January Thaw Coming to a Close

By: MAweatherboy1 , 12:13 AM GMT on January 16, 2014

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It's been a busy few weeks for me, between working through the college process and preparing for midterm exams (the last of which I took today), so I haven't had much time for blogging lately. Frankly, there hasn't been much interesting weather to blog about lately. Ever since the storm early in January that brought up to two feet of snow for parts of the north shore of MA (though most areas were under 18", with many under 12"), we have been at least temporarily pushed out of the wintry pattern. We're in a January thaw, with today being a fifth consecutive day of well above normal temperatures. The snow cover has vanished, even into areas farther north. Technically, many areas are above normal for snowfall this season, but the trend has been for light to moderate snowfalls followed soon after by warm weather that quickly cuts down the snowpack. The thaw we are in will likely continue into the weekend, but temperatures will be moderating back to more seasonal levels, with upper 40s and low 50s replaced by upper 30s and low 40s, with temperatures near freezing returning by around Monday. As far as precipitation/snowfall goes, the next few days look mainly dry as we dodge a couple storms. One strung out system will pass well east of us tomorrow, keeping us dry. Another system or two will try to get going over us Saturday and Sunday. These days will provide us with a better chance for rain or snow showers, but any snow accumulations through Monday would be light, with western zones having the best shot at 1-3" of snowfall. Eastern areas will probably be too warm for snow even if a bit of light precip does work in this weekend.
The next real storm on the horizon comes along Tuesday-Wednesday of next week. It's too far out to get into much detail, but as it stands now the GFS has been fairly consistent on keeping the storm far enough out to sea to avoid impacts, while the last couple of ECMWF runs have shown a moderate (~6-10") snowfall event over that time. There is some potential here for a decent storm. It could even be a situation similar to the storm early this month where most of the moisture stays south but we achieve a moderate snowfall due to high snow ratios that could be in place as cold air moves in. Despite this, I would say the out to sea scenario is most likely at this time. Lots of time to watch this one. I will be providing updates as necessary. Here's just a quick look at the 12z ECMWF's total snowfall through 192 hours, with most (though not all) of this occurring next Tuesday-Wednesday.

(Deleted)

And here's the same map for the GFS, with almost no snow for the next 8 days:

(Deleted)

Thanks for reading; check back for updates!

MAweatherboy1

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59. WunderAlertBot (Admin)
11:19 PM GMT on March 31, 2014
MAweatherboy1 has created a new entry.
58. MAweatherboy1
3:56 PM GMT on January 22, 2014
Ended up with 9" here, about what I thought.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
57. trHUrrIXC5MMX
1:32 PM GMT on January 22, 2014
In Worcester county, you can get nothing to 12" of snow...lol

*Iknow it's a big county in Mass.
Member Since: April 23, 2011 Posts: 104 Comments: 14873
56. MAweatherboy1
11:58 AM GMT on January 22, 2014
Looking ahead now: We're very cold (sub-20F) and dry (except for lingering snow this morning) today through Friday night. A brief warmup to the mid 30s should occur Saturday, but another arctic front will charge through during the day Saturday, this one bringing a better chance of snow showers and squalls than the last one. Next storm threat is Monday, with the 6z GFS going for a pretty solid region-wide snow event (6-12"), while the ECMWF says no such thing. It's another one to watch.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
55. MAweatherboy1
11:45 AM GMT on January 22, 2014
Good morning. As with most storms this one had some tricks up its sleeves. The winners in terms of accumulation are the areas where that band set up yesterday, you can see it on the Taunton NWS accumulation map in post 53. A few 15-18" amounts have been reported. The Cape and Islands and far SE Mass. are getting their snow this morning, but they will not verify many amounts over a foot like many thought they would. In addition, NW of where the band set up, from the Merrimack Valley down to Worcester and north/west of there, you'll be waking up to no more than 1-3". Dry air ate away almost all of the snow there, that's a bad forecast bust. Not much you can do about anticipating a mesoscale band like we saw yesterday, but we should've been able to predict the dry air problems. I'll measure at my house later this morning. I won't be the jackpot amount, but I'll do okay, probably anywhere from 8-12", near or a bit more than what was expected, even if it wasn't exactly how I thought it would happen.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
54. MAweatherboy1
12:57 AM GMT on January 22, 2014
MESOSCALE SNOW BAND IS THE MAIN PLAYER THIS EVENING ACROSS NE
CT...RI AND SE MA WITH SNOWFALL RATES 1-2"/HOUR WITHIN THIS BAND.
HEAVIEST SNOW ACTUALLY FALLING FROM N RI THROUGH NORFOLK COUNTY.
HAVE RECEIVED SEVERAL REPORTS OF UP TO 6 INCHES ALREADY. MESOSCALE
BAND IS LINING UP QUITE WELL WITH AREA OF 850-700 MB FRONTOGENESIS
WITH RESULTING ASCENT WITHIN FAVORABLE DENDRITIC GROWTH ZONE.
NORTH OF THIS BAND...VERY DRY AIR IN THE LOW LEVELS HAS INHIBITED
NORTHWARD MOVEMENT OF THIS BAND.

That's right where I am.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
53. MAweatherboy1
12:51 AM GMT on January 22, 2014
With that heavy band that continues to dump snow on much of the region, the Taunton NWS has re-expanded the 10-14" range, a good call. Very sharp cutoff NW:



What a bust by the short range guidance.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
52. MAweatherboy1
11:35 PM GMT on January 21, 2014
Just measured (and shoveled off my driveway) 4" of very, very light, fluffy snow. I am right under a heavy band that has set up and persisted from south Boston SW to Providence. This is kind of the first batch of the storm. Already, this band will come close to verifying many forecasts for that Boston to Providence corridor. Farther west, like north and west of Worcester and even the Merrimack Valley, you guys are missing out. There will be very little out that way it looks like. The "second batch" of snow will be for the jackpot zones of the Cape and Islands. These areas really haven't gotten into the heavy stuff yet, but you will later, and by that time it will shut off or lighten up for many others.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
51. Bluestorm5
9:20 PM GMT on January 21, 2014
Quoting 49. MAweatherboy1:
It's interesting, the short range models (like the RAP, RGEM, and HRRR) are just awful for snow, they hardly show more than 3-4" for many. FWIW the 18z NAM held the course from 12z, still a widespread 8" or more. I'm seeing some good northward progress to the echoes on radar, I don't see how anyone just outside of I95 and east of there comes away with less than 6". The issues may be areas farther west, closer to Worcester. There will be a cutoff somewhere. This RAP map is bogus though. I'll have 2" by 5PM, much less through the whole storm.

SREF did pretty well here for today.
Member Since: August 1, 2011 Posts: 28 Comments: 8041
50. MAweatherboy1
9:05 PM GMT on January 21, 2014
NWS has confirmed my suspicion that the NAM and its higher totals are probably the way to go for this storm.

SNOWFALL: FURTHER ENHANCING THE SNOWFALL ACROSS SOUTHERN PORTIONS
OF THE AREA IS EXCELLENT FRONTOGENESIS AS SHOWN IN THE NAM. THE NAM
IS HANDLING THIS MORNINGS BANDING AS WELL AS ITS EVOLUTION FROM NEW
JERSEY NORTHEASTWARD INTO SOUTHERN RHODE ISLAND AND SOUTHEASTERN
MASSACHUSETTS VERY WELL. THIS AREA OF FRONTOGENESIS IS FORECAST TO
CONTINUE...AT ITS CURRENT STRENGTH...THROUGH MUCH OF THE NIGHT...
ALLOWING FOR A BAND OF HEAVY SNOW TO AFFECT EASTERN CONNECTICUT...
RHODE ISLAND...AND SOUTHEASTERN MASSACHUSETTS. SNOWFALL RATES IN
THIS BAND ARE LIKELY TO BE IN THE ONE TO TWO INCH PER HOUR RANGE
RESULTING IN A QUICK ACCUMULATION OF 3 TO 6 INCHES OF SNOW THIS
EVENING...MUCH OF WHICH WILL FALL AROUND THE EVENING COMMUTE.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
49. MAweatherboy1
8:47 PM GMT on January 21, 2014
It's interesting, the short range models (like the RAP, RGEM, and HRRR) are just awful for snow, they hardly show more than 3-4" for many. FWIW the 18z NAM held the course from 12z, still a widespread 8" or more. I'm seeing some good northward progress to the echoes on radar, I don't see how anyone just outside of I95 and east of there comes away with less than 6". The issues may be areas farther west, closer to Worcester. There will be a cutoff somewhere. This RAP map is bogus though. I'll have 2" by 5PM, much less through the whole storm.

Member Since: February 11, 2012 Posts: 84 Comments: 7948
48. MAweatherboy1
8:14 PM GMT on January 21, 2014
Good afternoon. Snow has started here, it started about two hours ago actually. Snow amount forecasts have fluctuated today; recently a lot of short range guidance has sent this more out to sea and given us less moisture (see the NWS Taunton map above). My forecast from comment 35 still stands and I think it will verify very nicely, except Cape Cod and the islands may come in closer to 12-14". We're mostly nowcasting at this point.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
47. MAweatherboy1
11:36 AM GMT on January 21, 2014
Morning P, thanks for stopping in. It is looking pretty good for snow this morning. Here's the NWS Taunton snow map, which I agree pretty well with:



Have to head to school soon, so enjoy the start of the storm!
Member Since: February 11, 2012 Posts: 84 Comments: 7948
46. Pcroton
11:04 AM GMT on January 21, 2014
Ya know. The 18Z guidance wasn't bad last night now that the 0Z came in. It was a little too amplified but it had the right idea. More northerly track in the eastern half of New England.

This is due to the storm organizing quicker which is due to the trough evolving towards neutral (and eventually negative) much fast than originally thought.

Looks really good this morning.
Member Since: September 26, 2011 Posts: 60 Comments: 9319
45. MAweatherboy1
11:22 PM GMT on January 20, 2014
Quoting 44. Pcroton:
Here's that Boston SREF Plume, from that link you provided.

Total snow...in inches? Is that correct? And the thick line smooths the average?





Just not familiar with this product yet.


That is all correct. Told you it was crazy high on amounts, lol. It's usually a pretty reliable short range model though.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
44. Pcroton
11:19 PM GMT on January 20, 2014
Here's that Boston SREF Plume, from that link you provided.

Total snow...in inches? Is that correct? And the thick line smooths the average?





Just not familiar with this product yet.

Member Since: September 26, 2011 Posts: 60 Comments: 9319
43. MAweatherboy1
10:12 PM GMT on January 20, 2014
I like this plot, it shows the 12z ECMWF deterministic run vs. its ensembles for Norwood, MA, a little ways southwest of Boston. You can see that the ensembles are in pretty good agreement with the operational, just slightly more robust on QPF in general. Remember, double these numbers for a more realistic estimate (about 8"). It still puts the ECMWF on the lower side of guidance.

Member Since: February 11, 2012 Posts: 84 Comments: 7948
42. Pcroton
10:07 PM GMT on January 20, 2014
Quoting 40. MAweatherboy1:

Agreed, I'm just having some fun with the scenarios :)

It's looking real good for both of us in terms of getting big snow!


Yeah looking very nice. Wide spread totals with an expanded precip swath width. Very nice compared to what we thought we had just a day ago (nothing).
Member Since: September 26, 2011 Posts: 60 Comments: 9319
41. Pcroton
10:06 PM GMT on January 20, 2014
Let me finish that thought a little better.

We currently have a few disturbances that have not yet combined to organize into a storm system. When we're in this stage of development, the off cycle runs aren't very good at putting things together, and can come in overly amplified or overly flat.

By tomorrow morning we will of course have an organized system rapidly developing and the 6Z guidance would probably be the first off-cycle suite you could put more trust into.


Member Since: September 26, 2011 Posts: 60 Comments: 9319
40. MAweatherboy1
10:02 PM GMT on January 20, 2014
Quoting 39. Pcroton:
Don't put much faith into 6Z or 18Z guidance. They don't incorporate soundings and are considered incomplete runs...or simple runs if you will.

Once you have a well developed storm and are closer to an event then the off cycle guidance is more trustworthy.

See what the 0Z guidance shows.

Agreed, I'm just having some fun with the scenarios :)

It's looking real good for both of us in terms of getting big snow!
Member Since: February 11, 2012 Posts: 84 Comments: 7948
39. Pcroton
9:57 PM GMT on January 20, 2014
Don't put much faith into 6Z or 18Z guidance. They don't incorporate soundings and are considered incomplete runs...or simple runs if you will.

Once you have a well developed storm and are closer to an event then the off cycle guidance is more trustworthy.

See what the 0Z guidance shows.
Member Since: September 26, 2011 Posts: 60 Comments: 9319
38. MAweatherboy1
9:51 PM GMT on January 20, 2014
Wow, not only did the 18z GFS not trend south like I thought it might; it trended noticeably north, to the point where jackpot amounts of around a foot move off the Cape and southeast Mass and into parts of eastern CT, western RI, and more towards Worcester MA as snow ratios get held down some further southeast.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
37. MAweatherboy1
9:31 PM GMT on January 20, 2014
Here's the NWS Taunton hazard map.



Blue is a winter storm watch. Pink is a winter storm warning. Lime green is a blizzard watch.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
36. MAweatherboy1
9:29 PM GMT on January 20, 2014
Ok, here's the NWS map. A bit higher on amounts than me.



18z GFS just starting now.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
35. MAweatherboy1
8:22 PM GMT on January 20, 2014
Here's the new map, taking into account all of the aforementioned 12z guidance, the 15z SREF, and the 18z NAM. The 15z SREF was crazy high on its totals, widespread 12" or more for most of the region. Definitely not buying that full on, but I've factored it in. The 18z NAM was running as I was making the map. It came in weaker and farther south, not a lot but it didn't show quite as much snow as the previous run. It caused me to shave about an inch off most of the amounts on the map, since I have been using the NAM as my model of choice. I'm very interested to see how the Taunton NWS map compares to this, and also interested in the 18z GFS to see if it trends farther south.

Member Since: February 11, 2012 Posts: 84 Comments: 7948
34. MAweatherboy1
6:24 PM GMT on January 20, 2014
12z ECMWF is in. It shifted north, though it remains a bit southeast of some of the other models. Here's the snow map:

(Deleted)

Assuming a 20:1 ratio (double those numbers) that is a widespread 6-10" east of Worcester with some 12" jackpots on the Cape.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
33. MAweatherboy1
5:12 PM GMT on January 20, 2014
The 12z NMM and ARW (that "short-range high resolution guidance" I was talking about earlier) are now on board for snow. 12z CMC was good for a widespread 6" or more. 12z GFS and its ensembles were good for that as well, along with of course the NAM and SREF. Getting harder to avoid the fact that a sizable snowstorm may be on the way. Definitely need to see the 12z ECMWF in an hour and a half or so to see if it comes on board, since it has been in the south/mostly out to sea camp. If it trends north as well I will probably up my numbers later today. Still over 24 hours out, which considering how quickly this has evolved is plenty of time for more changes.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
32. MAweatherboy1
3:56 PM GMT on January 20, 2014
I'll make a new snow map for New England this evening. Still plenty of 12z data left to come in, including the 12z ECMWF.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
31. MAweatherboy1
3:50 PM GMT on January 20, 2014
The 12z GFS is in; it's good! First of all, it's slower. Delays the start time but hangs onto the precip for longer. Track is similar, but it's a stronger low, leading to more snow than the 6z run, not far from the NAM. Widespread 6-10" assuming 20:1 ratios.

(Deleted)
Member Since: February 11, 2012 Posts: 84 Comments: 7948
30. MAweatherboy1
2:27 PM GMT on January 20, 2014
My thoughts on the 9z SREF and the 12z NAM:

1. The 9z SREF decreased snow amounts, but is still well above consensus. For example, despite a roughly .2" drop in mean QPF, there are still only 3 members out of 25 with 5" or less of snow for Boston, with the majority at 10" or more and several at 15" or more.
2. The 12z NAM was great for snow, up substantially on amounts from the 6z run. I've been liking the NAM on this storm so far, because it hasn't shown its typical bias to way overdo the storm run after run. It's behaved like a model should leading up to a storm, not perfect but stable at least. Here's its snow map. Remember, this map is based on a 10:1 ratio. I'm assuming 20:1 for this storm, like the one after New Years. So this is a widespread 6" or more with some 12" jackpots.

(Deleted)

Some of last night's short range/high resolution guidance seemed to be indicating a track farther south than the global models and the NAM, keeping us mainly dry. That scenario is still very much on the table, albeit not the most likely at this time. We'll see what the rest of the 12z guidance has to say.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
29. MAweatherboy1
12:22 PM GMT on January 20, 2014
By the way, there remains a threat of some snow showers/squalls late today with the arctic frontal passage. Northern MA and southern NH have the best shot, but I still think a general 30% chance for most areas, with maybe a 40-50% chance for southern New Hampshire.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
28. MAweatherboy1
12:09 PM GMT on January 20, 2014
OK, here's my map for New England:



I went a little heavier on snow than the NWS for areas farther north and west. There's still time for changes.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
27. MAweatherboy1
11:55 AM GMT on January 20, 2014
Good morning. Models continued to trend north last night although they seem to have leveled off the trend now. There's still disagreement with the GFS and SREF the most robust with widespread QPF. The ECMWF is farthest southeast and doesn't show much snow except for the Cape. The 6z NAM is in between. Here's the snow map from the Taunton NWS:



I think that's reasonable but I will be making my own map shortly and will post it here.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
26. MAweatherboy1
2:30 AM GMT on January 20, 2014
And now, guess what: The 0z NAM trended weaker and farther south! It shows 1-4" inside of I95, highest amounts on the Cape. Nothing elsewhere. A trend stopper? We'll see with the 0z data later tonight.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
25. MAweatherboy1
2:04 AM GMT on January 20, 2014
So if this forecast wasn't hard enough already, now we have this: The 21z SREF mean snowfall for Boston? ~17 inches. 8 members with 20" or more. All but two members with 5" or more. Mean QPF up to .7" from .5" on the 15z run (note those very high snow to water ratios). I'm certainly not jumping on this, it'll swing back the other way, but wow. Watching the 0z NAM now, which in its 18z run was in pretty good agreement with my forecast.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
24. Pcroton
12:55 AM GMT on January 20, 2014
That's a great link. Never came across it on SPC. They got so much on their site I just overlooked I guess.



Member Since: September 26, 2011 Posts: 60 Comments: 9319
23. Bluestorm5
12:46 AM GMT on January 20, 2014
Quoting 22. MAweatherboy1:

WeatherBell has SREF products, but I like these charts from the SPC more. Very easy to read and understand.

Link


This is much better than WxBell. I've seen it on Twitter, but never knew where to find it. Thanks!
Member Since: August 1, 2011 Posts: 28 Comments: 8041
22. MAweatherboy1
12:37 AM GMT on January 20, 2014
Quoting 21. Bluestorm5:


Are SREF members on WeatherBell or different source?

WeatherBell has SREF products, but I like these charts from the SPC more. Very easy to read and understand.

Link
Member Since: February 11, 2012 Posts: 84 Comments: 7948
21. Bluestorm5
12:33 AM GMT on January 20, 2014
Quoting 20. MAweatherboy1:
Good evening. Unfortunately I had to watch the Patriots season end tonight :( We lost to a better team though, that's how it goes. Very much an overachieving season! A few updates to the weather forecast:

Continued low confidence all around. There remains a chance of snow showers and squalls tomorrow afternoon/early evening. I think they will be hit and miss, with more misses than hits, not unlike summertime thunderstorms. Odds of any one location seeing one is about 30%, but where they hit a quick coating to an inch is possible. The big development today is the storm threat for Tuesday night, which is suddenly looking like a better snow opportunity than the Thursday-Friday event. Most models have trended north, with most of them showing accumulating snow for parts of the region (mostly southeast areas) for the storm. Since this event is only 48-60 hours out, it's already time to throw up a first thought snow map. Lots of disagreement and uncertainty with this storm. There are some mets sticking to the original idea that this will remain out to sea, and some biting on a more significant event. As for me, I'll steer a middle course for now. If I had to pick between a complete miss and a perfect hit, I'd take the miss. But as it stands now, I think we'll get enough of a graze to see the following amounts:



A few cautions:
The models have trended north faster than usual today. They could keep charging that direction, or they could go back the other way. As I've been saying, it's a volatile pattern that the models are struggling with. There's a real chance this misses us and goes completely out to sea, maybe just grazing the Cape and Islands with an inch or two of snow. But I certainly won't get caught off guard with this one like with what happened yesterday. I can always adjust amounts down if necessary.
Also, the "ceiling" on this storm in terms of amounts is very high. This adds to the uncertainty. As a perfect example of what I'm talking about, I'll use the 15z SREF (for Boston). The SREF is an ensemble model comprised of about 25 members. A few members show a complete miss, zero QPF. Several show the graze scenario, my forecast. A tenth or two of QPF (for Boston) which would equate to 2-4" of snow with expected high ratios in place. But listen to this- of the 25 members in the model, 5 of them (20%) show greater than 20" of snow at Boston, with one showing 33". That's wild. I certainly don't expect that to happen, but it's worth pointing out. Hopefully it gives some appreciation of how hard it is to make a forecast like this.


Are SREF members on WeatherBell or different source?
Member Since: August 1, 2011 Posts: 28 Comments: 8041
20. MAweatherboy1
12:25 AM GMT on January 20, 2014
Good evening. Unfortunately I had to watch the Patriots season end tonight :( We lost to a better team though, that's how it goes. Very much an overachieving season! A few updates to the weather forecast:

Continued low confidence all around. There remains a chance of snow showers and squalls tomorrow afternoon/early evening. I think they will be hit and miss, with more misses than hits, not unlike summertime thunderstorms. Odds of any one location seeing one is about 30%, but where they hit a quick coating to an inch is possible. The big development today is the storm threat for Tuesday night, which is suddenly looking like a better snow opportunity than the Thursday-Friday event. Most models have trended north, with most of them showing accumulating snow for parts of the region (mostly southeast areas) for the storm. Since this event is only 48-60 hours out, it's already time to throw up a first thought snow map. Lots of disagreement and uncertainty with this storm. There are some mets sticking to the original idea that this will remain out to sea, and some biting on a more significant event. As for me, I'll steer a middle course for now. If I had to pick between a complete miss and a perfect hit, I'd take the miss. But as it stands now, I think we'll get enough of a graze to see the following amounts:



A few cautions:
The models have trended north faster than usual today. They could keep charging that direction, or they could go back the other way. As I've been saying, it's a volatile pattern that the models are struggling with. There's a real chance this misses us and goes completely out to sea, maybe just grazing the Cape and Islands with an inch or two of snow. But I certainly won't get caught off guard with this one like with what happened yesterday. I can always adjust amounts down if necessary.
Also, the "ceiling" on this storm in terms of amounts is very high. This adds to the uncertainty. As a perfect example of what I'm talking about, I'll use the 15z SREF (for Boston). The SREF is an ensemble model comprised of about 25 members. A few members show a complete miss, zero QPF. Several show the graze scenario, my forecast. A tenth or two of QPF (for Boston) which would equate to 2-4" of snow with expected high ratios in place. But listen to this- of the 25 members in the model, 5 of them (20%) show greater than 20" of snow at Boston, with one showing 33". That's wild. I certainly don't expect that to happen, but it's worth pointing out. Hopefully it gives some appreciation of how hard it is to make a forecast like this.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
19. MAweatherboy1
1:10 PM GMT on January 19, 2014
Good morning. Here's a look at my thoughts for Southern New England for the next few days...

A few snow showers are possible this morning, if you happen to get caught under one you could see an additional coating of snow. Otherwise, clouds will break late morning and it turns into a pretty nice day, temperatures 35-40F. An arctic front will move through tomorrow, finally opening the floodgates for much colder air to move in. We'll hit the mid 30s again but by afternoon the temperature will drop with the frontal passage. This front may be accompanied by snow showers or squalls Monday late afternoon/early evening. That will have to be watched because models often struggle with snow squall events related to arctic frontal passages. Tuesday-Thursday are all very cold days. Highs will generally be between 15-20F, with Wednesday shaping up to be the coldest. Lows will be anywhere from 10 below to 10 above.
As far as precipitation goes, there are two main threats to watch. One is an ocean storm that should pass safely southeast of us late Tuesday and Tuesday night. The 6z GFS and its ensembles did trend this farther north, enough to give southeast Mass. 1-4" of snow late Tuesday/Tuesday night. I'm not buying that for now. I think this will stay well out to sea like most models show and as would seemingly be expected in this situation. Nonetheless, there is a chance of light snow on the south coast Tuesday night. Finally, we have a better chance of some snow Thursday/Thursday night as another low develops to our south, this one probably close enough to bring snowfall. It's not a big storm, but there is a fair chance of some light snow with minor accumulation possible, especially southeast MA. Here's a link to the NWS Taunton forecast discussion.

Link
Member Since: February 11, 2012 Posts: 84 Comments: 7948
18. MAweatherboy1
2:13 AM GMT on January 19, 2014
So now that this event is over, let's do a little forecast review...

48 hours ago there was supposed to be no snowfall accumulation today, with just scattered rain and snow showers expected. 24 hours ago there was some expectation for 1-3" of snow in northern and western areas, especially Worcester north and west. Then last night the models very abruptly trended stronger and colder on the storm, so that by this morning there was some expectation for a decent light snow event (see the maps in comment 8). It still looked like north and west areas would get the most in general, around 3-5" but it also appeared a small 6-8" bullseye would be likely for parts of southern Maine and southern New Hampshire. For western zones, the forecast ultimately verified pretty well, with lots of C-2" and 2-4" amounts in the areas where I thought they would be, even those these didn't turn out to be the highest totals from the storm like these areas were supposed to have. A major exception was a small zone of 8-10" that occurred in northwest Connecticut and far western MA. This wasn't expected at all, and the forecast busted completely there. The original bullseye from comment 8 verified very well. Several 6-8" amounts from in there. The main area that caught everyone off guard was eastern MA. In my map from comment 8, much of the light blue coating-2" zone east of Worcester ended up getting 3-6". That's a pretty bad forecast bust. From what I can tell I actually did better with my forecast than most of the local TV mets. Really though, no one can take credit for a good forecast on this one because it was such short notice. This one just popped up on us. I kind of figured this morning when that area of heavy sleet and snow set up across RI and eastern MA that those areas would see more than forecast, because the temperatures weren't going up. They very slowly came down during the day, allowing snow to accumulate. The 12z GFS really ended up being the first major model to key into what would happen (even though I basically disregarded it at the time). Here's a link to an NWS map showing reported snowfall totals across the area. This is an imperfect product; for one, reports are from various times; You could see a random .8" amount in a zone of 4-7" because that report came in before most of the snow fell. Also, these are all human measurements, and while today's snow consistency was favorable for easy measuring, there is an element of error. For example, the 5.0" inch amount southwest of Boston is suspect to me. Overall though, this shows what happened pretty well.

Link
Member Since: February 11, 2012 Posts: 84 Comments: 7948
17. MAweatherboy1
7:32 PM GMT on January 18, 2014
I've picked up about an inch and a half of heavy, wet snow at my house. Enough to build two pretty good snowmen :)

The steady snow has ended for my area but light snow and snow showers will continue for the next couple hours.

If you're curious, the 12z ECMWF fell in line with the GFS, as I expected, and dropped the storm threat for this week. It could swing back the other way, but I doubt it. Cold and dry look to be the keywords for this week.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
16. MAweatherboy1
7:24 PM GMT on January 18, 2014
Here's the latest snow map from Taunton:



It's really not all that far off from my forecast this morning, which as a whole is probably going to do alright; as I noted earlier, and as the Taunton map alludes to, the 6-7 (and maybe 8)" bullseye is going to be expanded a little more south and east.

5.2" in South Hudson, NH is the jackpot so far, though that number has probably increased. A winter storm warning has been posted for areas shaded in pink. Areas shaded in blue are under a winter weather advisory.

Member Since: February 11, 2012 Posts: 84 Comments: 7948
15. MAweatherboy1
5:56 PM GMT on January 18, 2014
I have to give some credit to the 12z GFS; if this snow had actually been accumulating at a 10:1 ratio, we may very well have seen some 5-6" amounts in eastern MA! Very interested in seeing final totals as they come in. Already up to 3" in Stow, MA and Littleton, MA. I just measured 1" of wet snow at my house, with the intensity now letting up.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
14. MAweatherboy1
5:27 PM GMT on January 18, 2014
What a rapidly evolving situation this has turned into. Look at the new 15z HRRR, contrasted with the 13z run in comment 12.



The takeaway from this: the forecast did not work out well for much of Rhode Island and parts of southeast Mass. Many of those areas will end up with a coating to 2" of snow and should have been included in that zone on the map. The north shore of MA that is currently in the C-2" zone will now need to be included in the 2-4" zone. The bullseye still looks pretty good, although it may need to be shifted or expanded to the south and east. Finally, it doesn't look like as much precip as expected is going to work into western zones. Western portions of the 2-4" zone will probably only see 1-3", and western portions of the 4-7" zone should only see 3-5". It sure has been fun to watch this happen though!

Edit: From Providence north and west, the steady precip will come to and end in the next hour, though additional, occasional rain or snow showers are likely for the rest of the day.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
13. MAweatherboy1
5:04 PM GMT on January 18, 2014
Heavy snow at my house right now, it's been like that for half an hour or so. Temperature has actually fallen a couple degrees to 33.5F. Big, wet flakes that have coated the ground. Very slow accumulation for such heavy snow, as expected. It's cool to watch though. No big forecast changes though, except northern areas of the "mainly rain" zone may actually see a coating to inch of snow if they haven't already.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
12. MAweatherboy1
3:53 PM GMT on January 18, 2014
Now I'm really confused. Check out this 12z GFS run. You're reading it right- 6" of snow in eastern MA.

(deleted)

That has to be a combination of a couple of problems. One is that the GFS appears to have initialized surface temperatures too low, causing it to show snow in areas that aren't seeing snow. Another is in the map itself; it assumes any snow that falls will accumulate at a 10:1 ratio. With temperatures above freezing and having been above freezing for days, that'll never happen. So this really doesn't change my thinking on anything; I have had a few sleet pellets and big wet snowflakes mix in recently, but it's mainly rain. The short range HRRR is modeling things well. Here's it's latest map through 15 hours, not quite the whole duration of the storm.



It doesn't have many totals over 4 or 5" through this period. It's possible an inch or two may need to be trimmed off all the zones in my map in comment 8.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
11. MAweatherboy1
3:26 PM GMT on January 18, 2014
Here's a good radar image from just a little while ago. Notice the spotty lines of precip to the north and west; those are snow showers which have already put down some coatings. The bright yellows, organges, and reds are not necessarily very heavy areas of precip or thunderstorms like those colors would often suggest. Rather, it is the radar beam detecting sleet pellets, which causes those bright returns.

Member Since: February 11, 2012 Posts: 84 Comments: 7948
10. MAweatherboy1
3:13 PM GMT on January 18, 2014
Been watching radar this morning; this is an interesting situation. I had some thunder at my house just a few minutes ago and there have been some other reports of thunder and lightning. It's safely above freezing at my house near the MA/RI border; we had some sleet earlier though. Late in the storm, cold air will wrap in to the storm, and there should be just enough moisture left to put down a coating to an inch in those southern areas of my C-2" zone. Radar is showing a few pockets of sleet right now. Temperatures remain at or below freezing in the areas that are expected to see mostly or all snow from this event, and they shouldn't come up a whole lot so the forecast looks good there. It remains unlikely that there will be a lot of reports of over 5-6" of snow.
Member Since: February 11, 2012 Posts: 84 Comments: 7948
9. MAweatherboy1
12:29 PM GMT on January 18, 2014
Today's event has the majority of my attention right now, obviously, but there remains a storm threat for Thursday/Friday. In brief, the GFS still keeps it totally dry, while the ECMWF still shows a storm, with the 0z run being more robust than yesterdays' runs. For now, I still favor the dry solution, but some snow, especially near the south coast, is possible. More on that later if necessary.
Member Since: February 11, 2012 Posts: 84 Comments: 7948

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About MAweatherboy1

Average 18 year old weather nerd. Freshman at Plymouth State University, majoring in meteorology, with the goal of becoming a professional forecaster.

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