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Two large rain/wind events 10/25-26, 10/28-30 w probable totals by Oct 31 of 2.5-8" in the NYC subforum, damaging wind and SVR potential for one of these storms


wdrag
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Active Pacific pattern assisting downstream northeast USA blocking of two large 500MB trough passages next week. This should result in at least one Nor'easter and possibly a classic fall severe weather event if a 985MB low moves northward through central PA.  

Max isolated rainfall potential of ~7" somewhere in the NYC subforum (interior) would lead to isolated Flash Flooding but the dry October of generally less than 1/2" so far in NYC 'should' limit the flash flood threat. There has been more rain I84 northward so the flood threat may eventually be targeting the interior NYS/CT portion of our forum. 

The general non-astronomically high tide cycles should at least partially limit the potential for moderate coastal flooding.

Of greater concern appears to be softening of the ground by next weeks rains and the probability for a period of 45-55MPH wind gusts on fully leaved wet tree branches in parts of the area, which would lead to a power outage problem. 

At this Friday October 22 608AM issuance time, it's far too early to focus on the details.  The headlines of this topic will adjust a bit as we move through the weekend, including tags. For now have left SVR and FF out of the tags.  

430P/Saturday the 23rd added the FF Tag.

7P/Sunday the 24th increased general rainfall to a range of 2.5-8" up from 1.5-4". 

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  • wdrag changed the title to Two large rain/wind events 10/25-26, 10/28-30 w probable totals by Oct 31 of 1.5-4" in the NYC subforum, damaging wind and SVR potential for one of these storms
  • Rjay pinned this topic

Good Saturday morning everyone,

Prepare for adverse weather, possible power outages and possible flood related problems, especially north of I80 next week.

The first of the real deal rainfall probably begins Sunday evening-night with evolution of a nor'easter by late Tuesday, followed by a second large scale event though possibly of a differing more inside runner flavor, next Friday-Saturday.

Details tbd but here are some graphics to ponder.  I'll probably add FF to the tags late Sunday or Monday pending further model confirmation, and SVR will be reserved for last add but it's on the table.   WPC has a minimum of 3" forecast for I80 north next week.

Graphics below: This mornings D3 SVR outlook for Monday, The EC EPS 500MB pattern 00z/Wed (tue eve), the EC EPS sfc pattern for the same time, and then the GEFS as well at the same time, and finally a rather impressive EC EPS rainfall forecast for just our area...EPS have 5" in central MA (more to the east not seen here) and general 1-3" in our area. 

 

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Screen Shot 2021-10-23 at 5.52.56 AM.png

Screen Shot 2021-10-23 at 5.52.32 AM.png

Screen Shot 2021-10-23 at 5.46.25 AM.png

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Bring the umbrella... follow the HRRR for today.  

Forecasts and outlooks look a little weak this weekend through next week with little heads up of the coming and already in progress dismal weather. Had drizzle/sprinkles last evening here in nw NJ per prior Mping reports.  (EC did the best with its new convective scheme, especially the midnight ish showers that occurred here early Friday morning). It's raining now (650A) here in Wantage and more to come today... a rather chilly and occasionally wet day here in far nw NJ, probably closer to the city too.  Tomorrow's forecasts seem too optimistic. This all plays into cutting grass and outdoor chores putting away summer stuff.  

Probably off line most of the morning, 

Walt

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Courtesy Weather.US as are many of the graphics I post.  Look at these 06z/ECMWF OP graphics.   I don't think it's too early to lean hard on EC ideas.  It's just a matter of severity and location that it begins. That's 5" of rain e LI and 5+ Ct River Valley.  Possibly too much or mis located.  Part of this has the 06z/23 EC raising PW to 2" near LI.  

 

 

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Screen Shot 2021-10-23 at 8.23.40 AM.png

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We are seeing some very large #'s this week for the NYC subforum.  Also some of the modeling doesn't agree in the GFS/NAM/EC modeling which i do believe...it's where.  12z/23 GFS as I'm sure you saw has 8" for NYC this coming week.  I would necessarily focus in on NYC itself but somewhere in our forum,  there seems to be a pretty good chance of spot 7-9" amounts by Halloween. 

 

Attached is the new midday NWS WPC ensembled approach to next Fri-Sat.  We'll see what happens, if this occurs as predicted but the potential exists for somewhere along and N of I80 up into central NYS-central New England.   Those reds are about 3-4.5". 

Will append the new 7 day totals at about 4P as my time allows and available from WPC. 

Modeling also is suggesting two separate storm occurrences of 850MB 70 knot se inflow.  Again we/I don't know anything for sure, but am confident some validated warning events are coming next week. Where, am unsure... there can be important shifts but the focus continues here, somewhere in our area. 

Screen Shot 2021-10-23 at 12.41.18 PM.png

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Unusual storm evolution on the 12z Euro. Cutoff low taps deep tropical moisture from offshore hybrid type low. The moisture channel along an inverted trough-stalled front becomes the focus for very heavy rainfall. Almost looks like a PRE merging with the cutoff.

 

B33D6AED-23DF-451F-B8A5-C11BA30223EE.thumb.png.8d6d9e843923374c0d21fd55508f00aa.png

 

 

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WPC 7 day qpf.  Everything inside the red contour is 5".  I would have to think media is going to have to start arousing concern.  It is not everyday that WPC puts out 5 and 6" weekly contours in our area.  

I will add FF to the tag now.   I am aware that river flooding might be the more common result of these events later this week,  but I have to think FF will occur when intense rains are continuous for 3-6hours at 1"/hr rates. 

FF added at about 430P/23. 

 

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So, this is a new tool to use for many on here...  click the 0 hour on IWT or IVT and then use your arrow keys to slide through the model guidance.  This is GFS and NAM only op runs.  However,  you see something of what Blue wave wrote.  Also, imo, the second event late this coming week may have some of Hurricane Rick RH in it.  Take a look at the eastern side of the storm. 

https://cw3e.ucsd.edu/ivt_iwv_namerica/

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16 hours ago, donsutherland1 said:

Seeing the 10” at Portland is a good reminder that some of Portland’s biggest rainstorms have occurred in October, including the October 20-22, 1996 storm that dumped 14.67” of rain in three days, including 11.74” on October 21st.

we could get that much rain in NYC too, looks like an Ida type rainfall with wind this time

 

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The NYC metro should see a widespread 1-3" rainfall w/locally higher amounts especially as you head further north and east. Severe weather also possible tomorrow night into the first half of Tuesday. I think the SPC may eventually go with a slight risk for the area. We'll see. Wednesday could be a windy day behind the system. 

Storm #2 Friday into Saturday details TBD but potentially stronger and more impactful then storm #1??

The fuse was light and the active pattern has now exploded after an extended break post Ida.

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  • wdrag changed the title to Two large rain/wind events 10/25-26, 10/28-30 w probable totals by Oct 31 of 2.5-8" in the NYC subforum, damaging wind and SVR potential for one of these storms
  • BxEngine unpinned this topic

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