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Spring severe weather chatter


Ian

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That is impressive. So disappointed I'm going to miss tracking this thing. On the bright side, I might get a chance to see some big heat and chase tropical where I'm going.

Are you riding Greyhound to SC this weekend or going elsewhere??

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Need some help  here guys. My church is asking me to make the final call on the church bbq sunday. Its from 12 to 2 and they need to know in the next 1-2 hours.

 

What i told them was i think there may  be some rain saturday night into sunday morning and then a break through the afternoon...but there will be the chance of severe weather later on sunday afternoon. Do you guys think we will be okay from 11am to 2:00pm on Sunday?

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Need some help  here guys. My church is asking me to make the final call on the church bbq sunday. Its from 12 to 2 and they need to know in the next 1-2 hours.

 

What i told them was i think there may  be some rain saturday night into sunday morning and then a break through the afternoon...but there will be the chance of severe weather later on sunday afternoon. Do you guys think we will be okay from 11am to 2:00pm on Sunday?

 

I just had to make that call for a group outing as well and bagged mine. Issue is whether we get that clearing or whether we end up with pre-frontal showers to screw up the atmosphere for the severe and make the whole day a washout. I have learned around here not to bet against the latter scenario...

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     I'm going to agree here that the combination of moderate instability, 35 kt or so of deep layer shear, and at least some forcing arriving later in the day argues for a threat of isolated severe reports here later Saturday and Saturday evening.

 

 

Sneaky severe Sat evening into Sat night is what I am watching as well... case in point can be seen in the soundings below from the 06z NAM:

 

EZF at 03z SUN

 

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          The NAM nest (NAM4) tends to run high with instability, because it doesn't have a full shallow convective scheme to properly mix the PBL, so its low level structure tends to be too moist and warm which ramps up the cape.    The parent NAM is usually a better choice for evaluating instability.    That said, even the NAM parent has 1000-1500 up your way, with 3000+ over central VA.   That in combination with modest shear certainly leaves the door open for some storms later Saturday to become severe.    We'll see if the new SPC day2 maintains the 5% or bumps it up to 15.

 

 

no idea if that matters or not... 

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       I can't blame you for this line of thinking, and it's certainly possible, but I think that happens more here when the upper flow is more backed.     I like looking at the NAM nest for details at this range, and it does show a few showers around early Sunday afternoon, but nothing widespread.    They don't prevent the model from cranking out some beefy cells across northern VA a few hours later that roll across the metro areas during the late afternoon.

 

 

I just had to make that call for a group outing as well and bagged mine. Issue is whether we get that clearing or whether we end up with pre-frontal showers to screw up the atmosphere for the severe and make the whole day a washout. I have learned around here not to bet against the latter scenario...

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          The NAM nest (NAM4) tends to run high with instability, because it doesn't have a full shallow convective scheme to properly mix the PBL, so its low level structure tends to be too moist and warm which ramps up the cape.    The parent NAM is usually a better choice for evaluating instability.    That said, even the NAM parent has 1000-1500 up your way, with 3000+ over central VA.   That in combination with modest shear certainly leaves the door open for some storms later Saturday to become severe.    We'll see if the new SPC day2 maintains the 5% or bumps it up to 15.

 

do you mean later sunday? 

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Very nice sounding at KDCA at 21z SUN from the 12z GFS:

 

Nice instability - still would like to see some more backing IMO for a tornado threat. I'm going with damaging wind as a primary threat still. We'll see if we can back the winds a bit more and also if our primary mode ends up being supercells vs linear. Always safest bet to bet on linear around here. 

I'm like 6/10 in on this one (Sunday). Sneaky severe tomorrow would be nice as well. 

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Meh, MLCAPE is pretty weak there (probably in part due to the GFS' bias with shallowness of BL moisture). The sounding is also pretty saturated as I've seen with a number of others.

Yup. Also, don't sleep on Saturday. Soundings are better saturation-wise, but shear is lacking a bit for my taste, at least at the lower levels. It should be noted that the RPM has storms breaking out down this way (CHO) tomorrow late-afternoon/evening. The end of the 4km RPM run (51 hours) also has discreet storms firing up early Sunday afternoon (18Z or 2 PM) along the western shores of the Chesapeake. My target zone this far out would be areas east of US 15 & north of US 33 to the PA/MD line.

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Meh, MLCAPE is pretty weak there (probably in part due to the GFS' bias with shallowness of BL moisture). The sounding is also pretty saturated as I've seen with a number of others.

There is no EML and very little cap. Those setups only work in landfalling TCs.
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Meh, MLCAPE is pretty weak there (probably in part due to the GFS' bias with shallowness of BL moisture). The sounding is also pretty saturated as I've seen with a number of others.

Good points.  We also have to realize that 9/10 times we don't clear out to the degree needed and we'll probably be socked in all day Sunday at 67 and overcast.

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Not every day you see a Day 3 ENH for our area. Sub 1000mb lows don't go quietly into the night. My Spidey sense is tingling.

 

 

Good points.  We also have to realize that 9/10 times we don't clear out to the degree needed and we'll probably be socked in all day Sunday at 67 and overcast.

 

So... are you for Sunday or are you out?

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    yep, I definitely got my days crossed there.

 

   what I mentioned about the cape was for Saturday.   Sunday in the NAM is ~1500 area-wide with quite a bit more in the NAM nest (as noted by Mappy).    Part of the difference is likely due to the NAM nest biases, but the parent NAM is likely low since it seems to be convecting too early.    My guess is that, assuming we don't see widespread early showers, there should be sfc cape in the 2000 range.     As noted by others, the weak lapse rates seem to preclude larger values.

 

 

 

He is talking about Sat, but I think he was confused as the the people canceling events were talking about Sunday. Thats how I see it. 

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    yep, I definitely got my days crossed there.

 

   what I mentioned about the cape was for Saturday.   Sunday in the NAM is ~1500 area-wide with quite a bit more in the NAM nest (as noted by Mappy).    Part of the difference is likely due to the NAM nest biases, but the parent NAM is likely low since it seems to be convecting too early.    My guess is that, assuming we don't see widespread early showers, there should be sfc cape in the 2000 range.     As noted by others, the weak lapse rates seem to preclude larger values.

 

yeah, if it was Saturday we had planned to go to King's Dominion, would have gone. Sunday, I couldn't ultimately make that make sense.

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