Sunday April 11 2021 Forecast (7:57AM)

DAYS 1-5 (APRIL 11-15)

When my forecast works out, as my self-expectation is that it should daily, my practice is not to point that out, but I do like to point out things that I missed in a forecast. Yesterday, I was torn on whether or not to put the risk of a pop-up shower from the “heat of the day” (in a relative sense) and ahead of an approaching back-door front. I saw that 2 fairly reliable pieces of short range guidance had forecast these pop ups across central Maine and parts of NH, and I thought about adding a pop up possibility to at least southern NH, but opted to leave it out of the written forecast thinking it was the longest of long shots there. Alas, a decent cluster of moderate to even briefly heavy showers popped up over south central NH and made their way into northeastern MA during the late afternoon and evening Saturday. Certainly not a huge forecast buster, but I’m shore that a few folks’ had a surprise on their evening walks, but at least may have been treated to a rainbow after getting unexpectedly wet. Sometimes a forecaster can worry about putting too much in a day’s forecast, but yesterday when doing a regional forecast it would have been accurate to talk about South Coast low clouds and fog, clouds giving way to sun in the major metro areas, a lot of areas getting well into the 70s, a sea breeze still making an appearance for a while along the eastern shore before giving up again late in the day, and the above-mentioned pop up shower cluster. I didn’t have the last 2 on that list in my forecast, but I should have. Ah well – time to move on! During the early morning hours, the aforementioned back-door cold front did slide across the region and while it was not accompanied by a lot of wind or any precipitation, it did introduce a deck of stratus clouds from the northeast, and a notable temperature drop (Logan Airport, for example, from 58 at 3 a.m. to 49 at 4 a.m., now down a bit more to 48 as of 7 a.m.). The temperature drop was a bit more subtle over inland areas as the front got there a little bit later (some areas are still in the middle to upper 50s as of this blog writing). But by late morning all of the region will be in the marine air mass, generally covered in stratus clouds. There was already a deck of stratus and areas of fog back along the South Coast where the wind was still from the southwest before the front’s arrival since last evening, so they had their marine layer there, just from a different direction, now to mix with the new marine layer from the northeast. While this is going on down here at the surface, another arm of moisture from decaying low pressure to our west is moving into the region from the southwest, and its rain area has struggled to make any significant progress. And while still a decent area of rain, it sits still southwest of New York City early this morning, but will make progress toward and into New England from southwest to northeast, so that by the time it gets into the WHW forecast area during the afternoon and evening it will be in the form of patches of mainly light rain. That’s a shame, honestly, because we could really use a decent rainfall. And even though this low pressure area is going to take 2 1/2 days to pass by our area (center passing to the south of here) and we will be in its circulation, it’s really not going to manage to produce any beneficial rainfall, just lots of clouds, cool temperatures, and some damp weather. We may get a sneaky milder day in about Wednesday as we find ourselves with a small ridge of high pressure sliding across the region and offshore between departing low pressure and the approach of another low from the southwest. By Thursday, we may already be back in the envelope of clouds from this approaching low along with a southeasterly air flow.

TODAY: Cloudy. Areas of fog South Coast mainly during this morning. Areas of fog and drizzle developing East Coast mainly during this afternoon. Chance of light rain mid to late afternoon, favoring areas south and west of Boston. Coastal temperatures fall slightly to 45-52. Inland temperatures 50-57 early fall to 45-52 during the day. Wind NE to E 5-15 MPH.

TONIGHT: Cloudy. Periods of rain possible. Areas of fog and drizzle. Lows 42-49. Wind NE to E 5-15 MPH.

MONDAY: Cloudy. Areas of fog and drizzle. Periods of rain possible. Highs 47-54, coolest coastal areas. Wind E to NE 5-15 MPH.

MONDAY NIGHT: Cloudy. Lows 41-48. Wind NE up to 10 MPH.

TUESDAY: Mostly cloudy. Areas of fog and drizzle possible near the East Coast. Highs 47-54. Wind NE to N 5-15 MPH.

TUESDAY NIGHT: Mostly cloudy. Lows 39-46. Wind N up to 10 MPH.

WEDNESDAY: Partly sunny. Highs 55-62, coolest coastal areas. Wind variable to S up to 10 MPH.

WEDNESDAY NIGHT: Variably cloudy. Patchy fog. Lows 45-52. Wind S to SE up to 10 MPH.

THURSDAY: Mostly cloudy. Highs 52-59, coolest coast. Wind SE 5-15 MPH.

DAYS 6-10 (APRIL 16-20)

Slow eastward progression of large scale pattern. While guidance can lead one astray beyond a few days, the current expectation based on a combo of guidance and pattern anticipation leads to a forecast of cloudy/damp/cool weather for April 16 with and east to northeast wind as low pressure passes to the south, but it remains to be seen if we’ll have any significant rainfall. It may even be cold enough for some mixed precipitation and or snowflakes in parts of the region. This low should exit with a drier/cool northerly air flow by April 17. As high pressure ridging nudges eastward we should end up milder/dry for April 18-19 before the next low from the west brings at least clouds back by the end of the period.

DAYS 11-15 (APRIL 21-25)

Still not putting much faith in guidance beyond general pattern ideas out this far into the future. Early idea: Dry start, then some wet weather chances. No temperature extremes.

Saturday April 10 2021 Forecast (8:49AM)

DAYS 1-5 (APRIL 10-14)

I’m not sure if you’ve been keeping track, but this is going to be the 5th consecutive “nice weather” Saturday. Two caveats to start the day though: 1) Low level moisture is causing some fog and low clouds near the South Coast which may take some time to break and dissipate. 2) A band of cloudiness from mid level moisture is rolling across eastern MA and south central NH as of 7:45 a.m. and has even had a few sprinkles of rain falling from it. This band of clouds will thin and break with time, but other patches of clouds will be around today, so don’t expect 100% sun. Despite that, it’s going to be even warmer today in some areas I anticipated would be cooler (eastern coastal areas, for example). You can thank the break-down, or weakening, of an “omega block” that has been responsible for several days of really nice spring weather here (though it has down sides: high pollen count, high fire danger, and lowering water supply). Today, everybody gets into a southwesterly air flow a little stronger than I had previously expected as high pressure sinks to the south, so other than the cooling influence in coastal areas where a southwest wind travels over water first, it’s going to be a rather warm day for mid April, with many areas reaching or exceeding 70. Enjoy it if you can, but don’t get used to it! One of our famed “back-door” cold fronts is on the way, and will charge across the region from northeast to southwest during the early hours of Sunday, introducing a northeast to east wind and much cooler marine air, complete with low clouds and eventually areas of fog and drizzle. Some areas that are in the lower 70s this afternoon will find themselves around 25 degrees cooler, in the upper 40s tomorrow afternoon. While this is going on regionally, the larger scale pattern shift will allow low pressure that has been stuck to our west to finally move eastward, kind of. It’s not going to charge in here because it’s still being met with resistance from the high pressure ridge that is moving slowly to the east off the East Coast, and the trough’s surface low will be trying to send lobes of moisture eastward that run into dry air. One such lobe will bring an area of rain into the region on Sunday, but as it advances in it will also be falling apart, so while some areas may see rain from it, other areas may not see a drop from that and are more likely to get wet from the drizzle caused by the air flow from the ocean. Either way, plan on Sunday being far different weatherwise than today is, which is certainly the pick of the weekend for outdoor activity! Looking ahead to the first part of next week, back to more of springtime reality for the Northeast as a large upper low, once the western portion of the omega block, swirls over and just south of the region. While this low is not loaded with moisture, it is likely to keep us on the cooler and somewhat cloudier side for several days. Unfortunately it does not look like it will generate much in the way of rainfall, which we could use.

TODAY: Fog/stratus South Coast into mid morning, variable clouds elsewhere with a possible sprinkle of rain eastern MA into mid morning. Sun/cloud mix midday-afternoon. Highs 58-65 South Coast, 66-73 elsewhere. Wind SW 5-15 MPH.

TONIGHT: Increasing clouds. Lows 45-52. Wind SW up to 10 MPH shifting to NE 5-15 MPH overnight.

SUNDAY: Cloudy. Areas of fog and drizzle. Chance of light rain in the afternoon. Temperatures generally steady 45-52. Wind NE to E 5-15 MPH.

SUNDAY NIGHT: Cloudy. Periods of rain possible. Areas of fog and drizzle. Lows 40-47. Wind NE to E 5-15 MPH.

MONDAY: Mostly cloudy. Areas of fog and drizzle. Periods of rain possible. Highs 47-54, coolest coastal areas. Wind E 5-15 MPH.

MONDAY NIGHT: Mostly cloudy. Lows 40-47. Wind NE up to 10 MPH.

TUESDAY: Partly sunny. Highs 48-55. Wind NE to N 5-15 MPH.

TUESDAY NIGHT: Mostly cloudy. Lows 39-46. Wind N up to 10 MPH.

WEDNESDAY: Partly sunny. Highs 50-57. Wind N 5-15 MPH.

DAYS 6-10 (APRIL 15-19)

Upper level pattern crawls eastward, starting out with low pressure near and just east of the region and our region in a coolish and slightly unsettled pattern. Eventually ridging pushes eastward and we may warm up (still cooler coast) by the end of the period. No significant precipitation in sight.

DAYS 11-15 (APRIL 20-24)

I’m not crazy about the medium range guidance timing of large scale features. Based on this my current idea is to slow everything down from what is shown on guidance. This would keep us mostly dry into late April finally with a rain chance increasing later in the period. Low confidence on this outlook.

Friday April 9 2021 (7:29AM)

DAYS 1-5 (APRIL 9-13)

Blocking continues and keeps high pressure in place through Saturday, then weakens and allows low pressure to run at the region from the southwest later in the weekend into early next week, but enough high pressure remains in eastern Canada to try to force this series of lows to the south as well as resulting in them running into dry air. To get any rain we need to rely on enough dynamics from the lows surviving, then maybe adding some drizzle to the mix via low level moisture from an eastern air flow off the Atlantic. This basically results in unsettled but not total wash-out weather Sunday into early next week. I’ll repeat here what I said in yesterday’s discussion: Any rain we can get will be welcomed as we are running a precipitation deficit of a few to several inches for the year-to-date with the latest U.S. Drought Monitor reporting abnormal dryness across most of southeastern New England, and of course the continued high fire danger.

TODAY: Sunny. Highs 55-62 coast, 63-70 inland. Wind variable up to 10 MPH with coastal sea breezes developing.

TONIGHT: Mostly clear. Interior lower elevation ground for forming. Lows 40-47. Wind variable under 10 MPH.

SATURDAY: Mostly sunny. Highs 57-64 coast, 65-72 inland. Wind variable up to 10 MPH with coastal sea breezes developing.

SATURDAY NIGHT: Increasing clouds. Lows 42-49. Wind SE under 10 MPH.

SUNDAY: Cloudy. Areas of drizzle and fog developing. Chance of rain. Highs 48-55 coast, 56-63 inland morning, then falling. Wind SE to NE 5-15 MPH, gusts to 20 MPH eastern coastal areas.

SUNDAY NIGHT: Cloudy. Periods of rain possible. Areas of fog and drizzle. Lows 40-47. Wind NE to E 5-15 MPH.

MONDAY: Mostly cloudy. Areas of fog and drizzle. Periods of rain possible. Highs 48-55, coolest coastal areas. Wind E 5-15 MPH.

MONDAY NIGHT: Mostly cloudy. Areas of fog and drizzle. Lows 40-47. Wind E up to 10 MPH.

TUESDAY: Mostly cloudy. Chance of coastal drizzle and patchy fog. Highs 49-56, coolest coast. Wind E to SE up to 10 MPH.

DAYS 6-10 (APRIL 14-18)

Look for renewed blocking, this time with low pressure generally near or just off the East Coast, an often easterly to northerly air flow here with episodes of unsettled weather but no widespread soaking rainfall. Temperatures while on the cooler side will average closer to normal due to nights that aren’t that chilly but days that aren’t that mild.

DAYS 11-15 (APRIL 19-23)

Indications for a nudge eastward of features and high pressure moving over this area which would result in mostly dry weather, cool nights, cool coast & warm inland days. Confidence remains low on the forecast this far out.

Thursday April 8 2021 Forecast (6:56AM)

DAYS 1-5 (APRIL 8-12)

A moderate to strong blocking pattern will keep a ridge of high pressure parked over our area for the next 3 days, resulting in nice spring weather. With a general light northerly to variable air flow, expect daily sea breezes and cooler conditions in coastal areas while inland locations see a slow daily warming trend. By Sunday and Monday, the block will have weakened enough to allow features to move from west to east once again, but this means the first of a series of low pressure areas will begin to impact the region on Sunday when rain chances increase. How much rain is able to get into the region Sunday will depend on how much dry air there is to battle. While I’m not seeing anything that resembles a heavy rain event, I do expect it to be rather overcast and damp with some rain Sunday into Monday. Any rain we can get will be welcomed as we are running a precipitation deficit of a few to several inches for the year-to-date, are teetering on the edge of a drought again, and continue to see high fire danger with dry ground and the area still pre-leafout.

TODAY: Variably cloudy morning. Mostly sunny afternoon. Highs 50-57 coast, 58-65 inland. Wind N up to 10 MPH with coastal sea breezes by noon.

TONIGHT: Partly cloudy. Fog patches interior lower elevations. Lows 37-44. Wind calm.

FRIDAY: Sunny. Highs 52-59 coast, 60-67 inland. Wind variable up to 10 MPH with coastal sea breezes developing.

FRIDAY NIGHT: Mostly clear. Interior lower elevation ground for forming. Lows 38-45. Wind variable under 10 MPH.

SATURDAY: Mostly sunny. Highs 55-62 coast, 63-70 inland. Wind variable up to 10 MPH with coastal sea breezes developing.

SATURDAY NIGHT: Increasing clouds. Lows 42-49. Wind SE under 10 MPH.

SUNDAY: Cloudy. Areas of drizzle and fog developing. Chance of rain. Highs 48-55 coast, 56-63 inland. Wind SE to E 5-15 MPH.

SUNDAY NIGHT: Cloudy. Periods of rain possible. Areas of fog and drizzle. Lows 45-52. Wind E 5-15 MPH.

MONDAY: Mostly cloudy. Areas of fog and drizzle. Periods of rain possible. Highs 48-55, coolest coastal areas. Wind E 5-15 MPH.

DAYS 6-10 (APRIL 13-17)

What was once the western trough of an omega block will likely become the eastern trough of a newly formed omega block during this period and will be over or just east off the East Coast during this period. For us this means no big warm ups but also not that cold, and somewhat unsettled weather, but more in the form of occasional showers with spokes of energy rotating about the larger upper level system.

DAYS 11-15 (APRIL 18-22)

Only very little change to the overall pattern at most, with possibly a slow eastward drift to the overall set-up again, which may put our area back under a high pressure ridge with more dry weather, cool nights, cool coast & warm inland days. Confidence remains low on the forecast this far out.

Wednesday April 7 2021 Forecast (7:36AM)

DAYS 1-5 (APRIL 7-11)

The large scale blocking pattern (omega) continues with a slight eastward progression to the set up expected during the next 5 days. Today through Friday the high pressure ridge that makes up the middle of the block will move eastward over New England while the low pressure area that has been doing a cyclonic loop to our east continues to pull away. As this happens, the very dry Canadian air that had come in behind that low Monday and Tuesday will be replaced by air with a little more maritime moisture in it, and this will lead to the advance and development of low level cloudiness that may overtake the sky in much of the region by this afternoon and certain tonight into early Thursday, before it gets eaten away by some drier air and the warming influence of the sun. By Friday, the an extension of surface high pressure should shut off any maritime influx and limit the low cloud potential, so that day should end up clearest of the next 3. The upper pattern continues a slow eastward shift by the weekend, nudging the ridge off the East Coast and allowing the western low pressure trough to approach. It’s still up in the air (figuratively) as to how much impact we see here from the trough and its associated surface low pressure area. For now, introducing the chance of some wet weather for Sunday’s forecast, knowing that it may also be held back from arriving or never make it here at all. So if you are making outdoor plans for the weekend, Saturday is your more guaranteed dry day at this point.

TODAY: Lots of sun followed by lots of clouds. Highs 49-56 coast, 57-64 inland. Wind N to NE up to 10 MPH.

TONIGHT: Mostly cloudy. Lows 38-45. Wind NE up to 10 MPH.

THURSDAY: Lots of clouds followed by partial sun. Highs 49-56 coast, 57-64 inland. Wind NE to E up to 10 MPH.

THURSDAY NIGHT: Partly cloudy. Lows 37-44. Wind calm.

FRIDAY: Sunny. Highs 52-59 coast, 60-67 inland. Wind variable up to 10 MPH with coastal sea breezes developing.

FRIDAY NIGHT: Mostly clear. Interior lower elevation ground for forming. Lows 38-45. Wind variable under 10 MPH.

SATURDAY: Mostly sunny. Highs 53-60 coast, 61-68 inland. Wind variable up to 10 MPH with coastal sea breezes developing.

SATURDAY NIGHT: Increasing clouds. Lows 42-49. Wind SE under 10 MPH.

SUNDAY: Cloudy. Chance of rain. Highs 48-55 coast, 56-63 inland. Wind SE to E 5-15 MPH.

DAYS 6-10 (APRIL 12-16)

What was once the western trough of an omega block will likely become the eastern trough of a newly formed omega block during this period and will be over or just east of the East Coast during this period. For us this means no big warm ups but also not that cold, and somewhat unsettled weather, but not likely any big storms either – again fairly typical blocky springtime set-up. Can’t really determine day-to-day details this far out with that kind of pattern.

DAYS 11-15 (APRIL 17-21)

Only very little change to the overall pattern at most, with possibly a slow eastward drift to the overall set-up again, which may put our area back under a high pressure ridge with more dry weather, cool nights, cool coast & warm inland days. Not high confidence on this forecast though.

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