5/16 Strong/Severe Thunderstorm Obs

[Rainshadow]

[susqushawn]

830am update SPC:

...NY to the Mid-Atlantic from late morning to late afternoon...
   A midlevel shortwave trough over the OH Valley this morning will
   progress east-northeastward over the Mid-Atlantic and New England by
   tonight, as an associated surface cyclone deepens across the Saint
   Lawrence Valley and a trailing cold front likewise moves eastward
   and offshore overnight.  Low-mid 60s boundary-layer dewpoints will
   spread northward ahead of the front, and pockets of surface heating
   will boost buoyancy by afternoon (MLCAPE of 1000-1500 J/kg). 
   Deep-layer flow/vertical shear will increase with the approach of
   the midlevel trough from the west, contributing to an environment
   supportive of organized line segments and some supercell structures
   from late morning through the afternoon.

   Thunderstorms are expected to increase in coverage/intensity by late
   morning from the Finger Lakes region southward along the leading
   edge of the pre-frontal convective band moving into western PA this
   morning.  These storms will subsequently spread eastward across NY
   and the Mid-Atlantic through late afternoon, and other storms could
   form farther west and southwest along the synoptic cold front,
   assuming sufficient cloud breaks occur by midday.  The presence of
   organized convective bands and strengthening wind profiles suggest
   that wind damage with peak gusts of 55-70 mph will be a common
   threat this afternoon, west of any cooling marine influence.  The
   threat for significant (75+ mph) gusts is more questionable given
   rather modest downdraft potential (DCAPE generally less than 500
   J/kg) and low-midlevel flow no stronger than 30-40 kt.  Otherwise,
   low-level shear may be strong enough to support a couple of
   tornadoes with pre-frontal supercells or circulations embedded in
   line segments, and the stronger storms may also produce isolated
   large hail of 1 to 1.5 inches in diameter. 

 

Wind Risk:

 

[ACwx]

8 minutes ago, susqushawn said:

830am update SPC:

...NY to the Mid-Atlantic from late morning to late afternoon...
   A midlevel shortwave trough over the OH Valley this morning will
   progress east-northeastward over the Mid-Atlantic and New England by
   tonight, as an associated surface cyclone deepens across the Saint
   Lawrence Valley and a trailing cold front likewise moves eastward
   and offshore overnight.  Low-mid 60s boundary-layer dewpoints will
   spread northward ahead of the front, and pockets of surface heating
   will boost buoyancy by afternoon (MLCAPE of 1000-1500 J/kg). 
   Deep-layer flow/vertical shear will increase with the approach of
   the midlevel trough from the west, contributing to an environment
   supportive of organized line segments and some supercell structures
   from late morning through the afternoon.

   Thunderstorms are expected to increase in coverage/intensity by late
   morning from the Finger Lakes region southward along the leading
   edge of the pre-frontal convective band moving into western PA this
   morning.  These storms will subsequently spread eastward across NY
   and the Mid-Atlantic through late afternoon, and other storms could
   form farther west and southwest along the synoptic cold front,
   assuming sufficient cloud breaks occur by midday.  The presence of
   organized convective bands and strengthening wind profiles suggest
   that wind damage with peak gusts of 55-70 mph will be a common
   threat this afternoon, west of any cooling marine influence.  The
   threat for significant (75+ mph) gusts is more questionable given
   rather modest downdraft potential (DCAPE generally less than 500
   J/kg) and low-midlevel flow no stronger than 30-40 kt.  Otherwise,
   low-level shear may be strong enough to support a couple of
   tornadoes with pre-frontal supercells or circulations embedded in
   line segments, and the stronger storms may also produce isolated
   large hail of 1 to 1.5 inches in diameter. 

 

Wind Risk:

 

I appreciate the SPC in their discussion highlighting the fact that although the wind risk is higher than we normally see for this area, the risk of severe 75+mph winds is pretty low - intuitively some people outside of the weather community may think a higher risk means a higher overall magnitude of winds. Good point for communication.

[Qtown Snow]

Our school district decide to go with an early dismissal per pending thunderstorms, i don't recall an early dismissal ever for pending thunderstorms.  

[Qtown Snow]

[ACwx]

Scattered showers and more cloudcover moving up towards us from the DC region

[Animal]

1 hour ago, Qtown Snow said:

Our school district decide to go with an early dismissal per pending thunderstorms, i don't recall an early dismissal ever for pending thunderstorms.  

Is todays possible event expected to be a historic day?? All I am hearing is very bad storms today. Stay home etc.

Wawa this morning the talk was very bad weather coming,

 

[mb2231]

13 minutes ago, Animal said:

Is todays possible event expected to be a historic day?? All I am hearing is very bad storms today. Stay home etc.

Wawa this morning the talk was very bad weather coming,

 

Historic? Probably not. I think after the severe weather last summer there's a much needed focus on keeping people safe. 55-70mph gusts are more than enough to knock down large trees. Better one of them doesn't land on a school bus full of kids.

[susqushawn]

Clouds/showers rolling up from NE MD could muck up the fun for someone.  1st batch favors far north, 2nd batch more philly/south.  There will be a weenie out there later today whining about a 7-10 split (probably me)

[irishbri74]

11 minutes ago, susqushawn said:

Clouds/showers rolling up from NE MD could muck up the fun for someone.  1st batch favors far north, 2nd batch more philly/south.  There will be a weenie out there later today whining about a 7-10 split (probably me)

Lotta cloud debris for sure. 

[eastonwx]

52 minutes ago, Animal said:

Is todays possible event expected to be a historic day?? All I am hearing is very bad storms today. Stay home etc.

Wawa this morning the talk was very bad weather coming,

 

 

37 minutes ago, mb2231 said:

Historic? Probably not. I think after the severe weather last summer there's a much needed focus on keeping people safe. 55-70mph gusts are more than enough to knock down large trees. Better one of them doesn't land on a school bus full of kids.

Historic may be subjective, especially if you experience a tornado or high winds knocking down 100 year old trees. Historic overall? Hopefully no. Locally? Possible.

[foxonwheels]

Hearing a few rumbles, this little guy is coming right overhead 

[Allsnow]

Always hate the morning crap mucking up the fun. Concerning for potential late afternoon 

[el_nino]

Looks like we have some lightning in NE Philly, moving into Bucks

[colonel_kurtz]

74 degrees, cloudy

Thunder from little cell just to west in Bensalem.

[foxonwheels]

Dang just had a strike very close by, almost zero delay after the flash. Kabooom! 

[susqushawn]

Just now, foxonwheels said:

Dang just had a strike very close by, almost zero delay after the flash. Kabooom! 

that gets the adrenaline pumping

[foxonwheels]

10 minutes ago, susqushawn said:

that gets the adrenaline pumping

Sure does. It's fun hearing things around the house rattle and shake that don't typically make those types of noises. 

[Qtown Snow]

[Animal]

Pouring here at the moment.

[colonel_kurtz]

Back home quick 0.12" with that cell

[susqushawn]

meso up for watch likely SE PA, DE/NJ.  awaiting SPC text to load

[susqushawn]

SUMMARY...Increased thunderstorm coverage is expected over the next
   few hours, with supercells capable of damaging wind gusts and hail
   possible.

   DISCUSSION...Recent radar and satellite imagery has shown an
   increase in the showers from northern VA into NJ, with a few
   stronger embedded updrafts. This area is indicative of the increased
   ascent preceding the shortwave trough and attendant cold front. Air
   mass over most of the region has warmed into the low 70s amid
   dewpoints in the mid 60s. While cloud cover may impede heating
   somewhat, this air mass is still expected to further destabilize
   over the next few hours. As it does, a few stronger updrafts may
   manifest within this warm-air advection regime. Moderate shear is in
   place, so any stronger, more persistent updrafts could organize, and
   the potential for a few supercells capable of isolated hail and
   damaging wind gusts exists. Greatest chance for severe thunderstorms
   during the next few hours appears to be across NJ and into the
   Hudson Valley where temperatures are highest. Convective trends are
   being monitored across the entire region for likely watch issuance.

[Qtown Snow]

my son a senior just got home, he said everyone was saying there are tornado warnings so thats why school did an early dismissal  😲

[susqushawn]

6 minutes ago, Qtown Snow said:

my son a senior just got home, he said everyone was saying there are tornado warnings so thats why school did an early dismissal  😲

you need to sit him down and have a talk.