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July 2020 Discussion


Baroclinic Zone
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   Mesoscale Discussion 1253
   NWS Storm Prediction Center Norman OK
   0604 PM CDT Fri Jul 17 2020

   Areas affected...much of North Dakota and northwestern Minnesota

   Concerning...Severe Thunderstorm Watch 379...

   Valid 172304Z - 180100Z

   The severe weather threat for Severe Thunderstorm Watch 379
   continues.

   SUMMARY...The severe threat continues across WW 379.  Storms
   increasing in southwestern portions of the WW will pose a risk for
   wind, hail, and isolated tornadoes over the next few hours.

   DISCUSSION...An ongoing, mature MCS has evolved across northern
   portions of the WW this afternoon.  The leading edge of this MCS was
   demarcated by a stout outflow boundary located from near/just south
   of GFK westward to near N60.  A surface trough extended south of N60
   to near Y22.  South and east of these boundaries, steep mid-level
   lapse rates and 70s F dewpoints were contributing to strong to
   extreme instability, and the influence of a subtle shortwave trough
   over Wyoming on the western edge of this pool of instability was
   contributing to new convective development along the surface trough.
   Over time, models (including CAMs/WoF and to a lesser extent
   coarser-grid operational guidance) indicate that these storms will
   grow upscale into forward-propagating linear segments and clusters
   that will pose a risk for large hail, damaging (perhaps significant)
   wind gusts, and a tornado or two.  WW 380 has been issued south and
   east of the WW 379 to account for this potential scenario.

   North of the outflow, convective towers continue to deepen southeast
   of the Minot vicinity.  Given steep mid-level lapse rates and
   appreciable cloud-bearing shear in the region, large hail is
   probable despite being rooted above the boundary layer. A couple of
   storms have developed appreciable mid-level rotational signatures,
   with should also increase the large hail risk and may contribute to
   isolated severe wind gusts.  This threat should continue for at
   least a couple more hours.  Pending convective trends, temporal
   extensions of WW 379 may be needed beyond the scheduled 01Z
   expiration.

   ..Weatherwiz; American WX Forum affiliate.. 07/17/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...FGF...ABR...BIS...UNR...

   LAT...LON   48950191 49099867 49069587 48729519 47689533 47399629
               47369785 46839896 46049980 45760116 45680263 45920334
               46970329 48470252 48950191
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Only 0.01" here today as the heavier stuff stayed north.  Soil is plenty moist however, though the high of 61 doesn't do much for what's growing there.  Next 3-4 days will make up for that.

And on another topic, misty drizzly cloudy days in the 60s with matching dews are probably about as common in October as in July - maybe one every couple years.

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NAM is putting up dangerous numbers on Sunday. 
 

580 thickness eeesh. 
 

2-meter 98’s ALB and BTV about 95 BOS but that’s likely to even out. Either way 578-580 hypsometric with those kind of temps probably sends concurrent DP over 75 for dangerous HIs

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1 hour ago, Typhoon Tip said:

NAM is putting up dangerous numbers on Sunday. 
 

580 thickness eeesh. 
 

2-meter 98’s ALB and BTV about 95 BOS but that’s likely to even out. Either way 578-580 hypsometric with those kind of temps probably sends concurrent DP over 75 for dangerous HIs

Tee it up 

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15 minutes ago, TauntonBlizzard2013 said:

Tomorrow looks like a scorcher..... good thing we have a cart for golf.

yeah... right, it's called EMT's ... to cart people off the fairway with eyes rollin' around and white foam oozing out of their trembling cooked skulls...

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Mmm... I wonder what the model biases are wrt to specifically DP?  

The Euro DPs on Sunday are a suspiciously dry - just me ...  Just a-priori synoptic existentialism ... we end up richer.  Plus, academia teaches us that a 588+ DAM hydrostatic scaffolding supports higher hypsometric numbers ... then, compounding, we are already tracking a hypsometric plume that's successfully integrating a SW expulsion/EML kinetic air layer, together with continental biomist as it is ...  those 57's of the Euro just come off as suspiciously dry to me...    The NAM 'seems' like a better fit?  Bit, that said...it could be too wet in its own rights. 

So as usual ...the art dictates the result ... how much or little does one use which guidance and/or morphology in mind synthesizes the right anticipation...

That said... conceptually I'm not sure how we're deriving a hypsometric depth of 578+ dm with only 94 F ... It's like 94/76 or 100/66 ... take a pick -

There's got to have some rich R vapor numbers in the ideal gas law lower to upper integral to do that... I can understand that the Euro may just be varying drier... but 57 to 60 over much of PA where it is 72-ish in the other guidance... that seems a little light.

In any case the models  ..the Euro is drier, no doubt. Where the 3KM NAM has a 68 to 73 DP air mass spread ubiquitously through NYS/PA/NJ/MA/VT/NH ... the Euro is tanning lawns... The NAM version interestingly also reflects the elevations changes rather nicely.. with d-slope regions at the lower end of that range, wavelet to the higher accordingly... It's either more right or high resolution garbage - lol

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Quick comment on this 07/18/2020 00z operational Euro run ...

That D8 is nothing shy of an astoundingly hot layout across everywhere ... W of 80W and S of the 50th parallel, across the CONUS!   What does one's snark want to call that ... the largest ubiquitous layout 100 F readings since the late Ordovician ? My god... Pittsburgh to San Francisco is 20 to 28 C at 850 mb ... everywhere

But, we notice... one way or the other... the model won't included NE - no shocker there...

Anyway, there is a pretty strong signal in all the ensemble means to bulge the heights around Chicago from D6 to 8.5 in there ... I'm watching that. .. because the whispers of the "non-correlating summer teleconnectors" do offer some support for WAR-bridging into that region.  But, ...probably owing to the extended time range more so than anything else, ... we see the usual hemispheric dance of first building the ridge nodes 90 to 80W and than immediately pulling/retrograding them back to the perennial N/A base-line that re-situates the ridge over the Rockies... which is code for that could just be losing the signal do to normalization/'beta' correction more than anything else... So we'll have to see where that goes...

I'm also a bit leery of the Euro's front ... the GFS for that matter...  The latter is understandable - it stretches everything embarrassingly W-E beyond D4's regardless of season, planet or galaxy... so, having 0 physical means to drive a cold front half way across the Atlantic is perfectly a viable solution to that thing...  But, the Euro as quick as D4.5 has the flow paralleling the front by late Tuesday and rightfully... stalls the boundary for frontalysis or wobble right through the area ... I could almost see this correcting toward a wash, and having the heat from Sun/Mon settle out to just 90 through Thur before that aforementioned signal might portend another extreme .... perhaps notably related, the Euro did feature a couple few cycles in the lead up to this period that has more persistent heat signaled to 40 N ...

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18 minutes ago, Damage In Tolland said:

So I’m doing the weekly yardwork and shrubs trimming and it’s balls deep in dews at 69-70. Where’s the dry?

Late morning and BDL and ORH are 66°. We usually get the late morning bump as dew evaporates, but it’ll mix and dry out somewhat in the afternoon. Are you new here?

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