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Tonight's action is focused right up the Susquehanna mainstem to the merge with the West Branch and up that through IPT....coinciding with a corridor of very high PWATs greater than >2". Not a tropical system but it essentially might as well be given the rich moisture fetch and high rainfall efficiency. You Sus Valley folks always know how to do the heavy rainfall events right. 

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12 minutes ago, TheDreamTraveler said:

Yeah this is really starting to remind me of the September 2011 flooding. Do any of you think this will get close to the top 3 worst flooding for our area? I know the 2011 flooding was the 3rd worst ever.

The Susquehanna is not going to come anywhere near 2011 numbers. 2011 featured Irene then Lee - something like 18” rain in a week. 

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Picked up 0.81" here since midnight with the heaviest falling right as my wife was leaving for work. As for me, I get to go to Honesdale this afternoon and pick up a group and take them into JFK Airport. it'll be interesting to see what I encounter during my travels, AND what I might come home to later.

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9 hours ago, canderson said:

Rough night here x flooded out city roads, Dockside Willies on fire, and a woman in Lancaster County swept away in flood waters apparently.

reason for my 2 hours of sleep.

 

Currently heavy rain in Da Burg

 

Edit- My neighbor just text, Sunday/Monday Rainfall total in Summerdale is 7". That doesn't count anything after midnight. and believe me, it fricking dumped

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1 hour ago, canderson said:

I'm now beginning to worry a bit about the river, though the lack of heavy rain in the northern mountains probably saves us. 

Susquehanna is currently forecast to crest at 18.4' on Thursday...flood stage is 17'. Looks to crest at about 2' above flood stage down this way at Marietta. 

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New warning just terrified my office as all phones went off at once.

lash Flood Warning
PAC041-043-071-133-241745-
/O.NEW.KCTP.FF.W.0023.180724T1454Z-180724T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service State College PA
1054 AM EDT TUE JUL 24 2018

The National Weather Service in State College PA has issued a

* Flash Flood Warning for...
  West central Lancaster County in south central Pennsylvania...
  York County in south central Pennsylvania...
  Southern Dauphin County in south central Pennsylvania...
  Northeastern Cumberland County in south central Pennsylvania...

* Until 145 PM EDT..

* At 1045 AM EDT, Doppler radar indicated an area of heavy rain
  moving into the warned area. Up to eight inches of rain has
  already fallen in this region over the past few days, with
  flooding ongoing in many locations. An additional 1 to 3 inches of
  rainfall is likely by early afternoon. This will increase
  the severity of the flooding.

* Some locations that will experience flooding include...
  Harrisburg, York, Lower Allen, Hanover, Hershey, Colonial Park,
  Weigelstown, Elizabethtown, Progress, Mechanicsburg, Middletown,
  Camp Hill, Palmyra, New Cumberland, Parkville, Red Lion,
  Linglestown, Enola, Steelton and Spry.

The Codorus Creek is already above flood stage, and this will
exacerbate flooding problems along the creek. Additional rapid rises
on the Conowingo and Little Conowingo Creek are also expected.
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Nothing out yet from CTP but HBG fire officials are concerned about the Susky hitting 22' or so and not the 18' currently forecast. 

For those unfamiliar, that difference makes a massive difference in the problems it causes. At 18' it's fairly minor basement flooding and City Island parking lot flooding. At 21.5' it breaches the banks in Shipoke and near the Governor's Mansion.  

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2 minutes ago, canderson said:

Nothing out yet from CTP but HBG fire officials are concerned about the Susky hitting 22' or so and not the 18' currently forecast. 

For those unfamiliar, that difference makes a massive difference in the problems it causes. At 18' it's fairly minor basement flooding and City Island parking lot flooding. At 21.5' it breaches the banks in Shipoke and near the Governor's Mansion.  

oh man, 22' is not good.

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30 minutes ago, canderson said:

Nothing out yet from CTP but HBG fire officials are concerned about the Susky hitting 22' or so and not the 18' currently forecast. 

For those unfamiliar, that difference makes a massive difference in the problems it causes. At 18' it's fairly minor basement flooding and City Island parking lot flooding. At 21.5' it breaches the banks in Shipoke and near the Governor's Mansion.  

Question that maybe no one can really answer - how is the expected crest forecast? If we "only" get an inch or two of rain for the remainder of the event, will the crest be lower, and conversely, if we get 5" will the crest end up higher? 

I view the hydrology page several times daily and the expected crest seems to fluctuate each time i check. Just wondering how the crest is determined. I'm sure it is highly variable given how many waterways empty into the main stem. 

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WPC Target again for 2-4” additional today

Mesoscale Precipitation Discussion 0531
NWS Weather Prediction Center College Park MD
1245 PM EDT Tue Jul 24 2018

Areas affected...Northern Maryland/Delaware into central
Pennsylvania, far western New Jersey and southern New York

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

Valid 241643Z - 242130Z

SUMMARY...Flooding and flash flooding appear likely over the next
3-5 hours from northern Maryland/Delaware into portions of central
Pennsylvania, western New Jersey and southern New York. An
additional 2-4 inches of rain with rainfall rates of 1-2 in/hr
through 21Z can be expected.

DISCUSSION...Regional radar imagery at 16Z showed a NNW-SSE axis
of heavier rainfall in the vicinity of the northern Chesapeake Bay
with rainfall rates of ~1 inch in 15-20 minutes per
Wunderground.com observations. The broken line of heavy rain was
coincident with weak low level confluence beneath locally
diffluent flow aloft given the presence of a narrow upper level
ridge axis along the East Coast. The line has been gradually
shifting to the north and east which has prevented potentially
much higher rainfall totals over the past 2-3 hours but the
northern Mid-Atlantic region is saturated from a widespread 4-10
inches of rain which has fallen over the past few days.

CAPE values across the northern Mid-Atlantic into southern New
York are generally less than 1000 J/kg given cloud cover, but
given the moist environment, higher CAPE values are not needed to
support heavy rainfall rates. Nonetheless, clearing over eastern
Pennsylvania may allow for increasing instability through the
afternoon along with the development of new convection. Little
change to the synoptic environment is expected over the next
several hours which will keep precipitable water values over 2.25
inches and 30-40 kt 850 mb flow from the south helping to support
repeating and brief training of heavy rain cores. Given the
antecedent conditions, flooding and flash flooding are considered
likely.

 

https://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=0531&yr=2018

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