I have already discussed how terribly painful these next few weeks will be for the East Coast..So why not discuss how things the past few days have started showing seeds of a pattern change. Lets keep in mind that this is a ways away, and there is likely some major variability to be exposed among these forecasts, but the trend is shown. Yesterdays EPO forecast was the 4th day in a row that Ensembles have forecasted such a big drop, and it jumped out at me a bit..


As shown..the EPO takes a major nosedive around the 8th of Jan..and if such a nosedive were to verify..EC Posters should watch out. However, I think the Ensembles are moving this pattern change along way too fast, and would forecast two things different from that map..One being no nosedive..more of a gradual drop..and two being about 5-7 days later placing the pattern change around January 15th-20th or so.

However, there are other things that need to be watched as well..The NAO is currently forecasted by ensembles to stay Nueutral to Positive through January 15th. With more implications comes the AO Index..which has been raging Positive since Late November. Ensemble forecasts bring the AO way up before it comes down..and for the range we are looking at, the agreement that it will come down a bit is fairly good..however it is still a ways away and I feel we are looking way to far into the future by trying to forecast what ensembles will say.


All in all, I think we need to patient, as I expressed in a post about a week ago. Seeds of a pattern change are beginning to grow on models and long range ensemble forecasts, but we must not become over anxious..this will be a slow process with alot of things working at once. I think all eyes need to be on the AO and the Pacific Pattern..both which are absolutely horrendous for a cold Eastern Conus. Hang in there folks.

And I will throw the EC Snow Hounds a bone--

Jan 25th

NYCDiscussion
Short Range: JMH
Long Range: BMC

Short Term

A very gloomy start to this Friday so far as a Southwesterly Flow has brought mild conditions into the area. Surface Trough will move into the region with a Low Pressure region over the Great Lakes. Fog has been an issue this morning, and may not burn off until mid afternoon in some regions. Cold front and associated vorticity move over the region later this afternoon, providing a good chance at at least scattered showers across the area. SPC had placed the area in General Thunderstorm area but the new 1630z Outlook has removed that area, and will not include thunder in the graphical forecast this afternoon. Front passes through tonight and most clouds clear out making for a nice day tomorrow with Highs Generally in the Low 50's across the region. High Pressure will take over the weather for the most part across the region for early next week.

JMH

Long Term

Things will begin to get interesting, especially later in the week and towards the Holidays. However, model guidance is all over the place. How do we figure out which solution is right? I think we must learn to question the legitimacy of model output in correlation with synoptic features and indicated factors such as NAO and PNA. If we are able to due this, their is no question in my mind we can resolve the confusion and illustrate what will unfold based on the laws of meteorology as we know them. I think many people are focusing to much on individual aspects as to whether one storm will do this or another will do that etc. What we should however take into consideration is any blocking apparent or bound to occur will eliminate any chances for current model forecasts to verify. Point being that with blocking the scenario should unfold according to sound laws of meteorology. Suppression of the SE Ridge is usually apparent if not excessive in allowing for the dissipation of such an occurrence which lowers ridging or heights in the east. Also what must be inferred from blocking is that with it present, no northern stream impulse will be able to pass shortwaves, that cut through the lakes or northeast and set up an overrunning scenario. Simply laws of sound meteorology indicate that with blocking present any shortwave will be forced to dig and inevitable phase with sw shortwave energy ejected into the central US or at best re spawn/redevelop.

Simply a phase is the only solution viable during a period of blocking (mod-strong) and with such features present and with possibly a -NAO and +PNA the phased energy will be forced under the blocking and into the eastern US serving as a coastal threat. No two pieces of energy-one splitting off and heading straight into the block, or a lake cutter into the block-only a bonifide coastal low in the eastern US would be possible with such synoptics. Never the less with no blocking anything can happen and chances severely decrease for snow in the northeast. In my opinion if the aforementioned period in question is to favor snow blocking must be present. Something to watch unfold in the models as the days go by.

BMC

Now that I am sitting here in my room with all of my windows open, and the thermometer reading 60 degrees Fahrenheit, I figured it would be a good time to put together a post formally releasing my thoughtsregarding the pattern From Mid December to January. I will try to make this post as easily read as possible, but it is a pretty complicated situation. There are a few things that I personally look for in regards to a colder and stormy period. But are these signals here for this years Late December Pattern? Currently, we are sitting in a pretty unfavorable pattern. But there are changes abroad. The first thing I like to do is take a look at the indexes, the ones that can often spell out our pattern. What we can look at here is the NAO, or the North Atlantic Oscillation. The NAO has been positive since Late November. However, the forecasts are trending in the right direction as seen below.

So, we have the NAO trending in the right direction, really, for the first time this winter. The model reflections in this period are extremely variable, but need to be watched. Over the past few days, I personally have been focused mainly on the storm threat around Christmas, but now it appears that we may have even another shot prior to that. Taking a look at some of the latest guidance, this situation is quite the complicated one. I was surprised to see the differences in this mornings guidance (6z), and this afternoons guidance (12z). As we watch this pattern unfold, we need to look at the key features. This starts around 130 hours, as energy moves into the Southwest, and Northern Plains. Firstly, lets look at the 6z GFS December 14th, and its positioning of major features at 132 hours. We can see Major Southern Stream energy, ready to eject to the NE. We can also see another major feature, energy over the Northern Plains. As shown, the 6z GFS takes our southwest energy and interacts it with the Northern Shortwave over the Plains. What is the result? Some snow over portions of Texas and Oklahoma, and a huge rainstorm from the Midwest to The Northeast.


The 12z Guidance is MUCH MUCH Different folks, and it is a difference which is big, simply because it puts the guidance into line with the ECMWF and GEM solutions. The 12z GFS keeps the Northern Stream energy from interacting with the energy in the SW and has it move north as its own storm.


These are major differences. In the short term, the difference is that New England gets absolutely PUMMELED. And yes its a ways away, but this thing bombs offshore and the shortwave heads off too Northeastern Canada. But this shortwave is NOT done helping us. HERE IS WHERE THE GFS GOES OFF FOLKS. Take a look at the pattern being shown at 168 hours. This is an EXTREMELY favorable pattern. There is obviously High Latitude support..basically a 50/50..you cant really miss it.


However, surprisingly enough, the GFS takes this storm from the GOM, suppresses it, and sends it out to sea. Now you tell me folks. Does the upper air pattern support this storm going out to sea? NO!. In fact, the upper air pattern on the 12z GFS supports the storm coming out of the gulf, turning NW and bringing the first significant snowstorm to I-95. With high latitude support, and plenty of cold air, I see no reason why it wouldn't be. The GFS is making a big mistake here by sending this out to sea, and it makes no sense to me. This will need to be watched carefully over the next few days, the potential is screaming at me.

I will continue to update and continue to watch the guidance and modeling and their handling of the pattern. In Summary, Right now, I think we are in a very good spot for New England to have their first snow event around December 19th-21st. Secondly, I think the December 22nd-24th time period needs to be watched for the first threat of an I-95 Snowstorm.

John

Short Post today..not much time. Quickly, we will be looking at an interesting event this afternoon and into tonight. Two Arctic Cold Fronts will pass through the region. This morning, it seems like there will just be some clouds and not enough lift for any showers. Tonight, there will be some more lift available with the front, and snow squalls seem likely around the CWA. Northeast NJ and NW Connecticut seem to be in the best spot to pick up a fresh coating of snowfall. Otherwise, we get even colder after this front passes through and a massive trough sits over the area. Todays NYMetroWx Forecast:


John

Today was another extremely cold day here in the New York City Metro Area, mainly thanks to the upper air trough sitting over our region. Shortwave digging across the southern end of the
trough has helped to spark snow showers and flurries across much of the region, seen on the DIX Radar Loop from 5pm This Afternoon. The flurries should End as the evening progresses, and the shortwave begins to make its Trek out of the area and up off the NE Coast. Below is the forecast for the rest of this cold and chilly evening.

We are all aware of the potential threat for a Miller B late this week. As time shrinks until the anticipated event I would like to add my commentary on the latest aspects and details of this complex situation.

As time nears it is evident the trend in all models to amplify and dig the shortwave further into the trough and even attempt to close it off. This trend is seen on many models but most still fail to show any relatively close area of LP developing off the coast and no or little QPF throughout the northeast. Although this is the case, the trending in recent models might lead some credence to the possibility of seeing this forthcoming in the future. Right now it’s more of a sit and watch, as the models try to determine what unfolds in the future. The 0z should be interesting in determining the extent of this wet dream, or should I say white, and the validity of it.

What is and what isn’t working? Well I personally think the adjusted and increased appeal by the models to focus more on a negatively tilted trough axis is important in increasing our chances for an area of LP developing off the coast and moving northward while staying close enough to provide some QPF of importance. The boundary (baroclinic zone) also adds more credibility to the development of a lollipop area of LP just off shore. The threatening N-S orientation leads to the possibility of greater strengthening and development just off shore if energy transfer or redevelopment occurs. No blocking is something I always fear and so should you, but its not going to hamper our cold more so the potential of this storm either staying coastal or going sea bound. Timing really is crucial and any SE ridging could be the savor quite ironically. If this LP is progressive with this fast paced pattern and develops to far off the coast than forgetta bout it. Hence why blocking is not something to laugh at and disregard as if it doesn’t matter.

The erroneous mishaps of the models seem evident to me. I feel too much upstream energy is being given to the northern shortwave and this eliminates the strength and potential of our coastal feature. I feel that any closing off from the pattern would allow for a closer to the coast solution (the pulling/phasing effect) and digging is a necessary component in allowing further southern regions to get into the action. Confluence will be in place and with the vorticity and strength of the shortwave projected by modeling even if we don’t get any coastal action watch for some whippy winds and very unseasonably cold temps with some low level moisture advection leading to snow showers and lake effect snows.

What to expect? As I said watch future model trends as 0z might be more foretelling on the upcoming situation. Never the less this is a chance that losses probability as time inevitably closes but it also seems to be one gaining slight credibility at the same time. Nothing to be excited or confident about but definitely something to watch for in the future and see if what was aforementioned unfolds favorably or unfavorably. Your guess is as good as mine!

BMC

Over the past few days we have seen some extreme model shifts. We had the GFS about 500 miles offshore a few days ago, and the NAM with a Strong Low Pressure off the NJ Coast just two days ago. This madness has sent the weather community ( ). But what exactly are the differences in what we are seeing? So far I have seen a few, that have been pointed out by others a few times as well. Number One would definitely be the behavior of our shortwave. The NAM/GFS and other models have been handling the shortwave differently every single run. A few days ago, The GFS didn't even really dig our shortwave, bringing it up into Upstate New York. Even now, 30 hours out, the NAM and GFS have some visible differences in the shortwaves progression. The NAM seems alot slower with the shortwave, and it also opens up the trough a bit more. My second concern is interaction with the energy upstream, or the kicker. It seems at this point that there will definitely be some sort of interaction with the kicker upstream, the question to me is how much and when. Often you will see a kicker aid in keeping a storm in the "sweet spot" or not allowing it to be pulled to close, or too far away from the coastline. However, you can also have those extreme cases when interaction is too small, or too much. The guidance seems to slowly be coming together with the fact that interaction with the upstream disturbance will be much less, allowing for rapid deepening to occur, but just a bit too far offshore. So all in all, unless we have some major model guidance shifts in the next 12 hours, this storm will be a near miss from NYC Southward, and a light event from NYC into Eastern New England. Keep in mind though, that this event is, and was, all about timing, and timing that had to occur just right for this storm to be a major player. A Note For the SNE Posters: I was going to go a bit higher in SNE, especially portions with higher elevations, but I figured I should be conservative here, especially with the mixing factor. Will wait and see as we get closer to the event.