Heating up Monday

A tight thermal ribbon to our southeast with warm air advection aloft is contributing to overcast skies and scattered showers over portions of the northeast this morning. Most shower activity is dissapating at this time, and most of the afternoon will likely be dry. Cloudiness will prevent high temperatures from getting out of the 70's. Overnight, The surface warm front boundary approaches with strong warm air advection and moisture advection. Lows should not drop much further than the mid 60's. We could see a round of thunderstorms move from the WNW toward the region with gusty winds and heavy rainfall possible.

On Monday, the ridge axis will slide to the east coast sending 850mb temperatures to around 18 to 20C supporting highs in the upper 80's and 90's across the northeast. In addition, dew points will reach the low 70's yielding heat indeces near 100 in some areas.

The second concern Monday is the potential for severe thunderstorm activity later in the evening. We should remain capped most of the day, which will allow partly to mostly sunny skies. By the late afternoon however, the cap may break giving way to rapidly growing thunderheads. Current severe parameter projections give support to >1" hail and >70mph gust potential. Certainly something to keep an eye on for the next 36 hours. Monday night, a true uncomfortable summer night with lows in the upper 60's to around 70 and saturated low levels.

The last shortwave arrives Tuesday, with one last day of warm and muggy weather. Expect highs to reach the mid 80's. Cold front approaches in the afternoon trigging another round of thunderstorms through the evening hours.

Wednesday through Friday look dry at this time with high pressure moving in from the west. Temperatures will be around seasonal normals. Beyond this point, the forecast becomes more uncertain. There are some signs pointing toward another period of above normal temperatures. Both the GFS and ECM push ridging into the Ohio Valley, but its ability to make it further east is the question.

Weekend Warmup

High pressure will remain in control of the region through tomorrow. Sunny skies should quickly burn off patchy morning fog, and we'll recover from morning lows in the 50's to highs reaching the upper 80's. Diurnal cumulus will likely develop through the afternoon. Upper level jet remains well to our north so we should stay dry.

The next storm system will be approaching overnight with surface low pressure located up in northern Quebec and a cold front hanging down across the Great Lakes. Model guidance indicates that instability parameters will remain favorable overnight and with increasing forcing there is a slight chance for a nocturnal thunderstorm complex to cut through western New England. On Wednesday, the cold front will be slowing up with flow becoming parallel to the boundary. As daytime heating contributes to instability, we may see a second round of storms in the early afternoon. The main potential for any severe weather will be to our east though with more favorable dynamics.

Once the front pulls through, a tight temperature gradient sinks to our south. Much cooler and drier air will arrive on Thursday. Expect mostly sunny skies through the early afternoon, however temperatures will struggle into the upper 70's. A shortwave will be swinging north of the region during the evening and overnight. This will likely add some cloudiness and a slight risk for a shower.

More of the same on Friday. Upper low to our north will be rotating eastward with surface high pressure sliding into the eastern Great Lakes. Expect sunny skies but highs only reaching the mid 70's. Overnight lows will tumble into the low 50's.

Some questions arise on Saturday as there is disagreement in model guidance on the evolution of a system developing along the baroclinic zone to our south. The ECM keeps the disturbance weak and our area dry while the GFS develops a stronger low and in fact shows a very wet day for southern New England. At this point I have kept the forecast dry for Keene, NH with the expectation of any rain being kept to our south.

Weather on Sunday could be starkly different from Saturday. Strong ridging to our southwest will be expanding eastward. This will push the tight temperature gradient through New England. The exact timing of this change will dictate high temperatures. The day will likely be dry, but temperatures could top out more than 10 degrees warmer than Saturday (in the 80's, maybe 90).

The lifespan of the heat is in question however as disturbances moving through could suppress the core of the heat southward by midweek. Expect periodic thunderstorms Monday through Wednesday in this summertime pattern.

Chilly end to the week

Frontal boundary crossing the region tonight will usher in drier air aloft allowing for sunny skies tomorrow. This will help highs into the low 80's. The frontal boundary will stall to our east through the evening, which may provide a focus for isolated showers over eastern MA/CT.

The next system will be swinging into the Great Lakes on Tuesday. We'll see winds backing to the southwest and a return of a more unstable airmass. A weak midlevel shortwave will trigger scattered showers and thunderstorms into the evening hours. Warmer air will be advecting into the region through the afternoon, boosting highs into the upper 80's.

The associated cold front will be moving into New England Tuesday night. Flow becomes parallel to the front into Wednesday resulting in it moving very slowly through the region. With moderate instability parameters scattered showers and thunderstorms will continue along the front through Wednesday. Highs should reach the low 80's despite increased cloud cover and cooler air advecting in later in the day.

As the front slides south of New England on Thursday, cooler and much drier air will move in with high pressure over the Great Lakes. We'll still be under the influence of an advancing shortwave which will prevent complete clearing, but we'll at least remain dry. Despite sunshine, highs will struggle into mid 70's, against northwest flow.

Friday, dry air continues to take command and with the shortwave trough departing, we should see full clearing. However, once again highs struggle into the 70's and overnight lows will tumble into the low 50's. Indeed it will feel like the beginning of autumn (not that we're not used to that this summer).

Low pressure will slide south of the region on Saturday along a baroclinic zone where the previous frontal boundary faded. This will spread some clouds into the area, but areas north of I90 should remain dry. South of I90, there will be a chance for showers. Highs again on the cool side.

On Sunday, a new chapter begins. Ridging over the southern plains will be pushing east. Remember the mentioned baroclinic zone? That's where there is a tight temperature gradient present. The developing ridging will be pushing that gradient northward. Surface high pressure slides to our east and southwest flow will blast the region with warmth. There are signs that this could in fact open the doors to heat we havent seen yet this summer. However, a number of factors also oppose that idea. First, the ground is very very moist in the northeast. In the summer months, this has a significant bearing on the potential of a heat wave. Second, an anomalous low in Canada will be spitting shortwaves southeast toward New England which will constantly suppress the core of the heat to the south. So overall it is more likely that New England sees a sharp but quick warm up early next week.

Beautiful start to the weekend

Cold front will be departing tonight with high pressure building in from the west tomorrow. The mid level should dry out nicely with plenty of sunshine, however low level humidity will still hang strong especially with how soaked the ground is now. Highs should make the low to mid 80's.

Next system approaches on Sunday, with a cold front crossing the Great Lakes Saturday night and positioned over New York state Sunday afternoon. This will provide a focus for showers and thunderstorms. High low level dew points and sufficient morning surface heating will promote scattered strong cells with potential for more heavy rainfall.

The front will clear the region by Monday morning with decreasing clouds and another rebound in temperatures.

Tuesday will start out with partly cloudy skies with decent surface heating bringing us into the 80's again. Another short wave will drop into the Great Lakes Tuesday morning with associated frontal boundary moving into New York in the afternoon. This will spark another round of showers and storms through the evening and overnight.

The same frontal boundary will stall to the south of the area through Thursday. While weak high pressure builds to our southwest, there will remain a focus for scattered afternoon showers and thunderstorms. Weak waves will carve out a trough over the northeast with cooler air diving south out of Canada.

By Friday, this trough will be shifting to our east with rising heights through the weekend. Model guidance is slowly reaching a level of consensus on a closed low over the eastern Pacific sliding ashore, pushing ridging into the central plains. This ridging may expand briefly into the northeast US sometime early the following week, bringing a quick warm up to the region.

The big picture heading into August

This past week has featured the most summer-like weather we've seen since April. And yet, the heat wave of late April still boasts the highest temperatures for the year in many locations. The shift west in Atlantic ridging developed a strong southerly flow over the eastern US which in addition to warmer temperatures, also transported copious moisture northward. What was already a wet month in the northeast has reached record levels after multiple rounds of tropical rains swept through the area.

Looking ahead over the next 10 days, here are some of the highlights:
(An updated official forecast will be posted tomorrow)

Frontal system moves eastward with strong upper level dynamic and moisture, producing more heavy showers and thunderstorms Friday.

Saturday through Sunday morning, the atmosphere stabilizes with sunny skies across interior New England. Highs will reach the mid 80's both days.

The next system approaches on Sunday with another round of showers and thunderstorms Sunday night into Monday.

The weather dries on Tuesday followed by a frontal boundary bringing showers Tuesday night and then drying again Wednesday with another round of showers Thursday afternoon. The general trend of temperatures will be downward through the period. Generally, looking at highs in the upper 70's to near 80 next week.

Ridging will be developing in the center of the nation next week, and will expand eastward for the weekend. The highest heat will be suppressed southward with weak disturbances riding through the northern US, however we could see a day or two with highs 5 to 10 degrees above normal.

This brings up the next point: Normal temperatures have turned the corner and are on the decline. Looking at the big picture, winter is coming up quick.

First autumn comes, and with that, increased hurricane activity. It is July 30th now, and the Atlantic has yet to see its first named storm. Activity in the Atlantic basin continues to be very quiet and no development is expected in the short term. I'll post a more detailed long term discussion and hurricane statistics in the tropical weather outlook later in the week.

The situation in the Pacific continues to be somewhat uncertain for the upcoming boreal winter. June featured a significant warming east of the dateline with weekly Nino3 anomalies reaching +1C by June 24 and Nino3.4 at +0.9. Since then, SST anomalies have held steady. However, trade winds have strengthened through July and have notably dampened anomalies. The warmest waters are currently between 160E and 180 with totals around 29.5C. The strongest anomalies remain between 120W and 130W, just west of the influence of the Chilean current. But increasing easterlies will likely begin to chip away at these anomalies over the next few weeks. Further west, a strong westerly wind burst has developed near 150E. This argues for increasing totals propogating eastward in the next couple weeks and rising anomalies in the west Nino regions. In general, through the end of August expect the development of a west-based El Nino. Whether the configuration lasts through the autumn and into the winter is the big question.

As I've mentioned in a few discussions on here over the last few months, signs for the upcoming winter (including the developments in the Pacific and a rapid tumble in the QBO) are pointing toward overall below normal temperatures and above normal snowfall in the northeastern US. More details will be added on through the autumn and of course in my winter seasonal outlook coming later in September/October.

Increasing warmth and humidity

High pressure nosing in from the southwest will keep the weekend dry. Skies started out cloudy this morning, but we should see gradual clearing through the afternoon. This will help high temperatures into the low 80's. On Sunday, drier air will be advecting westward, contributing to mostly sunny skies.

Model guidance continues to support a shift in the overall pattern with ridging building over the west Atlantic and the mean trough axis shifting into the Great Lakes regions. This will develop a strong baroclinic zone along the east coast helping moisture transport into the region. With weak shortwaves riding northeast through the week, rounds of showers and thunderstorms, locally heavy, will be common across New England. Expect highs generally around 80 and lows in the low 60's.

Atlantic ridging takes a brief break Friday and Saturday with an upper low moving north of New England. That low will then lift toward Greenland, forcing a rising NAO with a resurgence of the ridge to the south. A near tropical airmass will be transported into the region early next week on southerly flow. Count on a threat for thunderstorms each afternoon. Highs in the 80's, possibly touching 90 on Monday.

Sunny and warmer Wednesday

Overall, we will see increasing temperatures through the next week along with an increasing dew points. Despite sunny skies the last few days, anomalously cold air aloft has limited high temperatures over the region. Clear skies have also allowed for notable radiational cooling. This will be no different tonight and tomorrow night, as temperatures dip into the 40's.

Cyclonic flow and cold pool aloft will maintain some instability over New England tomorrow, so similar to today, we will likely see a diurnal increase in clouds. However, moisture is very limited, so precipitation is not expected.

Wednesday, cyclonic flow departs / negative vorticity advection. Surface high pressure will move into place. The column will be very dry so should maintain sunny skies through the day. Highs making it to the upper 70's.

By Wednesday night, winds back to the southwest ahead of the next piece of energy dropping into the Great Lakes. This will transport warmth and moisture northward overnight and into Thursday morning. Expect clouds and showers through the morning. The cloudiness should limit high temperatures despite 850mb temps reaching 15C. Surface based instability may lack as a result, however cold air aloft should help elevated convection to develop and a chance for thunderstorms has been inserted into the forecast accordingly.

Friday through Saturday, shortwave remains to our west, but there is more confusion in the model guidance as to a focus for precipitation over the region. We will have the moisture available, but organized precipitation remains questionable. At this point kept Friday dry but cloudy and showers possible Saturday. Sunday, the trough lifts northeast which could drag a final boundary across the region triggering a few showers. In addition, model guidance has been developing a wave along the boundary and riding it northeast, which could mean an even wetter forecast mainly for eastern New England.

Monday, should see partial clearing with dry conditions. Pattern-wise, model guidance continues to push toward more zonal flow by next week. Although maintaining above normal high latitude heights, below normal heights begin building over polar latitudes / finally a neutralization of the Artic Oscillation. At this point I'm expecting a westward shift in the trough axis toward the Ohio Valley, and ridging building slowly over the west Atlantic.