Briefly Updating Snow Chances

Just wanted to throw down a brief entry to outline snow chances more specifically.

Snowfall Forecast for the Friday Storm (click to enlarge)

To the left is my first and last call snow map for the Thursday night and Friday “storm.” Again, this will be a quick mover and really not a big system at all. It may get its act together to throw back some briefly heavy snows into New England, and dump mainly a 2-4″ sort of snow back in the red area. Most other areas will only see a coating-2″, with an isolated 3″ amount report or two possible. Timing…arrives in the Philly area after midnight Friday and exits the Boston area Friday after sunset. Quick mover.

Next week’s storm continues to show up on the models today. It does look as though this will be a rather large and strong storm. But the overall track is going to be what is impossible to nail down for several more days. I do expect someone in the interior Northeast to see a decent shot of snow, some areas with potential for a mix, and some areas with a cold, raw rain potentially. I still would avoid hyping this one in the big cities, as it’s far too early to even try and guess how it will unfold specifically. A lot of what does happen is dependent on how a system plowing into the Northwest US this weekend behaves. I’ll be traveling much of the next week, and I’ve been watching forecasts for northern New Mexico fluctuate between sunny and dry to heavy snow for the last several days. Why do you care? Because that shows you the volatility of what that Washington/Oregon storm will be doing…we simply can’t say, and in order to peg down who gets the snow next week in the Northeast, we need to know what will happen out west. So stay tuned.

————-

State of Occlusion is on Facebook! I’m posting some additional cool links and videos, quick model status updates, and snow maps earlier than you’ll get here. All kinds of cool stuff available on our “Like” page. “Like” the blog by clicking here!

Advertisements

Historic (?) Southeast Storm Could Be Next Northeast Snow Threat

Overall pleased with the forecast for the current storm for the Big Cities. Definitely underestimated parts of CT that saw 8-16″ of snowfall on average in the western part of the state, even down to New Haven County. Just a reminder… State of Occlusion is on Facebook. I’ve posted some additional cool links and snow maps early on that page. “Like” the blog by clicking here! On to the fun…

The Eastern 2/3 of the US are going to be peppered by winter events over the next five days or so. Let me run through things here.

Snowfall Forecast from Friday Overnight-Sunday Morning

First off, tomorrow, as all of the energy responsible for the unsettled eastern weather the last couple days starts to slide offshore, it will begin to develop into a nor’easter, but rapidly exit to the east. However, as it intensifies, it could produce a pretty well organized band of snow from about Southern NJ/Central DE through E Long Island and possibly Cape Cod. The snow map is over to the left if you want to enlarge it and see my thoughts through Sunday morning. Not a big storm, but there could be some heavy snow for an hour or two, especially east of Rt. 206 in NJ as the storm pulls away. Lingering snows will produce perhaps a couple more inches in New England, with upslope areas of the Green Mountains and Berkshires more favored. I don’t believe accumulations will be that high. There is some chance the Cape and Islands, as well as the Boston area may see some enhancement too.

GFS Forecast of Total Ice Through Tuesday Morning (Credit: wxcaster.com)

That will exit tomorrow night and by Sunday morning or so, things will be quiet. But that sets the stage for the next event, and this one might be an absolutely punishing doozy of a storm. The map to the right shows the GFS forecast for total accumulated freezing rain through Monday. A strong storm system is going to trek across the Southeast in an unusually cold air mass, and with it will come plenty of moisture…almost an El Nino type storm. Winter Storm Watches are posted almost to the Gulf Coast for Mississippi and Alabama, and for most of northern Georgia and Louisiana, as well as Arkansas. This amount of ice this far south would be absolutely crippling…that isn’t hyperbole either…these are places that almost never see frozen precipitation of any kind, let alone to this extent. The raw model outputs in some of these places is absolutely mind boggling. Atlanta is showing anywhere from 6-12″ of snow, with 1/4″ of ice! Of course, that’s raw model and has to be taken with a grain of (road) salt. But still, that’s absolutely insane, The all-time snow record for Atlanta is (I believe) 10″ in January 1940. It’s tough for me to put this in historical context, as I’m not THAT familiar with Southeast wintry climatology, but this would be, from a meteorological perspective, one of the most incredible things we’ve seen over the last couple winters (and we’ve seen a LOT). Check out the total snowfall forecast through Tuesday morning in the Southeast below (from http://wxcaster.com/regional_snowfall.htm).

Southeast NAM Snowfall Forecast Thru Monday Night (Credit: http://wxcaster.com/regional_snowfall.htm)

The next question becomes, where does it go? The three main models to look at for tonight, taking them (since the NAM only goes out 84 hours) to Tuesday morning shows the low sitting somewhere off the northeast South Carolina coast. Not surprisingly, where this storm sets up, will determine how it impacts areas up the coast. The European model sets up the furthest northwest. Not surprisingly, as you run it out further in time, the European delivers a quick moving, but solid snow event (6-12″ish) for most areas from I-95 south and east. The GFS is a glancing blow, but mainly a miss (not bad for New England). The NAM stops at hour 84, but is a little closer to the European model than the GFS. So my feeling is that despite model flip flopping the last couple of days, we could still see a pretty potent little storm from the Carolinas up into New England. The timing on the snow would be later Tuesday to the south, ending Wednesday from Jersey through New England. Stay tuned on this, especially if you have midweek plans. I’ll do my best to keep you posted.

 

Clipper Snowfall

Still looking at a volatile and challenging system for the Northeast tomorrow and Saturday. My first and final accumulation map is below:

Snowfall Forecast: Thursday Night-Saturday Evening (Click to enlarge)

There could still be some significant variability in the snow totals, especially in the area bounded by Syracuse-Albany-Worcester-Hartford-Newburgh, NY. Snow will move in tomorrow morning. From about Trenton, NJ south this looks to be a very low impact event. There may be a brief period of heavier snow to cause some havoc on roadways, but accumulation will be limited. The main area of impact for this storm should be the Catskills, Mohawk Valley, Adirondacks, Berkshires, Litchfield Hills, and perhaps parts of SW Connecticut and Long Island. The main event will wind down Friday evening, but lake enhancement will begin to deliver heavier snow to parts of Upstate NY through Saturday night, leading to the chance of higher amounts there. The Norlun trough effect could take over in Maine and southern New Hampshire Saturday night, leading to higher totals than advertised above (remember this map ends Saturday 7 PM). Max amounts could top off around 12″, with a few higher amounts, primarily in the mountains/upslope of Upstate NY courtesy of lake enhancement or pure lake effect.

Models continue to show a favorable pattern for a large storm for midweek next week. More on that after this system passes.

Select snow amounts through Saturday evening:

DC/Baltimore, MD: Trace
Philadelphia, PA: Coating-1″
Trenton, NJ: Coating-2″
New York City: 1-2″ average
Morristown, NJ: 1-3″
Bridgeport, CT: 2-5″
Syracuse, NY: 3-6″
Utica, NY: 4-8″
Albany, NY: 3-7″
Hartford, CT: 2-5″
Boston, MA: 1-3″

———–

Don’t forget, State of Occlusion is on Facebook! I’ll post some additional cool links and snow maps before they’re published here on that page. “Like” the blog by clicking here!

Quick Weekend Snow Risk Assessment

Not much to say beyond what was said yesterday. Just looking at the models today and going off past experience, I feel this first system Friday-Saturday is not going to be a backbreaker on a large scale. I think we’re dealing with a more localized storm in areas more suited to handle heavy/surprise snow…an Alberta Clipper system that starts to explosively develop off the New England coast, which may for some point carry one of my favorite descriptions: A ballistic clipper. These types of storms can really hammer areas north of I-80 if the situation is right.

Snowfall Risk Assessment for the Northeast Friday-Saturday (Click to enlarge)

So anywhere from about Rochester or Syracuse eastward is fair game for this possibly overachieving. Right now, I think the odds of the “clipper” overachieving are highest in the Catskills, but this could easily be extended north toward the Mohawk Valley or even the southern Adirondacks and Berkshires. The secondary area is where the intense coastal development will take place, which is off the Massachusetts coast, possibly putting Portsmouth, Boston, Providence, and Cape Cod under the gun for a period of heavy snow. I’m non-commital on that area though, and more enthused with the idea of parts of the interior being “surprised” by this. For now, you can see my highest risk areas. These may be expanded or contracted later. Additionally, the area of 3″ accumulating snow could end up pushing a little further south, but if I lived south of I-195 in Jersey, I wouldn’t be too concerned or enthused for snow at this point. I think this first event will be primarily a north of I-80/east of I-81 storm. I’ll keep you posted.

We still have this other system showing up on the models for midweek next week, and that one I’m still not writing off or committing to at this point…but I will say, given recent model trends and the overall pattern, it would make sense that someone will see a significant winter storm for the middle of next week. Stay tuned.

———–

Don’t forget, State of Occlusion is on Facebook! I’ll post some additional cool links and snow maps before they’re published here on that page. “Like” the blog by clicking here!

The Boxing Day Blizzard

Well, it’s underway, and miraculously, there haven’t been any dramatic changes in the forecast in the last 12 hours. The main areas of concern to me seem to be:

  • Cape Cod/Providence/Boston/Long Island: How much falls as sleet/rain vs. snow, thus cutting down snow totals there. The low should ride the coast from about Montauk to Martha’s Vineyard, so this will both lead to a mix/changeover scenario on Cape Cod/southeast Connecticut/Rhode Island and may even have to a dry slot cutting down totals in general. Will this make it as far north as Boston? Doubtful, but we’ll see.
  • Jersey Shore from LBI south: There could also be some mixing issues here. In my experience there are almost always mixing issues in this region when a low passes this close to the coast. So this may cut down totals, and I’ve lowered the range a little to 7-14 (down from 8-16). It’ll still be a good storm, but the combination of a little less precip and this mixing scenario has me cutting back a smidge.
  • Philly-Morristown-Albany: The biggest question of all is regarding how far west the heavy snow will get. And this corridor stands the most to gain or lose depending on the exact amount the precip shield barges inland. I could see this being as little as 6″ in Philly to as much as 12-16″ there depending on the exact track (same goes for the I-287 corridor in Jersey and I-87 from Newburgh to Albany.
  • NYC-Hartford-Interior New England: This could be an absolute wallop for places like Worcester, the Berkshires, the Litchfield Hills, etc. A lot of potential for a lot of snow in these areas, and there could be a cluster of significant 20″+ amounts anywhere between NYC and Boston depending on where the best mesoscale banding sets up.

Lastly, the wind impact from this cannot be stated enough. This is a storm which is going to see its barometric pressure fall from about 996mb off Cape Hatteras to perhaps 970 mb or lower south of Long Island. In meteorological terms, we call this an atmospheric “bomb.” In other words, it’s going to be rapidly deepening, and it will be progressing along close to shore. This is going to create absolutely ferocious winds all the way up the coast and rather far inland. With everyone’s Christmas lights up, coupled with heavy snow, the wind has the potential to cause a LOT of damage/mess. It may not be a bad idea to secure some of the holiday displays Sunday morning. There will also be the potential for significant power outages as well, so be prepared, especially because temperatures will drop into the low 20s to teens Monday night and Tuesday morning, with wind chill on top of that.

Travel is going to be next to impossible and is not recommended, especially from Northeast NJ into New England after about 9 AM-Noon tomorrow. And it may be that this is the case throughout most of eastern PA/NJ/DE/eastern NY as well. This really to me seems like last February, shifted a couple hundred miles further north. So please use caution if you have to travel, and be prepared for numerous road closures/states of emergency by Sunday evening.

7:30 AM Sunday Update: I would likely trim some of the snow totals back east a bit in the 3-7″ range, esp in NY/PA. The storm is moving along at a decent clip. The real intensification takes place this evening…that’s when the “blizzard” aspect will begin to take shape. In terms of the actual amounts, I might be apt to trim back south Jersey/Delaware a bit (more like 6-12 now to me). Overnight models (not going to read into them too much at this point) did cut back snow totals there to the 6-10″ range). Still looks good that the bullseye is between NYC and Boston..but not IN NYC or Boston. Boston may end up on the lower end of my forecast range, but inland areas will push the higher end. The western extent of the snow between the Delaware River and the Hudson River is going to be EXTREMELY sharp now it appears. Could easily go from 2-4″ far west to 12″+ over a very short distance. Whether that gradient is centered over the Delaware Water Gap or Denville in North Jersey, I’m still not sure. Still a tough forecast. Keep an eye on things throughout the day. Also, from northeast NJ into New England, the bad travel may not start until more like 11-2, rather than 9-12.

1:30 PM EST Update:  Everything still on track. Morning model guidance and current radar trends validating a major storm that’s underway. Latest SPC Mesoanalysis showing that the storm is rapidly deepening off the NC coast as it gradually pulls north. This will bring blizzard conditions to most of coastal NJ/Delmarva and inland to about Rt. 206. The blizzard conditions will spread north into NYC and New England this evening. The worst of the weather will be bounded on a line south of I-90 in New England and east of I-287 in NJ-I-87 in NY.

If you live in Southeast Jersey, snowfall rates of at least 1″/hour are occurring and those heavier bands will continue to push onshore from time to time this afternoon and evening. Heavier snow continues to gradually push inland, and to be honest, the snowfall map from last evening doesn’t look too bad at this point (though I’d still shift the 4-8″ area a little further east). Some totals so far include Somers Point at 6″, ACY at 4.3″, a little over 3″ at Ocean City, MD, and 6-10″ in the Hampton Roads area of Southeast VA and parts of Northeast NC, back through Raleigh/Durham. The DC/Baltimore areas have been for the most part “shut out” of the storm so far, and it’s not looking likely that those areas will be hit nearly as hard as others north and east.

Travel and conditions in general will continue to deteriorate this afternoon. Be safe!

Here’s your map for new snow tonight-Monday (click to make it bigger). Feel free to add any questions in the comments, and if you like the updates or have any comments/ideas for future items, let me know! And Happy Boxing Day!

Final Snowfall forecast for Boxing Day Blizzard (click to enlarge)
The storm is moving along at a decent clip. The real intensification takes place this evening…that’s when the “blizzard” aspect will begin to take shape. In terms of the actual amounts, I might be apt to trim back south Jersey/Delaware a bit (more like 6-12 now to me). Overnight models (not going to read into them too much at this point) did cut back snow totals there to the 6-10″ range). Still looks good that the bullseye is between NYC and Boston..but not IN NYC or Boston. Boston may end up on the lower end of my forecast range, but inland areas will push the higher end. The western extent of the snow between the Delaware River and the Hudson River is going to be EXTREMELY sharp now it appears. Could easily go from 2-4″ far west to 12″+ over a very short distance. Whether that gradient is centered over the Delaware Water Gap or Denville in North Jersey, I’m still not sure. Still a tough forecast. Keep an eye on things throughout the day.

Yes, This is a Christmas Miracle

Irony of ironies, almost all the models are converging on a solution. There are still uncertainties on this storm, especially regarding how far inland the significant snow goes. One model is suggesting it goes almost all the way to Pittsburgh. Another says it barely crosses the Delaware River. So that will be what needs to be worked out over the next 12-18 hours. Not going to be a very relaxing Christmas for many meteorologists in the East.

This storm has truly been remarkable to watch. It’s been all over the place, and there are a number of very well seasoned meteorologists I’ve heard from that say they have never seen anything even remotely this poor in their careers. This just serves to remind everyone that weather is a VERY inexact science…and it will always throw us curve balls. I’ve included an updated snowfall forecast map below, and like I would encourage you with any snow map you see today and tonight, take it with a grain of salt. There’s uncertainties that still cloud this forecast. The bottom line: There will be a high impact storm for most areas north and east of Baltimore. Regardless of specifics, this will be significant for a number of areas, and travel within and to the Northeast and Mid-Atlantic is going to be difficult to perhaps impossible on Sunday afternoon through Monday afternoon. There will be mixing issues along the coast of NJ, Long Island and Southeast Massachusetts. Those mixing issues could even extend inland a bit too, depending on the exact track of the storm. Any mixing will cut significantly into snowfall totals in those areas. There is the potential for higher amounts in the eastern areas of the blue color (4-8) region, again, depending on the exact track. There will be blizzard conditions when it’s snowing on the coast and possibly a bit inland.

This is a big storm, so despite the uncertainties, doubts, and changes you’ve heard of, and the jokes you may be inclined to make about “those weather people,” do take it seriously, as it will be a high impact storm that could still throw curve balls. And if you hate snow, it looks to warm up a bit with an early January thaw soon after this storm.

Click the map to enlarge.

Revised Snowfall Forecast for Christmas Weekend-Monday

It’s a Christmas Miracle? Flip a Coin.

Just a quick update. I won’t be drawing a snow map this evening for a couple of reasons: One, it’s Christmas Eve, two, the Euro won’t be out for another hour+, and three, the amount of inconsistency and volatility regarding this storm is something I’ve heard people with years of forecasting experience beyond my own, say they have never ever witnessed. In other words: You’re looking at one of the most complex storm systems we’ve ever seen…moreso because of the location it may or may not impact rather than because of the storm itself.

But I will provide you with a couple of major teases. The two maps I place at the end of this entry are raw snowfall forecasts from the GFS and NAM computer models from this evening. Now, don’t go shouting from the rooftops. I STILL am not behind this storm. I still see flaws. I still think the models are suffering problems (given their wild swings and disagreements over the last 2-4 days or so, this may seem obvious). And I still think we’re in for changes here in the final 36-48 hours before gametime. The Hydrometeorological Prediction Center’s model discussion this evening is once again hinting at the potential that the models are erring, and that could be leading to solutions later in their runs that are, well, incorrect.

CONSOLIDATING UPPER LOW OVER THE EAST...
LOW PRESSURE FORMING UP THE EAST COAST...PREFERENCE FOR A 00Z
NAM/15Z SREF MEAN COMPROMISE
THERE ARE SMALL SCALE DETAILS THE NAM/GFS/ECWMF ARE SHOWING ISSUES
WITH WHICH MAY IMPACT ITS FORECAST LATER ON.  THEIR SOUTHERN
STREAM SHORTWAVE IN TEXAS ARE 30-40 METERS TOO WEAK AT THE 500 HPA
LEVEL BASED ON RAOB REPORTS FROM TEXAS.  THE NAM DOES NOT CAPTURE
THE ONGOING CONVECTION IN EASTERN TEXAS.  THE 18Z AND 00Z GFS RUNS
ARE SHOWING SIGNS OF CONVECTIVE/GRIDSCALE FEEDBACK AS THE SYSTEM
MOVES ALONG THE GULF COAST WHICH COULD BE MAKING ITS SOLUTION AT
THE SURFACE AND ALOFT TOO STRONG.  THERE ARE HINTS THAT THE RIDGE
INITIALLY ALONG THE EAST COAST IS MORE AMPLIFIED THAN THE
NAM...WHICH WOULD BE CLOSEST TO THE 12Z ECMWF/12Z ECMWF ENSEMBLE
MEAN FORECASTS FOR 00Z.  ANY OF THESE DETAILS COULD
DEGRADE/NEGATIVELY AFFECT THE SHORT RANGE FORECAST.

So there’s still much uncertainty. I mean, honestly, there’s NO forecast out there now that stands much chance of being right on, including my own. This is simply one of those storms where you sit back, roll the dice, and pray you come close.

Consider a compromise of the maps below as the potential for the maximum impact of this storm. Click on either map to enlarge it. Consider my forecast map from earlier this morning the potential for minimum impact of this storm. So enjoy the tease, because tomorrow is going to tell us that either a hefty dose of reality is going to kick in, or you really will believe in miracles. Merry Christmas!

00Z NAM Forecast Snow: http://wxcaster4.com (Worth bookmarking)
00Z GFS Forecast Snowfall: http://wxcaster4.com