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SVR-PRE (ELSA) potential NYC subforum Tue-Fri morning July 6-9, 2021


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The evolving pattern this coming week is continuing to model high CAPE (Heat Index NYC metro non-marine influenced near 100F) Tue-Wed and even Thursday afternoons with enough wind aloft and instability to permit one or 2 days of SEVERE storms in our area.  Tuesday SVR appears relegated North of I80 (mainly NYS/CT). Wednesday to me looks like a potentially big day, especially I80 region northward with TT in the lower 50s, big CAPE.  

Thursday into Friday:  Uncertainty on evolution but big CAPE and instability probably remain in the vicinity of our subforum.  It too could be a severe day, however of interest is the eventual position of the frontal boundary.  IF, it drifts down into our subforum with light north-northeast flow north of it,  then it seems to me the projected path of decayed ELSA wind fields and moisture plume - convergence (925-850MB southerly flow overrunning a cool frontal  boundary,  ranging up to the 200MB RRQ of jet located in se Canada) would promote the potential for a Predecessor Rainfall Event (PRE) as documented in research by NYS associated well known mets.  Have added a couple of their composites. These 4+" events occur 24-36 hours in advance of the TC, located hundreds of miles north or northeast of the TC even though the TC itself can miss to the south. If it doesn't and tracks over the PRE then that magnifies the potential sub-basin (mesoscale) trouble.  As we are aware,  we're starting to pile up the water across our subform so this potential result-NOT guaranteed,  should be monitored and we'll see if it can occur, fritter, or displace north of our subforum.  I'm doubtful if the potential displaces south of us.   My guess is we'll know by Tuesday or Wednesday.

In the meantime,  I think we can expect severe storm wind/hail in parts of our area during midweek, along with possible storm cluster FF in PW air of 1.6", and probably should monitor the evolution of ELSAs ensembled wind fields up this way. Composites are added, as well as 00z/3 EC PWAT for late Thu (showing the TC well south but PWAT axis up near here). This is imperfectly modeled, the speed and location of ELSA and associated wind fields will adjust and affect the results.  Let's see how this may breakdown and whether or not we can pick up ISOLATED 4-6" new rainfall between Tue-Fri in parts of our area-ISOLATED.  WPC went to press this morning with a general 1"+ for our area, which supports embedded isolated heavier. You probably recall around the 28th-29th they had our entire area 1.5" for the current ongoing event with general 2"+ central and S NJ. Appears they did quite well. 

 

638PM Monday July 5- EDITED Title to include ELSA- Too much modeling is drifting its track within range of coastal NJ and LI for Tropical Storm considerations Thu night-Friday AM. While it's not certain  to make a direct second landfall across LI/southeastern New England, think it best to open the door a little more, at the least for 4+" rains this week combined convective outbursts and whatever Elsa. 

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  • Rjay pinned this topic

Happy 4th of July to all!

The overall pattern remains favorable for at least 1 day of SVR, in a portion of our subforum between Tue and Thu of this coming week. The PRE and/or direct Elsa remains for Thursday-early Fri is up in the air, in part due to strength of whatever is ELSA as it passes by,  and the position of the cool front.  

WPC-SPC have no indicators of significant SVR-FF threats to our region this week, so taking that into account along with your views of the modeling, this thread may be of little value.

On the other hand, while wind fields aloft are marginal for SVR these upcoming 3 days, the CAPE/KI and some model yields suggest potential for SVR. Thereafter, modeled PW for Thu night in the tropically benign EC reduces the risk for isolated 4"+ rainfall, but there is time for models to adjust including a better looking ELSA in the EC.   For now, one might consider the GGEM an outlier ELSA solution.  

All I do know from the modeling, despite PW down a bit... TT remains in the lower 50s for these 3 days. That combined with NYC metro non-marine influenced HI 95-100, a nearby front and potential for divergence aloft with the upper level westerly jet across Northern New England, opens the door for an active period... especially NORTH of I80 from ne PA through se NYS-CT.  

I may not add anything more til Monday the 5th.

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SPC Marginal added to our area Tue and Wed (please see simple attachment)...  think both days warrant consideration due to pretty high HI, CAPE, KI and TT 48-51.  Wind fields a little on the light-marginal side, but the soundings show a concentration of modeled near 35 KT winds near 680MB.  NW flow SVR generally in my mind needs to be considered faster moving and potent (Tue afternoon) and in this case as modeled, develops somewhere north of I80 and rolls all the way south through the subforum.  One scattered-broken line? 

Wed I think has improved divergence aloft-RRQ upper level se Canada jet and should have some SVR, especially I80 north.

Thu: cirrus outflow from ELSA could minimize convective threat? otherwise IF there is to be a PRE, it's probably Northern New England or Quebec? Meanwhile, follow NHC on track. Am noting slight northward shifts the past 12 hours in EPS/EC op but that could again shift south.  Not yet a guaranteed no direct rainfall impact, though for now at least, probably not much contribution here - still worthy to monitor.

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Pay attention to the modeling as I think we're good on the entire thread.

 

Already ACCAS (AC castellanas 11A here in Wantage, now buildups). Some of the modeling picking up on a big cell NYS/NJ border mid afternoon (hill driven?).

 

Tuesday and Wednesday continue to look good for the potency and at least scattered heavy convection.  Thursday: 12z GFS outlier or continuing a northwest trend??? Don't know but IFFFF NWS buys into it, then I suspect a TSWatch would eventually be needed for NJ/LI coasts for marginal TS wind.  

Screen Shot 2021-07-05 at 10.52.35 AM.png

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Thanks.. cant count the chickens, so to speak  - but so far, opportunity has not waned.  New 12z OP is slightly closer.   My thinking I-84 corridor is best chance isolated 4+ by 18z Friday, even if ELSA is a narrow miss to vcnty KACK. 

Probably won't comment much more til around 6A Tuesday, then off line through 230PM Tue.

 

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  • wdrag changed the title to SVR-PRE (ELSA) potential NYC subforum Tue-Fri morning July 6-9, 2021

638PM Monday July 5- EDITED Topic Title to include ELSA- Too much modeling is drifting its track within range of coastal NJ and LI for Tropical Storm considerations Thu night-Friday AM. While it's not certain  to make a direct second landfall across LI/southeastern New England, think it best to open the door a little more, at the least for 4+" rains this week combined convective outbursts and whatever Elsa. 

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Good Tuesday morning everyone, At 559AM, i see little change from previous. 

Today: SPC D1 outlook continues and modeling is favoring a new line forming to our north early this afternoon and driving south-southeast through NYC/I80 sometime between 5P-8P. Plenty of CAPE/KI/ and wind 35 kt near 680MB with TT49 should permit a few reports of SVR in our area. A second weaker line of showers may develop near I80-LI after dark but not be svr. Max point rainfall today probably close to 1.5 or 2". Many might only get a gusty shower?

Wednesday: SPC D2 marginal risk.  Less wind aloft but greater instability including TT near 52, to me permits SVR from I80 north late in the day. Of interest is whatever develops,  may stall in its southward progression around sundown and then drift east-northeast as showery rain for a few hours.  IF we get a band of heavy cells Wednesday, training and isolated point rainfall over 2" possible.

ELSA: 00z/6 EC OP cycle continues northward drift of the track while the 00z/6 CMC stabilized or even slightly southeast from yesterday. 06z GFS se toward the NHC official, NAVGEM more threatening but no experience on this model.UNCERTAIN...follow NHC/Local NWS forecast offices on tracking, possible impacts. 

Am offline through 230P.  Hopefully something of interest happens for our participants.  My focus for heaviest total rainfall in our subforum the next 4 days is North of I80.

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We are on track for the first two Julys in a row with a tropical storm around the 9th-10th.

 

Area Forecast Discussion
National Weather Service New York NY
232 PM EDT Fri Jul 10 2020

.SYNOPSIS...
Tropical Storm Fay will move northward along the Mid Atlantic 
coast today


Latest EPS Elsa forecast

 

AD61471F-8E1D-453D-A482-E6BBA988A17A.thumb.jpeg.627da86dbbe9d7d732cc143b3f5fafa9.jpeg

 

 

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Definitely noting the concern for flooding. Came back from an errand on Sunday (early day so limited crowds) and the Delaware (NY side/Narrowsburg) was already looking pretty angry. The hit and miss storms these next few days and whatever Elsa may bring will not help things. 

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7 minutes ago, crossbowftw3 said:

Definitely noting the concern for flooding. Came back from an errand on Sunday (early day so limited crowds) and the Delaware (NY side/Narrowsburg) was already looking pretty angry. The hit and miss storms these next few days and whatever Elsa may bring will not help things. 

Headed to Narrowsburg this weekend for two days on the River. Good to hear that it’s moving. 

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1 hour ago, bluewave said:

We are on track for the first two Julys in a row with a tropical storm around the 9th-10th.

 

Area Forecast Discussion
National Weather Service New York NY
232 PM EDT Fri Jul 10 2020

.SYNOPSIS...
Tropical Storm Fay will move northward along the Mid Atlantic 
coast today


Latest EPS Elsa forecast

 

AD61471F-8E1D-453D-A482-E6BBA988A17A.thumb.jpeg.627da86dbbe9d7d732cc143b3f5fafa9.jpeg

 

 

WAR once again being stronger than forecast nudging track further west.

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3 hours ago, IrishRob17 said:

There have been a number of drownings over the past week, wear a life jacket if going in/on the river. 

I hear you; been going up there since 2006. Feet downriver at all times.

I am always amazed by some of the stories of how people have drowned on that river. One young lad decided to swim across the river at midnight after drinking all day; there's no cure for stupid.

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2 hours ago, hudsonvalley21 said:

In addition, the park rangers will ticket you. They also pose as regular people in canoes in their stealth mode.

As long as the vest is in the boat and free to access (not clipped to the cross-brace in the canoe), I have not had a problem.

I do know a group of long islanders in the camp site next to use got popped one year, but they were also standing in the canoe and funneling for a while.  

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WW0336 Warnings

https://www.spc.noaa.gov/products/watch/ww0336.html#:~:text=* Effective this Tuesday,WOUS64 KWNS WOU6).

  * Effective this Tuesday afternoon and evening from 130 PM until
     1000 PM EDT.

   * Primary threats include...
     Scattered damaging wind gusts to 65 mph possible

   SUMMARY...Clusters of storms are expected to develop southeastward
   into the region by late afternoon and early evening with damaging
   winds as the primary risk.

   The severe thunderstorm watch area is approximately along and 100
   statute miles east and west of a line from 30 miles northwest of
   Bridgeport CT to 20 miles south southwest of Wilmington DE. For a
   complete depiction of the watch see the associated watch outline
   update (WOUS64 KWNS WOU6).
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2 hours ago, Gravity Wave said:

Can we get a replay of this image in 6 months please?

But seriously, that looks like fun.

I understand both your verbiage and intent, Anthony. …… But considering the population density under those delightful colors, I’m just not sure about the fun part, now or six months from now. As always …….

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