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Bands of Heavy Rain along and se of I84 Sunday 4AM-11PM


wdrag
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Hi!  

Decided to start the topic. It would be for rainfall reports primarily, and easing of some recent dryness in a few spots of our forum.  FF not likely except maybe southern Ocean County?  Lesser flood advisories would probably occur for poor drainage urban flooding Sunday near NYC (IF I'm reading this right?)  

1.5"+ qpf differences in operational solutions through the 18z/15 (Saturday) with the EC/UK/HRRR op runs very-very light while the NAM continues furthest north with the 1+".  

Preliminarily I see a very sharp cut off of rainfall somewhere from Sussex County NJ northward or I84 ~HFD.  Suspect two bands of heavy rain in our area...one maybe along I80-I78 corridors thru LI (deformation mid level FGEN ~700 MB  in the morning-afternoon, then LI getting the direct storm additional contribution during Sunday evening).  The second band across southern Ocean County NJ.  This is a best estimate based on modeling.  There will be error. 

The northern band narrow, but widespread 0.5 to a few pockets of 2". The drier zone just south of that band in Monmouth to near I195 Trenton,  then the other band over southern Ocean County in the 1.5-3" zone.  E Suffolk County total from both daytime deformation FGEN and evening storm  1.5-3".  

My guess is much of interior se NYS doesn't receive much if any rain and maybe Sussex County too, while we watch some pretty decent bands along I80 or I78?  

If it's any consolation...the 12z GEFS is a tick higher for NJ/LI and as far north as it's been since the 18z/14 run with 1" skirting the s coast of LI. It's broad output so doesn't get into the banding etc. The 12z EPS is noticeably heavier than the 12z EC operational and about 1/2" shy of the GEFS for LI.

I think there is enough information to see a dismally damp midday-evening for much of NJ/LI and some decent rainfall. I think definitely wetter than the 12z SPC HREF. 

If anything, this a model contest trying to understand reality today and the associated modeling, with the follow through for Sunday.  Compromise is always best realizing the downside of forecasting too heavy too far north. 436P/15  (I do not plan to post anymore until Sunday morning - have to ride it out now).

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25 minutes ago, wdrag said:

Hi!  

Decided to start the topic. It would be for rainfall reports primarily, and easing of some recent dryness in a few spots of our forum.  FF not likely except maybe southern Ocean County?  Lesser flood advisories would probably occur for poor drainage urban flooding Sunday near NYC (IF I'm reading this right?)  

1.5"+ qpf differences in operational solutions through the 18z/15 (Saturday) with the EC/UK/HRRR op runs very-very light while the NAM continues furthest north with the 1+".  

Preliminarily I see a very sharp cut off of rainfall somewhere from Sussex County NJ northward or I84 ~HFD.  Suspect two bands of heavy rain in our area...one maybe along I80-I78 corridors thru LI (deformation mid level FGEN ~700 MB  in the morning-afternoon, then LI getting the direct storm additional contribution during Sunday evening).  The second band across southern Ocean County NJ.  This is a best estimate based on modeling.  There will be error. 

The northern band narrow, but widespread 0.5 to a few pockets of 2". The drier zone just south of that band in Monmouth to near I195 Trenton,  then the other band over southern Ocean County in the 1.5-3" zone.  E Suffolk County total from both daytime deformation FGEN and evening storm  1.5-3".  

My guess is much of interior se NYS doesn't receive much if any rain and maybe Sussex County too, while we watch some pretty decent bands along I80 or I78?  

If it's any consolation...the 12z GEFS is a tick higher for NJ/LI and as far north as it's been since the 18z/14 run with 1" skirting the s coast of LI. It's broad output so doesn't get into the banding etc. The 12z EPS is noticeably heavier than the 12z EC operational and about 1/2" shy of the GEFS for LI.

I think there is enough information to see a dismally damp midday-evening for much of NJ/LI and some decent rainfall. I think definitely wetter than the 12z SPC HREF. 

If anything, this a model contest trying to understand reality today and the associated modeling, with the follow through for Sunday.  Compromise is always best realizing the downside of forecasting too heavy too far north. 436P/15  (I do not plan to post anymore until Sunday morning - have to ride it out now).

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18z 3k NAM came quite a bit North from 12z to more reflect precip placement of NAM. A bit lighter totals in far NNJ/ Orange Cty (. 5+ as compared to 1"+) but nonetheless at least it wasn't a dry run like 12z

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As we awake,  it looks like the EC/UK have admitted to decent 1/2"+ rain for LI/NJ and the 06Z NAM says, I'll be the exceedingly dry EC/UK of many past cycles.  WPC D1 is a good start and a bit less than my expectations from yesterday. I stay with yesterdays topic starter, except the sharp cutoff on the northwest side may end up somewhere interior se NYS extreme nw CT. In other words further nw than evaluated yesterday.  Banding of heavier showers s definitely occurring through early afternoon and whether I targeted the heaviest axis properly, is up for debate but it all merges into one every nice summer nor'easter late today...a nasty afternoon-evening for LI and the NJ shore.  

You'll also note contribution from the warm Atlantic waters in the form of low top showers moving ashore (westward) this morning, beneath the mid level northeast moving rains. Pretty impressive for summer, I think, in terms of the mixed cyclonic system event.

For what it's worth .04 here at our house in Wantage so far, since it began ~330A. 

I will post again at times today. 637A/16

 

 

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59 minutes ago, wdrag said:

As we awake,  it looks like the EC/UK have admitted to decent 1/2"+ rain for LI/NJ and the 06Z NAM says, I'll be the exceedingly dry EC/UK of many past cycles.  WPC D1 is a good start and a bit less than my expectations from yesterday. I stay with yesterdays topic starter, except the sharp cutoff on the northwest side may end up somewhere interior se NYS extreme nw CT. In other words further nw than evaluated yesterday.  Banding of heavier showers s definitely occurring through early afternoon and whether I targeted the heaviest axis properly, is up for debate but it all merges into one every nice summer nor'easter late today...a nasty afternoon-evening for LI and the NJ shore.  

You'll also note contribution from the warm Atlantic waters in the form of low top showers moving ashore (westward) this morning, beneath the mid level northeast moving rains. Pretty impressive for summer, I think, in terms of the mixed cyclonic system event.

For what it's worth .04 here at our house in Wantage so far, since it began ~330A. 

I will post again at times today. 637A/16

 

 

The  Euro has been too suppressed at times with the northern edge of precipitation with tracks near the benchmark in recent years. ECMWF did a good write-up on the January 2016 historic blizzard. Maybe the model upgrades did something in the 2014-2015 time frame? I can remember it doing very well with the February 2013 Nemo blizzard from 5 days out.


https://confluence.ecmwf.int/display/FCST/201601+-+Snowstorm+-+US+east+coast

5. Good and bad aspects of the forecasts for the event

  • Early signal (from Sunday 17 Jan 00z) and very consistent forecasts
  • Too low accumulation over NYC
  • Question about snow density for the case

 

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So far as of 1030AM attached, NJ only.  Back edge of the w NJ steady band will progress east of I95 by evening but low top junk drizzle sprinkles will sweep west into w NJ this afternoon.  

Biggest rains after 2P should shift to all of LI  

Am okay with the two bands through 2P, thereafter we should see some sort of merger NYC eastward. 

 

Added MARFC fall analysis last 12 hours. seems a little shy in Ocean County. 

Screen Shot 2020-08-16 at 10.25.39 AM.png

Screen Shot 2020-08-16 at 10.38.58 AM.png

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0.07 Wantage and probably ended up 1/2" too high on all I80 south expectations. Will post CoCORAHS map around Noon Monday.  Still, had this been winter... the modeling problem was excessive at 24 hours (18z/15) and even the 06z/16 NAM was poor-reversing it's excesses of the 15th to very low qpf values for today. Difficult to understand such a lack of agreement in the very short term (non convective driven). 

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