Through Thursday Night
Although surface dewpoints have fallen slightly behind the first front, there is still plenty of moisture around in the lower atmosphere waiting to be converted into clouds and rain. A developing Lake Erie breeze once again this afternoon could be enough convergence to spark an isolated thunderstorm. Due to the very isolated nature, no need to advertise the threat too much in the forecast. Better overall dynamics arrive around sunset so PoPs will be bumped up for later this evening.

After midnight, things will begin to dry out as everything shifts east.

Friday
By sunup, we will see a fair amount of “un-hazy” sunshine making a return to Rochester. The feel on Friday will be significantly different than prior days this week as much drier air will spill down from Canada. In addition, highs on Friday will struggle to make it into the mid 70s.

As noted above, a third front may generate a few light showers Friday evening, especially south and west of town. If you have any outdoor activities, they should be fine. Only a few sprinkles possible.

Saturday/Sunday/Monday
A large area of high pressure will set up camp over the Great Lakes beginning on Saturday with no worries of any showers or thunderstorms during this time period. The only thing to worry about are overnight lows Friday and Saturday night. Away from the lake and urban areas, overnight lows will drop well into the lower 50s with some locations south of the Thruway seeing 40s. It’s getting to the time of the year now where cool nights and warm days will be common.

Tuesday
First, the easy call. With partly to mostly sunny skies and 850mb temps of around 16°c, highs in the mid to upper 80s is as easy as it gets. As for precipitation potential, that’s the challenging issue at hand. We have plenty of moisture in the air and daytime heating will lead to some instability in the air, but finding a trigger will be the final ingredient we’ll need to develop any isolated thunderstorms. On Monday, the eastern edge of the Lake Erie breeze served as a focal point for yesterday’s scattered showers and storms. With winds a little more southerly today, I don’t think it will reach the Rochester area. With that said, the best chance for a trigger will be from oragraphical influences across the Southern Tier and Finger Lakes region so best chances will be south and east of Rochester. Any activity will quickly wane this evening with the loss of daytime heating. A warm and muggy night ahead.

Wednesday
Pretty much the same story for Wednesday as above. 850s a couple of degrees warmer ranging from 18°-20°c so expect highs on Wednesday to be a couple of degrees warmer as well. With the cold front well to our northwest, still looking for a source of lift. Best chance again will be from a Lake Breeze or from differentials in terrain. Nearly impossible to fine tune exact locations at this time.

Thursday
Our focus turns towards the approaching cold front with models wanting to bring it through Thursday morning. If this is the case, we can expect just a few showers during the morning. If the front slows down a bit, we could be in for a few hefty thunderstorms on Thursday. Either way, we’ll see something out of this front. I’ll work the details out in the graphical forecasts above when the time comes.

Long Term
Surface high pressure builds for Friday and the weekend. Looks like a great forecast with plenty of sunshine, low humidity, and temperatures around 80° for Friday, Saturday, and Sunday. There are no huge indications of any big heat building during the next 5-7 days.

These thunderstorms are sandwiched between the Lake Erie lake breeze and the Lake Ontario lake breeze. These two colliding breezes show up beautifully on satellite imagery as the low level flow is indicated by the yellow arrows in the image. This convergence in addition to the already warm and soupy airmass already in place, was more than what was needed to get things firing.

As the evening wears on, this area of activity will die down as both lake breezes fizzle out; however, we still have a cold front on our doorstep that may develop more thunderstorms a little later this evening. Could see more strong winds and heavy downpours.

In other news, I’ll be out of town beginning tomorrow morning until Sunday evening so I’ll be unable to update any of the forecasts.

Sunday Night
Radars upstream of us over the upper Great Lakes show plenty of on going showers and thunderstorms as of Sunday afternoon. They should hold together as the move to the east and will be on our doorstep after dark. A few weak showers are out ahead of this activity, so a passing sprinkle or two is possible for the remainder of Sunday.

Monday
Monday will be an active day with passing showers and thunderstorms, especially before 3pm. There may even be some clearing by early evening. Temperatures will mainly in the upper 70s.

Tuesday
Partly to mostly sunny skies during the morning will give way to increasing clouds, similar to the day on Sunday. May even see a few showers by late afternoon on Tuesday. Highs in the upper 70s again.

Wednesday/Thursday
High pressure begins to build on Wednesday leaving us with mostly sunny skies, low humidity, and comfortable temperatures right around 80. Same forecast for Thursday, but a degree or two warmer.

Anyways, the weather setup as of midday Thursday looks like this. A low pressure system over extreme north western Ontario is moving southeast, but will still remain well to our north. Its associated warm/cold front will both cross our area over the next 24-30 hours or so. In fact, based on current surface conditions, it looks like the warm front has already lifted north of Lake Ontario. Temperatures and dew points are both climbing leading to a warm and sticky afternoon. With the cold to our west (Chicago area now), it will be a warm and muggy night heading into Friday.

On Friday, the “cold” front will move through, but temperatures on each side of the boundary are not significantly different; however, dew points are much lower behind it. With the passage of the front, showers and thunderstorms can be expected on Friday, mainly during the morning to early afternoon. Will need to keep an eye out for a few more slow moving thunderstorms, especially with all of the recent rainfall. Flooding could be a concern.

Friday
Showers and thunderstorms will be crossing the area. The best window for this activity will be between 7am and 2pm. Again, a few storms will be capable of dropping an inch or two of rain in a short period of time. Look for an evening high in the mid 80s as I think we might break out into partly to mostly sunny skies for the late afternoon.

Saturday
On Saturday, just a small chance of an afternoon shower or thunderstorm. The models show a weak front dropping south and cannot rule out a wayward storm or two developing. Not everyone will get in on this action though. Otherwise, temperatures will climb back into the mid to upper 80s.

Sunday
And finally, for Sunday, expect mostly sunny skies. Temperatures will be within a few degrees of 90.

Plenty of showers and heavy thunderstorms out ahead of the front with passing heavy downpours. Some locations have likely picked up between 2-3″ of rain already today, and there’s more to come. As of 4pm, about 3/4″ are officially in the bucket at the airport.

After this front is east of us, precipitation will come to an end as drier air quickly fills in. Looking upstream from here, dew points range from the low to upper 50s out across the upper Great Lakes indicating comfortable air. We will tap into that air-mass for the upcoming weekend.

As of right now, it doesn’t look like we’ll see the mid 90s again for a little while, but temperatures this weekend and early next week will still be above normal.

Saturday
With all of the rain we’re receiving on Friday and Friday night, there will be plenty of low level moisture around Saturday morning. Dense fog could be an issue, especially south of the Thruway. Any fog will quickly burn up leaving us with mostly sunny skies. Certainly much more comfortable on Saturday with afternoon highs in the low 80s.

Sunday
Sunday looks great. Mostly sunny again, low humidity, and temperatures in the low 80s. Perfect day for any outdoor activities.

Monday
The flow turns a little more southwesterly. We’ll see an increase in humidity, but shouldn’t be as bad as it’s been. The mercury will climb back to near 90. Remaining mostly sunny.

Basically, from Friday to Tuesday, the forecast will be vary similar day to day with mostly sunny skies and temperatures climbing into the low 90s starting on the 4th of July and maybe even mid 90s on Monday or Tuesday. Humidity levels will be low on Friday and Saturday, but by Sunday, it will really begin to feel tropical.

The combination of temperatures in the 90s and dew points increasing into the 60s, the heat index will be in the upper 90s to near 100 degrees. Last summer, we only had one day that hit 90 degrees, 90 exactly so it’s been some time since we’ve seen these kinds of readings.

Overnight lows Sunday night into Monday and Monday night into Tuesday won’t make it out of the 70s, so buy those fans or A/C units now.

Any ongoing scattered showers and a few heavy downpours will come to an late Monday night into Tuesday morning. A weak area of high pressure will give us a blend of sun and clouds for Tuesday. Clouds and showers return for Wednesday.

Tuesday
On Tuesday, we can expect a few fair weather cumulus clouds, especially from late morning to late afternoon. May see an early morning sprinkle, but nothing that will slow anyone down. Much cooler, with a high only around 70.

Wednesday
The upper level low I spoke of above will dominate our weather for Wednesday. Cold air aloft will keep skies gray with passing showers. Some locations Tuesday morning, especially south of the Thruway, may see morning lows in the low 40s, low 50s closer to home.

Now, I was reading through the forecast discussion put out by the National Weather service and am baffled they have the word “graupel” in their discussion. I don’t think it will be that cold as seeing graupel in the final days of June is unheard of.

As for those afternoon highs, I honestly think the low 60s are the best we’re going to do, especially if those clouds are staying thick.

Thursday
Some improvement for Thursday as the upper level low will pull northeast as far enough away from us to bring a return to more breaks of sun and an end to any showers. Despite the sunshine, I don’t think we’ll even hit 70. Mid to upper 60s.

Anyways, a cold front has swept through the area clearing skies and lowering humidity levels in its wake. For the upcoming weekend, another system will affect us Saturday bringing with more scattered showers and thunderstorms. A tough call for Sunday’s weather, more below.

Friday
High pressure will allow skies to remain partly to mostly sunny for the end of the work week. A comfortable days with low humidity levels and highs in the upper 70s.

Saturday
A warm front lifts north with a return to warm and muggy conditions. As temperatures climb, moisture levels increase, and another cold front takes aim, the threat of afternoon showers and thunderstorms will greatly increase. Looks like temperatures will reach back into the low 80s.

Sunday
A different system than that of Saturday is on the board for Sunday. Right now the models are all over the board for Sunday’s weather making it a difficult forecast to put together. As of now, I am led to believe it will pass more to our south leaving us with only a small chance of a shower, chances increase to the south. Temps near 80.

Right now, the SPC has all of Western and Central NY in a slight risk for severe thunderstorms today. I’ll update as needed…

– Previous Discussion Continued —

The summer solstice came and went Monday morning officially commencing summer 2k10. From now until December 21st, our slow, but inevitable approach to winter has also begun. On the bright side, our weather will certainly be characteristic of early summer here in Rochester over the next several days.

Tuesday
A warm front will lift north from through the Ohio Valley Tuesday morning. Currently (Monday afternoon), some hefty showers and strong thunderstorms are roaring across southern sections of Ohio. That activity won’t affect us, but the atmospheric dynamics triggering all of this activity will be over us tomorrow afternoon and all indications are that the WNY area will have a similar fate.

With that said, expect scattered showers and thunderstorms to move in anytime from mid morning forward. A few storms could be strong with locally heavy downpours. More humid with highs around 80.

Wednesday
A hazy, warm, and humid day is in store on Wednesday. We’ll see a mix of sun and clouds through the afternoon. With the heat (mid to upper 80s) & humidity (dew points in the mid 60s) around, in addition to lake waters in the 60s, an isolated mid to late afternoon shower and thunderstorm is possible developing on the lake breeze.

Wednesday Night
A “cold” front will generate numerous showers and thunderstorms. This front means business as the Storms Prediction Center already has the entire area in a slight risk for severe thunderstorms. I’ll have another post out Wednesday afternoon if things look wild. Stay tuned.

Thursday
We’ll have a few showers or thunderstorms lingering around, mainly during the morning hours. Temperatures around 80.