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Arctic April

Webberweather53 said:
The most progressive, least interesting GFS solution is definitely not trending towards a nothingburger, stream separation is consistently increasing w/ each successive run.

View attachment 38402
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Problem is, heights keep trending flatter as it shows increasingly more blocking and a deeper trough, which suggests limited moisture return and low level convergence for organized convection.

The wave separation will really only make a difference for the Texarkana region.
 
SouthATLwx said:
Problem is, heights keep trending flatter as it shows increasingly more blocking and a deeper trough, which suggests limited moisture return and low level convergence for organized convection.

The wave separation will really only make a difference for the Texarkana region.
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No, wave separation makes a difference everywhere because more means the parent s/w is stronger, so is the QG forced ascent, it changes the tilt of the wave (more neutral) and the track of the surface low (further NW) as well as the intensity and breadth of the warm sector (stronger & further north).
 
This 12z Euro is shaping up to be another big run. We had more than enough stream separation, the SW US wave is slow enough to pump the heights over the SE US and start advecting warm/moist air off the gulf into the SE US

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Webberweather53 said:
Wave separation makes a difference everywhere because it means the parent s/w is stronger, so is the QG forced ascent, it changes the tilt of the wave and the track of the surface low as well as the intensity and breadth of the warm sector.
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I suppose if the shortwave coming out of Texas slows down long enough for heights to recover ahead of it and doesn't get sheared apart as it migrates eastward (close to what the 00z EURO showed), there's a chance.

The GFS and GGEM are both a long ways off from that solution though, and the 00z EURO was kind of on its own with its depiction.

Personally, I'd rather we get back to that triple phase the 18z GFS showed a couple days ago (yes, I know, fat chance :()
 
SouthATLwx said:
I suppose if the shortwave coming out of Texas slows down long enough for heights to recover ahead of it and doesn't get sheared apart as it migrates eastward (close to what the 00z EURO showed), there's a chance.

The GFs and GGEM are both a long ways off from that solution though, and the 00z EURO was kind of on its own with its depiction.

Personally, I'd rather we get back to that triple phase the 18z GFS showed a couple days ago (yes, I know, fat chance :()
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GFS & GGEM tend to be too progressive w/ these SW US shortwaves and this bias is ringing true here. The EPS was a hair faster than the ECMWF but significantly slower than the GFS & GEFS which are also slowing down.
 
SD said:
Impressive soundingson the euro when you clear out the initial rain and go full warm sector View attachment 38407
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Yep, diurnal timing verbatim sucks in the western piedmont (what else is new) but a secondary low passing overhead w/ already absurd amounts of low-level shear and somewhat respectable instability should raise more eyebrows.
 
We've had our fair share of mid-April freezes, so I definitely wouldn't be shocked to see one this year. Unfortunately, I feel like this is shaping up to be a very active spring in terms of severe wx. We're long overdue for a large scale tornado outbreak, we can all hope it doesn't happen this year, but given our pattern going forward, I am not very optimistic that this will be the case.
 
The 12Z ensemble consensus is still looking N to BN for 4/10-20 in the SE US. Caution is advised due to cold bias, but hopefully this time will be different. One thing that makes me optimistic is that the EPS is just about as cold as the GEFS/GEPS, something not seen often as it has had the least cold bias. Even after adjusting for cold bias, it appears that we're headed for a similar period to what we just experienced of pleasantly mild to cool with low dewpoints thanks to dry Canadian air. Looks promising for good walking wx! Actually, the coldest relative to normal still looks to be NW of the SE. To the NW, it looks to go solidly BN if the models aren't exhibiting too strong a cold bias.
 
Impressive at this range.

1586129295870.png



The ceiling could go considerably higher than even what the Euro is leading on depending on the interaction w/ this trailing northern stream wave

1586129345084.png
 
pcbjr said:
Interesting.

Possible?

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Definitely possible. Mid-April Freezes aren't that terribly uncommon, especially up in the northern parts of the Southeast. Heck, Raleigh had a minor snowstorm on April 19, 1983, for that matter.

I think RDU's last freeze was March 8th (or about that time). I have to wonder if that's one of the earliest last freezes on record? That seems pretty early to me. There's always a chance we get another still, but we're running out of time, especially as the near-term pattern doesn't look conducive. I believe Raleigh's latest freeze on record is May 10th.
 
Hrrr has some nice multicellular clusters tomorrow, with some 60+ dbzs in ENC, likely from better CAPE/DPs, might be some marginally severe hail around there tomorrow w/ some isolated downbursts, as you head west into WNC, boundary layers will be well mixed with large inverted Vs, which may allow a more gusty wind threat, once thing to watch is that sea breeze boundary which may enhance the strength of storms around ENC 04E1B5B4-89C2-4B21-A228-EAFC2DD44153.png4E1BEDD1-713A-44E8-BD64-6D7E8EB9BB5C.png
 
Here’s a sounding from ENC from the hrrr, better CAPE with decent 0-6km bulk shear 0CFB0272-9FB7-48CA-AFD6-75EB2F49B93B.png
one from near CLT, boundary layer is effectively mixed, dewpoint depressions around 30+, this sounding reminds me of one out in the SW us, lol AEAF2BF5-AE31-41DB-B9E6-378DD2756313.png
 
0Z GEFS is cold throughout the country and pretty cold even into most of the SE for days 6-15., The question is how much is it overdone due to persistent cold bias. Even if it is off a good bit, it certainly doesn't look like a warm pattern like we had in March and dewpoints should be nice and low most days.

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