2019 Mid-Atlantic Severe Wx - General Discussion

[Kmlwx]

7 minutes ago, Zanclidae said:

And probably the last?

Slight is best we usually see. 

Enhanced is not that uncommon - it used to be included in the slight category. But semantics. 

[Eskimo Joe]

1 minute ago, Kmlwx said:

Enhanced is not that uncommon - it used to be included in the slight category. But semantics. 

There are, on average, less than 3 D1 ENH risk per year in any point in LWXs forecast area and less than 1 D1 MOD risk.  

[Stormfly]

Yes for us MOD is rare.  I do remember back in 1998 we got clobbered with baseball sized stones.  We were in the hatched area but didn't get the damaging winds they got to the north and west.  But those hailstones are damaging enough.  Marbles with the occasional golf ball mixed in is OK.  Once they get tennis ball sized it's not fun any more.

[yoda]

Tornado Watch till 8pm for SW VA... includes the RNK counties that just about border the LWX CWA... Lynchburg is in the watch... just SW of CHO

[yoda]

Wonder if that 10% TOR will be expanded at all on the 2000 SPC OTLK

[Kmlwx]

Just now, yoda said:

Wonder if that 10% TOR will be expanded at all on the 2000 SPC OTLK

Probably not lol - at least not for us

[yoda]

Tornado Watch within the hour for W PA - https://www.spc.noaa.gov/products/md/md0344.html

[southmdwatcher]

10 percent tornado chance dropped for OH/WV, looks like everything else stayed the same with the SPC update.

[Eskimo Joe]

6 minutes ago, southmdwatcher said:

10 percent tornado chance dropped for OH/WV, looks like everything else stayed the same with the SPC update.

This has not been a well forecasted event from the start.  

[southmdwatcher]

SPC has certainly not proven to be great at forecasting severe weather events northeast of Dixie Alley. This has my red flag up for tonight.

[Eskimo Joe]

12 minutes ago, southmdwatcher said:

SPC has certainly not proven to be great at forecasting severe weather events northeast of Dixie Alley. This has my red flag up for tonight.

Forecasting severe weather for the Mid Atlantic, Carolinas and Northeast is far more difficult than other parts of the county.  You have terrain, cold air damming, marine influences and dense urban populations all within miles of each other.  There is no doubt the skill set that resides in Norman, OK is tremendous but SPC seems to bust too many times in this neck of the woods.  I've always been a bearish, conservative forecaster and it seems to work out to under forecast severe weather in these parts. 

[CAPE]

Mount Holly is a tad bullish on the severe threat- mostly for damaging straight line winds...

The main concern for severe weather looks to be for the very late evening and especially overnight as forecast models continue to indicate a strong squall line forming to our west ahead of a cold front and moving west to east across the CWA roughly in the 6-10z time frame. Overall, severe weather parameters are some of the most favorable seen for the mid Atlantic this time of year. 0-1/0-3/0-6 km shear values look to be 30/45/65 knots respectively. This, coupled with ML CAPE values looking to be 500+ j/kg as convection enters our eastern PA zones. Not terribly impressive on its own but plenty given the very strong shear and dynamics along with L57 lapse rates that look to be in the 6.0 to 6.5+ C/km range. Of additional concerns is 0-1 km SRH values progged to be 300+ m2s2. What this all means is that damaging winds look to be a big concern as this squall line moves through with the SPC having placed an enhanced risk for severe weather for a large portion of the CWA except the coast and far northern NJ. In technical terms, a QLCS type event. Damaging straight line winds are typically the biggest threat with these types of events but given the parameter is place, isolated tornadoes are possible. In addition, the very heavy rain accompanying the showers/storms will bring a good potential for at least urban, small stream, and poor drainage type flooding with isolated flash flooding also possible.

[osfan24]

7 minutes ago, Eskimo Joe said:

Forecasting severe weather for the Mid Atlantic, Carolinas and Northeast is far more difficult than other parts of the county.  You have terrain, cold air damming, marine influences and dense urban populations all within miles of each other.  There is no doubt the skill set that resides in Norman, OK is tremendous but SPC seems to bust too many times in this neck of the woods.  I've always been a bearish, conservative forecaster and it seems to work out to under forecast severe weather in these parts. 

On a lot of predicted severe weather days for our region, I feel like we end up with morning cloud cover that either never fully clears or clears for a very brief period and limits instability.

[CAPE]

10 minutes ago, Eskimo Joe said:

Forecasting severe weather for the Mid Atlantic, Carolinas and Northeast is far more difficult than other parts of the county.  You have terrain, cold air damming, marine influences and dense urban populations all within miles of each other.  There is no doubt the skill set that resides in Norman, OK is tremendous but SPC seems to bust too many times in this neck of the woods.  I've always been a bearish, conservative forecaster and it seems to work out to under forecast severe weather in these parts. 

This could be said for pretty much all weather types in the MA, except for heat. Being bullish on heat is a near 100% hit.

[yoda]

MD out... watch possible soon

[poolz1]

Being bearish is one thing...outright discounting the possibility is foolish.  Im not a severe guy but follow when things are a little interesting....this is one of those times.  Somebody will see a severe level storm tonight.

[yoda]

Mesoscale Discussion 0347
   NWS Storm Prediction Center Norman OK
   0350 PM CDT Sun Apr 14 2019

   Areas affected...Areas near/east of the Blue Ridge of North Carolina
   into Virginia

   Concerning...Tornado Watch 62...

   Valid 142050Z - 142215Z

   The severe weather threat for Tornado Watch 62 continues.

   SUMMARY...The risk for supercells potentially capable of producing
   tornadoes continues, and could increase at least a bit further
   through 6-7 PM EDT.  Trends will also continue to be monitored for
   northward development toward the northern Virginia vicinity, which
   may require an additional severe weather watch.

   DISCUSSION...A zone of enhanced near/surface warm advection and
   convergence to the lee of the Blue Ridge mountains may remain a
   focus for discrete thunderstorm development across North Carolina
   into Virginia through the 22-23Z time frame.  Aided by peak boundary
   layer instability associated with daytime heating (including CAPE up
   to 1000 J/kg), a few supercells are possible, in the presence of
   strong low-level and deep layer vertical shear.  The Rapid refresh
   suggests that southwesterly 850 mb flow may continue to strengthen
   in excess of 50 kt, contributing to further enlargement of low-level
   hodographs and perhaps increasing tornadic potential.

   ..Kerr.. 04/14/2019

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...AKQ...LWX...RAH...RNK...GSP...

[canderson]

My 4 pm flight delayed until 7:30, landing at BWI 11:30 pm. lol sure.

Yea I’m not getting home tonight. 

[Eskimo Joe]

3 minutes ago, C.A.P.E. said:

This could be said for pretty much all weather types in the MA, except for heat. Being bullish on heat is a near 100% hit.

From a SVR / TOR "climo" from LWX we're actually running pretty quiet so far this year.  According to the IEMDataPlot, only 8 SVR and 0 TOR issued by LWX and by now you'd typically see a dozen SVRs and a half dozen TORs issued.

[southmdwatcher]

8 minutes ago, osfan24 said:

On a lot of predicted severe weather days for our region, I feel like we end up with morning cloud cover that either never fully clears or clears for a very brief period and limits instability.

This is one of those days where the morning cloud cover could be less important than the moisture and shear available, and will be included as a mitigating factor. Either way it is a forecasting nightmare. 

[Kmlwx]

1 minute ago, canderson said:

My 4 pm flight delayed until 7:30, landing at BWI 11:30 pm. lol sure.

Yea I’m not getting home tonight. 

Is it delayed due to the inbound flight though? That's different than being delayed due to weather on your leg of the flight. A takeoff at 7pm could still easily get you into the area. 

[canderson]

2 minutes ago, Kmlwx said:

Is it delayed due to the inbound flight though? That's different than being delayed due to weather on your leg of the flight. A takeoff at 7pm could still easily get you into the area. 

Yea but that flight is stuck in Nashville. With the winds tonight I don’t see how BWI will have any inbound flights after say 8 pm. 

[southmdwatcher]

Nashville Intl Airport has winds 20mph gusting to 35, ouch. 

[southmdwatcher]

It would be a rough takeoff, but Ive been on worse takeoffs and landings with surface winds.

[Kmlwx]

9 minutes ago, canderson said:

Yea but that flight is stuck in Nashville. With the winds tonight I don’t see how BWI will have any inbound flights after say 8 pm. 

Winds suck for flights (especially crosswinds) but most non-severe winds won't cause ground stops etc

[Tater Tot]

That cell near Warrenton looks suspicious.

[NorthArlington101]

Tornado warning for just west of Amherst, on route to CHO eventually. Not in a a great radar coverage area.

[Eskimo Joe]

FYI, if you GR radar program isn't showing warnings correctly, it's because v2.8 was released on March 20th.  You'll have to re-download the program from the website www (dot) grlevelx (dot) com.  

[NorthArlington101]

4 active warnings in Virginia now. Not bad.

[southmdwatcher]

Watch coming soon for NVA and DC area, SPC meso issued just now, probability is 95%