5/29 Day II Of Enhanced Thunder OBS, Take That Stinkin' 90s.

[tombo82685]

Looks like enhanced was increased with this morning’s outlook for today 

[irishbri74]

12 minutes ago, tombo82685 said:

Looks like enhanced was increased with this morning’s outlook for today 

Bump north with the enhanced zone. Models targeting same corridor as yesterday. Yesterday, they were a littl more south towards dc-sepa region. 

[Rainshadow]

Given the thread for yesterday's storms already has six pages and 
info about it is not done, I decided to split the threads out. 

...Upper Ohio Valley east to the mid Atlantic Coast...
   In the wake of remnant/early-morning convection, airmass
   recovery/destabilization is forecast ahead of a short-wave trough
   (now centered near southern Lake Michigan) which will cross Lake
   Erie and reach western Pennsylvania by early afternoon.  As this
   feature -- and a weak/associated surface low -- advances,
   redevelopment of scattered thunderstorms is forecast to occur,
   possibly beginning as early as midday, across Pennsylvania, and
   adjacent parts of West Virginia, Maryland, and northern Virginia.  

   With the airmass forecast to become moderately unstable, storms
   should quickly intensify -- aided by the persistent belt of strong
   westerly deep-layer flow across the area.  While some tornado risk
   is expected -- particularly near/ahead of the weak surface low and
   associated warm front, where backed low-level flow will be present,
   the greater risks appear to be locally damaging winds, and hail. 
   Some CAM guidance suggests that storms may grow upscale through the
   afternoon, eventually merging into an at least loosely organized
   cluster, as it sweeps across eastern portions of the risk area and
   off the Atlantic coast during the evening.  Should this occur, more
   widespread wind risk would likely evolve, and thus have expanded the
   ENH risk area slightly, extending it off the mid-Atlantic coast.

   Other/more isolated cells are expected farther south across central
   Virginia, with convective potential -- and severe risk -- decreasing
   with southward extent, as indicated by the gradient in severe
   probability lines across northern and central Virginia.

[cbelke]

Threat map looks  a little more focused in our area. Going to be another interesting day.

[Rainshadow]

2 minutes ago, cbelke said:

Threat map looks  a little more focused in our area. Going to be another interesting day.

This has looked like an eventual squall line plowing through the area.  Not that I preferred tornadoes plowing thru the area under any circumstances, but yesterday's individual storms made it relatively speaker easier to detect and issue tor(s), today's probable QLCS makes it that much harder. 

[Rainshadow]

Speaking of 90s:

This is going to come close, Philly's high looks like 88 or 89. 

[cbelke]

1 minute ago, Rainshadow said:

This has looked like an eventual squall line plowing through the area.  Not that I preferred tornadoes plowing thru the area under any circumstances, but yesterday's individual storms made it relatively speaker easier to detect and issue tor(s), today's probable QLCS makes it that much harder. 

Yeah, easier to see the rotation in the individual cells instead of a squall line.

Question for you. I see the squall line on some of the models, yet the NWS briefing is mentioning training and a flash flood watch. Why do they expect training of the storms in this instance?

[andrewmo.tennisman]

I know weather a bit but not a 100% expert on it, but does today look more like squall line rather than those hook echoes from yesterday? I live in Lionville/Exton area, and I think yesterday's storms (we got a Tornado Warning alert yesterday) was possibly the most stressful storm I've been through. I would rather a squall line than those hook echoes. I used to fear the squall lines, but after yesterday's hook echo thing, squall lines are tame for me. Ha!

[Rainshadow]

51 minutes ago, cbelke said:

Yeah, easier to see the rotation in the individual cells instead of a squall line.

Question for you. I see the squall line on some of the models, yet the NWS briefing is mentioning training and a flash flood watch. Why do they expect training of the storms in this instance?

To me it looks like potential multiple hits in the same areas. The slowing of the front and thunderstorms along it near the Mason/Dixon line (10z HRRR) comes closest to training on that model output.

Glad you posted about the flash flood watch, here it is:

[Rainshadow]

37 minutes ago, andrewmo.tennisman said:

I know weather a bit but not a 100% expert on it, but does today look more like squall line rather than those hook echoes from yesterday? I live in Lionville/Exton area, and I think yesterday's storms (we got a Tornado Warning alert yesterday) was possibly the most stressful storm I've been through. I would rather a squall line than those hook echoes. I used to fear the squall lines, but after yesterday's hook echo thing, squall lines are tame for me. Ha!

The convecting models do form a squall line later today, but there is still shear around and one can still get tornadoes along a squall line, although their potential strength is typically less than with super cell type storms.  Here is a couple of comparison guidance maps for yesterday vs today.  While the predicted shear is less than yesterday, it is still high enough to think about tornadoes occurring.

This sgfcnt tornado parameter came out after I retired, so I would use this as a proxy of where the strongest storms are.  Yeah this 12z run nailed the likely Sussex County tornado, but it is bouncy and the 06z run did not.

Yesterday:

Today:

I used to use 30 kts of effective bulk shear to think about tornadoes.

Yesterday:

 

Today:

[andrewmo.tennisman]

4 minutes ago, Rainshadow said:

The convecting models do form a squall line later today, but there is still shear around and one can still get tornadoes along a squall line, although their potential strength is typically less than with super cell type storms.  Here is a couple of comparison guidance maps for yesterday vs today.  While the predicted shear is less than yesterday, it is still high enough to think about tornadoes occurring.

This sgfcnt tornado parameter came out after I retired, so I would use this as a proxy of where the strongest storms are.  Yeah this 12z run nailed the likely Sussex County tornado, but it is bouncy and the 06z run did not.

Yesterday:

Today:

I used to use 30 kts of effective bulk shear to think about tornadoes.

Yesterday:

 

Today:

Thanks a ton! I can live with that haha!

[Rainshadow]

BTW having large (for us) severe weather events around this time of year is nothing new.  I was a much younger and spry person when I was the warning met on this day 24 years ago:

A severe thunderstorm caused wind damage in downtown Norristown. As the storm was exiting Norristown, it dropped a tornado (F1 estimated winds 80 mph) between High and Tremont Streets. The tornado proceeded east into Plymouth Township and lifted around the Plymouth Country Club. Nevertheless, damaging wind gusts associated with the severe thunderstorm continued along a east path until the Germantown Pike. The worst damage in Norristown was inflicted upon the Curren Terrace Apartment Complex as a piece of the roof was removed. Two dozen residents of the complex were evacuated from the damaged building. Several other houses, mainly in Norristown, had structural damage to their roofs and chimneys. Two were rendered structurally unsound. The remaining damage was inflicted upon trees which were sheared and toppled. Streets which reported the most damage included DeKalb, Elm and Hamilton in Norristown and Graves, Nursery Drive Sandy Hill, Thomas and Walnut Lane in Plymouth. No injuries were reported. The severe thunderstorms throughout Montgomery County caused 17,000 homes to lose electricity.

[andrewmo.tennisman]

1 minute ago, Rainshadow said:

BTW having large (for us) severe weather events around this time of year is nothing new.  I was a much younger and spry person when I was the warning met on this day 24 years ago:

For a minute I thought you meant the Limerick tornado which I don't remember at all as I just turned 6 years old and just moved into the area with my family from York County, but I just Googled it and saw it was in July 94. My one ex-GF at the time lived in that one neighborhood but was spared. Yeah I figured it was nothing new. A lot of people in general outside meteorology I think don't realize that, and I think it is something more people should know more about. Could calm some people's nerves more ha.

[Rainshadow]

6 minutes ago, andrewmo.tennisman said:

For a minute I thought you meant the Limerick tornado which I don't remember at all as I just turned 6 years old and just moved into the area with my family from York County, but I just Googled it and saw it was in July 94. My one ex-GF at the time lived in that one neighborhood but was spared. Yeah I figured it was nothing new. A lot of people in general outside meteorology I think don't realize that, and I think it is something more people should know more about. Could calm some people's nerves more ha.

Lol, I was working the midnight shift the day of the Limerick tornado.  There was a sanfu with data dissemination from the radar that evening/night.  The choice was either have us see the radar information and everyone else be blind or the reverse (which was chosen).  Sterling was backing us up and Andy Stern ( he is a great met) was calling us with details.  There was a severe in effect but no tor with that cell in Montgomery County.  It was a cell that split, but it was the left mover (strange occurrence, normally it is the right mover that has the tornado) that dropped that tornado. Sadly the family that was killed, their child's savings bond fell back to the ground in Northampton County.

[susqushawn]

2 hours ago, Rainshadow said:

Lol, I was working the midnight shift the day of the Limerick tornado.  There was a sanfu with data dissemination from the radar that evening/night.  The choice was either have us see the radar information and everyone else be blind or the reverse (which was chosen).  Sterling was backing us up and Andy Stern ( he is a great met) was calling us with details.  There was a severe in effect but no tor with that cell in Montgomery County.  It was a cell that split, but it was the left mover (strange occurrence, normally it is the right mover that has the tornado) that dropped that tornado. Sadly the family that was killed, their child's savings bond fell back to the ground in Northampton County.

I know we discuss that Jul 94 storm periodically, and while my memory might be slightly inaccurate, I do recall that to be an unusual south to north moving long track supercell that was tornado warned in states to our south.  I could have sworn central MontCo ( I was living in Hatfield at the time and got the weaker right splitting cell) was warned as I called my neighbors and woke them up, but maybe that was a different storm I'm thinking about.  Either way, it stood out in my 13 year old memory as being an anomalous setup

[Rainshadow]

34 minutes ago, susqushawn said:

I know we discuss that Jul 94 storm periodically, and while my memory might be slightly inaccurate, I do recall that to be an unusual south to north moving long track supercell that was tornado warned in states to our south.  I could have sworn central MontCo ( I was living in Hatfield at the time and got the weaker right splitting cell) was warned as I called my neighbors and woke them up, but maybe that was a different storm I'm thinking about.  Either way, it stood out in my 13 year old memory as being an anomalous setup

Mighty have been the '95 tornado warning.

https://www.philly.com/philly/news/20140727_A_storm_without_warning.html

This was what came up from the D.C. area:

https://www.weather.gov/lwx/events_19940724

[susqushawn]

2 minutes ago, Rainshadow said:

Mighty have been the '95 tornado warning.

https://www.philly.com/philly/news/20140727_A_storm_without_warning.html

This was what came up from the D.C. area:

https://www.weather.gov/lwx/events_19940724

Could very well be, that might be right, thanks!  Is that what starts to happen as the years pile up behind me?

[gravitywave98]

95% chance of a watch by 1 pm per SPC - https://www.spc.noaa.gov/products/md/2019/md0881.html

Long, nearly straight hodographs through mid levels and related 40-50 kt of effective bulk shear should favor  scattered splitting supercells early this afternoon. Large hail will  probably be the initial concern with this convection, with some increase in the damaging wind threat with time as storms potentially congeal into one or more bowing line segments as they move east-southeastward across PA into NJ.

[mshaffer526]

Wow.  

 

[gravitywave98]

Tornado Watch for the whole area until 8 pm

Today's probabilities vs. (yesterday's):

Tornadoes:  40% / (50%)

EF2+ Tornadoes:  20% / (20%) 

Severe Wind:  70% / (60%)

65 kt+ Wind:  20% / (20%)

Severe Hail:  70% / (60%)

2"+ Hail:  30% / (30%)

So, looks like slightly lower chance of tornadoes but higher chance of severe wind compared with yesterday.  Also have Flash Flood Watch for today.

[greg ralls]

Hopefully, people are prepared and will take this seriously. Having two likely tornadoes in Berks County, PA and Sussex County, NJ yesterday should help.

[irishbri74]

14 minutes ago, greg ralls said:

Hopefully, people are prepared and will take this seriously. Having two likely tornadoes in Berks County, PA and Sussex County, NJ yesterday should help.

 

[chescowx]

Thunder shower underway here in NW Chesco - notice on latest radar that the sea breeze front has made it thru Trenton and is now just NE of NE Philly airport...will be interesting to see if this boundary triggers or enhances some activity as we move through this PM

Sea Isle was up to 88 warmest of year before sea breeze cut temp 12 degrees in 8 minutes

[colonel_kurtz]

5 minutes ago, chescopawxman said:

Thunder shower underway here in NW Chesco - notice on latest radar that the sea breeze front has made it thru Trenton and is now just NE of NE Philly airport...will be interesting to see if this boundary triggers or enhances some activity as we move through this PM

Sea Isle was up to 88 warmest of year before sea breeze cut temp 12 degrees in 8 minutes

assume that easterly flow will put a damper on significant weather, CNJ & adjacent portions of PA in the dead zone once again?

[frankdp23]

My brother just sent a pic to me of quarter sized hail at his office near Allentown.