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2020 Mid-Atlantic Severe Weather - General Thread


Kmlwx
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Meanwhile the Tidewater is getting clocked pretty good with heavy rain.

Looks like a nice dead zone setting up between the line passing well to the NW, and the stuff to the SE. Not interested in the least in severe,  just some heavy downpours.

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Don't look now...but the 12z CIPS analogs in the Southeast domain have June 29, 2012 in the analogs - along with some other VERY robust events. The domain that is over us isn't showing much for now - but that period really bears watching now. 

 

http://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=SE&fhr=F132&rundt=2020052912&map=thbPPF

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3 minutes ago, Kmlwx said:

Don't look now...but the 12z CIPS analogs in the Southeast domain have June 29, 2012 in the analogs - along with some other VERY robust events. The domain that is over us isn't showing much for now - but that period really bears watching now. 

 

http://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=SE&fhr=F132&rundt=2020052912&map=thbPPF

8/15 referenced events have a DC hotspots and we are overdue for a derecho in these parts from a climo perspective.

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6 minutes ago, Eskimo Joe said:

8/15 referenced events have a DC hotspots and we are overdue for a derecho in these parts from a climo perspective.

Here's what I predict - it will start looking REALLY ripe in the next few model cycles. And then by the time the day rolls around - it will be a miserable failure with socked in clouds and crap mid-level lapse rates. 

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1 minute ago, Kmlwx said:

Here's what I predict - it will start looking REALLY ripe in the next few model cycles. And then by the time the day rolls around - it will be a miserable failure with socked in clouds and crap mid-level lapse rates. 

I agree. June 2012 was an anomalous event. We had extreme temps and a stout EML. 

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Just now, Eskimo Joe said:

I agree. June 2012 was an anomalous event. We had extreme temps and a stout EML. 

Triple digit temps and like 5500 CAPE. Not sure we'll see something like that for a long while. I think if anything the trajectory of an MCS next week could be similar - impacts you'd have to assume would be much lower. 

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Just now, Kmlwx said:

Triple digit temps and like 5500 CAPE. Not sure we'll see something like that for a long while. I think if anything the trajectory of an MCS next week could be similar - impacts you'd have to assume would be much lower. 

The 850 temps sampled on the 18z special RAOB ahead of the line occurred only 5 times before in recorded history at the IAD site. You could tell early in the day on the 12z ILN site that something big was about to happen because the EML was evident so early in the morning.  That airmass advected ahead of the complex and sustained it over the mountain. Reanalysis of the event showed that every meso model that correctly modeled the EML successfully predicted the derecho making it to the coastline. If there's on big takeaway from that event, it was that correctly sampling, identifying and modeling EMLs in the Mid Atlantic will significantly increase the ability of forecasters to anticipate these events and provide timely IDSS to the appropriate officials.

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Just now, Eskimo Joe said:

The 850 temps sampled on the 18z special RAOB ahead of the line occurred only 5 times before in recorded history at the IAD site. You could tell early in the day on the 12z ILN site that something big was about to happen because the EML was evident so early in the morning.  That airmass advected ahead of the complex and sustained it over the mountain. Reanalysis of the event showed that every meso model that correctly modeled the EML successfully predicted the derecho making it to the coastline. If there's on big takeaway from that event, it was that correctly sampling, identifying and modeling EMLs in the Mid Atlantic will significantly increase the ability of forecasters to anticipate these events and provide timely IDSS to the appropriate officials.

EMLs really do seem to be our "magic bullet" for our highest end events - at least of the derecho variety. 

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2 hours ago, Zanclidae said:

That includes us.  Nice soupy southerly breeze.  It's quite disgusting actually.  Running central a/c for the first time of the year.

Didn’t get much but a shelf cloud and two rumbles of thunder. Light rain as the best stuff missed me and went into pa. Saw some tree damage in Shrewsbury when I went out to get dinner 

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11 minutes ago, mappy said:

Didn’t get much but a shelf cloud and two rumbles of thunder. Light rain as the best stuff missed me and went into pa. Saw some tree damage in Shrewsbury when I went out to get dinner 

Pretty much same here.  Some wind and rumbles and alerts for CG lightning <20 miles from the antenna here.  Breeze settled down a lot but just had the dog outside and it's quite muggy.

I don't know if anyone here remembers that silly movie "Click" but if I had a remote that let me skip things I'd probably skip to November.  Of course skipping 7 months/year means you'd notice everyone around you aging faster.  Even in an imaginary world there are limits. ;)

Skipping traffic jams and taxes though, wouldn't mind that at all.

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45 minutes ago, Eskimo Joe said:

This is a must read paper about the role of EMLs and severe weather from DC north.

https://journals.ametsoc.org/doi/pdf/10.1175/2010WAF2222363.1

       The EML is definitely essential here if we want a wind system to survive its trip over the mountains.   In 2000, a bow echo was racing east towards us, and SPC put out the rare PDS severe thunderstorm watch, and it completely crapped out trying to cross the mountains of West Virginia and Virginia.    We ended up with showers that gusted to 30 kt.

 

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27 minutes ago, high risk said:

       The EML is definitely essential here if we want a wind system to survive its trip over the mountains.   In 2000, a bow echo was racing east towards us, and SPC put out the rare PDS severe thunderstorm watch, and it completely crapped out trying to cross the mountains of West Virginia and Virginia.    We ended up with showers that gusted to 30 kt.

 

What month was that?

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9 minutes ago, Kmlwx said:

Wow - that was a quick recall. 

https://mesonet.agron.iastate.edu/GIS/apps/rview/watch.phtml?year=2000&num=666

Anybody have the watch text?

Yeap.

 

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 666
STORM PREDICTION CENTER NORMAN OK
1219 PM EDT WED AUG 9 2000

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

DISTRICT OF COLUMBIA
MARYLAND
SOUTHERN PENNSYLVANIA
NORTHERN VIRGINIA
CENTRASL AND EASTERN WEST VIRGINIA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 100 PM UNTIL
700 PM EDT.
...THIS IS A PARTICULARLY DANGEROUS SITUATION...

DESTRUCTIVE WINDS. ALSO...HAIL TO 1 INCH IN DIAMETER...

THUNDERSTORM WIND GUSTS TO 95 MPH...AND DANGEROUS LIGHTNING ARE
POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 70 STATUTE MILES
NORTH AND SOUTH OF A LINE FROM 60 MILES WEST SOUTHWEST OF
MORGANTOWN WEST VIRGINIA TO 10 MILES EAST SOUTHEAST OF BALTIMORE
MARYLAND.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

OTHER WATCH INFORMATION... CONTINUE...WW 665...

DISCUSSION...INTENSE BOW ECHO OVER SERN OHIO IS EXPECTED TO
CONTINUE EWD AT 55 KT ACROSS THE APPALACHIANS WITH WIDESPREAD
DAMAGING WINDS LIKELY. ACTIIVTY WILL REACH THE BALTIMORE/WASHINGTON
DC AREA AROUND 5 PM.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1 INCH EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 80 KNOTS.
A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION
VECTOR 27055.

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10 hours ago, high risk said:

nice work, everyone!    I remember that event quite well.    I was warning people at work not to be on the roads at rush hour.    That alert didn't work out too well......

I'm just glad that I was not old enough (4 years old) to remember that debacle of an 'event'. :yikes:

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