Eta and/or Theta remnant potential Wed-Sun Nov 11-15, 2020

[wdrag]

This is potentially a failed topic 7-12 days in advance, but Eta and/or Theta remnant moisture or the actual ET transitioning leftover tropical wave has a chance of advancing into our NYC forum area either midweek, or next weekend.  Reasoning is based on an ensembled strong WAR near Bermuda forcing any Tropical systems that enter the GOM early next week, inland over the eastern USA, then northward and eventually east-northeast by the time it reaches our latitude. The 52 member NAEFS and WPC have qpf in the eastern USA by the middle of next week.  Additionally, there is a substantial RRQ of the upper level jet during mid week over se Canada, and then next weekend it is modeled to redevelop southward into New England. RR Quads of the upper level jet are favorable for generating heavy qpf near a surface front with PWAT over 1.6".  

This is not saying it will occur... but we may find it's worthwhile having a topic to discuss our views/supporting guidance as we advance in time.

IF....IFFF...the remnants of the tropical system miss the first opportunity to accelerate northeastward the middle of next week,  then a colder scenario could unfold next weekend, but that colder scenario would be the less likely,  threading the needle, so to speak.

For now: I'm thinking 1-3" rainfall opportunity either next Wednesday or Thursday (already 1" 12z/4 GEFS/EPS)  or maybe again next weekend.

So... this is just a topic that may come in handy based on the idea that the main trough in the USA the next two weeks is in the west with a strong ridge over the western Atlantic and east coast. 403P/4

[LibertyBell]

Thanks Walt!  Any ideas about wind with this?

 

[wdrag]

No--sorry.. first I want to see moisture get up here.  Will let the modeling try to draw some consensus by Sunday afternoon and by then we might know more about a hybrid or something else, including track/size.

[wdrag]

Hi!  As of the 12z/5 cycle...  there is a potentially interesting 1-2 punch coming to the mid Atlantic states as alluded to in the topic. Unsure how much of either will strike the NYC forum but odds favor at a minimum, beneficial rains of 1-3" by next Sunday night (5 day threat period), possibly twice that much if we get both opportunities. Getting two sizable rains with a tropical connection  (PWAT near 2") in 5 days is not common up here, at least to my knowledge. 

The first for Wed-Thu is a tropical connection more related to the GOM cyclonic flow pulling high PWAT air northwest then north from Fl. through the Carolinas and into the northeast; the second for next weekend, a bit more tenuous - less certain, but is more Eta direct. It's primary impact could be a narrow miss south.  

For now; ensembles have decent rainfall coming.  the 12/5  52 member NAEFS poses the probability of 2+" of rain by next Sunday night the 15th.  The prob as seen from the legend is 35-45%.  Not too bad, for essentially a rain risk period 6-10 days in advance.  We shall see if we get glancing shots, or more direct involvement. For now, I think the odds are pretty good for 1-3" of rain next Wed-Thu, greater uncertainty for the weekend following. 

Continuing to monitor modeling- and probably wont have much more to add til this weekend. 

[wdrag]

Good Friday morning all, 

Interest continues for tropical interaction in the NYC forum Wednesday-Sunday (11-15).  For now, per ensembles and multi 00z/6 operational modeling, favored tropical (best risk PWAT briefly 2") days are Wed-Thu, but now Friday is a possibility too... with the Sunday 15th event maybe just a fast moving cold front with bigger PWAT just south?

No matter: GOM cyclonic circulation PWAT is going to make it up here, mostly likely Wed-Thu, with a possible revisit Friday, or still even possibly Sunday.

I've added WPC QPF issued early today for Wed-Thu,  also tropical ensemble tracks for Eta (EPS, GEFS), which tend to show recurvature somewhere between NC-New England (IF it remains a transitioning wave) around Friday-Saturday. 

Just have to wait this out, but I'm pretty sure of one,   .... possibly 2 batches of 1-3" rainfall here in our forum between Wed-Sunday. 

[wdrag]

Continuing prior posts for multiple significant rainfall events Wed-Sun, despite two successive GFS OP (12z/18z) runs of nil on Sunday there 15th. GFS seems completely at odds with the GGEM and EC op, as well as GEFS thru the 18z/6 cycle today an'd the EPS from 12z/6 whereby it appears our NYC forum will generally average at least 1-3" in that 5 day period, perhaps quite a bit more in spots provided two significant 1+" rainfall events occur. 

[wdrag]

Good Saturday morning everyone,  It appears the 5 day outlook is still on track.  GFS via it's 06z/7 cycle is starting come back to another event late Sunday.

A few graphics are added to put things in perspective.  

The differences in the GFS/EC-GGEM groups for Sunday appear to be related to the ejecting of a strong shortwave out of the West Coast trough toward the Great Lakes-Northeast USA...the latter EC-GGEM  are stronger.  

Also, fwiw, the EC operationally is leaving behind Eta's 850 vort near PNS Fl late this coming week. For now, that is uncertain, but a cyclonic circulation of sorts seems to be left behind in the northern GOM next Friday.  IF that occurs, you can count on another brief period of near 2" PWAT coming into the NYC forum at the end of next weekend.  That would cue my interest after being primed Wed-Thu (possibly with a little more rain on Friday as well).  

So, I envision a rainy period coming Wed-Thu, Sunday, possibly Friday as well. Timing on those days less than certain though am very confident of Wednesday into Thursday 1-3", as a start with near 2" PWAT hanging around and opportunity for more than 3" in central NJ. Even so, this first event should be below FFG with only a small region just w of NYC vulnerable to flooding. 

00z/7 cycle WPC 7 day qpf is added, plus the GEFS prob of 3+" in 36 hrs and GEFS plumes for ISP for the entire 7 day period...showing the range of possibilities as seen in the 00z/7 GEFS.

[bluewave]

Walt, great thread. The 2” PWATS you mention would be a new record for November. So there is the potential for heavy rains if the tropical moisture plume gets close enough.
 

 

[wdrag]

5 hours ago, bluewave said:

Walt, great thread. The 2” PWATS you mention would be a new record for November. So there is the potential for heavy rains if the tropical moisture plume gets close enough.
 

 

VERY-very good the you look at all that detail.  I didn't think too much about a record.  

I'm liking what I see overall w the 12z cycle, especially if we park a boundary to our south for the warm frontal comeback Friday-Sunday.  

On the climate stats...  maybe they need to add a climate warming bias to the stats. ie.  warmer 1000-500 MB thickness (often translates to sfc temp), permits better chance of high side records...  which sooner or later, will translate to higher monthly daily and monthly (Nov) precip record...presuming GW continues.  I'll attach 12z op EC PW as soon as they arrive, as well as 12z/7 EPS 850 wind and PWAT anom, as time permits later.  Fri-Sat less certain on amounts but I like the potential.  Will need another 6-18 hours to reevaluate as tied up w home stuff. 

This first attached image shows EC op image of Eta in GOM, but the ridge-ETA driven separate segment of PWAT driving northward. 

I'm not sure if I want to yet believe the WPC D4-7 qpf i saw at 15z for their day cycle.  It's been beefed up quite a bit (graphic not added in this reply) and might sit on high side of the envelope. Certainly possible but need more time to figure it out. 

 

Added a Wednight PWAT axis graphic...  close to 2"... and one for Sunday evening... that one only 1.5" in NYC... higher to the east where the OP model has 6+" rainfaLL sse of BID Wed-Sun night. Also EC OP now spewing some gale gusts near LI late Sunday-no big deal but does suggest the somewhat robust nature of what will be happening in the east third of the country this week. 

 

 

[wdrag]

No additional info at this time. GFS continues comparatively weak to the EPS after Thursday...  Tomorrow morning should show some trend one way or the other.  WPC toned down it's expected qpf D4-7 at 18z. NAEFS is pretty bullish on widespread 1-3" qpf Wed-Thu.

More tomorrow... have a good night all. 

 

[wdrag]

Good Sunday morning everyone,  All seems on track... models are converging... 1-3" burst for much of four NYC forum Wed-Thu, a touch under 1/4" Fri morning, then a warm frontal generated rain Sunday, culminated by a decent cold frontal burst Monday morning.  If I add this all up in a broad sense... it seems to me a general 2-4" by Noon Monday (yes the back end of this 5 day thread is seeming to need to be extended 12-18 hours).  I can see isolated 6" amounts, depending on where the axis of rains overlap.  

Models also converging on agreement that the Sunday-Monday short wave will be pretty decent for us.  

PWATs briefly 1.8-2" Wednesday night (near record for Nov as noted by Bluewave), and back up to a brief 1.5-1.7" Sunday and/or Monday morning. 

Wind: EC second consecutive cycle of 35 MPH or greater for the eastern parts of the area with the cold front... and now flagging a broader 35-50MPH burst with the CFP Monday morning the 16th, mainly I95 corridor eastward. If the short wave continues as modeled by the EC-EPS--then this will probably happen.

Thunder: small chance of rumbles Wednesday night.  Better chance of thunderstorms with the CFP Monday morning.

Dynamics: upper level RRQ of a jet over se Canada-Maritimes Wed-Thu, even Fri AM; then a combined RRQ of jet south of Nova Scotia later Sunday with the LFQ of the approaching short wave barreling into PA-NJ. 

Please see WPC for the first part of the QPF outlook (1.5"+) and then Monday morning we should be able to post their most of their event(s) total.  At that time, I may add some more supporting graphics. 613/8

 

at 618A..I added there prob of wind gust more than 40MPH from the GEFS.  Thought you might like to see this. It's low chance but interesting this far in advance. 

[wdrag]

Good Monday morning everyone,  Today and maybe tomorrow, are probably good days to put away the patio rugs/furniture for the winter, dig out the bulbs that can't handle winters deep freezes and plan for quite a bit of rain Wed-early Monday, followed by brisk weather next week.  

Two graphics are appended this morning. WPC 7 day qpf...  Looks pretty reasonable to me.  and, a small chance potentially excessive rainfall Wednesday evening.

My thoughts: GFS op is not probably not onto the evolution very well, but it's a consideration that Wednesday-Thursday might be a less than the EC, GGEM-RGEM-ICON. Even UKmet is not quite as bullish as I'd like to see. So that said... am going to going to continue the 1-3" theme for Wed-Thu w maybe a rumble of thunder and a pretty good chance of PWAT lingering near a November record of 2" for 18 hours late Wed-midday Thu. A decent fairly persistent sw 850 MB jet aids convergence-lift of the moisture-structured by the strong WAR which forces quite a bit of low level convergence along the E Coast. Another factor--diffleent 1000-500MB thickness suggesting quite a bit of divergence aloft. 

Friday: some modeling tries to lift Eta remnant or otherwise an ET low, northeastward from NC.  I think the latter option for sure, per EC ensembled 850 MB flow and therefore I think we'll have some mid level qpf for a time Friday..less than 1/4" mostly NJ-LI-coastal CT. This is not certain but possible.

Saturday: probably dry and cool.

Sunday-Monday morning: The final part of this 5 day rain risk period. Models are converging on a triple pt low developing in the LFQuad of GEFS-EPS 500 MB jet heading into PA-NJ. This is  associated with a short wave that had departed the southern Rockies.  Thunder may or may not occur. PWAT will not be 2", but yet Eta remnant moisture may still be  involved since Eta might get lost in northern GOM late this week (for me an unknown). Still worthy to track Eta's 850MB vort. We're certainly going to have another burst of above normal PWAT.  I foresee a pretty east-west oriented thickness barrier across our area providing opportunity lift and wring out quite a bit of qpf here. Drizzle-periods of moderate rain etc. Will go with WPC D7 of 1/2-1" right now but I could see heavier. 

So... my guess is widespread 2-4" this 5 day period in the NYC forum. Isolated 6" possible. Where it's heaviest still unknown. I'd like to see the GFS/UK beef up the qpf in the future cycles... since it's still possible 5 day totals are only 1-3". 

Snow: I've seen couple of models try to offer a touch of wet snow to NYS-CT either Saturday or Sunday.  I don't want to explore that possibility now---too far in advance with marginal thermal profiles, but not impossible for the northern fringe of the NYC forum...north of I84. 

 

 

 

[LibertyBell]

Walt looks like a widespread 2-4 inches everywhere from NE PA to Long Island?  In your latest map I see a spot of 5"+ right in NE PA.

 

[wdrag]

We'll see.  Don't like the first batch shifting southward a bit...  still time to return north. If the frontal system passes too quick, we lose the bigger amounts.  

I hope tomorrow morning we have more confidence on 1-3 or 2-4 iso 6. Bottom line, at least two events coming and pretty nicely modeled around the 3rd-4th. In fact, I think modeling for this current warm dry spell has been very well advertised well in advance. 

[LibertyBell]

12 minutes ago, wdrag said:

We'll see.  Don't like the first batch shifting southward a bit...  still time to return north. If the frontal system passes too quick, we lose the bigger amounts.  

I hope tomorrow morning we have more confidence on 1-3 or 2-4 iso 6. Bottom line, at least two events coming and pretty nicely modeled around the 3rd-4th. In fact, I think modeling for this current warm dry spell has been very well advertised well in advance. 

What is the time line for the second event, Walt?  Is that from the remnants of another tropical system?  I see there are two more TC possibilities on the board now.

 

[wdrag]

So, looking at 12 and 18z/9guidance-ensembles, the trend for the first event is less than 1" n of I80 and heavier e LI and central NJ. but that is not locked... and guidance could easily refocus further north.  The second sure event is Sunday into Monday morning. That one while less in PWAT than that of Wed-Thu - (which is tropical related but not directly Eta),  might have remnant Eta as I see some of the models are tracking from central GOM into the northeast late this weekend. Long ways to go and the usual amount of uncertainty. 

[wdrag]

Good Tuesday morning everyone,

Overall: little change from yesterdays post. Am thinking the higher of the two options by Monday morning for our NYC forum. Expecting 2-4", isolated 6 with the least in se NYS interior CT. If this fails down, then I think it would be general 1-3". All in all, modeling favors heaviest rainfall NJ, LI. Will not try to detail, since I can't possibly get three or four events correct.

I've added this mornings WPC 7 day qpf, which includes just very little after 8AM Monday. It's slightly less than what was posted yesterday but the legend gives the idea. I also added PWAT but not for Thursday evening (which should be briefly 2-2.2" at OKX, but whether the sounding captures a Nov record 2+??? I don't know, since the highest PWAT will probably occur between the standard sounding interval of 00z/12z).  The PWAT displayed is for the subtle burst near 12z Friday (associated with a Quebec short wave that cleans us out for 36 hours Friday afternoon to Saturday night).  Then I added the PWAT axis for early Sunday. Note the Sunday morning connection to the GOMEX. I think this is remnant ETA.  I saw the NHC depiction  of ETA Sunday morning.  Stay with that for official purposes though my low confidence guess is remnant ETA is swept northeast toward NJ Sunday.  I'll be following the 850MB vort for this.  Sunday morning qpf could be impressive for 6 hours. 

Wednesday-Thursday: periods of rain-drizzle, most of it W afternoon-night, but lingering into Thursday.  General 1/2-2" with the least in se NYS-CT. Iso 3.5" expected, probably in NJ or LI.  This is tropical PWAT but indirectly associated with Eta. Rumbles of thunder expected Wednesday evening for LI/CT/NJ. 

Friday morning: Less than 1/4" for a few hours of showers.  We should see this coming out of the Ohio Valley late Thursday (separate from the departing band in our area). It moves east northeast through our are Friday morning-midday.

Sunday: Widespread showers and drizzle. 0.5-1.5" expected with isolated 3". Best chance 3" LI. Could have iso thunder?

Monday: The CFP could have isolated thunder in the morning. No details.

May not be able to comment further until late today or this evening. Have a good day. 440A/10

 

[wdrag]

My guess is that this will be the minimum of the WPC D1-2 combined Tue afternoon QPF forecast (tends to be patterned off the SPC HREF). Looks reasonable, with the heaviest band probably arced newd through s NJ (s of our area) but still a pretty decent event here.  

Have seen the dry GFS for Sunday.  While possible I don't think Sunday will be dry.  We'll know more by Thursday night but am thinking the GFS in our area has been a little on the low side through all its forecast cycles for the entire period Wed-Sun night.  Hopefully the 12z/10 UK/EC op show decent rains coming Sun-Sun night. 

[wdrag]

Good Wednesday morning all,  Going to let this play out. Looks to me like periods of rain from late today through midday Friday, with tonights event initially slated to be the biggest, but don't be surprised at decent qpf Thu and Fri, especially LI. Sunday's event not as robust looking but time to change the modeling scenario. Still think 3 or 4 events with Sunday-early Monday maybe the least likely. 

Modeled amounts haven generally trended down, so I may have been wrong to look for general 2-4" iso 6" by Monday morning. WPC's 5 day looks decent but am not going to be surprised if it comes in a little heavier. Subtle convergence changes can result in larger yield. PWAT NYC 1-8-2.0 tonight and still a bit above normal into Friday morning.  Still a chance of thunder tonight LI. 

Least qpf for this entire period probably POU-DXR northward.  Heaviest seems slated for near ILG-PHL thru Ocean County to e ELI. 

May comment further later today?

 

[Brian5671]

some models have a sharp cutoff with not much north of NYC-if the cutoff is off by 50 miles a very different forecast for some places

[qg_omega]

GFS has rain later today and that’s it

[LibertyBell]

3 hours ago, wdrag said:

Good Wednesday morning all,  Going to let this play out. Looks to me like periods of rain from late today through midday Friday, with tonights event initially slated to be the biggest, but don't be surprised at decent qpf Thu and Fri, especially LI. Sunday's event not as robust looking but time to change the modeling scenario. Still think 3 or 4 events with Sunday-early Monday maybe the least likely. 

Modeled amounts haven generally trended down, so I may have been wrong to look for general 2-4" iso 6" by Monday morning. WPC's 5 day looks decent but am not going to be surprised if it comes in a little heavier. Subtle convergence changes can result in larger yield. PWAT NYC 1-8-2.0 tonight and still a bit above normal into Friday morning.  Still a chance of thunder tonight LI. 

Least qpf for this entire period probably POU-DXR northward.  Heaviest seems slated for near ILG-PHL thru Ocean County to e ELI. 

May comment further later today?

 

Maybe we could get 1-2" with this first event and then another 1-2" Sunday into Monday?

 

[Brian5671]

31 minutes ago, qg_omega said:

GFS has rain later today and that’s it

New NAM shows the same thing-tomorrow's event ends up well south.

[bluewave]

Could be the highest PWAT so late in the year for OKX with the heavy rains around the 0z sounding.

Precipitable water:        1.93 inches

[wdrag]

Even the 12z/12 sounding might be near record NOV PWAT per the 12z/12 EC op.  Letting this all play out...  likely that it rains some more Thursday morning and again Friday and late Sun or Sun night. I think some of this could be little fun for LI/central NJ.  New EC is trying for some wind with the CFP Sun night.  

[bluewave]

1 hour ago, wdrag said:

Even the 12z/13 sounding might be near record NOV PWAT per the 12z/12 EC op.  Letting this all play out...  likely that it rains some more Thursday morning and again Friday and late Sun or Sun night. I think some of this could be little fun for LI/central NJ.  New EC is trying for some wind with the CFP Sun night.  

Impressive record to our south.

 

[LibertyBell]

Wow that water vapor graph reminds me of the spike in 75+ dew points JFK experienced a few years ago

 

[wdrag]

Corrected OKX potential near record PWAT date to 12z/12.  Got a day ahead of myself.  

Nevertheless, tonight's 00z/12 OKX 1.88" (may need independent confirmation) 'appears' to me as Bluewave noted: The latest wettest PWAT at OKX for Nov.

So far the yield has not been impressive. 

[wdrag]

Here's some PWS's from se NYS s of POU (bunch of 1's so far) and central NJ- near I-195 bunch of 1.4-2".  Long ways to go, I think, for NJ-LI... periodic into midday Fri.  Noticed the HRRR is lighting up pretty good on LI 2-5A Thursday, after the current batch moves through. My spot in Wantage is on the low end so far  0.43".  

[hudsonvalley21]

0.67 in the bucket so far today. Currently light rain 64/63