Friday Forecast

104 Comments

7:29AM

DAYS 1-5 (APRIL 17-21)
You never call the snow season over in February, March, or even April, around here. Yes, it’s fairly rare to get measurable snow on any given day in April, but since Logan Airport averages over 1 inch of snow for the month of April, you know that it happens sometimes. Will Logan measure in this system? I think so. Will it be over 1 inch? Tough call. For snowfall accumulation in April you often need elevation, which will help in this situation, but it’s also going to be a nighttime event with cold air above us, even though the surface air will be above freezing and the ground temperatures considerably above freezing. So we have competing factors here with regards to accumulating snowfall. In fact it will be mild enough so that a fairly large portion of the region will see raindrops to start out before it cools enough for a flip to snow. I do think it may snow heavily enough for long enough during the dark hours to manage to get measurable snow right at the airport, but it may only be a thick coating, to perhaps 1 inch maximum, which will also be the case down the coast to north of Plymouth, over to near Providence RI, then southwestward into eastern CT. South of there, probably nothing more than flakes in the air in an otherwise mainly rain event, and even a burst of snow in those locations would be falling into air and onto ground to warm to really accumulate at all. Heading north from there is where 1 to 3 inches will accumulate, but mainly on grass, dirt, and cold vehicle tops, etc. The amounts will probably be on the lower side of that range and may not even make 1 inch from the Merrimack Valley to southeastern NH where the precipitation will be lighter. Add elevation, such as the Worcester Hills, then 3-5 inch amounts are possible, though I think that the lower side of that range is also the way it will go. You’d need heavier precipitation for as long as possible to get higher amounts and that may not be possible with the heavier bands remaining to the south, but there with a milder surface you’ll still need some elevation to realize anything more than the lower side of the range. For pavement and cement, cut these amounts at least in half. This event will be caused by low pressure passing just south of New England as it moves west to east and will wind down early Saturday, though it may take much of the day for clearing to begin. The balance of the weekend sets up to be nice on Sunday as a small area of high pressure moves off the Mid Atlantic and we turn mild with fair weather. Two systems will miss a phase on Monday, which will probably be an unsettled day with cloudiness and at least a chance of some rain, but the bulk of rainfall from low pressure passing to the south of the region may miss to the south. Still have to watch that as it’s not a certainty yet. A cold front will charge across the region west to east Tuesday with a rain shower threat.
TODAY: Sunshine followed by increasing clouds. Highs 45-52. Wind variable up to 10 MPH.
TONIGHT: Cloudy. Precipitation arrives as mostly rain, then turning to mainly snow, except mixed with rain at times Merrimack Valley and southeastern NH and down the eastern coastline to north of Plymouth, but mainly rain from Plymouth southward and westward along the South Coast region. See the discussion above for expected accumulations. Lows 32-39. Wind N up to 10 MPH.
SATURDAY: Cloudy with lingering rain/mix/snow morning. Breaking clouds afternoon. Highs 45-52. Wind NW 5-15 MPH.
SATURDAY NIGHT: Partly cloudy. Lows 35-43. Wind W 5-15 MPH.
SUNDAY: Sun then increasing high clouds. Highs 48-55. Wind variable up to 10 MPH.
SUNDAY NIGHT: Mostly cloudy. Lows 40-47. Wind variable up to 10 MPH.
MONDAY: Cloudy. Chance of rain. Highs 45-52. Wind variable up to 10 MPH except E 10-20 MPH near the South Coast.
MONDAY NIGHT: Mostly cloudy. Lows 40-47. Wind variable up to 10 MPH.
TUESDAY: Variably cloudy. Chance of rain showers, mainly afternoon. Highs 50-57. Wind S 10-20 MPH.

DAYS 6-10 (APRIL 22-26)
Dry April 22. Low pressure area impacts the region with a rain chance late April 23 and April 24, and another low probably tracking further north brings a rain shower threat sometime April 25 into April 26.

DAYS 11-15 (APRIL 27-MAY 1)
Temperatures near to below normal. Rain shower risk around April 28 and possibly again at the end of the period.

104 thoughts on “Friday Forecast”

  3. Some re-posts from earlier

    JpDave says:
    April 17, 2020 at 6:21 AM
    HRRR Receives an upgrade soon. HRRRv4 due to be released in June. Currently available at College of DuPage Website.

    https://stormtrack.org/community/threads/hrrrv4-upgrade-june-2020-also-rap-to-v5.31305/

    Reply
    JpDave says:
    April 17, 2020 at 6:28 AM
    All of the high resolution models are relatively robust for tonight’s snow.

    Here is the latest NWS map

    https://www.weather.gov/images/box/winter/StormTotalSnowWeb.png

    Some High resolution models,all 10:1
    HRRR
    https://www.tropicaltidbits.com/analysis/models/?model=hrrr&region=neus&pkg=asnow&runtime=2020041706&fh=34

    HRDPS

    https://www.tropicaltidbits.com/analysis/models/hrdps/2020041706/hrdps_asnow_neus_34.png

    WRF-ARW

    https://www.tropicaltidbits.com/analysis/models/wrf-arw/2020041700/wrf-arw_asnow_neus_40.png

    WRF-ARW2

    https://www.tropicaltidbits.com/analysis/models/wrf-arw2/2020041700/wrf-arw2_asnow_neus_40.png

    WRF-NMM

    https://www.tropicaltidbits.com/analysis/models/wrf-nmm/2020041700/wrf-nmm_asnow_neus_40.png

  4. Good morning and thank you TK.
    Snow accumulation will depend upon snow intensity and duration of said intensity.
    I expect about 2 inches here in JP, but I wouldn’t be surprised at more or less. It’s
    a real crap shoot this time of year. Intensity will overcome most mitigating factors, should we get it. Should be most interesting come tomorrow morning.

    1. My daughter said that yesterday too. The air has had a real bite even when the temps are a higher.

  12. To Joshua’s point above :

    Logan’s January avg temp was 38.1F, 9.1F above average

    Logan’s April avg temp is currently 46.0F

    At first glance, that’s a 7.9F difference. But, if you take the avg high in mid Jan to be 38F and mid April to be 57F, there should be a 19F or so difference, not 8F.

  13. Thanks TK.

    Haven’t looked super closely, but I’m fairly bullish on the snow potential in SNE tonight. The NWS expected range map looks pretty reasonable to me, I’d favor the higher end. Agree with TK, amounts will not only be elevation dependent but surface type dependent. The overnight timing is clutch in terms of getting accumulation. Certainly a chance we overperform and end up with a widespread 6” of glop. Somewhat concerned for power outages but think that should be fairly limited.

    1. Thanks WxWatcher

      Higher resolution models seem to be holding firm on around 4 inches
      Kuchera. Higher amounts in some locations.

      That RPM model had a decent swatch of 4-6 inches.
      When will the HREF be out?

      thanks

  14. I’m looking at the HRRR, the 12z NAM, southern suburbs of Boston look like they may get more snow than I am seeing on many snow map projections.

    I believe it too, timing, low dp’s ……..

  15. HREF coming out now. Showing 1 inch per hour snow falls downstream/upstream? from us.
    (Is downstream correct or is it upstream? If I compare the 500 mb flow to a river,
    then something to the west of us should be Upstream as it is flowing Eastward, shouldn’t it?)

    1. Ending 8 AM tomorrow morning, which “should” pretty much coincide with
      the snow shut off or close to it.

  20. I am going to be missing out on the fun unless that snow area could come just a tad further south.

  23. Some of the models are showing rain for several hours before changing to snow.
    With the cold air above and intensity of precip, I believe that it may be all snow
    from the start or at least a brief period of rain before changing over. In short,
    more snow than some models are showing. I have seen this situation many times
    in April before. Most of the area should be seeing 4-6 inches, imho, but what
    the hell do I know. We shall see. Should be interesting tonight.

    I’ll probably be looking out the window wondering when the bleep the rain will
    change over to snow. 🙂 🙂 🙂

  24. Latest NWS snow map

    https://www.weather.gov/box/winter

    MAZ006-007-014>016-172215-
    /O.CON.KBOX.WW.Y.0009.200418T0600Z-200418T1600Z/
    Western Essex MA-Eastern Essex MA-Southeast Middlesex MA-
    Suffolk MA-Eastern Norfolk MA-
    Including the cities of Lawrence, Gloucester, Cambridge, Boston,
    and Quincy
    1003 AM EDT Fri Apr 17 2020

    …WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 2 AM TO NOON
    EDT SATURDAY…

    * WHAT…Snow expected. Total snow accumulations of 2 to 4
    inches.

    * WHERE…Essex, Southeast Middlesex, Suffolk and Eastern
    Norfolk Counties, away from the immediate coast.

    * WHEN…From 2 AM to noon EDT Saturday.

    * IMPACTS…Plan on slippery road conditions.

    PRECAUTIONARY/PREPAREDNESS ACTIONS…

    Slow down and use caution while traveling.

    &&

  27. From Eric Fisher
    Most likely adjustment to snow forecast this afternoon will be to shift our 2-5″ band a bit farther south. Will have an updated version shortly

    1. For Boston:

      …WINTER WEATHER ADVISORY NOW IN EFFECT FROM 11 PM THIS EVENING
      TO 10 AM EDT SATURDAY…

      * WHAT…Snow expected. Total snow accumulations of 2 to 5
      inches.

      * WHERE…Portions of eastern, northeastern and western
      Massachusetts.

      * WHEN…From 11 PM this evening to 10 AM EDT Saturday.

      * IMPACTS…Roads will become snow covered as rain changes to a
      period of heavy snow. Plan on slippery road conditions. There
      is also a low risk for isolated power outages where snow
      accumulations exceed 4 inches.

      * ADDITIONAL DETAILS…A period of heavy snow with snowfall rates
      around 1 inch per hour are possible for a few hours after
      midnight, spreading west to east.

      PRECAUTIONARY/PREPAREDNESS ACTIONS…

      Slow down and use caution while traveling.

  29. From Eric Fisher
    4.1″ is the number to beat in Boston tonight
    Top that, and it would be the biggest snow event on record this late in the season. 2.3″ would be good for 2nd place.
    Would come after the least snowy astronomical winter on record
    Looks unlikely, but not impossible

    2. Doesn’t relate at all to what it will do here. The climate of the mountains and southern New England are vastly different from each other. The things that made this storm overachieve out there have zero impact on the storm’s performance here.

  34. Not sure what it means, if anything, but the HRRR has come down in total Kuchera Snow Every run since sometime this morning. Now only about 2.9 inches
    for Boston whereas it was up to 4.7 or 4.9 at one point.

    2. It’s still too high for Boston.

      And the only place that has a shot of four to six inches out of this, probably more like four or five, would be higher elevations where intensity is at its greatest for longest.

  36. Kind of at the intersection of weather and the COVID crisis, and worth posting: Northern Vermont University, previously known as Lyndon State College, is in serious jeopardy of being closed down after new proposals from trustees, with the state university system facing huge deficits. NVU/Lyndon is one of the top meteorology programs in the East (the whole country, even). It’s particularly popular among broadcast meteorologists. They also host the annual Northeastern Storm Conference, among many other things.

    I visited Lyndon, and while it was not the right fit for me I personally know a number of people who have gone there, and their alumni network is vast and global. For a small school, the atmospheric science program is really their cornerstone. It would be sad to see it go. There is a change.org petition to save the school.

    https://www.change.org/p/vermont-state-senate-securing-the-future-of-the-vermont-state-colleges?source_location=topic_page

    2. Beautiful campus and a great community.

      Get use to hearing many more stories like these. A lot of what we knew will no longer be.

      1. More than one campus is impacted. This is not a new problems according to this report and others. They may yet get funding. And yes, things will change. But then things don’t supersede life

  37. No changes after a glance at the latest info…

    We get out late-season snow event (for most) tonight.
    Monday’s rain event looks like largely a miss or glancing blow.

    1. No way. That’s too high. If they win the lottery they’ll get an inch. Probably less.

    1. Intensity & elevation needed.

      Other than the HRRR and to some extent the GFS, the models are crap on this. I’m not really sure what NWS was thinking UPPING their #’s on 2 successive updates. SAK explained this in his last couple blog updates.

      Meteorology, not modelology. We say it over and over. 😉

      As of 2:15AM I have light rain and a temp of 41 in Woburn. I may chop my #’s down a bit more.

      1. I think we are going to see a huge disparity in totals between the hills and valleys/coast with this one! Typical late season storm.

  45. 2” now and really coming down hard! Walkway, driveway and road now covered as well.

    Going to bed and will set the alarm for 630 to measure.

    1. I think you may be in one of the “jackpot zones” as you have some elevation and intensity combined with darkness. Areas to the north and east are going to struggle to get into the lower sides of my ranges. Earlier I tweaked my discussion amounts to reflect this.

      Let me know what you end up with. Should be over 3.

  46. Oh I will report in the AM for sure. Hate to go to bed during this but need a few hours of sleep!

  47. snowing moderate to heavy in East Bridgewater. temp is 34, grass covered, roads are a slushy white. about an inch has fallen so far

  48. snowing moderate to heavy in East Bridgewater. temp is 34, grass covered, roads are a slushy white. about an inch has fallen so far

  49. Snowing quite hard here in JP. 33 Degrees. Looks like about an inch on the ground.
    Maybe Logan won’t see an inch, but clearly we will here, probably 2 by the time it
    is done. 🙂 back to bed….

  50. 4.2” of heavy wet snow here in Coventry CT. 32 degrees and Snow has tapered to a mist/light drizzle. Beautiful winter wonderland outside with everything plastered in snow!

    1. Nice! Enjoy as it’s going to melt fairly quickly, most especially tomorrow
      if any is left. 🙂

  51. Still snowing decently here in JP. Temp still 33.
    Looks like about 1.5 inches. Hard to say for sure.

    Here are a few photos from 2nd floor windows.

    https://imgur.com/a/lx89D7d

    Looks like maybe 1/2 to 1 inch in last 2+ hours. Like it is melting from the ground up
    as fast as it is accumulating. One of the issues for accumulation this time of year.

    3. That’s why SAK & I said that a lot of the model #’s were not going to work out. Ground too warm. Also no daytime accumulation. Our #’s are verifying.

    1. Yup, they certainly tell the story. Thanks.
      Didn’t get as much here, but it sure does look Wintry!

  53. Between the initial rain and any snow that melted, my rain gauge is currently
    showing 0.24 inch of melted precip. How much more will melt into as we gone on here? Time will tell. Gauge says the precip event has been going for 6 hours.

    1. NWS forecast #’s were too high as SAK & I suspected. The #’s look like they are falling mostly in the ranges predicted by SQ & WHW, and most TV outlets.

  55. 4” on my snow board and probably 2.5 on the ground. Sun should wipe this out today hopefully.

  57. Barely a coating where I am. It did come down for a little bit around midnight but as is the case this time a year elevation played a key role. It is snowing now where I am but it won’t accumulate.

    1. It’s interesting how you seem to always miss out and Mark gets all the fun who is much farther east.

      1. It’s a matter of elevation here, not so much east vs. west. Directions don’t play nearly as much a role in regional weather as many people believe. It’s geography (maybe coast vs. inland) and elevation more than anything, depending on each situation.

  61. Philip I miss out in these situations due to elevation. If you take a ride north of where I am it looks like a winter wonderland this morning. Northern Litchfield County looks different than Southern Litchfield County this morning.

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