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

[Will - Rutgers]

Just now, Brian5671 said:

that and the shear are likely why this won't develop much more (at least according to today's models)

The shear has relaxed a bit in front of it and the forecasts look favorable for muted upper-level shear where it's likely to be this weekend.  Shear further relaxes Monday.

[PB-99]

7 minutes ago, bluewave said:

There are two things that are usually off with the Euro products from weather.us, weathermodels.com, and weatherbell model maps. The wind gusts are almost always too high compared other guidance. The other guidance gust products seem closer to what you would expect from the soundings. The other issue is that those maps unrealistically drop NYC temperatures with snow cover during the winter. We can remember all those false -10 to -15 readings for NYC several winters back. It would probably be helpful to have someone here that works for ECMWF and ask them about these issues directly. Whether it’s an issue with the model or how some venders process the data.

Which leads me to believe it`s a ECMWF issue and just gets caught up in the coding. The snow ratio map issues crosses over even into Levi`s site and no one really uses them to forecast.

I would love to see a 10m wind gust chart from another algo from yesterday, pivotal etc and see how far off Ryan was with a 120 max gust S of LI. 

According to him he is just using the soundings. 

But Forky could be right, I just want to see how far off he was/ is. 

[nycsnow]

What do you guys think we might be able to get wind wise up here ?

[NJsnow89]

18 minutes ago, nycsnow said:

What do you guys think we might be able to get wind wise up here ?

Wind will not be an issue here. Rain will the biggest threat. 

[Brian5671]

NAM landfalls a weak storm in SE Florida tomorrow overnight

[NJsnow89]

Just now, Brian5671 said:

NAM landfalls a weak storm in SE Florida tomorrow overnight

I think it’s getting clear that landfall in Florida will occur as a weak storm. 

[Brian5671]

7 minutes ago, NJsnow89 said:

I think it’s getting clear that landfall in Florida will occur as a weak storm. 

Once it became clear this would not intensify, that took away the poleward option some talked about had that happened.  The weaker storm will just cruise NW and into FL.   

edit-however the 3K nam has a stronger storm further east....

[Will - Rutgers]

1 hour ago, Brian5671 said:

Once it became clear this would not intensify, that took away the poleward option some talked about had that happened.  The weaker storm will just cruise NW and into FL.   

edit-however the 3K nam has a stronger storm further east....

I think it'll hug near the coast and stay offshore.  We've seen that kind of behavior before.  The convection fires up over the ocean, so the center gets pulled to it, at least that's my interpretation of what happens.

[Brian5671]

37 minutes ago, Will - Rutgers said:

I think it'll hug near the coast and stay offshore.  We've seen that kind of behavior before.  The convection fires up over the ocean, so the center gets pulled to it, at least that's my interpretation of what happens.

Friction with the land too coming in at that angle.  Michael missed entirely...wonder if the 3K nam is onto that....

[Will - Rutgers]

7 minutes ago, Brian5671 said:

Friction with the land too coming in at that angle.  Michael missed entirely...wonder if the 3K nam is onto that....

I'm thinking a path kinda like Matthew until it gets picked up in the current between the trough and ridge.  SC landfall.

Looking a little better organized.  Tonight could get really interesting with all the bathwater it's sitting on.  If it can stay organized enough to exclude all the dry low-level air in front of it, anyway.

[bluewave]

2 hours ago, PB-99 said:

Which leads me to believe it`s a ECMWF issue and just gets caught up in the coding. The snow ratio map issues crosses over even into Levi`s site and no one really uses them to forecast.

I would love to see a 10m wind gust chart from another algo from yesterday, pivotal etc and see how far off Ryan was with a 120 max gust S of LI. 

According to him he is just using the soundings. 

But Forky could be right, I just want to see how far off he was/ is. 

He needs to apply post processing to remove the ECMWF overestimation bias of the wind gusts. If he can’t, then he probably shouldn’t post those wind gust maps for the general public. It’s something that they have worked out in Europe.

https://www.ecmwf.int/sites/default/files/elibrary/2014/13777-improving-wind-gust-and-precipitation-form-forecasts-post-processing-ecmwf-data.pdf

ECMWF model overestimates wind gusts
Forecaster data is based on ECMWF model output => postprocessing removes or decreases the positive bias (NOTE: ECMWF data is a 3-hourly maximum wind gust)

[PB-99]

Recon down to 985.

[PB-99]

59 minutes ago, bluewave said:

He needs to apply post processing to remove the ECMWF overestimation bias of the wind gusts. If he can’t, then he probably shouldn’t post those wind gust maps for the general public. It’s something that they have worked out in Europe.

https://www.ecmwf.int/sites/default/files/elibrary/2014/13777-improving-wind-gust-and-precipitation-form-forecasts-post-processing-ecmwf-data.pdf

ECMWF model overestimates wind gusts
Forecaster data is based on ECMWF model output => postprocessing removes or decreases the positive bias (NOTE: ECMWF data is a 3-hourly maximum wind gust)

 

So it's model bias that he didn't correct.

He doesn't overestimate,  he just doesn't adjust for the error.

 

I bet the same can be said at 2m in the winter 

[bluewave]

20 minutes ago, PB-99 said:

 

So it's model bias that he didn't correct.

He doesn't overestimate,  he just doesn't adjust for the error.

 

I bet the same can be said at 2m in the winter 

Too bad those vendors don’t provide the ECMWF bias corrected MOS like they do in Europe.

https://www.dwd.de/EN/ourservices/met_application_mosmix/met_application_mosmix.html

https://www.europeandataportal.eu/data/datasets/de-dwd-mosmix-m552?locale=en

DWD’s fully automatic MOSMIX product optimizes and interprets the forecast calculations of the NWP models ICON (DWD) and IFS (ECMWF), combines these and calculates statistically optimized weather forecasts in terms of point forecasts (PFCs). Thus, statistically corrected, updated forecasts for the next ten days are calculated for about 5400 locations around the world. Most forecasting locations are spread over Germany and Europe. MOSMIX forecasts (PFCs) include nearly all common meteorological parameters measured by weather stations. For further information please refer to: [in German: https://www.dwd.de/DE/leistungen/met_verfahren_mosmix/met_verfahren_mosmix.html ] [in English: https://www.dwd.de/EN/ourservices/met_application_mosmix/met_application_mosmix.html ]

 

[PB-99]

Speaking of the Euro, last recon had this at 985, where's the Euro at 12z during this time,  between 995 and 1000 ? 

[forkyfork]

maue doesn't adjust for the bias on purpose 

[PB-99]

18z east of 12z

 

 

[PB-99]

East of N Florida at hour 72.

[MJO812]

New

[Will - Rutgers]

Looking pretty spicy now... oooh.

Nice concentrated center to the southwest.

Undeniable organization and strengthening happening.

[jm1220]

Small differences mean a Matthew grazer track or one that goes inland along I-95 in FL. In a way we should hope for (for a less intense system up here) the 50 mile west track into FL. It being over water for 24 hours longer or more gives more time to strengthen before hitting NC and speeding up here. 

[Allsnow]

The track will continue to bounce around until Monday.  Its hard to really get a idea on what the track will be until then 

[Will - Rutgers]

The robust southwest convection might favor center relocation there and a more likely FL hit.  Central dense overcast seems to be developing.

Or not, I don't know anything, I just post what I feel until someone tells me why I'm wrong.

I'm trying though.

[MJO812]

Hi res Nam misses Florida 

[forkyfork]

27 minutes ago, Allsnow said:

The track will continue to bounce around until Monday.  Its hard to really get a idea on what the track will be until then 

this. don't focus on individual model runs

[MJO812]

[TriPol]

I like Hurricane Bertha 1996 for the track here.

[PB-99]

Close to Floyd, closer to the Florida coast but then right on up.

[MJO812]

[Rtd208]

SPC Day 2

...Northeast...
   Moderate destabilization near and south of the surface warm front,
   combined with veering wind profiles with 35-50 kt of effective
   shear, will result in a conditionally favorable environment for
   supercells across much of central/eastern PA/NY and northern NJ by
   Sunday afternoon. However, substantial uncertainty remains regarding
   storm coverage across the region with the most favorable
   environment. Large-scale ascent associated with the departing
   shortwave trough is expected to primarily remain north of the
   international border, with a capping inversion around 700 mb
   potentially limiting deep convection across much of the warm sector.

   At least isolated thunderstorm development will be possible along an
   eastward-moving surface trough Sunday afternoon. All hazards would
   be possible with any sustained deep convection. A Slight Risk has
   been introduced from northeast PA into central NY, where confidence
   in storm coverage is somewhat greater due to potentially stronger
   heating and instability compared to areas further north and east.