Tropical connection NYC forum area Fri-Sun 8/28-30/20

[wdrag]

The NYC forum is likely (55-60% personal opinion) to be impacted by a portion of the remnants of recurving Laura.  That means a 40-45% chance of a complete miss.

Starting with moisture, not only from Laura but even if Marco peels off to the west into Texas, a bit of its moisture should precede Laura into the weather mix here Friday the 28th. There will be a notable RRQ of the upper level jet over the Canadian Maritimes that will assist drawing the moisture northeast, then east into the Mid Atlantic states and I think help keep Laura somewhat intact as a viable low pressure system with its jet dynamics. Track clusters are  attached from the 00z/23 EPS/GEFS, tending to show a passage of transitioning Laura's center-what ever it is- somewhere between ALB-HAT.  For now the favored passage appears to be somewhere between NJ and Virginia, per several days of modeling. There is improving NAEFS support for heavier QPF but not enough information yet to clearly define.  Potential exists, if Laura tracks within 70 MI of NYC for 3+" rains and gusts to at least 35 kt in parts of coastal plain.  This is quite a bit different than ISAIAS, passing over the Mississippi Valley. So this for now, should be considered mainly a rainfall contributor and potential marine hazard, IF and only IF the remnant definable center passes within 70 MI of NYC. So tracking is uncertain and what's left of Laura but worthy of discussion-monitoring and absolutely no consideration of ISAIAS impact severity.  Let's see what's left and where it tracks.  I just like the idea of contributing to rainfall in part of our area, for now. If everything becomes favorable, it could be a pretty good 6-12 hour summer nor'easter, or a squally southerly event -keeping in mind tracking is probably the biggest uncertainty at this topic issuance time. Have left this a broad timing impact,  thinking its mostly later Friday-Saturday, but some guidance suggests it could slow down into early Sunday.  Added 00z/23 GEFS ensemble QPF attempting to show the track across the Ohio Valley and then redeveloping mid Atlantic coast. And the 500MB ensembles coupled jet s structure from the 00z/23 GEFS.  655A/1055Z-23

[lee59]

58 minutes ago, wdrag said:

The NYC forum is likely (55-60% personal opinion) to be impacted by a portion of the remnants of recurving Laura.  That means a 40-45% chance of a complete miss.

Starting with moisture, not only from Laura but even if Marco peels off to the west into Texas, a bit of its moisture should precede Laura into the weather mix here Friday the 28th. There will be a notable RRQ of the upper level jet over the Canadian Maritimes that will assist drawing the moisture northeast, then east into the Mid Atlantic states and I think help keep Laura somewhat intact as a viable low pressure system with its jet dynamics. Track clusters are  attached from the 00z/23 EPS/GEFS, tending to show a passage of transitioning Laura's center-what ever it is- somewhere between ALB-HAT.  For now the favored passage appears to be somewhere between NJ and Virginia, per several days of modeling. There is improving NAEFS support for heavier QPF but not enough information yet to clearly define.  Potential exists, if Laura tracks within 70 MI of NYC for 3+" rains and gusts to at least 35 kt in parts of coastal plain.  This is quite a bit different than ISAIAS, passing over the Mississippi Valley. So this for now, should be considered mainly a rainfall contributor and potential marine hazard, IF and only IF the remnant definable center passes within 70 MI of NYC. So tracking is uncertain and what's left of Laura but worthy of discussion-monitoring and absolutely no consideration of ISAIAS impact severity.  Let's see what's left and where it tracks.  I just like the idea of contributing to rainfall in part of our area, for now. If everything becomes favorable, it could be a pretty good 6-12 hour summer nor'easter, or a squally southerly event -keeping in mind tracking is probably the biggest uncertainty at this topic issuance time. Have left this a broad timing impact,  thinking its mostly later Friday-Saturday, but some guidance suggests it could slow down into early Sunday.  Added 00z/23 GEFS ensemble QPF attempting to show the track across the Ohio Valley and then redeveloping mid Atlantic coast. And the 500MB ensembles coupled jet s structure from the 00z/23 GEFS.  655A/1055Z-23

Laura is holding together surprisingly well despite its weakness and interaction with land. This could become the first major storm of the season if it makes it to the Gulf and it appears like it will.

[MJO812]

This should be interesting 

[MJO812]

[wdrag]

It's real early...  some of the trends are little south of this mornings 00z/23 cycle but this could vary for the next few days.  AND, we don't know the interaction with the southward moving cool front Fri-Sat which could be lit up with the additional infusion of trop moisture.  Long ways to go.  One thing I'm pretty sure of... am glad I'm not cruising south from NYC to HAT Friday or Saturday.  I do think it's going to be  rough for some of the marine areas (50kt gusts) south of wherever the track axis is. If an anticyclone doesn't build southward fast enough for a good nor'easter, then the action is rain, with south side strong squalls.  The other aspect of the post trop transition is a possibility of intensification of the remnants as it crosses the Apps, per the upper level jet dynamics.  So, lots to monitor to see what actually comes to pass as reliably predictable. 722/23

[wdrag]

No change in the outlook: Laura's remains probably track east across VA-Delmarva Saturday...still with a shift south or north possible. Moisture contributions from Laura and even a bit of Marco pushed ahead of Laura, should be infused into a frontal system across the NYC forum, possibly enhancing rainfall late Friday or Friday night.  This far in advance... my concerns are tracking and a possible southward slippage of the guidance in the future model cycles. 

The primary center of the potentially dynamically reinvigorated remnant Laura will probably pass with its primary envelope of possible damaging wind gusts (40-50 kt) across VA-far northern NC or even the Delmarva Saturday.  Guidance is cyclically consistent suggesting potentially 40-50 knot gusts in squalls south of the center (south of the forum area) Saturday.  NO guarantee of those gusts. We'll see if that vigor and track holds.  This also continues my concern for marine area just south of eventual center passage.  For now... that should be south of our NYC forum coverage. It is only mentioned here, since there should be no surprise just south of the eventual track. 

Meanwhile the 00z/24 52 member NAEFS has shifted north a bit with its heavier rainfall.  The models RRQ of the westerly upper level jet continues locked in over Maine and Nova Scotia.  Model guidance suggests west-southwest flow in the 850-700mb layer ahead of Laura into the NY forum and so any boundaries in our area late Friday-Friday night could yield heavy rainfall.  We'll see if that holds?

Saturday's remnant Laura heavy rains-squalls might end up on the southern edge of the forum or south of the forum. So for now... am not favoring a direct eastward NJ remnant track but Laura's influence should be more so via the advance dynamics late Friday.  Plenty of room for error and associated less impact. Guidance so far seems to be locked on a Louisiana - Arkansas to Ohio River heavy rain path then eastward, with uncertainties further north, including our NYC forum area. 607A/24

 

[wdrag]

Good Tuesday morning everyone,  No significant change to my update of Monday morning.  

Timing has slowed slightly but otherwise I think everything looks good for a moisture infusion and potential for some heavy rains in parts of our forum. The primary event looks to be centered mostly Saturday.

Added some NAEFS (52 member graphics), inclusive of the 24 hr QPF axis, the ensemble low position Saturday evening (it's a broad area of low pressure. and imagine there will be 2 lows,  one further north in or near the eastern New England coast, and one down off Virginia or Delaware at that time,)   jet dynamics (200mb jet core over the Canadian Maritimes leaving us in the RRQ).  and finally the probability of more than 1" axis between Wednesday evening and Sunday evening-showing the primary qpf axis with this tropical influenced pattern. 551A/25

 

[MJO812]

[wdrag]

I ran some backward trajectories off Hysplit to see origens of parcels. Only goes out to 22z Friday but gives an idea of origin for NYC. 918A/25

[NJwx85]

Looks like Saturday afternoon and evening might be a washout. Other than that don't see wind being much of a factor. The storm does intensify as a hybrid or possibly sub-tropical storm once off the coast but the wind looks to be confined to areas South and East of the center, largely staying offshore.

[LongBeachSurfFreak]

8 minutes ago, NJwx85 said:

Looks like Saturday afternoon and evening might be a washout. Other than that don't see wind being much of a factor. The storm does intensify as a hybrid or possibly sub-tropical storm once off the coast but the wind looks to be confined to areas South and East of the center, largely staying offshore.

That would make sense given the track and speed. Basically the opposite of what occurred with Isaias 

[Brian5671]

16 minutes ago, NJwx85 said:

Looks like Saturday afternoon and evening might be a washout. Other than that don't see wind being much of a factor. The storm does intensify as a hybrid or possibly sub-tropical storm once off the coast but the wind looks to be confined to areas South and East of the center, largely staying offshore.

We could use the rain, just hate to see it on a weekend.  

[NJwx85]

8 minutes ago, LongBeachSurfFreak said:

That would make sense given the track and speed. Basically the opposite of what occurred with Isaias 

We could get quite the soaking depending on what track ends up verifying. Right now I would hedge the majority of the heaviest rains falling over Southern NJ and the mid-Atlantic.

If you look at the soundings from the HWRF, they show a lot of mid-level dry air North of I-78.

 

[NJwx85]

3 minutes ago, Brian5671 said:

We could use the rain, just hate to see it on a weekend.  

The 00z UKMET had 3-5" totals.

[FXWX]

4 hours ago, wdrag said:

Good Tuesday morning everyone,  No significant change to my update of Monday morning.  

Timing has slowed slightly but otherwise I think everything looks good for a moisture infusion and potential for some heavy rains in parts of our forum. The primary event looks to be centered mostly Saturday.

Added some NAEFS (52 member graphics), inclusive of the 24 hr QPF axis, the ensemble low position Saturday evening (it's a broad area of low pressure. and imagine there will be 2 lows,  one further north in or near the eastern New England coast, and one down off Virginia or Delaware at that time,)   jet dynamics (200mb jet core over the Canadian Maritimes leaving us in the RRQ).  and finally the probability of more than 1" axis between Wednesday evening and Sunday evening-showing the primary qpf axis with this tropical influenced pattern. 551A/25

 

Hey Walt; nice job as usual.  What do you make of the UKMET being so persistent with its deep and intensifying system???

[CIK62]

12Z GFS is weaker by 9mb. at landfall, but right up Tx-La border still.      JB thinks it will be farther west.

Beaumont TX may be in trouble here.

[wdrag]

1 hour ago, FXWX said:

Hey Walt; nice job as usual.  What do you make of the UKMET being so persistent with its deep and intensifying system???

It seems to be in error... HOWEVER, I think some sort of center will remain intact across there Apps (VA-s NJ) with squally 40-50kt gust potential s of the center, which eventually probably ET transitions to an intensifying n Atlc storm in its rapid poleward departure.   What has caught my attention now, is the 12z GFS with seemingly a weak boundary in CT Fri night.  That may serve for a weak PRE... unsure, but any boundary in our forum area with this pwat coming up to ~2" should (corrected) let loose at night.  

[FXWX]

1 minute ago, wdrag said:

It seems to be in error... HOWEVER, I think some sort of center will remain intact across there Apps (VA-s NJ) with squally 40-50kt gust potential s of the center, which eventually probably ET transitions to an intensifying n Atlc storm in its rapid poleward departure.   What has caught my attention now, is the 12z GFS with seemingly a weak boundary in CT Fri night.  That may serve for a weak PRE... unsure, but any boundary in our forum area with this pwat coming up to ~2" so let loose at night.  

Agree...

[NJsnow89]

5 hours ago, MJO812 said:

Is this going to become a tropical storm once off the NE coast? 

[NJwx85]

12z HWRF quite a bit further South with the low exiting the coast near VA Beach. Rains confined mostly to the Mid-Atlantic.

[NJwx85]

8 minutes ago, NJsnow89 said:

Is this going to become a tropical storm once off the NE coast? 

It's going to be transitioning into an extra-tropical storm. The guidance is showing a deepening system once it reaches the TN Valley, but that's due to baroclinic forcing and not processes that normally are associated with deepening tropical systems. 

The trough is positively tilted in this case so most of the bad weather associated with the surface low should be South of our area. If the track ends up further North it could get slightly more interesting. 

[Brian5671]

12 minutes ago, NJwx85 said:

It's going to be transitioning into an extra-tropical storm. The guidance is showing a deepening system once it reaches the TN Valley, but that's due to baroclinic forcing and not processes that normally are associated with deepening tropical systems. 

The trough is positively tilted in this case so most of the bad weather associated with the surface low should be South of our area. If the track ends up further North it could get slightly more interesting. 

what looked like a wet stretch from Thur-Sun from several different features now looks like mostly a non event for us

[NJwx85]

The 12z HMON would be a significant rainstorm up here. Decent winds at 850mb as well. Still looks rather mundane at the surface although it does have some 30-40kt wind potential along the coast for a period of time.

[NJwx85]

Euro is a bit further NW when it nears our area, but still well South and East. We would need the system to track to our North in order to get significant wind impacts, and even then it would be dependent on deep convection mixing down the strong winds aloft. 

[Cfa]

This is like our third or fourth time being in the “cone” this hurricane season, I’m impressed.

[Dan76]

1 hour ago, Cfa said:

This is like our third or fourth time being in the “cone” this hurricane season, I’m impressed.

[MJO812]

[PB-99]

Poss Tor threat this weekend ? 

[qg_omega]

Just now, PB-99 said:

Poss Tor threat this weekend ? 

Looks like Delmarva for now

[wdrag]

Good Wednesday morning everyone,  I don't see much change from yesterday's early morning expectations.  Please follow SPC discussions/graphics of SVR for both Thursday and Saturday in our area, as well as NHC discussions-tracks and of course, local NWS office discussions-statements.

It appears that the remnant surface center of Laura will track through southern VA or extreme northern NC Saturday and zip northeast from there.  That means the strongest gusts of 40 to possibly 50 kt in squalls will occur south of NYC fortum area...probably within 70 miles of ~ the southern semicircle of Laura's passage. Therefore only an indirect influence on our area weather in terms of jet dynamics (hybrid Laura-possibly still a TS per 5AM/26 Wednesday NHC discussion) and moisture. PWAT increases to ~2" Saturday (trajectory models from the NAM and GFS ending Saturday show a vast low level moist influx ending up at 500 meters at LGA on Saturday. 

To get there... A period of WAA showers/elevated isolated thunderstorms early Thursday north of I78 for much of the forum, then the potential nw flow severe weather event sometime between 4P and midnight late Thursday.  KI 35-40 late Thursday and PWAT temporarily up to at least 1.8. Plenty of wind aloft and see SPC. Should be steamy  in NYC Thu afternoon (HI 95-100?)

Friday evening-night---a period of showers and thunderstorms possible in once again WAA, well in advance of Laura.  If there is a well defined wind shift boundary in our area...this could light up as a 3-6 hour period of heavy rain. Right now, an unknown and not something to count on. HI near 95?

Saturday afternoon-night: PWAT2", northern fringe of Lauras moisture and a cold front should trigger a severe weather event in parts of the northeast, along with a couple pockets of heavy rain.  How much severe here, if any... just follow the evolution. HI 95-100 but max value dependent on cloud cover, especially associated w Laura.

I don't want to overpromise: WPC's early morning 5 day totals are generally 3/4-1.5" in our area...nothing to write home about, but potential exists for 3" totals somewhere.  It appears to me the risk of heaviest totals, whereever,  first is CT, followed by LI, then se NYS, with NJ maybe lagging on the lower risk for any spotty 3" totals. 

I may not be able to post very much until Saturday evening per the next several days of family celebrations.

Appended trajectory data, SPC D2 and 4 outlooks, and the NAEFS mean pressure pattern for Saturday evening (primary low in New England but think that there should be another low somewhere near ORF?)  540A/26