5/16 WESTERN NE Severe Threat Disco

[ChrisM]

Let's hope Wiz is scoring a Little League game to get the juju flowing.

[CoastalWx]

Moneypitmike FTW.

[ChrisM]

Wednesday: A chance of showers and thunderstorms, mainly after 3pm. Some of the storms could be severe. Cloudy, then gradually becoming mostly sunny, with a high near 78. South wind between 5 and 10 mph. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

[ineedsnow]

first slight risk of the year

[ineedsnow]

[HoarfrostHubb]

That is actually not too bad...

[CoastalWx]

Not directly related, but wow.

It was a waterspout that moved onshore and became a tornado. Watch 4 min in if you get bored.

[ineedsnow]

I saw that a couple days ago those guys were lucky!

Not directly related, but wow.

It was a waterspout that moved onshore and became a tornado. Watch 4 min in if you get bored.

[wxsniss]

Hey guys!

Had a week-long tornado chase trip last week, what a bust as you can imagine --- persistent death ridge in the west, a trough we haven't seen all winter here along the east coast keeping gulf moisture at bay --- overall disappointing.

About 3000 miles driving spanning Kansas, Oklahoma, Texas, and New Mexico.

Best play for a few days was along the Texas-Mexico border where there was decent moisture return and reasonable southwest jet support for a few days

we did see a rotating wall cloud near Eagle Pass, Texas Thursday which was a thrill (velocity couplet below, with our GPS location), and some decent hail (photos below).

In any case, nice to see a severe threat, however marginal, in our own backyard.

Velocity couplet and our GPS location south of Eagle Pass, Texas, last Thursday... clearly rotating wall cloud was visible for a few minutes:

Hail produced by above storm:

Hail damage from above storm:

[CoastalWx]

Nice wxniss. Congrats on seeing better severe than we'll see in our own backyards for another 15 years.

[wxsniss]

Nice wxniss. Congrats on seeing better severe than we'll see in our own backyards for another 15 years.

yeah it's been an elusive lifelong dream.

was following this pro met todd thorn, he was very good... learned lots of field skills like targeting a tail-end-charlie, how to tell from winds direction/temps on the ground that a cell had become outflow dominant, and so on

we were interviewed/filmed on the Travel Channel one day (actually was extremely annoying and staged)

unless we get another 6/1/2011, i may try to fly out for a high-risk setup later this year

[CoastalWx]

yeah it's been an elusive lifelong dream.

was following this pro met todd thorn, he was very good... learned lots of field skills like targeting a tail-end-charlie, how to tell from winds direction/temps on the ground that a cell had become outflow dominant, and so on

we were interviewed/filmed on the Travel Channel one day (actually was extremely annoying and staged)

That's great. On my bucket list as well.

unless we get another 6/1/2011, i may try to fly out for a high-risk setup later this year

[HoarfrostHubb]

Not directly related, but wow.

It was a waterspout that moved onshore and became a tornado. Watch 4 min in if you get bored.

]

That one house got nailed.

[CoastalWx]

That one house got nailed.

Yeah that video came out last week. I just showed my wife that earlier and figures I'd post it here if nobody saw it yet. Goes to show you how even a narrow tornado like 30 yards wide can damage so much. It's not just the horizontal motion of the wind, but the vertical motion too.

[ChrisM]

Any updated thoughts?

[weatherwiz]

Home from the Red Sox game!

SLIGHT RISK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Guess I'll have to stay up longer and look over stuff, even though I'm completely exhausted.

[ctsnowstorm628]

Looks like some decent elevated and surface cape away from the water in NW CT and adjacent western areas. Maybe 1000-1500j/kg?

Should be fun if we get those progged surface temps too. Somewhere near NW CT, PSF or like springfield will see something good I think.

[weatherwiz]

It will be interesting to see if there is any convection ongoing across the region between like 21z and 0z...or even going back to 19z. Shear/helicity does increase. Hopefully, any action can wait until later in the afternoon and this would also allow us to destabilize more (or give us a better chance).

[weatherwiz]

Quick little writeup I just did.

A strong cold front will be moving towards southern New England from the northwest on Wednesday bringing the potential for showers and thunderstorms to the region. Out ahead of the cold front a very warm and moist low-level airmass will be in place leading to a marginally unstable airmass to develop across the region.

With enough late morning/early afternoon sunshine the atmosphere will have the potential to be heated up even more allowing for stronger instability to develop. As of now several computer forecast models are in agreement that by late morning clouds will start to break across eastern NY/VT/western MA/southern NH/western CT. Temperatures across these areas should get into the mid to upper 70's with dewpoints into the lower to near mid 60's.

With the presence of fairly cold mid-level temperatures (500mb temps around -15C) mid-level lapse rates should be pretty decent as well, around 6.5 C/KM or so and this should yield to some modest instability values with SBcape values in the 1500-2000 J/KG range, MLcape values around 1500 J/KG, MUcape values in the 1500-2000 J/KG range, and LI values in the -3C to -5C range. Wind shear to start the day will be rather weak, however, as the morning and afternoon progress winds at all levels of the atmosphere are expected to increase as the cold front/trough approach. Vertical shear values are expected to increase in the 35-45 kt range.

Some forecast soundings, especially across northern CT also show some turning of the winds with height leading to some increased helicity later in the afternoon. This is something that will have to be watched, especially if more instability than modeled develops. Looking at wind alignment aloft it appears that the storm mode will be more multicells/line segements, thus leading more towards a threat for strong winds. Given how cold the mid-level temps are and with the steep lapse rates along with increasing helicity hail can't be ruled out either, especially if any discrete cells can get going. This potential will be further examined tomorrow morning.

Besides the questions regarding the level of instability tomorrow there are a few other issues as well. One issues is mid-levels could dry out rather quickly as it's possible the upper-level front approaches quicker than the surface cold front. With atmospheric mixing it would be possible for some of this drier air to mix down into the lower levels of the atmosphere and to the surface mixing out dewpoints and thus leading to lower instability values. This would also allow for more in the way of sunshine but with the lower dewpoints that would have a negative effect on stronger instability.

As of now it doesn't appear there will be widespread severe weather. There may be numerous t'storms but any strong/severe storms may be rather isolated but this will be watched and monitored throughout the morning.

[Hoosier]

I'm not sure if this will apply to your area but the models have been way overdone with surface dews the past couple days in the Midwest (talking like 10+ degree errors even on the same day). It caused instability progs to be way overdone but what did develop today had extremely high bases like you would see in the western Plains. Maybe something to look at more closely.

[weatherwiz]

I'm not sure if this will apply to your area but the models have been way overdone with surface dews the past couple days in the Midwest (talking like 10+ degree errors even on the same day). It caused instability progs to be way overdone but what did develop today had extremely high bases like you would see in the western Plains. Maybe something to look at more closely.

Interesting to note, thanks!

Looks like around here models have dewpoints anywhere from about 63-65F for tomorrow. As of now dewpoints are mainly 59-61F but to our south and west there are more 61-63F readings...have to watch how this unfolds in the AM.

[OKpowdah]

I do think sfc dews are probably slightly overdone, but we do have quite a bit of low level moisture left from days of rain here. It's an impressive sharp upper level trough that will be swinging through, and we have the instability, especially if mid level drying opens up the clouds a little ahead of the storms. Actually a pretty high confidence situation for thunderstorms I think.

mid level dry air intrusion could enhance the threat of strong downdrafts once storms have developed later in the afternoon. Hodographs leave something to be desired, but we could see some more low level backing especially further north that will really help these organize into a multicell line. Damaging wind threat is certainly real.

[weatherwiz]

I do think sfc dews are probably slightly overdone, but we do have quite a bit of low level moisture left from days of rain here. It's an impressive sharp upper level trough that will be swinging through, and we have the instability, especially if mid level drying opens up the clouds a little ahead of the storms. Actually a pretty high confidence situation for thunderstorms I think.

mid level dry air intrusion could enhance the threat of strong downdrafts once storms have developed later in the afternoon. Hodographs leave something to be desired, but we could see some more low level backing especially further north that will really help these organize into a multicell line. Damaging wind threat is certainly real.

If dews are overdone it's probably by 2-3F...so not a great deal but would certainly lead to a bit more instability being progged. mlvl lapse rates look decent though which could compensate.

If the llvl flow was like 10 knots stronger there would possibly be the threat for a brief isolated tornado perhaps but I'd like to see a stronger llvl flow before thinking about that.

[weatherwiz]

0z NAM has an area of ~7C/KM mlvl lapse rates moving thorugh NYS during the afternoon, however, weakening before moving into SNE...interesting.

[Damage In Tolland]

Looks like mostly a PHAIL..Anyone surprised?

[wxsniss]

haha

what a terrible pattern for chasers in the plains

[CT Rain]

Pretty much looks AWT. Have to burn off low level junk and then hope we get an area where best shear/best cape overlap. Best guess is Berks, Litchfield Hills up to ALB/GFL.

[Damage In Tolland]

Clear skies to our west..bodes well for us

[wxmanmitch]

I like my location for some potential excitement this afternoon, but I'm still waiting for this low-level crud to clear out. A lot of leftover moisture has resulted in fog, stratus, and drizzle this morning, which should hopefully clear out by the noon hour, if not a bit sooner so we can maximize heating and lapse rates. Visible satellite is clear as a bell through much of NYS, which is good as it will maximize heating. There's no high or mid-level crap that will limit solar insolation.

Like I said last night, while instability isn't prolific, there is enough instability and shear to produce some bow echo segments, strong straight-line winds, and some small hail. If we can get some cells out ahead of the main line, there is a chance of a supercell or two. The best threat looks to be E NY, and W NE, including NW CT, W MA, VT, and interior NH.

[CoastalWx]

The best low level moisture/dews look to be from Albany eastward. TDs near the cold front are actually only in the upper 40s to near 50. So we have a little bit of a discontinuity here it seems. Looks like there is a weak pre frontal trough near the Hudson valley right now. I noticed meso models fire weak cells over western and central areas after 18z. Maybe they are seeing that feature?