USCAPEWEATHERAF

With the many arctic shortwaves present in the flow of the northern stream, the Arctic is opened for business but remains extremely hostile for any significant coastal storms to impact the region. With the questions remain about phasing or not phasing streams in the split flow regime spells extreme instability in the model fields. With this in mind, no snow midweek and the next weekend system remains in question and minimal at this time.

Right now all options are on the table. In the next 84 hours, the solutions will vary greatly in detail and overall vigor. The reasoning for why so many options remain open for a blizzard to sunny days remains the unknowns. The unknowns are the strength, wavelength, positioning of the factors at play. One is the Arctic Shortwave, this is either the kicker s/w or the phasing backside s/w that determines if the storm gets whisked out to sea or comes to the benchmark location. IF the phase happens like we all hope it does if you love snow, then the arctic shortwave in question is not fully sampled yet and therefore the models have no idea on the details of this shortwave. Two is the southern stream shortwave, our energetic system for coastal development. This should be sampled shortly within the next 12-20 hours of time on the west coast of the US. Its strength and position have a lot to do with where the storm exists off the East Coast. Right now, models, have it exiting around NC without phasing, this goes east and never hits the Northeast US. If the phasing occurs, we get the storm to hit the benchmark. Those are the questions that need to be answered in the next 84 hours.

00z NAM returned with heavier Precipitation on Saturday morning, could lead to accumulating snows. Stay tuned for further updates later tomorrow afternoon.

There are two kinds of tracks that impact the severity of a New England blizzard, one is the NJ track, where a surface low is west of the Apps and combines with southern energy and develops a coastal storm off the New Jersey Coastline. Normally these primary systems with NJ coastal die off before they reach eastward or northward and combine with the coastal energy to form a monster snowstorm for Cape Cod. The second track of this type of snowstorm is the Cape Hatteras track. Now when the primary low and system in the upper-levels develops and tracks northeastward, it originates in the Gulf of Mexico region and then redevelops off the NC coastline, otherwise known as Cape Hatteras. These tend to be powerful as well, perhaps with more energy involved as they mature and therefore a potentially deeper surface pressures. These tend to be less precipitation type issues and more snow even for Nantucket, MA. Now both tracks have been kind to me on Cape Cod, where I received 30" from both tracking lows. So what are some examples of these type of storms, one the NJ low is the Blizzard of 2005 (35") and the Hatteras track is the Blizzard of 2015 (32").

These five images are the four most reliable guidance models we have in determining a snowstorm its track, intensity and future impacts to New England. What they all agree on is the overall setup and teleconnections featured on December 5th, 2018 their forecast in the next 7 days. The models show a classic El Nino pattern, with a sub-tropical jet cutoff low approaching or over the Baja, CA region, with a large +PNA ridging into Alaska and the NW Canada Territories. The GFS is the furthest north with the sub-tropical cutoff upper-level low. This could have impacts downstream over New England with the main shortwave in question being too far northwest compared to the other three guidance members, this flaw could change within the next run. I will side with the Means for now given the setup is favorable for an east coast snowstorm. They all agree on a developing central based -NAO ridge over eastern Greenland, building westward. As well as in agreement over the -AO polar vortex location which is further northwest in a position of least impact. The 50/50 low is in a good position for a blocking pattern to slow down the duration of the storm's movement allowing a longer duration, while the models don't show it quite yet happening just like that, I will wait until within 96 hours before using any one of the operational guidance as gospel. Once the NAM gets in the range we will narrow down impacts and what not, but once we get in range of the 3KM NAM HIRES guidance, we won't have a great handle on the shortwaves and their interactions. GFS is most amped but that is the operational model, the Means are less amped. Also, another threat seems to take place a few days later. We will keep you posted. Stay Tuned!

The latest ensemble guidance suggests the negative AO stays negative for the next two weeks. This could mean snow or no snow for coastal SNE. Depends upon the location of the vortex.

Could we see snow in the next 6-10 days, I believe so, do not pay attention to individual runs of the operational models, they will have flaws in them run to run, but look at the ensembles and their means and they will show you the way. I found this map on PSU EWALL website, the models are 12z runs of the EURO, GFS and CMC from left to right. They pretty much agree on ridging in Alaska, our -EPO/+PNA feature, along with a ridge in northern Greenland and some ridging in northeastern Canada west of New Foundland. Stay tuned, we could be tackling a major east coast snowstorm in this time frame.

A major winter storm is pegged to strike the Central US plains and the Central to western Great Lakes region later Sunday night through Tuesday of next week. This is all a part of a large weather system powered by a central US trough, anchored by a large upper-level low-pressure center. Large widespread snow amounts of 10-12" is possible especially in banding from MO to IL to MI. More widespread amounts of 3-6" is likely in the region either side of the 10-12" isolated 14". The system should bring potential rain later this week to New England and snow to the mountains of western ME and NH.

A rather potent -NAO block is occurring in our atmosphere in the Western Hemisphere this upcoming week into the weekend. The GFS forecasts 850mb temps to be rather mediocre for intense Ocean Effect Snows, but with northerly winds at the surface through 850mb, there is a strong chance we could see ocean enhanced snowfall later next week, around the 30th of November into the weekend. Stay tuned!

12z EURO and EPS mean show potential for blocking pattern for an east coast snowstorm, with cold air present, and a coastal storm on the New England coastline, models show potential for winter weather on the 27-29th of November, this could be a long duration event, but it could be rain on the coast. Right now specifics are not smart to forecast given its still 5 days away in time. This is still an eternity. However, models have flipped the pattern in the longer range to a less favorable pattern for cold and snowy chances and instead have a ridge of high pressure over the region. This could easily change back and forth for the next few days. Snow is a potential, not the forecast.

Right now the start time for the snow to enter the region is around 5 pm EST tonight after sunset as instability increases and winds come more northerly. This will bring snowfall rates near 2"/hour over the Cape.

Here is the snow map for the Thanksgiving OES event forecasted for tomorrow.

I decided to wait until tomorrow's 6z runs before making a snowfall map. After 7 am.

I can finally say with confidence, after watching the models the last four days the minute this threat come up, we are going to have our first Ocean Effect Snow event this season. After watching the model data come in today, I will watch the models tonight, and after the GFS comes to pass, I will update the snowfall map I expect for Thanksgiving, the key is accumulations are likely. Stay tuned!

Eastern Cape Cod, east of Hyannis, MA will receive the bulk of the snow threat. Several inches is likely. 850mb temp to the surface of the ocean differential (Delta Ts) are around +30 to +32C, and this will provide the kind of instability that will lead to thundersnows. This is what the Tug Hill Plateau sees and so does Buffalo with SW winds. However, the Cape does well with NNW and N winds at the surface, if we get any convergence we will see a singular band producing 2-4"/hour snowfall rates. This could surpass the events of the past. Stay tuned, snow map tonight after 00z models

Due to the presence of an -20C 850mb temp anomalies, we can expect the presence of ocean effect snow squalls, on NNW winds across most of the mid to outer Cape Cod, NWS BOX mentions 40% chance at snow over my head in Harwich, MA, and a chance at a few inches in localized areas. Stay tuned! As snow squalls, tomorrow night could also add to travel hazards.

Arctic front comes through the region by 00z Thursday, Wednesday evening around 7 pm, OES cloud streets develop several hours later as 850mb temps drop 30-40 C, around -20C by Thursday 12z (7am EST), where the OES machine should be in full force, over the ocean south of Nova Scotia the accumulations would bring 6-12" of snow over the water, but given we are close to land and need a northerly wind, that chances are we see more than .5" of snow is around 15%, snow chance around 40%, that includes mood flurries. Right now mesoscale models are not in range yet, so will have to monitor if trends allow higher precip amounts. Stay tuned!

Here is the latest ideas I have for the November 20th, Tuesday Snow event, mainly a central and eastern New England event north of Providence, RI snow band

Given that inversion heights are quite low on the GFS even, chances are flurries might be the only threat on Thanksgiving here in Harwich, MA and the rest of the outer Cape Cod area given dry air in place and the close proximity for a high-pressure center to near the area

Parameters are in place for an outbreak of snow showers and snow squalls on Cape Cod, early Thanksgiving through Friday afternoon of this upcoming holiday week. GFS forecasts -20C 850mb temps, coupled with +10C of ocean water temperatures equals a very unstable atmospheric profile, I will have to watch this potential closely as it is still about five days away. But the potential exists at least for festive flurries on Thanksgiving day. Stay tuned!

I busted on the warm side of things with this storm, the storm came in colder and stronger with the omega and theta E airmass. I should have known this was an overperformer.

Right now if I were to do a snow map I would focus on areas just west of the Canal and focus on a Providence, RI to Boston, MA route along I95. Snow could accumulate quickly with a quick band of heavy snows, precip shows about .50 to .75" of a quick burst on the GFS and its members, EURO and CMC are too far southeast for anything substantial at this time. And NAM is just getting into the frame of time. Right now there is about a 35% chance the mid levels of the atmosphere could be cold enough to turn the rain to snow for me on Cape Cod on Tuesday as a very cold airmass follows this system into the region, highs on Thanksgiving could lead to Ocean Effect Snows, but we all know how fickle that can be on the models. Stay tuned! Snow map tomorrow afternoon.

This is the current thinking I wanted to show regarding this late week snowstorm threat from the 15th to the 16th of November. Here is the snow map first call.

Hey models are forecasting a big trough to enter the region with a pacific and sub-tropical jet phasing system. Could there be enough cold air present? That is still a great question.

Models are beginning to show signs of a potential winter storm in the 6-8 day period. EURO and GGEM show this storm impacting SNE, with ocean effect snows and synoptic precip, the GGEM is a little warmer than the 00z EURO, which shows this potential as a trough swings through the upper level flow. I have been keying on this potential as there appears to be a Quebec, Canada Arctic high in place north of the storm and north of NYS. This will lock in the cold air at the surface into the coastline. GFS is finally showing snow precip accumulating for CHH. There is a strong potential for a storm center on the East Coast, but that is where the forecast departs on the model guidance. Stay tuned!