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tombo82685

May 23rd Enhanced Risk For Severe Weather

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Just looking at Thursday, one thing this has going for it is much better lapse rates which would increase hail and damaging wind threat. NAM so far is not that bullish on instability and looks a bit capped right now but we are still out of its range. 

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4 minutes ago, tombo82685 said:

Just looking at Thursday, one thing this has going for it is much better lapse rates which would increase hail and damaging wind threat. NAM so far is not that bullish on instability and looks a bit capped right now but we are still out of it range. 

NAM is just showing a broken line around 00Z. 

 

 

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1 minute ago, cbelke said:

NAM is just showing a broken line around 00Z. 

 

 

yup, thats because it never really builds good instability and we are a bit capped too. The lapse rates though are solid. If we can get better instability and lose some of the cap it could be an active day. Better chances west of river than east due to timing. 

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day2otlk_0600.gif.af041444904ac5232aa89d10f2bbec04.gif

...Northeast States through Ohio Valley...

   The warm sector will gradually moisten west of the warm front during
   the day with low to mid 60s F dewpoints beneath 6.5 C/km lapse
   rates, along with diabatic warming contributing to modest
   instability (800-1200 J/kg MLCAPE). Current indications are that
   storms will most likely develop along and ahead of
   southeast-advancing cold front spread southeast through the OH
   Valley and Northeast States during the afternoon and evening. Winds
   will strengthen as the mid-level speed max attending the shortwave
   trough approaches the region with effective shear supporting
   supercells. These storms may produce large hail, damaging wind and a
   couple of tornadoes as they move southeast through the region later
   Thursday afternoon into the evening.

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11 hours ago, tombo82685 said:

Just looking at Thursday, one thing this has going for it is much better lapse rates which would increase hail and damaging wind threat. NAM so far is not that bullish on instability and looks a bit capped right now but we are still out of its range. 

Yeah just glancing at the poor man's quick look of predicted total totals in the lower 50s for PHL according to the GFS, that is not shabby.  It is cold enough aloft at 500mb.

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3km NAM starts capped during the afternoon and the cap goes as dew points pool.  This is starting to get kind of late here, but the timing looks better for Mitch & JamieO.

 

nam3km_mslp_pcpn_frzn_neus_33.png

nam3km_mslp_pcpn_frzn_neus_37.png

nam4km_2019052212_036_39.92--75.21.png

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Nothing has changed IMO since yesterday. Lapse Rates look solid, but the lack of instability and timing could limit potential. Once out towards reading and lancaster on west think they will have a nice event. The morning showers/convection could muck a lot of it up as well. Need to see how fast the cap can break and how much instability we can get. This is opposite of earlier this week. That was instability driven with lack of Lapse rates. High lapse rates severe events usually produce very well as the downwelling of higher winds is much easier. 

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Man, tomorrow has some potential. A few pros and cons. 

Pro’s

 

1. Good height falls as trough approaches.

2. 40-60 knots shear is plenty for severe. 

3. Areas that get higher dews should be suitable enough for severe parameters, and increase the chances. 

South central pa to dc looks like better thermodynamics, while n&w will have a bit stronger trigger. 

cons. 

1. Early convection coould screw the boundary. 

2. Questionable dew forecasts on guidance, especially further east you go. Timing issues as you head east as well. 

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Not sure if the 3k NAM is just being random with its convection placement, or if this mornings stuff is already screwing the pooch for eastern pa. But stuff later in kinda splits around eastern pa 

8B7D5E88-A02D-45FB-9D6B-5192266F4447.gif

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Meanwhile, HRRR is plowing a big mcs/squall like through the area later on. 

AB8F1834-3750-4C8A-9E07-3C2C1641CBE8.png

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29 minutes ago, irishbri74 said:

Not sure if the 3k NAM is just being random with its convection placement, or if this mornings stuff is already screwing the pooch for eastern pa. But stuff later in kinda splits around eastern pa 

8B7D5E88-A02D-45FB-9D6B-5192266F4447.gif

That makes sense. Best lapse rates and dynamics being closer to low pressure are north. Best instability is southwest. There are issues that need to be overcome for this to produce a good severe event around here. I’m skeptical. We will know around noonish. 

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19 minutes ago, tombo82685 said:

That makes sense. Best lapse rates and dynamics being closer to low pressure are north. Best instability is southwest. There are issues that need to be overcome for this to produce a good severe event around here. I’m skeptical. We will know around noonish. 

That is typically our case where instability and kinematics do not coincide.   The 3km NAM does look slightly better than the 06z HRRR with what is going on.  Now that the NCAR mesoscale convective models are gone, the best of the rest is normally the arw (it is afar second though) and it has most of the meaty convection north of us.  Sprinklers on. That didn't take long...

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We’ll have to watch between 18z and 0z how dews behave. Hrrr has them roaring into the area and rising to 65-68°Range. 

 

I will say. Doesn’t feel very stormy out there right now. (Low dews)

AB440711-07D4-4427-A08C-0CFF7AB8F3B3.gif

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Things moving a bit faster than modeled? 

Screenshot_20190523-131131_RadarScope.jpg

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1 hour ago, cbelke said:

Things moving a bit faster than modeled? 

 

I was about to ask the same. it was forecast to start around 4 here.

rain and thunder here now

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4 hours ago, cbelke said:

Things moving a bit faster than modeled? 

Screenshot_20190523-131131_RadarScope.jpg

I don't know if it was faster or an unforecast area got going before what at one time was suppose to be the main show.

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2 hours ago, Rainshadow said:

I don't know if it was faster or an unforecast area got going before what at one time was suppose to be the main show.

Yeah, I was surprised it came in like it did, which was only a couple of hours quicker than modeled. I think the morning storms were a bit more robust since they had a little better instability to work with early on. 

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47 minutes ago, cbelke said:

Yeah, I was surprised it came in like it did, which was only a couple of hours quicker than modeled. I think the morning storms were a bit more robust since they had a little better instability to work with early on. 

What is going on now I think was what I thought was going to be the go to activity in PA.  I saw a NAM sounding that had a cap, but that part of the forecast didn't work. Yes plus the morning activity was more robust.  Anyway looking at this sounding, the NAM sounding is either wrong, or the thunderstorms lifted/formed above 900mb. The bases were pretty high and the lapse rates were accommodating.  

index.png.0b4bf9b1db2f20cf659e64988ba38948.png

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