Summer 2017 Forecast

I’m going to make this version of the summer outlook fairly quick, simple, and to the point. Our drought now essentially behind us, and the pattern having been wet, it’s obvious we are not going into summer 2017 the way we did just a year ago. The pattern in the spring was wet, with a cold March, a milder April, and a very cool May (the coolest since 2005 and the first below normal May in many parts of the region since 2008). What follows is a short summary of what I expect for the summer. I have observed forecasts from colleagues, NOAA, and other professionals and I will say that I’m in general agreement with most of them.

SUMMER 2017 OVERVIEW
A pattern of blocking at high latitudes has resulted in a pattern of frequently cool, often cloudy, and occasionally wet weather for New England during the last several weeks, and this general idea will continue into the early and mid part of June, though as climatology dictates, we continue to warm slowly as we advance the calendar so the direct impact, while less, will still be noticeable when compared to daily normal values, especially for temperature. As we move into late June, we should see a shift of the pattern as blocking weakens and dissipates, and a more zonal flow takes over. This will allow more episodes of westerly flow and more seasonable warmth with occasional spikes of heat alternating with brief cool-downs as air masses change with passing systems on a more progressive jet stream. Heading into the heart of summer, provided a forecast El Nino is slow to develop, and I suspect it will be, we should see an occasional Bermuda High setup as high pressure in the western Atlantic occasionally retrogrades (backs westward) toward the East Coast. During these times we will see our higher humidity, some heat, and episodic showers/thunderstorms. The shower activity this summer will be more prolific than that of last summer, keeping overall precipitation amounts near to above normal and preventing a slip back into drought. This, along with what ends up being a warmer middle and end, will skew temperatures to near to above normal. So the theme of summer 2017, after its cool start, will be warm and wet.

JUNE SPECIFICS
Current pattern of blocking and frequent troughing in the Northeast continues through mid month with precipitation above normal and temperatures below normal. Pattern breaks down around the summer solstice and the last third of the month will be warmer and drier with passing systems in a more progressive jet stream flow causing brief shower/thunderstorm threats.
Temperature: Below normal.
Precipitation: Above normal.

JULY SPECIFICS
The first half of the month should feature the pattern that is established during the latter third of June. The second half of the month will feature an alternating between the early July pattern and a more humid and showery Bermuda High pattern. Though this type of pattern does not typically produce all day rains, we’d have to be on the lookout for some tropical moisture feeds that could provide days with frequent showers/thunderstorms.
Temperature: Near to above normal.
Precipitation: Near to above normal.

AUGUST SPECIFICS
Take the pattern of the second half of July and continue it for August, but with more emphasis on Bermuda High and less so on westerly flow and progressive jet stream. Should be a warm and humid month with episodic showers and thunderstorms. Though we cannot predict very far in advance whether or not a tropical storm or hurricane will threaten the region, or any part of the US coast, we can say that a Bermuda High pattern can leave the East Coast vulnerable, should a storm form and be in the right position to get around the western side of such a high pressure area.
Temperature: Above normal.
Precipitation: Near to above normal.

Wednesday Forecast

8:20AM

DAYS 1-5 (MAY 31-JUNE 4)
This is the final day of what has been a cool and wet May overall, despite a 3-day heatwave for many locations during mid month. This will be the first May since 2008 where the temperature comes in below normal in Boston, and the coolest May there since 2005. Our final day of the month will feature more cloudiness but eventually some areas of sunshine. A weakening cold front in the region may trigger a few showers through early afternoon and then another approaching cold front will send showers/thunderstorms toward the region from the west this evening but they will have trouble surviving all the way through the region as we lose daytime heating and have somewhat more stable air in place compared to the air to the west of the region. Though it will be more unstable than it was yesterday so some of the activity may survive to some extent. Will watch this as the day goes on. A drier westerly flow will take over for Thursday but another weak disturbance may trigger a shower or 2 west of Boston in the afternoon. The next in a parade of fronts will approach later Friday with yet another risk of showers/thunderstorms. Current indications are that this will move along enough so that improvement will be seen Saturday. High pressure then moves across the region keeping most of the weekend dry though by late Sunday we’ll be watching the approach of a low pressure area from the southwest. At the moment I think this will hold off until at least Sunday night.
TODAY: Mostly cloudy through midday with isolated to scattered showers. Partly sunny afternoon with isolated showers. Mostly cloudy late.
Highs 63-68 coast, 68-73 interior. Wind SE to S 5-15 MPH.
TONIGHT: Mostly cloudy. Scattered showers and thunderstorms especially west and north of Boston in the evening. Lows 58-63. Wind SW 5-15 MPH with higher gusts early, shifting to W.
THURSDAY: Mostly sunny to partly cloudy. Isolated showers mainly west of Boston favoring central MA and southwestern NH in the afternoon. Highs 65-70 Cape Cod, 71-76 elsewhere. Wind W 5-15 MPH.
THURSDAY NIGHT: Mostly clear. Lows 54-62. Wind W 5-15 MPH.
FRIDAY: Variably cloudy. Chance of showers/thunderstorms mainly late day and evening. Highs 64-69 South Coast, 70-76 elsewhere. Wind SW 10-20 MPH.
SATURDAY: Decreasing clouds. Chance of showers early, favoring far eastern and southern areas. Lows from the upper 50s to middle 60s. Highs in the 70s except 60s South Coast.
SUNDAY: Increasing clouds. Chance of rain at night. Lows in the 50s. Highs from the middle 60s to lower 70s, coolest coastal areas.

DAYS 6-10 (JUNE 5-9)
A string of low pressure areas will pass south of the region with at least cool/cloudy if not wet weather June 5-6 with little or very slow improvement but continued cool weather June 7-9 as upper level low pressure hangs around.

DAYS 11-15 (JUNE 10-14)
Though not as cool as the previous 5-day period, temperatures likely remain below normal as the pattern favors a trough centered just to the east of the region and a cooler supply of air from eastern Canada. It should be drier during this period.

Tuesday Forecast

8:35AM

DAYS 1-5 (MAY 30-JUNE 3)
A 2-stage weather transition takes place during the next 3 days brought about by the passage of 2 cold fronts. The first one coming through tonight will have initiated showers/thunderstorms north and west of southern New England but they will run into air that is stable and has been fairly cool and lacking sun’s heating. The second one will arrive Wednesday evening and will send another batch of showers/thunderstorms toward the region, which may survive further east due to some solar heating and a more unstable atmosphere that results. Behind this front comes a wonderful day to start June on Thursday, but by the time the second day of the new month arrives, another low pressure system will approach and bring some humidity along with the chance of showers and thunderstorms. This system may be slow to get through the region so improvement may be slow to come on Saturday – something to watch as the week goes on.
TODAY: Mostly cloudy. Highs 58-63 coast, 64-69 interior. Wind light SE to S.
TONIGHT: Mostly cloudy. Scattered showers mainly west and north of Boston in the evening. Lows 53-58. Wind S 5-15 MPH.
WEDNESDAY: Variably cloudy. Highs 63-68 South Coast, 68-73 elsewhere. Wind S 5-15 MPH.
WEDNESDAY NIGHT: Mostly cloudy. Scattered showers and thunderstorms especially west and north of Boston in the evening. Lows 58-63. Wind SW 5-15 MPH with higher gusts early, shifting to W.
THURSDAY: Mostly sunny. Highs 65-70 Cape Cod, 71-76 elsewhere. Wind W 5-15 MPH.
FRIDAY: Variably cloudy. Chance of showers/thunderstorms. Lows from the middle 50s to lower 60s. Highs in the 70s except 60s South Coast.
SATURDAY: Variably cloudy. Chance of showers, favoring the morning. Lows from the upper 50s to middle 60s. Highs in the 70s except 60s South Coast.

DAYS 6-10 (JUNE 4-8)
An unsettled weather pattern is expected during this period. That does not mean rain every day all day. Will be watching for an approaching low early in the period that may keep much of its moisture to the south of the region, and another system mid to late period. Temperatures near to below normal on average.

DAYS 11-15 (JUNE 9-13)
Pattern will likely feature temperatures near to below normal and at least a couple threats of wet weather heading toward mid June.

Monday Forecast

12:13PM

DAYS 1-5 (MAY 29-JUNE 2)
A weakening low to the northwest and a developing offshore low to the southeast combine to bring unsettled weather for this Memorial Day, along with very cool air, especially in eastern areas due to an easterly wind. A somewhat milder southerly flow takes over for Tuesday and Wednesday, the last 2 days of May, but don’t expected brilliant sunshine as a couple of disturbances have to pass through the region bringing a couple opportunities for showers and a few thunderstorms. A break comes for the first day of June Thursday as a drier westerly air flow takes over before the next frontal system arrives Friday with a shower and thunderstorm threat once again.
THIS AFTERNOON: Overcast. Areas of drizzle. Periods of rain. Temperatures steady 48-53 coast, 54-59 interior. Wind E 5-15 MPH interior and 10-20 MPH coast with higher gusts.
TONIGHT: Cloudy. Areas of rain/drizzle gradually diminishing. Patchy fog. Lows 44-49. Wind NE 5-15 MPH.
TUESDAY: Mostly cloudy to partly sunny. Chance of drizzle early. Isolated showers. Highs 58-63 coast, 64-69 interior. Wind light SE.
TUESDAY NIGHT: Mostly cloudy. Scattered showers and a chance of thunderstorms. Lows 53-58. Wind S 5-15 MPH.
WEDNESDAY: Variably cloudy. Scattered showers and a chance of thunderstorms. Highs 63-68 South Coast, 68-73 elsewhere. Wind S 5-15 MPH.
THURSDAY: Mostly sunny. Lows in the 50s. Highs in the 70s except 60s Cape Cod.
FRIDAY: Variably cloudy. Chance of showers/thunderstorms. Lows from the middle 50s to lower 60s. Highs in the 70s except 60s South Coast.

DAYS 6-10 (JUNE 3-7)
Expect dry weather for the June 3-4 weekend but probably sun/cloud mix and temperatures near to slightly below normal. Cooler/unsettled weather looks more likely for the June 5-7 period.

DAYS 11-15 (JUNE 8-12)
Pattern will likely feature temperatures near to below normal and at least a couple threats of wet weather heading toward mid June.

Sunday Forecast

3:16AM

DAYS 1-5 (MAY 28-JUNE 1)
The middle day of the Memorial Day Weekend will feature fair weather courtesy of high pressure, but a reminder that tides are astronomically high and some coastal flooding may occur around high tide times. A low pressure system will approach from the west Memorial Day Monday, which its center destined to pass to the north of the region, however an occluding front trailing from it will help spawn another low offshore to the south and southeast of New England by evening. This setup and evolution leads to a mainly cloudy day with period of wet weather from midday through evening. Hopefully, it will stay dry for most of the morning when the majority of outdoor parades and ceremonies are. When we get to Tuesday and Wednesday, a warmer westerly flow will take over, but a couple passing disturbances may ignite some showers and possible thunderstorms. Dry weather is expected for Thursday.
TODAY: Partly cloudy. Highs 60-65 coast, 66-71 interior. Wind light variable with coastal sea breezes.
TONIGHT: Increasing clouds. Lows 52-57. Wind light SE.
MONDAY – MEMORIAL DAY: Mainly cloudy. Periods of rain mainly midday and afternoon. Highs 58-63 coast, 63-68 interior. Wind SE 5-15 MPH.
MONDAY NIGHT: Cloudy. Periods of rain and drizzle evening, ending overnight. Areas of fog. Lows 53-58. Wind light SE to E.
TUESDAY: Variably cloudy. Isolated to scattered showers. Highs 60-67 South Coast, 68-75 interior. Wind W 5-15 MPH.
WEDNESDAY: Partly sunny. Isolated to scattered showers/thunderstorms. Lows 53-60. Highs 70-77, cooler South Coast.
THURSDAY: Mostly sunny. Lows 53-60. Highs 73-80, cooler South Coast.

DAYS 6-10 (JUNE 2-6)
A frontal system may bring a few showers June 2 then fair June 3-4. Low pressure may bring some wet weather by June 5-6. Temperatures near to slightly above normal but may cool at the end of the period.

DAYS 11-15 (JUNE 7-11)
Episodes of unsettled weather as a broad trough sends disturbances across the region Temperatures near to slightly below normal.

Saturday Forecast

3:15PM

DAYS 1-5 (MAY 27-31)
Forecast update. Discussion on next post.
REMAINDER OF TODAY: Sun/cloud mix – clouds should be more dominant especially away from eastern coastal areas. Highs 60-65 coast, 66-71 interior. Wind N 5-15 MPH.
TONIGHT: Mostly clear. Lows 43-48 interior, 48-53 coast. Wind light variable.
SUNDAY: Sun/cloud mix – more dominant. Highs 60-65 coast, 66-71 interior, but may cool somewhat during the afternoon. Wind light variable becoming E 5-15 MPH.
SUNDAY NIGHT: Partly cloudy. Lows 52-57. Wind light E.
MONDAY – MEMORIAL DAY: Mostly cloudy. Chance of light rain favoring the midday and afternoon hours. Highs 55-60 coast, 60-65 interior. Wind E 5-15 MPH.
TUESDAY AND WEDNESDAY: Variably cloudy. Chance of showers/thunderstorms. Lows 50-58. Highs 68-76.

DAYS 6-10 (JUN 1-5)
This period is expected to feature a mainly westerly flow, near normal temperatures overall, and limited shower/thunderstorm chances for the first several days then a better chance of clouds and showers by the end of the period.

DAYS 11-15 (JUN 6-10)
This 5-day period is expected to feature somewhat unsettled weather and temperatures near to below normal.

Friday Forecast

9:57AM

DAYS 1-5 (MAY 26-30)
Low pressure spins right over southern New England today then drifts to the east later today through Saturday. As has been the thinking for several days, there will be enough cool air aloft and we’ll still be in close enough proximity to low pressure to hold some cloudiness in the region, especially eastern areas as it looks now, during Saturday. A narrow sliver of high pressure should allow for more sunshine on Sunday though I’m still not expecting a completely sunny day. The next system comes along on Memorial Day Monday but this system will be weakening as it moves through so its impact may not be all that significant. By Tuesday, with the long weekend in the rear-view mirror, we’re looking at a warmer westerly flow and a disturbance possibly resulting in a few showers and thunderstorms.
TODAY: Overcast. Areas of fog and drizzle. Periods of rain, most widespread morning and midday, becoming more spotty during the afternoon. Highs 56-61. Wind variable 5-15 MPH becoming N 10-20 MPH.
TONIGHT: Breaking clouds. Lows 47-52. Wind N 5-15 MPH.
SATURDAY: Sun/cloud mix – clouds should be more dominant especially east. Highs 60-65 coast, 66-71 interior. Wind N 5-15 MPH.
SATURDAY NIGHT: Mostly clear. Lows 43-48 interior, 48-53 coast. Wind light variable.
SUNDAY: Sun/cloud mix – sun should be more dominant. Highs 60-65 coast, 66-71 interior, but may cool somewhat during the afternoon. Wind light variable becoming E 5-15 MPH.
SUNDAY NIGHT: Partly cloudy. Lows 52-57. Wind light E.
MONDAY – MEMORIAL DAY: Mostly cloudy. Chance of light rain favoring the afternoon hours. Highs 55-60 coast, 60-65 interior. Wind E 5-15 MPH.
TUESDAY: Variably cloudy. Chance of showers/thunderstorms. Lows 50-58. Highs 68-76.

DAYS 6-10 (MAY 31-JUN 4)
This 5-day period is expected to feature a mainly westerly flow, near normal temperatures overall, and limited shower/thunderstorm chances.

DAYS 11-15 (JUN 5-9)
This 5-day period is expected to feature somewhat unsettled weather and temperatures near to below normal.

Thursday Forecast

1:31AM

DAYS 1-5 (MAY 25-29)
Low pressure approaches from the southwest later today and passes just southeast of or over southern New England during Friday before wandering eastward out to sea early in the Memorial Day Weekend. High pressure moves in Saturday and lingers into Sunday but then moves off to the east as another low pressure area approaches from the southwest by Memorial Day Monday, which looks like the coolest day with the highest chance of wet weather of the 3 long weekend days. In addition, from today through the weekend, tides will be astronomically high so some minor to borderline moderate coastal flooding is possible at high tide times, especially along east-facing shores.
TODAY: Thickening overcast early. Periods of rain develop south to north mid morning on. Highs 54-59. Wind E increasing to 5-15 MPH interior, 10-20 MPH coast.
TONIGHT: Overcast. Areas of fog and drizzle. Periods of rain, some possibly heavy especially late evening into overnight including the slight chance of thunder favoring eastern MA and RI. Lows 48-53. Wind E 5-15 MPH interior, 10-20 MPH coast, with higher gusts.
FRIDAY: Overcast. Areas of fog and drizzle. Periods of rain, most widespread morning and midday, becoming more spotty during the afternoon. Highs 56-61. Wind variable 5-15 MPH becoming N 10-20 MPH.
FRIDAY NIGHT: Breaking clouds. Lows 47-52. Wind N 5-15 MPH.
SATURDAY: Sun/cloud mix. Highs 60-65 coast, 66-71 interior. Wind N 5-15 MPH.
SATURDAY NIGHT: Mostly clear. Lows 43-48 interior, 48-53 coast. Wind light variable.
SUNDAY: Sunshine followed by increasing clouds. Highs 60-65 coast, 66-71 interior, but may cool somewhat during the afternoon. Wind light variable becoming E 5-15 MPH.
SUNDAY NIGHT: Mostly cloudy. Chance of rain late. Lows 50-55. Wind light E.
MONDAY – MEMORIAL DAY: Mostly cloudy. Chance of rain/drizzle. Highs 55-60 coast, 60-65 interior. Wind E 5-15 MPH.

DAYS 6-10 (MAY 30-JUN 3)
The last couple days of May should feature a warmer westerly flow but a couple disturbances bring a shower/t-storm risk to the region. Somewhat drier and seasonably warm weather expected the first few days of June but a shower risk may return at some point on June 3.

DAYS 11-15 (JUN 4-8)
Fair weather to start then a few episodes of showers as a broad low pressure trough progresses into the Northeast. Temperatures near to slightly below normal.

Wednesday Forecast

5:31PM

Very late update. Apologies once again! This is the forecast where I bend the segments a bit and go 6 days in the first segment to cover all of Memorial Day Weekend in as much detail as possible…

DAYS 1-6 (MAY 24-29)
Next low pressure area in a series passes south of the region late Thursday and Friday with more unsettled weather. This should be on its way out Saturday but some cool air left at upper levels may mean some cloudiness lingering or redeveloping during the day. Sunday looks largely dry as high pressure slides across the region, but an approaching warm front will send cloudiness in later in the day and eventually wet weather, but that should hold off until later at night. The wildcard is Memorial Day itself. Do we break into warmer air or stay on the cooler side of a a front that has difficulty pushing through. I’ll lean toward the latter at this time.
EVENING: Sun returns before setting. Temperatures 56-63 South Coast, 63-71 elsewhere, cooling slightly. Wind light variable.
TONIGHT: Clouds increasing overnight. Lows 47-54. Wind light E.
THURSDAY: Cloudy. Rain threat increases by afternoon but may hold off until late-day especially eastern MA and southern NH. Highs 58-65, coolest along the coast. Wind E 5-15 MPH.
THURSDAY NIGHT: Overcast. Rain likely. Areas of fog. Lows 50-57. Wind E 5-15 MPH.
FRIDAY: Cloudy. Periods of rain/drizzle, especially morning. Areas of fog especially early. Highs 57-64. Wind N 5-15 MPH.
SATURDAY: Partly sunny. Lows 48-55. Highs 60-67.
SUNDAY: Partly sunny. Chance of rain late night. Lows 50-57. Highs 63-70.
MONDAY – MEMORIAL DAY: Mostly cloudy. Chance of showers. Lows 53-60. Highs 63-70.

DAYS 7-10 (MAY 30-JUNE 3)
A few showers/thunderstorms May 30-31. Mainly dry weather June 1-3. Temperatures near normal.

DAYS 11-15 (JUNE 4-8)
Dry weather early in the period then episodes of showers. Temperatures near to below normal.

Tuesday Forecast

7:21AM

DAYS 1-5 (MAY 23-27)
No changes to the mid afternoon discussion from yesterday. Still expecting today to turn out quite nice. Most of the rain expected to the southeast remained offshore, which was erroneously brought too far north by guidance. I also still feel the same model errors exist but are being corrected for slowly, meaning more rain tomorrow morning, less rain Thursday during the day, more rain Thursday night and Friday, and lingering clouds Saturday to start the Memorial Day Weekend.
TODAY: Areas of low clouds and fog early then partly to mostly sunny. Highs 60-67 southeastern MA and southern RI, 68-75 elsewhere. Wind variable up to 10 MPH.
TONIGHT: Partly cloudy evening. Mostly cloudy overnight. Chance of rain southern areas toward dawn. Lows 55-62. Wind light variable.
WEDNESDAY: Cloudy. Rain likely, favoring eastern MA, RI, and southeastern CT, during the morning and midday. Partial clearing favoring northwestern areas later. Highs 63-70. Wind N 5-15 MPH.
THURSDAY: Mostly cloudy. Chance of rain at night. Lows 54-62. Highs 62-70.
FRIDAY: Cloudy. Periods of rain. Lows 53-60. Highs 60-68.
SATURDAY: Mostly cloudy to partly sunny. Isolated showers. Lows 48-55. Highs 64-72.

DAYS 6-10 (MAY 28-JUNE 1)
Remainder of Memorial Day Weekend current outlook features fair weather Sunday May 28 and some clouds and a shower risk for Monday May 29. Additional showers possible May 30-31 as a couple disturbances are in the region. Fair by June 1 if current timing works out. Temperatures near to slightly above normal.

DAYS 11-15 (JUNE 2-6)
Briefly warmer, then a cool down with a few showers around as the time of air mass transition.