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November Discobs 2020


George BM
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Wet! 

Graphic for MPD #0856

https://origin.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=0856&yr=2020

Mesoscale Precipitation Discussion 0856
NWS Weather Prediction Center College Park MD
534 PM EST Wed Nov 11 2020

Areas affected...far eastern TN, western NC into western/central
VA and southern MD

Concerning...Heavy rainfall...Flash flooding likely

Valid 112228Z - 120425Z

Summary...Flash flooding is expected from far eastern TN and
western NC as well as western and central VA into southern MD
through 04Z from an additional 2-4 inches of rain, on top of a
broad 1-3 inches which has fallen over the past 12-24 hours.

Discussion...22Z surface observations showed that a cold front
extended from western PA into northwestern GA, or just west of the
spine of the Appalachians. Moisture was highly anomalous for
November to the east of the front, with precipitable water values
ranging from 1.5 in western VA/NC to over 2 inches in
central/southeastern VA. In addition, MUCAPE was estimated to be
in the 500 to 1500 J/kg range across a broad section of the warm
sector, with CAPE values having increased 200-400 J/kg across much
of VA and MD over the past 3 hours via low level moisture
transport according to the 21Z SPC mesoanalysis. Southwesterly 850
mb flow was observed in the 20-35 kt range from western NC into
western/central VA via recent VAD wind plots.

As the cold front continues eastward early tonight, broad low
level directional confluence/speed convergence, extending from
western NC into western/central VA and southern MD, will support
an increase in the coverage of showers and thunderstorms. This
will occur beneath strengthening upper level divergence and
diffluence, located on the southern end of an upper level jet
streak, with a peak magnitude of 150-170 kt in southern Quebec.
850-300 mb flow, a proxy for cell motions, is parallel to the axis
of low level convergence, which will support repeating and brief
training of cells at times. With the degree of moisture and
instability in place, peak rainfall rates of 1-2 in/hr will be
possible with a few locations picking up an additional 2-4 inches
of rain by 04Z. Recent heavy rain over the past 12-24 hours has
lowered flash flood guidance values across a large portion of the
MPD threat area to 1 inch or less in 1 and 3 hours. Given the low
flash flood guidance, flash flooding is considered likely.

Otto

ATTN...WFO...AKQ...GSP...LWX...MRX...RNK...

ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...NWC...

LAT...LON   38997703 38627659 38257660 37087900 36667996
            36128119 35788239 35828262 36028268 36508197
            37048115 37947971 38517804
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9 hours ago, dailylurker said:

I've been in the rain jackpot for 6 months lol. 

I remember riding the bus to school that morning and it was cold and raining lightly. About half way to school I remember big snowflakes starting to mix in and come down heavier. By the time we got off the bus about 15 minutes later it was all snow and already starting to stick on grass and cars. That was probably about 8am. By 11 roads had caved and it was coming down probably 2+ inches per hour. I remember eating lunch in the cafeteria and hearing loud thunder and seeing flashes of lightning like a summer storm. I'd estimate it was snowing 3+ inches per hour at that point. That went on most of the afternoon. It finally ended around dark but by then we were stuck in school. Some kids had to stay all night. I remember measuring 16" when I got home that night. It fell in about 7 hours from i remember. We probably got a foot between 11am and 3pm along with intense lightning. It was an amazing storm. I've been a fan of  weather since I've been able to look out a window. 

That was a doozy.  Remember it well.  I was working downtown DC that day IVO the Dept of State Hqs on 23rd st NW.  USG closed down late morning.  My colleague Tim and I made the mistake of pulling a couple of people out of the parking lot in his Isuzu Trooper.  That delay cost us.  We skied a lot and had loaded his Trooper up with winter clothes and my logging chain that morning.  TG we did...

We headed down I-395 past the Pentagon and towards home in Lorton (me) and Woodbridge (him).  I-95 around the Pentagon was a parking lot.  That night the news said there were over 800 cars abandoned just IVO the Pentagon with pictures of women in high heels walking down Rt-1.  

We got off I-395 and went through Old Town to take the Mt Vernon Pky South with the chance a round about way would be better.  It was about 2pm then and it was coming down in buckets.  Got nearly to Mt. Vernon and the Pkwy was closed due to two big pines that lost the battle to the the very wet snow.  They had completely blocked all 4 lanes of the pkwy.  We bypassed the traffic backup and managed to get to the front of the backup with the Trooper.  We commandeered people from their cars and hooked up the logging chain to the tops of the pines and were able to drag the pines enough to reopen one lane in each direction.  We had 14 extra people sitting in the Trooper, on top of the roof, on top of each other, in the back, 2 on the hood, and more hanging off the open doors of the Trooper for weight (figured later it well in excess of 3000 lbs of weight).  In 4WD and granny gear it worked.  Wish I'd had a camera - it was a sight to see with all those people piled all over the Trooper.  Everyone was laughing so hard it was comical.  The crowd of onlookers in their dresses and suits wondered where on earth my buddy and I came from.  They also wanted to know where we were going because they wanted to follow the Trooper with the chain.  haha.  

We went through Ft. Belvoir, got on Rt-1 South and just sat there for over an hour.  Finally got over to Newington and onto I-95 South.  When we got to the Pohick Road bridge that goes over I-95 I got out, climbed over the fence and clawed my way up the embankment onto Pohick Rd.  Turned around only to see about 15 people behind me who liked the idea and followed me up the hill.  Everyone helped everyone else because nobody else had the right clothes or shoes on.  I walked the last mile home and arrived a little after 6pm.  Six+ hours after departing downtown DC.  Measured 17" on the flat behind my house.  The Mt. Vernon and Ft. Hunt area was bullseye for that one.  

 

 

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48 minutes ago, BlizzardNole said:

Great stories.  Can you imagine this board if that happened today with some getting 12-17" and areas not far away getting 2-4?

Looks like southern MD is gonna get some more heavy rain tonight.  Sorry about that Waterworlders!

Was thinking the same thing as I recalled that event.  There were hundreds of people walking down I-395 late that afternoon.  Once their cars ran out of gas, they became bipedal again.  Once they abandoned their cars, the plows could not get through.  Back in 1987, FFCO "only" had about 750,000 people, vice nearly 1.2M today.  With not many more roads to handle the load now compared to then, the results now would potentially make commutageddon in Jan 2011 a walk in the park.  

Here's a good write-up about the story from CWG a few years ago.  

https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/11/10/weathermen-recall-the-record-veterans-day-snowstorm-that-totally-fooled-them-30-years-ago/   

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From north and northwest...

 

9 hours ago, losetoa6 said:

Pretty much what I expected here . Lowest total probably in the area lol 

.97"

Note: @losetoa6 is probably over an inch as of this post but not by much.

19 minutes ago, WxUSAF said:

Just over 1.5”

34 minutes ago, midatlanticweather said:

Purcellville with 1.59"...healthy but not crazy excessive like others 

 

29 minutes ago, mappy said:

when? i really need to pay attention to the models more

Also, 1.8" as of this morning

 

To the metros...

 

1 hour ago, H2O said:

2.21” so far

 

To the south and southeast...

12 minutes ago, SnowtoRain said:

3.35" storm total, over 60" on the year now

1 hour ago, wawarriors4 said:

3.81”here so far. Looks like we will go over 4.00” with ease with more rain inbound 

 

36 minutes ago, PrinceFrederickWx said:

System total 4.04"

(2.65" yesterday and 1.39" today)

...

All is in balance. Just how everything is supposed to be in the year we call twenty-twenty.

However, everything equals out over time. North and west will get theirs... perhaps in time for winter. Snow and ice will rule the landscape with an icy scepter in the north and west burbs while 33-degree despair inducing rains will fall across the south and east burbs giving Mr. Reaper all-time record high stonks, turning the tides of the optimism of active weather weenies to the north and west.

...

OR, we continue this persistence into the winter and @CAPE will get his beach blizzard along with the south and east gang in January with the one good winter event of the season... Yeah that sounds more accurate... REEEEEEEEE! 

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