Click To Enlarge
The forecast track of tonight and Monday’s system has trended a bit further north in the past 24 hours. As a result, I believe that a lot of the snowfall forecasts I am seeing for this next system are too high. It looks to me like snow will mix with sleet, freezing rain, and rain in many parts of CT, RI, and southeastern MA, keeping amounts down somewhat. Looking at the snowfall forecast graphic above, generally speaking, the light blue line that extends from southeastern PA into central NJ and along the south shore of Long Island is roughly where I think about 2″ will accumulate. The further south of this line you live, the less you get. The darker blue line that extends from northeastern PA to near Waterbury and Hartford, CT, up into northern RI, is roughly where I think about 6″ will fall. Farther north of this line (much of MA, southern VT & NH) is where you should stay all snow and have the best chance to see 10″ or 12″. Amounts will be less than 6″ in parts of far northern New England and NY because less precipitation will fall that far away from the low pressure center.
NAM Forecast For 7 AM Monday
The initial flakes will reach southeastern NY between roughly 6-9 PM and CT between 9 PM-midnight. First flakes into Boston by about 1-2 AM. The snow will pick up in intensity during the predawn hours and change to mixed precipitation along the CT shore around 6-7 AM and across much of CT, RI, and southeastern MA by 9-10 AM. Once the changeover occurs, the bulk of your snow accumulation will be over, however the precipitation will tend to go back to some light snow & flurries in the afternoon in these areas. Areas of snow showers/flurries may linger at times into the first part of Monday night.
Mixing near the southern part of this band could result in lower amounts. (Click to enlarge).
Nothing has significantly changed regarding the Sunday night/Monday event since my post yesterday. It still looks like the developing low pressure area will pass out just south & east of New England Monday, threatening much of our region with a 6″-12″ type snowfall, and potentially more in some areas. There is still a 50/50 chance that mixing to the south & east, and especially along the coast would keep amounts below this range in those locations. This storm will be more progressive (i.e. it will keep moving along – not stall out) than the last one so it is not likely to be able to produce mega-snow amounts. Take the snowfall forecast map above with a grain of salt. It is just a rough approximation and subject to change – especially near the northern and southern borders of the 6″-12″ snowfall swath. Highest probability of verifying is in the area in the middle of the swath – not near the edges. Most of the snow will fall between late Sunday night and Monday afternoon.
NAM (North American Mesoscale Forecast System) Forecast for 1 PM Monday (Click To Enlarge)
Yep. Looks like. The interesting historic storm/historic bust event that we are still cleaning up from was the sentry sent by Mother Nature to put us on notice that the pattern had changed from the quiet and cold we had become accustomed to through December and much of this month. The next event that looms is scheduled for Sunday night into Monday. A developing area of low pressure will move out of the middle of the nation and track (according to today’s models) just south & east of New England on Monday.
If everything plays out as the latest model runs would have it we would be looking at a 6″-12″ type snowfall across much of the region Sunday night (especially late) into Monday. One possible exception could be along the coast, where mixing with sleet and rain could keep total somewhat lower. Of course it is still only Friday evening, so there is still time for things to change. We will continue to evaluate developments during the weekend and adjust the forecast as necessary.
Much of the region is under a wind chill advisory tonight for wind chills down to -15 to -20 degrees at times, so dig out those woolies!
Low pressure sliding in from the west will freshen up our snow cover tonight into Friday. There will be periods of light snow and flurries and some spots might even get a moderate burst of snow for a short time. Most of the precipitation will fall between midnight and noon Friday, however I wouldn’t be surprised to see a few flurries around earlier in the night. Also, a south wind will keep temperatures up tonight. In fact, they may rise a few degrees and it is possible that there could also be rain showers tonight in some locations south & east of Hartford, CT. This looks like a 1″-3″ type of event for us, with more places seeing 1″ or 2″ and fewer seeing 3″. It is even possible that a few spots could see less than an inch – especially in those locations where any of the precipitation is light rain/showers instead of snow.
Any lingering snow will taper to flurries by Friday afternoon and there could be some partial clearing. A northwest wind will be increasing during Friday afternoon and night, getting up to 15-30 mph, with higher gusts. Arctic air will flow in and take full hold Friday night and Saturday, sending lows into the single numbers and low teens Friday night, with the wind chill factor dropping to near -20 at times (this can produce frostbite on exposed skin in 30 minutes). Highs Saturday will be in the teens-low 20′s at best and it will still be windy.
So the big storm pretty much panned out as expected for eastern New England and many places in southern New England to the south & east of Hartford. But north & west of Hartford and for the 9 million residents of America’s largest city it was considered a historic bust! Although I would argue that because the atmosphere is always changing, the forecast is always changing, and there is really no cut-off time for the last forecast to be submitted. Adjustments should continue through the completion of the event. When people ask me how accurate I am, I have been know to say that I am 100% accurate, but sometimes I can only give you 2 minutes notice. I am only partially joking when I say that, but I realize people want to know what tomorrow’s weather will be today, so they have time to make or change plans. I hope that I was able to convey to you in some of my previous posts about the storm, the concern that there was a chance western areas might underperform. This was one of those situations where you had to wait until the storm was already in progress to know whether to expect 7″ or 27″ in some places, and it probably won’t be the last.
Part of the “bust” phenomenon is due to media and political events that swirl around these forecasts of the future. And I have to admit that I get a certain amount of satisfaction when a high profile, consensus forecast busts in spectacular fashion like this last one did for some heavily populated areas. And I know I am not the only one. I believe this is because it teaches us the virtue of humility. It helps to prevent us from becoming cocky and thinking we know everything. Our understanding is still no match for the complexities of nature.
“History shows again and again how nature points out the folly of men”
- Blue Oyster Cult
- The GFS (American model) outforecasted the ECMWF (European model) on this storm. For all the hype and groupie like devotion the Euro has generated, especially after Sandy, it was the main reason that so many forecasts busted so badly for New York City & western CT. It is a very good model, especially several days out, but when it is an outlier, it should not be followed with religious zealotry.
- The mission of the National Weather Service is to protect life and property. They rightfully use terms like “life-threatening” or “crippling” to illustrate the impacts a storm could have if it lives up to its potential. They will always err on the side of caution. What may be life threatening or crippling to a commercial fisherman or homeless person might just be another no work or no school day in the comfort of your living room for you, but they are attempting to keep everyone safe when danger lurks. Plan accordingly based on your own situation.
- Until yesterday, I haven’t watched The Weather Channel in years. They lost me through excessive commercial loads, reality programming vs. weather coverage, and becoming too political. I have to give them props on this storm, though. They had the guts to start scaling back the forecast in NY City and parts of CT hours before many of the local forecasters made that call.
- Once the media machine is in motion, trying to stop it is like standing in front of a tank. Once you provide newsrooms with forecasts that contain words like historic and reporters and weather people are placed in the usual outdoor locations, the show must go on, regardless of changes to the forecast. This is why you continue to see everyone basically still reporting the “Blizzard of 2015″ story in places where nothing close to a blizzard occurred. In fact, you’re still watching it, right? So why should they go back to syndicated programming?
- Politicians at all levels of government are intervening too much during significant weather events. They have discovered that (rightfully or wrongfully) how their actions are perceived during these events can make them or break them in terms of public opinion, so now they sometimes do too much. If being involved simply meant keeping the roads clear or announcing the locations of local homeless shelters, I’d be all for it. But closing down a city or state based on a forecast of the future? That frequently causes more problems than it solves. Was it really necessary to close down the NY subway system for the first time in history? NY city has had 6 storms of 20″ or more since records have been kept. They reported 26.9″ in a 2006 storm. The subways never stopped during any of those events. In fact they were built after the Blizzard of 1888 so that transportation could continue during blizzards and severe weather. Can’t we make contingency plans in case forecast severe weather comes to fruition, but hold off implementation until it actually starts to materialize?
What are your thoughts on recent events?
Surface Map 7 A.M. EST
Well, for areas north & west of Hartford, down into New York City, it’s certainly not historic. In fact it’s not even all that bad. Further east, it’s a more significant event, but it’s historical significance is open to debate. I’d prefer to wait until the dust (or in this case, the snow) clears before tackling that one. So far, it looks like many parts of CT saw between 12″-26″ of snow, however amounts are much smaller north & west of Hartford. At last check Bridgeport only had 5.0″. The storm track was a bit further east than some of the modeling had indicated, so basically everything was pushed east by about 60 miles. This was within the margin of error on the forecast map I posted yesterday, and is a good example of why I am uncomfortable when terms like “historic“, “epic“, and “crippling” start getting thrown around before an event has even begun (more on that later).
Temperatures today are in the low-mid 20′s and wind chills are in the single numbers. There will be periods of lingering snow and flurries at times today. Some places will get some additional accumulation – maybe even a couple inches. Others, just another coating. Areas of blowing & drifting snow will continue.
HRRR Model Forecast Radar at 5 A.M. EST (Click To Enlarge)
The Plot Thickens! I see The Weather Channel is downgrading the snow amounts for CT & southeastern NY based on short term guidance keeping the heaviest snow to the east. There is a surprising amount of disagreement between models, considering that the event is already in progress! I have been concerned about the same. For now, I’ll keep the forecast unchanged, but am watching developments closely. Notice how on the High Resolution Rapid Refresh model to the left, there is a sharp difference between precipitation amounts north & west of Hartford, CT vs. south & east at 5 A.M. Can you imagine if this were to verify and the 9 million people in New York City wake up to just an ordinary snowfall? What would the fallout be? Should be an interesting night!
This is a very rough idea of what I’m thinking for storm totals. The surface storm will get stacked up underneath the mid-level low (see black arrow on image below). This will cause it to slow down and move erratically for a while. This could cause further fluctuations in forecast snow amounts and how they line up. Based on differences between models, the snowfall forecast image contour lines have a margin of error of +/- 75-100 miles. These big storms always have mesocale bands that develop and produce the heaviest snow totals and sometimes contain thunder & lightning. The location of these bands really can’t
NAM 500-mb (mid-level) and Surface Forecast for 1 PM Tuesday
be placed accurately until they show up on radar, but that is where the “locally highest” totals will occur. The GFS is the least impressive model right now, but also a bit of an outlier, so I have underweighted it.
- The heaviest snow will kick in toward and after midnight. Many places in the 15″-30″ area will see over a foot fall in a 6-hour time frame.
- Winds will gust over 40 mph inland by early Tuesday and over 50 mph closer to the coast and in parts of eastern CT. Even higher gusts across southeastern New England.
- Wind-Chills will be in the single numbers to around 0 late tonight & Tuesday.
- Blowing & drifting of the snow will cause problems. It will be a dry, powdery snow.
- Visibility overnight into early Tuesday morning will be reduced to between 0 and 1/4 mile at times in the Blizzard warning areas.
1 AM NAM Total Precipitation Forecast (Liquid). Compare difference to previous run below.
After trending eastward a bit during Sunday, the overnight night model runs have jogged back to the west. This means that the threat for big snow amounts (15″-30″) continues across all of southern New England and parts of southeastern NY, including New York City. To give you an idea of the fluctuation in snow amounts being forecast in some places consider the past few runs of the NAM:
————————————————–1 PM Sunday 7 PM Sunday 1 AM Monday
Canaan, CT (Litchfield Cty.) 10.9″ 5.5″ 25.1″
LaGuardia Airport (NYC) 24.9″ 8.4″ 22.3″
Windsor Locks, CT 25.9″ 15.2″ 21.5″
Poughkeepsie, NY 8.8″ 5.0″ 18.7″
7 PM Sunday NAM Precipitation Forecast (liquid). Compare to most recent run above.
You can see how much these amounts have varied in some places from run to run on the NAM, however there has been less variability in other locations like Boston, which has been up around 20″ or so on the last few runs (currently at 23.9″). This illustrates why we shouldn’t put too much stock in a single model or single run, but have to give more weight to the trend and to a consensus of the models (after tossing outliers). The ECMWF (Euro) model has probably been the most consistent all along, and continues to thump the entire region with big snow. With the other models now trending back west, big snow looks like a good bet for all of southern New England, southeastern NY, and southern NH.
Expect some occasional light snow and flurries to get going during the day today. There could be a couple inches on the ground by evening. The real snow will come down between midnight and early Tuesday morning. In a few hours, the morning guidance will be available and it will be time to make a final call on specifics.