Tropical connection NYC forum area Sun-Wed, 8/2-5/20- Tropical Storm Isaias

[Sportybx]

Given the current track . How is it looking for NYC . Are we talking flooding or just some wind and heavy rain . With LI getting all the flooding ? 

[wdrag]

Good Friday morning everyone in our NYC forum, Little change from what was posted yesterday. Have used yesterdays as a starter with commented adjustments.  

It's likely we're going to see significant impact from Isaias.

1) Potential killer Rip Currents Monday-Wednesday for anyone who ventures into the waters s of LI.  I'd be wary of swimming, especially non expert surfers/non expert swimmers. The significant undercurrent 1 feet 15 second swell may start arriving this weekend. These surprise swimmers with their energy and are sneaky dangerous. The higher surf just preceding and following the storm (within 18 hours) usually scares off most swimmers.  
 

2) Rainfall as per multiple ensembles and WPC D4-5.  Best multiple axis of 6-12 hr 4+ rainfall, to be determined.  This on top of the amounts received Friday-Sunday will have to result in pockets of flooding. Where?  Ensembles with the east turn (northern shutoff), now further north or non-existent implying less chance for OTS (i just learned that one yesterday). I'll add PRE info for comment in separate post but I think likely for a part of our NY forum Monday or Monday night, then it shifts north and northwest Tuesday as Isaias rolls northeastward.

3) Presuming the NHC 5AM Thursday track is reasonable, surge and wind field risks on the western side of ISAIAS are minimal but if the track shifts to where a portion of our area is on the eastern side of the TC, then those risks would significantly increase.  I think eastern LI to the southeast New England coast are vulnerable for at least some of these stormier impacts. Not saying they will occur but my background preparation would include comments to that effect.

4) Isolated 7+" rainfall from the "necessary" combined events of Saturday nights WAA (warm frontal) event, Sunday afternoons probable fairly widespread severe storms, mainly nw NJ/se NYS westward into ne PA,  and then finally either a PRE, or a direct impact of Isaias Monday-Tuesday. (maybe the slower 00z/31 EC is correct for early Wednesday but maintaining continuity with NHC).  I'm more concerned today about a combined Predecessor Rainfall event and a possible direct ISAIAS impact in our forum.  The 7+" rainfall in my estimation would probably have to occur west of the I95 corridor due to the ensembles probable combined Sat night-Sunday afternoon events depositing biggest amounts somewhere near the western edge of our forum coverage (~Sussex-Orange Counties?).  If Sat night-Sunday does not occur (1-3" combined event band somewhere in that area), then a PRE or ISAIAS hit would have to do all the work by itself and at this time, this is too uncertain. So to get to 7+", it's a lot easier if we see sizable rainfall Sat night-Sunday.  

(There is still what I think is a diminishing chance not much happens here next Monday-Tuesday-it's in the envelope of possibilities).

Let's see what happens. I'll be particularly interested in PRE comments.  

I'm adding PRE composites.  Where this PRE occurs, IF it occurs, is unknown but my guess based on 00z/31 modeling is between I95 and Williamsport-Burlington Vermont.  I'll add a link for the powerpoint.  I'll also add modeling for the PRE which occurs in subtle convergence about 12-18 hours prior to the passage of the TC (usually east of the PRE so they don't necessarily overlap QPF events), and we need a decent RRQ of the UL jet (which is modeled to strengthen this coming week) and se inflow at 850MB, for a time. Plenty of PWAT and instability will be available. Looking for comments that this "possiblity"  canNOT occur.  I'm thinking it will but I don't know where. These 6-12 hour events can be easy 4-8" producers in 6-12 hours. I'm looking for narrow slices of darker or even brightly colored heavier QPF in the modeling 12-24 hours in advance of Isaias in the GFS/EC/GGEM.  If we get to 36 hours and it's still possible, then we shift to the NAM and HRRR SPC HREF.  

I added EC ensemble 24 hr qpf simulation implied PRE in e PA/NJ well ahead of Isaias, and also the IR simulation. It's just a model and it can vanish in the future but this has my attention until it goes away. It's easy to say NO it wont happen but in these situations where it can be a flash flooder, we need to be alert for the possibility. 

829A/31

https://www.wpc.ncep.noaa.gov/hmt/seminar_files/PRE_NWS_Teletraining.ppt

[jbenedet]

Full moon on the 3rd.. Surge will likely be a significant impact in the right front quadrant...*if* the storm track is ~perpendicular to coast upon landfall.

Will be critical to determine when (exactly) the velocity (track) gains a more easterly component. 

[SnoSki14]

28 minutes ago, PB-99 said:

I think this maxes near a 3 in the SE and hits NC from the south as a 2.

Then rips right up 95.

Gona be fun to track.

It could also impact Florida as a TS though that still seems unlikely.

I think it'll hit eastern NC as a TS or weak hurricane and trek either just inland or offshore until it hits LI.

Huge uncertainty regarding intensity though upper air pattern looks mostly unfavorable until it recurves n/nne. 

[PB-99]

And it's that RRQ where we have the most risk.

If it hits NC as a 2 , it rips NNE so is it still a 1 here.

 

If it`s shredded prior then it`s a nice rainer. 

[PB-99]

9 minutes ago, SnoSki14 said:

It could also impact Florida as a TS though that still seems unlikely.

I think it'll hit eastern NC as a TS or weak hurricane and trek either just inland or offshore until it hits LI.

Huge uncertainty regarding intensity though upper air pattern looks mostly unfavorable until it recurves n/nne. 

 

Yes the further off Florida the stronger in the SE which has implications here.

[jbenedet]

1 minute ago, PB-99 said:

And it's that RRQ where we have the most risk.

If it hits NC as a 2 , it rips NNE so is it still a 1 here 

As a cat 1, with a background flow of ~ 30 mph it would translate to impacts more similar to a high end cat 2 in the rear right quadrant. 

[jbenedet]

13 minutes ago, bluewave said:

This hurricane may have one of the most favorable RRQs for development near the EC at the beginning of August. The jet streak over the Southeast this weekend is forecast to max out near +5 SD. Could also lead to an unusually fast forward motion. This coupled with record SSTs could permit the storm to maintain its strength further north that we typically see. So the exact track as to which areas get into the RFQ will be very important.
 

 

 

Seasons in seasons. This looks much more like early fall, than mid summer.

Tenor of season has been above normal heights over the western Atlantic, and guidance having —in general—to correct higher with time. I don’t see how this misses the Carolina’s...he’s not gaining much of an easterly component before OBX...not this year... NHC’s cone is further east than both the EPS and GEFS. Risk to me seems much greater that this runs well inland than ots...

 

 

[SnoSki14]

10 minutes ago, jbenedet said:

As a cat 1, with a background flow of ~ 30 mph it would translate to impacts more similar to a high end cat 2 in the rear right quadrant. 

This has an equally good chance of plowing into SE FL with tropical remnants spreading north. 

In fact I think it'll be the likely scenario if it stays this disorganized into tomorrow.

[PB-99]

4 minutes ago, SnoSki14 said:

This has an equally good chance of plowing into SE FL with tropical remnants spreading north. 

In fact I think it'll be the likely scenario if it stays this disorganized into tomorrow.

I think it's going to want to move poleward.

But yes, this all hinges on is it a 1 2 or 3 at its peak.

 

[Brian5671]

44 minutes ago, SnoSki14 said:

This has an equally good chance of plowing into SE FL with tropical remnants spreading north. 

In fact I think it'll be the likely scenario if it stays this disorganized into tomorrow.

hard to hit FL's east coast from a SE angle.   We've seen time and time again that the storm will want to stay offshore...with that said a track into Florida makes this a non event up here outside of some remnant rains

[ForestHillWx]

After reading Walts analysis, I might start construction on the Ark and fire up the Genny just in case. 

[wdrag]

FFG is still high and River Flood ensembles are not amped. Still can see some problems develop if we get decent 1-3 total rains in NJ/se NYS Sunday and then followed by a coastal hugging Isaias track. 

[ForestHillWx]

Just now, wdrag said:

FFG is still high and River Flood ensembles are not amped. Still can see some problems develop if we get decent 1-3 total rains in NJ/se NYS Sunday and then followed by a coastal hugging Isaias track. 

I hope my comment was not perceived as a slight; by all means your analysis was fantastic and I appreciate it. 

[Brian5671]

11am:

[wdrag]

I worry when i put it out there, that some thing it WILL happen.  Usually when i put it out there, I think odds are greater than 60% it will happen but have trapped myself too often with too strong a Categorical pontifications (near 100%).  

I do think we need to be aware of precursor rains, IF indeed Isaias does the coastal hugging as a TS. Bluewave posted on the UL jet anomaly which is a good idea of the potential contributions of the UL jet.  Other on here noting the favorable upper air pattern (USA trough-WAR). 

Also for those using radar rains... I checked OKX and DIX estimates... they were too significantly too low in the east-west axis just below I78 last night.  I  its safe to say 3/4"-2.75" fell in that band last night (CoCoRAHS, WXUNDERGROUND and RU climate sites). It drains but soil remains a bit moist for whatever happens tomorrow night, then late Sunday svr risk,  then the tropics, if its still on NHC track.  

Let's monitor and look for errors in the thinking.  Not the end of the world but a player.  Glad I'm not a cruise. 1119A/31

[NJwx85]

I’m currently thinking that wind on the coast might be a problem, especially over E LI. West of the track should be lots of rain but it was so dry for so long we should still be in decent shape flooding wise unless we get 8”+ in ~10 hours like we did in Irene.

[Brian5671]

5 minutes ago, NJwx85 said:

I’m currently thinking that wind on the coast might be a problem, especially over E LI. West of the track should be lots of rain but it was so dry for so long we should still be in decent shape flooding wise unless we get 8”+ in ~10 hours like we did in Irene.

I think this is moving too fast for those amounts-it goes from NC to MA in 24 hrs...that's got to be 35-40 MPH forward speed?

[qg_omega]

Just now, Brian5671 said:

I think this is moving too fast for those amounts-it goes from NC to MA in 24 hrs...that's got to be 35-40 MPH forward speed?

May be a similar impact to the TS we had a few weeks ago around here, depends if it slides into southern FL

[Brian5671]

GFS has a western track-brushes FL east coast and then inland for good over SC-not much time over water and thus weak sauce-some quick heavy rains for us and that's it (Verbatim)

[bluewave]

2 minutes ago, Brian5671 said:

GFS has a western track-brushes FL east coast and then inland for good over SC-not much time over water and thus weak sauce-some quick heavy rains for us and that's it (Verbatim)

UKMET did the same. So onto the 12z Euro.

https://www.meteociel.fr/modeles/ukmo2.php?carte=1021&ech=72&nh=1&archive=0

[qg_omega]

1 minute ago, bluewave said:

UKMET did the same. So onto the 12z Euro.

https://www.meteociel.fr/modeles/ukmo2.php?carte=1021&ech=72&nh=1&archive=0

6z Euro went into southern FL and weak up the coast, weaker this stays more likely it goes into FL and an inland track up the coast

[Brian5671]

Just now, qg_omega said:

6z Euro went into southern FL and weak up the coast, weaker this stays more likely it goes into FL and an inland track up the coast

shows you how quickly things change with unpredictable tropical systems...went from Cat 2-3 into NC to weak sauce near FL and then inland up the coast in 12 hrs.   Still time for more changes of course...we track

[PB-99]

This was the GEFS at 6z as we wait for its 12z.

 

Per Ventrice. 

 

 

 

 

 

 

[bluewave]

3 minutes ago, qg_omega said:

6z Euro went into southern FL and weak up the coast, weaker this stays more likely it goes into FL and an inland track up the coast

Here it is...

[jm1220]

9 minutes ago, Brian5671 said:

shows you how quickly things change with unpredictable tropical systems...went from Cat 2-3 into NC to weak sauce near FL and then inland up the coast in 12 hrs.   Still time for more changes of course...we track

Small changes in the ridge-strengthen and it goes further west, and a small 50 mile difference could mean into FL vs no landfall until NC or no landfall at all. Either way hopefully some good rain makes it up here but a hurricane coming into LI is still quite unlikely. 

[Brian5671]

Just now, jm1220 said:

Small changes in the ridge-strengthen and it goes further west, and a small 50 mile difference could mean into FL vs no landfall until NC or no landfall at all. Either way hopefully some good rain makes it up here but a hurricane coming into LI is still quite unlikely. 

no hurricane has hit this early up here.     Closest match was Belle in 1976 which hit on 8/10.  (Read elsewhere)

[forkyfork]

the canadian barely has a system by the time it gets up here

[qg_omega]

Just now, Brian5671 said:

no hurricane has hit this early up here.     Closest match was Belle in 1976 which hit on 8/10.  (Read elsewhere)

Strong TS hit NJ a few weeks ago

[PB-99]

The stronger the storm the more likely it is to move poleward.

The 6z EPS was weaker so it`s able to drift into Fla. If it gets stronger ( models have a hard time with intensification sometimes ) it prob avoids Fla.

 

So it comes down to intensification. 

If it`s weak then NC dodges a bullet.