Jump to content
  • Member Statistics

    17,508
    Total Members
    7,904
    Most Online
    joxey
    Newest Member
    joxey
    Joined

Monday showers/thunder threat


free_man

Recommended Posts

  • Replies 385
  • Created
  • Last Reply

More detailed thoughts.

A cold front will be pushing southeast from Canada and upstate NY during the day on tomorrow. As the cold front slides into our region it will interact with a very hot, humid and moderately unstabe airmass. Temperatures are expected to climb into the upper 80's to lower 90's across the region with dewpoints well into the upper 60's to lower 70's. It's also possible that for a few hours at least dewpoints could spike into the mid 70's. The combination of heat and humidity will help lead to at least a moderately unstable airmass.

The potential also exists for an elevated-mixed layer to work into the region. As described in previous notes elevated-mixed layers are very important when dealing with the potential for widespread and high-end severe weather events. A few computer models are hinting at the potential for the elevated-mixed layer to work over the ridge and try to work it's way into New England. If this elevated-mixed layer is able to work into the region it will vastly increase the severe weather potential for tomorrow as it would also allow for the atmosphere to become even more unstable.

As of right now most computer model guidance is suggesting that Cape values will be on the order of 1500-2500 J/KG with LI values in the -4C to -7C range. Not only will the atmosphere be moderately unstable but there will be a good deal of wind shear aloft, and there will be both speed shear and directional shear present. The level of directional shear will also depend on the wind direction from about 900mb to the surface. If winds in this level stay more to the SW or WSW this will increase the amount of directional shear and also increase the helicity. With winds in the 700-500mb level on the order of 35-50 knots this will create about 30-40 knots of vertical shear across the region tomorrow. This is more than sufficient for storm organization and for some supercells to develop.

As a strong mid-level impulse cross the region decent height falls will overspread the region helping to erode any cap that is in place and this will also contribute to some vigorous updraft development. Mid level temps will begin to cool some as well and the winds aloft will strengthen a bit as well.

With a strong surge of theta-e working into the region and very high dews in place PWAT values will be very high, possibly in order of 1.5-2''.

If everything comes together tomorrow Monday should be a very active severe weather day with damaging winds, possibly in excess of 70 mph and very large hail, possibly as big as golf ball sized would all be possible in the strongest storms, if any supercells develop that would certainly increase the hail potential and the potential for very large hail.

An isolated tornado or two also can't be ruled out tomorrow either, especially within any supercells and if helicity is a bit higher than modeled. Damaging winds and large hail appear to be the main threats right now though.

With the high PWAT values torrential rains are also likely tomorrow with any storm and this could lead to some areas of localized flash flooding.

As of right now it's not entirely clear what the convective mode will be for tomorrow, will we mainly see bowing lines or will there also be some supercells? Right now current thinking is that early on the storm mode will be more in the way of supercells...this is where the highest large hail threat will be occcurring. Eventually the supercells will begin to conjoin and start forming line segments which will quickly begin to bow out. Given strong speed shear aloft and very steel low-level lapse rates from heaitng that will be going on this is where the highest damaging wind threat will exist.

If we do see lines develop and early on tomorrow could be a significant damaging wind event with widespread wind damage possible.

There are still some issues to contend with for tomorrow, however. There is the potential for a good deal of cloud debris tomorrow morning from any MCS activity that develops off to our west tonight and traverses the area overnight and early AM tomorrow. Any cloud debris could limit the amount of heating we actually see which could mean the atmosphere becomes a bit less unstable than modeled. Subsidence in the wake of the MCS could also be a killer as it could inhibit cloud/storm development later on in the day.

A few computer models are also suggessting activity firing early on in the morning hours which would really rob the atmosphere of alot of it's energy and could make the afternoon threat a bit less potent as well.

All these issues will be resolved in the AM tomorrow.

Link to comment
Share on other sites

Give it up dude. You always do this..you hang on until the bitter end even when things get progressively worse as we get closer. May not even be many storms tomorrow

What the hell is in your bong?

Things have been getting progressively better as we have gotten closer to Monday...the GFS and I guess the Euro have all been very similar and have been very consistent from run to run. The NAM has been the one that has been out to lunch and it has even came around to the GFS/Euro to a degree.

Okay, so the 12z runs backed off a bit...big deal, it's one set of model runs that have done that. If 18z runs do it, then the 0z runs as well as the 15z, 21z, and 3z SPC SREF runs then you worry...but not going to totally write anything off just b/c a set of model runs backed off...and even with the "back off" they still look good for tomorrow.

Link to comment
Share on other sites

My God, take a look at these numbers across the northern Plains right now.

SBcape: 4500-7500 J/KG

MLcape: 4000-6000 J/KG

MUcape: 4500-7000 J/KG

LI: -7C to -11C

Ncape: 0.35 to 0.45

Dcape: 1400-2000 J/KG

ML lapse rates: 6.5-7.5 C/KM

Vertical shear: 50-60 knots

0-3km helicity: 250-500 m2s2

0-1km helicity: 100-250 m2s2

Supercell composite parameter: 8-38

significant tornado parameter: 2-6

Link to comment
Share on other sites

Hope the AC in your car is fully charged. You will be going through some nasty stuff...

We are tenting for the most part lol. It's gonna be rough at night with high dews but the car has ac at least. We are heading to the rock and roll hall of fame then cedar point over the next two days. Chicago, Yellowstone and more to follow.

Link to comment
Share on other sites

Give it up dude. You always do this..you hang on until the bitter end even when things get progressively worse as we get closer. May not even be many storms tomorrow

I certainly don't think the threat is zero... but there are a lot of questions... especially in regard to what develops upstream and whether we can advect steep mid level lapse rates in here.

Link to comment
Share on other sites

For Wiz to be hanging onto a widespread major outbreak is ridiculous

You never know with these setups. Sometimes they can look like crap if there is showers/tstms in the morning..then by 10am it's cleared out and all hell breaks loose. Or...you have leftover cloud debris from an MCS to your sw, and things go to crap. The one thing I like, is the jet location with this..and the 500mb look. If we can't get the atmosphere to cook during the day, perhaps we may have to wait until the dynamics really help initiate stuff along the cold front. However, it's possible we may have just enough crud and lapse rate taint from any downstream convection. The 00z RAOBS over Quebec might be interesting tonight. We'll have somewhat of an idea of what is coming over the top of this ridge.

Link to comment
Share on other sites

We are tenting for the most part lol. It's gonna be rough at night with high dews but the car has ac at least. We are heading to the rock and roll hall of fame then cedar point over the next two days. Chicago, Yellowstone and more to follow.

Cedar Point sucks, whalom ws way better...:arrowhead:

You should see some interesting things wx wise on your trip. Will you be posting? (obviously you are...)

Have a great trip. That is a dream of mine someday

Link to comment
Share on other sites

LOL well the 15z SPC SREF went back to juicy probs here

I want to go back to what Scott had said before the last severe chance. It is always good when you have SVR weather in the Northern part of Michigan. I remember back to 6/1 where they had great SVR weather. This SREF props indicates that they will have good storms here

Link to comment
Share on other sites

I want to go back to what Scott had said before the last severe chance. It is always good when you have SVR weather in the Northern part of Michigan. I remember back to 6/1 where they had great SVR weather. This SREF props indicates that they will have good storms here

I wouldn't use that verbatim...but in general we have done well if that happens. Don't forget if the flow has too much of a meridonal component ( in other words more nw-se instead of wnw-ese), then it might mean the complex drives through PA and we are left with some leftover cirrus crud. As usual..just gotta watch how the trends look.

Link to comment
Share on other sites

Nice plume of steep midlevel lapse rates from update NY back through MI. Should help to sustain storms from Quebec into northern new england this evening. I would think I'd have an outside shot to see storms around midnight tonight.

post-13-0-99265000-1310934185.png

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...