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andyhb

Meteorologist
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Posts posted by andyhb

  1. Will likely be driving southbound on 35 tomorrow towards Austin, wonder if I might take a detour or two along the way...

    I have strong doubts that initiation will hold off until 00z given the synoptic setup. That is a pretty potent, negatively tilted wave ejecting right overtop of the warm sector, which should provide plenty of forcing for ascent and the cap is not overly strong. Have seen some funky looking wind fields in a few forecast soundings, but most of them don't seem to be too crippling in terms of storm mode problems. Speaking of storm mode given the degree of forcing, have to wonder if it is a relatively quick transition to linear, some more low level backing would certainly help.

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  2. If the Euro is on the right track (and it has been fairly steady), we could be dealing with a very significant severe weather event Monday evening continuing into Tuesday afternoon from E Texas and SE Oklahoma extending into AL and GA.

    Sampling one of the parameter spaces at 06z in along the I-55 corridor in MS reveals SBCAPE of 1000-2000+ J/kg, deep layer shear of 60-70 kts and low level shear in places in excess of 50 kts (this type of environment is generally in place through the whole period in one place or another). This would be an environment capable of long lived supercells with significant tornadoes. Moreover, this trough is quite low amplitude (compared to its wavelength) and would likely portend a long period of discrete/semi-discrete storm mode.

    Extent of the threat will be dependent on moisture return of course, but it is important to note that notable destabilization in this case will occur nearly independent of the diurnal cycle given the strong advective processes (WAA, moist advection) vs. diabatic insolation.

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  3. That trough early next week showing up across guidance, including quite a strong signal on the ensembles, has my attention for a potential severe wx threat (and a widespread one at that) assuming enough moisture return is available. There already is an established low amplitude trough across the central US and a powerful jet max slides SE into it and somewhat amplifies/kicks the trough negative tilt. The 12z Euro was getting 60s dewpoints all the way into Michigan.

    There are, as it sits right now, some similarities synoptically to the 10/18/07 severe wx event.

  4. The more problematic event might be early next week with a very favorable 500 mb pattern for a larger scale severe episode across the S US showing up on the ensembles. Going to hinge on how much moisture return can take place since there could be a FROPA or two through the Gulf prior to then, but that definitely looks to be something to watch especially since it may fall on Election Day.

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  5. 10% hatched tor added for the ND-SD-MN junction. Dare I say the setup doesn't look too bad with plenty of low level moisture and backing surface winds in this vicinity. Issue may be tendency for HP transition given the lack of flow aloft and also 0-1 km shear magnitude isn't ideal especially if storms fire earlier on.

    Addendum: Man is it hard to analyze setups in a season like this, motivation is at an all time low personally.

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  6. 18z 3 km NAM had a number of long tracking semi discrete cells across much of the Northeast, including a very strong one crossing the entirety of NH and VT.

    Difference this time compared to most NE setups is that we have the thermos, especially the thermos aloft, in place almost unquestionably (barring convection tonight). If those surface winds can take more of a SSW (or even SW) component tomorrow afternoon, there's liable to be tornado problems given the degree of low level instability and moisture along with very strong deep layer shear for bowing segments and supercells. It would be nice to perhaps have a bit more of a pronounced shortwave, but I'm rather impressed nonetheless.

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  7. HREF is going pretty nuts tomorrow across the northeast, albeit convection from today is certainly a factor. Certainly don't see lapse rates that close to dry adiabatic this far east very often at all, and when they are juxtaposed with rather strong shear -> higher end severe possible.

     

  8. 00z Euro presents quite a volatile looking setup near/E of I-35 in OK at 168 hrs. Secondary vort max rotates around the base of the synoptic scale trough and leads to a south-southwesterly/southerly LLJ surge underneath strong WSW 500 mb flow and plenty of low level moisture (if you're thinking this sounds a lot like the setups in the second half of May in 2013, you'd be right). As a result, the level of turning with height is quite impressive.

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