interestingly it has dewpoints in the low 70s, which is very similar to the GFS...maybe a tick higher.  The bigger difference is temps as the NAM is considerably warmer than the GFS.  If those dewpoints come to fruition then it's possible that CAPE could be near NAM levels.

Yes especially considering that it is driven predominantly by the cooler temperatures aloft. Although it is more like 4000 j/kg for NAM and 3000 for the GFS/Euro, they aren't that far off.

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I have a question for the actual mets on here so I don't jump to a conclusion.

The SPC didn't mention the threat for our subforum on their Day 4-8 outlook this morning, so what do you think about probabilities if any on the Day 3?

They will probably do a 5% at this junction though I'd argue they are focusing too much on the plains and ignoring this region so a 15% on the day 3 wouldn't shock me at all once they focus on our region.

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They will probably do a 5% at this junction though I'd argue they are focusing too much on the plains and ignoring this region so a 15% on the day 3 wouldn't shock me at all once they focus on our region.

I was thinking it was because we are in the open warm sector and I didn't see any sources of lift with the exception of the warm front, wherever that sets up. Along with that, the actual low is all the way invof the lee Rockies in the E CO high plains. I am trying to reference that storms could have coverage issues lacking a sufficient source of initiation, but that also raises the question: Would instability alone be enough to initiate storms? I could be wildly wrong here but could this have something to do with it?

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0Z NAM did get the high 4000 CAPE spread more evenly, hoping if the GFS agrees the SPC catches on to this thing.

For the time being, its like what LinnCounty said above. SPC  hasn't caught on to it yet because the models show we will be capped and there will be a stronger mid level ridge. The GFS was the first to show it and the Euro started following the same lines. Of course, this could change, but all of that would mean the largest convective risk will be west of us (particularly those of us in Michigan, I wouldn't count out parts of Illinois but the boat is kind of similar there, albeit a bit higher than MI). Sure we'll have 3k j/kg+ CAPE on Thursday evening, but we'll have weak lifting mechanisms at best. Unless something can come in and break the cap to provide wider coverage, convection will be rather limited.

 

Saturday seems to show some favorable deep layer shear as well as decent instability. A low level jet will be set up over Lower Michigan (basis of storms on Friday) and the Euro is showing a cold front dropping out of the Upper Plains into the region on Monday. That would enhance the risk in the Saturday time frame. 

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NWS Marquette @NWSMarquette 2m2 minutes ago

NWS personnel are en route to two possible tornado touchdown locations in Marquette County west of Republic & SE of the Greenwood Reservoir.

 

Just looking back at the radar around the time the storm passed through those areas, I think they might find some damage. There was a solid couplet for a while there.

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Some further looking into at that analog FWIW.

 

Nice bow crossing into the state about 7 pm EDT

post-5974-0-24283400-1464127018_thumb.pn

 

Still going strong at 10 pm

post-5974-0-42106000-1464127052_thumb.pn

 

Then an hour later at 11 pm, it's still a respectable MCS but almost completely misses SEMI. A good analog to have on our side, nonetheless.

post-5974-0-76694300-1464127101_thumb.pn

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NWS Marquette @NWSMarquette 17s18 seconds ago

Tornado confirmed: Touched down near Marquette/Iron/Baraga County border, traveled ENE across River Rd, lifted west of M-95 near Republic.

 

 

NWS Marquette @NWSMarquette 12s12 seconds ago

...2nd tornado traveled from CR 476 just south of the Greenwood Reservoir, traveled east, then lifted around CR 581 in Marquette County.

 

 

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NWS Marquette ‏@NWSMarquette 17s18 seconds ago

Tornado confirmed: Touched down near Marquette/Iron/Baraga County border, traveled ENE across River Rd, lifted west of M-95 near Republic.

 

 

NWS Marquette ‏@NWSMarquette 12s12 seconds ago

...2nd tornado traveled from CR 476 just south of the Greenwood Reservoir, traveled east, then lifted around CR 581 in Marquette County.

Unreal that the frickin UP gets tornadoes before we do. Haha what a boring year in weather it's been other than the April snowstorm

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Unreal that the frickin UP gets tornadoes before we do. Haha what a boring year in weather it's been other than the April snowstorm

There have been 5 tornadoes in Ohio If I remember correctly. They were all from a mini supercell day in Darke and Preble Counties.

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