Saturday, June 27 - Sunday, June 28, 2020 Convective Thread

[weatherwiz]

Finally...I'm getting tingles as my fingers stroke the keyboard typing this up. Intense tingles...just like the intense updrafts that will be plowing through the troposphere this weekend headed towards the stratosphere before the EL smacks them short. 

Low pressure associated with a fairly strong shortwave progresses slowly through southeast Canada over the weekend. As this strengthens we see an increase in winds aloft with 500mb winds in excess of 30-50 knots. At the surface a warm and humid airmass with sfc temperatures at least into the 80's with dewpoints into the 60's. Steeper mid-level lapse rates associated with the energy will help to contribute to MLCAPE values approaching 1500 J/KG both days...perhaps near 2,000 depending on degree of sfc heating. 

Given sufficient wind shear aloft, the main severe threat will be damaging winds, however, an early look at forecast soundings indicate straight and long hodographs. This would suggest splitting cells with an accompanied risk for large hail. 

Saturday looks to feature numerous t'storms from NY into northern New England...with the potential for the evolution of an MCS which could come with the threat for widespread damaging winds. Activity should persist into at least western sections of New England before beginning to diminish, however, activity may push through much of the region. The damaging wind threat could extend into MA should an MCS evolve (MA and southern NH). 

Sunday is a wildcard as it will all be dependent on cloud debris, however, strong shear and potential for sufficient CAPE will be there. 

FINALLY SOMETHING TO TRACK!!!!

[weatherwiz]

Lots to resolve of course but can't sleep on Saturday...Sunday may not be much (it's either going to be Saturday or Sunday) but Saturday is sneaky...could actually see a window for a few supercells 

[yoda]

New Day 3 from SPC heard about this thread and stopped the SLGT risk right at the border for SNE

SLGT risk is in SE NY... but as soon as the border to MA and CT came, straight to MRGL to troll @weatherwiz

[yoda]

Day 3 disco

   ...Eastern Ohio across Pennsylvania and southern New York...
   Some uncertainty still exists with respect severe potential across
   the central Appalachians region, given the likelihood for ongoing
   convection at the start of the period which would influence
   potential for subsequent afternoon destabilization.  Still, with
   moderately strong west-southwesterly flow aloft across the region
   ahead of the weak upper trough/cool front, any uptick in afternoon
   convective coverage would likely be accompanied by risk for damaging
   winds given fast-moving storms.  A SLGT/level 2 risk area is being
   introduced across the area given what appears to be reasonable
   potential for locally damaging wind gusts, with threat likely to
   peak during the late afternoon before waning into the evening hours.

[weatherwiz]

This is starting to become a bit more clear.

While I still think a good chunk of the region sees something late Saturday the severe threat should wane pretty quickly across western sections...though this could extend through central CT. Sunday looks more like eastern areas. 

[yoda]

New day 2 morning SPC OTLK has SW CT and LI now in SLGT... mainly for wind (15%)... hail is at 5 percent and there is a small 2 percent TOR for SE NY into E PA and NW NJ

[ct_yankee]

Slight risk extended into parts of CT... I think they did it just for you, Wiz.

[yoda]

2 minutes ago, ct_yankee said:

Slight risk extended into parts of CT... I think they did it just for you, Wiz.

Don't sound too enthused in the disco though lol

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0101 AM CDT Fri Jun 26 2020

   Valid 271200Z - 281200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN OHIO
   TO THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND COASTS...

   ...SUMMARY...
   Scattered afternoon thunderstorms may pose a risk for mainly
   damaging winds across much of Pennsylvania and portions of
   surrounding states on Saturday.

   ...Synopsis...
   Gradual amplification of the upper flow field over the U.S. is
   expected Saturday, as short-wave troughing digging southeastward out
   of the Gulf of Alaska leads to a large expansion of cyclonic flow
   over the western U.S. through the period.  As a result, downstream
   ridging will increase over the north-central U.S. and central
   Canada, still further east, some amplification of troughing is
   expected over eastern Canada and into the northeastern CONUS.  

   Meanwhile, several vorticity maxima are forecast to shift eastward
   in a train-like manner, from the central High Plains across the
   Midwest/Ohio Valley and into the Mid Atlantic region/southern New
   England through the period.

   At the surface, a very weak/ill-defined baroclinic zone is progged
   to extend from the lower Great Lakes region west-southwestward
   across the Midwest/Ohio Valley states and then westward to the
   central High Plains.  In the West, a strengthening cold front will
   shift southeastward across northwestern portions of the country,
   reaching as far east as the northern High Plains overnight.

   ...Eastern Ohio to Long Island...
   Convection is expected to be ongoing at the start of the period,
   which continues to complicate the forecast, with respect to
   diagnosing the thermodynamic quality of the airmass.  Still, given
   enhanced low- to mid-level flow across the area, and weak cold front
   moving across the Lower Great Lakes, scattered thunderstorms --
   possibly in multiple episodes -- will likely occur across the region
   through the evening.  Risk for locally damaging winds remains
   apparent, and thus will maintain 15%/SLGT risk for wind across this
   region.

[weatherwiz]

Key Saturday will be how much heating we can generate after morning clouds/showers. Should we be able to destabilize sufficiently there could be a corridor of widespread wind damage...so there is room for some higher damaging wind probs here. Also, still can't sleep on Sunday

[PowderBeard]

55 minutes ago, weatherwiz said:

Key Saturday will be how much heating we can generate after morning clouds/showers. Should we be able to destabilize sufficiently there could be a corridor of widespread wind damage...so there is room for some higher damaging wind probs here. Also, still can't sleep on Sunday

For sure. I'd lean towards south of the Pike, specifically Western CT to RI, on Saturday for best severe potential.

[weatherwiz]

1 minute ago, PowderBeard said:

For sure. I'd lean towards south of the Pike, specifically Western CT to RI, on Saturday for best severe potential.

agreed

[weatherwiz]

It does look like there could be a little bit of s/w subsidence behind the morning crap. Could be both good and bad...good in a sense it could help clear things out but if its too strong it would be an inhibitor for later development. 

[Baroclinic Zone]

pinned so we can see this fizzle out

[Damage In Tolland]

1 hour ago, PowderBeard said:

For sure. I'd lean towards south of the Pike, specifically Western CT to RI, on Saturday for best severe potential.

Could also miss CT entirely

 

[weatherwiz]

3 minutes ago, Damage In Tolland said:

Could also miss CT entirely

 

We want no part of the morning stuff...that's if you want PM stuff. 

[weatherwiz]

52 minutes ago, weatherwiz said:

It does look like there could be a little bit of s/w subsidence behind the morning crap. Could be both good and bad...good in a sense it could help clear things out but if its too strong it would be an inhibitor for later development. 

This is incorrect...disregard. 

[Damage In Tolland]

15 minutes ago, wdrag said:

Unsure...

 

What I do know is that the big stuff tends to turn right (south) of modeled (along 1000-500mb thick), because it wants instability-heat to drive it.  so for me, Its between BGM-POU-GON south to I195 (TTN) on Saturday....  I'd go w local NWS experts including SPC discussion info, and high resolution CAMS models (if you can get access to them).  I prefer no convection NYC metro 1330z-220z to get this to work to its potential. 850 winds are pretty strong. 

May post mid afternoon?

 

Later,

Walt

Head SW young man. NYC south 

[Chrisrotary12]

Pretty cool watching those thunderstorms south of Long Island blow up as soon as the sun came up.

[weatherwiz]

3 minutes ago, Damage In Tolland said:

Head SW young man. NYC south 

I do see two (or multiple lines with this). One down in that area but we should see another track through southern CT...biggest question is how much instability we have to work with.

[dryslot]

Warnings are up

[RUNNAWAYICEBERG]

Nam says mostly meh. I’ll golf.

[PowderBeard]

2 hours ago, Damage In Tolland said:

Could also miss CT entirely

 

Miss the note in the bottom right panel?  *NAM Sat rainfall prior to late day storms*

[Damage In Tolland]

1 minute ago, PowderBeard said:

Miss the note in the bottom right panel?  *NAM Sat rainfall prior to late day storms*

First round north second one NYC/ SW CT south 

[PowderBeard]

Soundings have some decent ingredients for an interesting day. 

[weatherwiz]

This is becoming rather complicated. That initial morning action may be more aligned for late morning/early afternoon and could really be the "main show". This would almost put a complete end to the severe wx threat. This is some straight up B.S. What a stupid fooking summer. Pathetic, ridiculous, and just a flat out freaking waste. At this juncture I hope the damn thing this becomes a blob of nothing and everyone's lawns just torch and wilt away. fooking summer. No more stupid threads...that's it. Fook it. Fook this

[RUNNAWAYICEBERG]

Melting over thunder and lightning is priceless.

[Baroclinic Zone]

17 minutes ago, RUNNAWAYICEBERG said:

Melting over thunder and lightning is priceless.

Right up there with throwing a tantrum over snow

[dendrite]

Congrats CT on breaking the drought.

[dendrite]

3 hours ago, weatherwiz said:

This is becoming rather complicated. That initial morning action may be more aligned for late morning/early afternoon and could really be the "main show". This would almost put a complete end to the severe wx threat. This is some straight up B.S. What a stupid fooking summer. Pathetic, ridiculous, and just a flat out freaking waste. At this juncture I hope the damn thing this becomes a blob of nothing and everyone's lawns just torch and wilt away. fooking summer. No more stupid threads...that's it. Fook it. Fook this

Mr. Gorbachev, tear down this thread.

[Damage In Tolland]

5 minutes ago, dendrite said:

Congrats CT on breaking the drought.

Huh?