Nor’easter Possible Tuesday into Wednesday

Miguel Pierre Winter Wx

Models and ensembles are staring to converge powerful nor’easter form off the East coast for Tuesday into Wednesday. However, some of the guidance keeps this storm far enough east, for just a glancing blow or close miss. While other guidance brings this storm farther west, giving us more heavy precipitation and strong winds. It is too early to say, which solutions are most likely are correct. The number one thing to keep in mind, is the lack of any Greenland Block. So this storm having a major impact on our area, will be dependent on phasing occurring at the right time. The main features to watch over the next several days are:

1. Pacific upper-level low and West Coast Ridge placement. A strong West Coast ridge with be initially supported by the deep ULL over the NE Pacific. However if that low moves east over NW coast faster, the West coast ridge will collapse east. This will give energy along the trough far less time to amplify and phase.

2. 50/50 low development. This low forcing the flow and heights to buckle along East Coast and cause phasing.  Some of the guidance shows storm intensifying near Newfoundland, that could act a 50/50 low. However, this feature seems overall weak and progressive, with the lack of blocking in the Atlantic.

3. Timing  of northern and southern stream energy. With the lack the blocking, the southern stream energy will try to escape further east. The northern stream beeds to catch up with this energy and phase sooner, for a storm track closer to the coast. The UKMET, GFS and it’s ensembles are slower in phasing the two streams than the ECMWF and it’s ensembles. Which result in low farther east.

18zGFSf13812zUKMET144hr12zMSLP_North32America_144

4. PV lobe dropping from Canada. If this feature were to dig into south into Midwest, this would pull trough back west and capture the southern stream low. Resulting a major phasing. Right now, only the GGEM and it’s ensembles shows this scenario.

12zGGEMf1445. High pressure moving out into the Atlantic. Unlike March last week, this will not prevent a more amplifed/phased storm from coming north. The guidance is actually more in agreement here.

These features and more will have an influence on final track and intensity of this storm. So trends with the features on the models, need to be monitored over next few days. Once these are are found, then we can discuss more details. Stay tuned for more blog posts and more frequent updates in the 7-day forecasts.

Winter Storm Possible Sunday Night into Monday

Miguel Pierre Uncategorized

Fri evening update: Latest guidance now keeps accumulating snow south of NYC. Due the less interaction between northern and southern streams. As well as a stronger high pressure over the Great Lakes/Northeast. My confidence is increasing that this will occur. But will continue to monitor for any changes. Look at 7-day forecast for updates.

Guidance shows another winter storm possibly for late Sunday night into Monday. What complicates this winter storm threat, are models handling of another system coming into Pacific NW and flattening heights over the Western US. Each model has slight differently 500mb pattern that results in different impacts in our area.

The 0z ECMWF and 6z GFS hangs back more southern stream energy over Gulf coast. While also showing a little northern stream interaction. This more strung out area of low pressure with two waves that remain weak and farther east. The reason for this because Pacific system has already moving into Northern Rockies.  These solutions would keeper is colder and drier.give a light to moderate snowfall for the tri-state area:

0zEC96hr

6zGFS84hrThe 0z CMC model is showing  more southern stream energy coming out and interacting with northern stream energy. This results in a stronger first wave and the second wave coming further north. The reason this can happen here, is that Pacific system is little slower coming into the Northern Rockies. Strong high pressure will also be supply us with cold air and enhance a thermal gradient just to our south.. This solution would result in moderate to significant snowfall for much of the tri-state area.

0zCMC84hrThe 6z NAM has more phasing between northern and southern streams. Therefore has more consolidated storm, tracking further west. The reason it is able to do this, is because Pacific system is much slower coming into NW coast and heights remain stronger over Northern Rockies. This solution would actually cause more warmer air to surge aloft, changing many of us over from heavy snow to sleet or freezing rain:

6zNAMf786zNAMf84 ECMWF,GFS, GGEM all have support form their ensemble means. The ECMWF and GFS , have a little more support from the current progressive pattern, as well. However, the GGEM has been most consistent with ejection of more southern stream energy. So it’s solutions should be strongly weighed here. The NAM at this range is unreliable for winter storms. So I would be wary of it, without any other model support. Models will get a better on all this energy as it comes onshore the next few days. I will have another update this evening, with new set of models runs.

Mild Today, Rain Wednesday, Bitter Cold Thursday

Miguel Pierre Severe Wx, Winter Wx

In my last post, I discussed hot the models where show temping the low and middle 50s. Temperatures actually soared into 60s today in many with west downslope winds. JFK set new record at 65. Beautiful late winter day to enjoy some outdoor activities. Tonight will see increasing clouds late with temperatures falling into upper 30s inland and lower 40s for the coast.

With this very mild airmass in place, the storm for Wednesday has trended warmer, deeper and further northwest. It now appears this will be a mostly rain event for even parts of Hudson Valley and Interior CT.  If fact, these could steadier and heaviest rainfall. Many of us will be in warm sector, with periods of light rain and drizzle with temperatures rising into 50s over NYC and lower 60s over Central and Southern NJ.  A strong 500mb shortwave and cold front, likely to produce a forced low-topped squall with some gusty winds later tomorrow afternoon or evening. With some elevated instability in the form steep mid-level lapse rates,TTs in the 50s and MUCAPE, some elevated thunderstorms are also likely. Any surface-based instability will be based on any clearing that takes place, tomorrow afternoon. This will enhance the threat for isolated severe wind gusts. Most-likely south and west of NYC.

12zNAMf3912zNAMrad36Behind this cold front, it will turn windy with temperatures will rapidly fall back into 20s and teens later tomorrow night. Any wet roadways could see some black ice form. Some snow showers that could coat the ground, are also possible with the upper-level trough with swinging through tomorrow night. Especially north and west of NYC.  Thursday will be big change from the last few days. It will be windy with temperatures only slowly climbing out of the teens into lower 20s. This arctic blast will not last longer, however. After a cold Friday morning, temperatures will rise into upper 30s and lower 40s in the afternoon.