Tropical Storm Isaias is long gone this morning and we’ll enjoy nicer conditions along with drier air in its wake. That drier air will drift into the region on WSW flow later this afternoon. First, we’re still dealing with a bit of southerly flow which means the humidity isn’t quite gone. As the drier air arrives, a few clouds will pop up along the boundary between the two airmasses (it would be too generous to deem this a cold front). Up in the mountains, a few of these clouds will become tall enough to pop off a brief shower or maybe even a thunderstorm. For the rest of us, dry weather will prevail today.
Highs will range from 75 in the north to near 90 in far southern NH. Aside from those afternoon clouds, skies will be mostly sunny today (just a few upslope stratocumulus in the mountains this morning).
As a quick note, I’m taking the next few days off to enjoy some time offline in the beautiful northern woods of Maine. I’ll be back Monday morning as per usual. The weather for the rest of this week looks fabulous with lower temps, lower humidity, sunshine (at least tomorrow), and generally dry conditions. A few more clouds and maybe some showers arrive later Friday into Saturday but overall shouldn’t be impactful. Temps will spend most of their time bouncing between 50s/low 60s at night (!) and 70s or low 80s during the day. It’s gonna be a great few days to get outside!
Today will feature the long-awaited arrival of Tropical Storm Isaias as it races up the East Coast ahead of an advancing trough over the Great Lakes. While the storm center is still located way down near the NC/VA border (as of 6 AM), moisture is streaming well north thanks to strong southerly flow aloft. The net result for us is that clouds are already thick across the region this morning, and will remain that way through the rest of the day.
Zooming out on the radar imagery this morning shows an impressive plume of heavy rain extending from the storm’s center (south of Richmond, not quite in the frame here) all the way up past Ottawa and Montreal. Note that the heaviest rain is focused away from the coastline in the Mid Atlantic and west of the Hudson River in New York. This general trend will continue as the storm races towards Quebec City today. If you’re to the west of the track, you’re mostly concerned about heavy rain. If you’re to the east of the track, you’re mostly concerned about strong winds. Because the storm is headed west of us, we’re mostly concerned about the wind. That’s not to say there won’t be heavy rain, it will just likely remain below the levels needed to cause major flash flooding concerns.
Forecast model guidance (this map valid 9 PM) suggests that as the storm moves through Vermont, we’ll see two areas at risk for particularly strong winds: western NH (closer to the actual circulation) and the coastline (less friction). Both of these areas will likely gust over 50 mph, resulting in tree damage and power interruptions. For spots in between or farther northeast, gusts should stay in the 35-45 mph range which could cause a few isolated issues, but likely won’t support widespread impacts.
The other threat we’ll have to think about is that of tornadoes. On the eastern side of the storm, we’ll have some instability (shaded in the peach-ish color on the map above), abundant wind shear (pretty much off the charts for our region), and a line of thunderstorms moving northeast associated with the outer bands of Isaias. This storm has already produced numerous tornadoes as it moved ashore in North Carolina last night, and all indications are that this will continue as the system moves up the coast. The SPC (Storm Prediction Center, like the National Hurricane Center but for severe storms) has outlined our area as having a significantly-above-normal chance to see a tornado this evening.
What does this mean for you? You should have a way of receiving NWS tornado warnings if they are issued for your location, and you should be ready to move to your basement or an interior room on the first floor with no windows. Tornadoes will develop and dissipate rapidly so despite the best efforts of our friends up at NWS Gray, you might not have much time to act once a warning is issued. Remember that statistically speaking, your odds of getting a tornado tonight are still quite small. The vast majority of us probably won’t even get a warning. But it’s good to be prepared in case that happens, especially on a day like today when the risk is much higher relative to normal.
As far as timing goes today, expect showers to continue through the rest of the morning and into this afternoon. Generally, coverage and intensity of rain will tend to decrease as we move towards the later afternoon hours. Then this evening, the main part of the storm will rotate through in the form of that outer band which will bring briefly heavy rain, strong winds, and the threat for tornadoes as it moves northeast between 7-8 PM (SW NH), 8-9 PM (central NH/SW ME), and 9-10 PM (points north/east). Gusty winds will continue overnight before calming down tomorrow.
Temps today will be a bit on the cooler side thanks to all the clouds and southeasterly flow off the (very warm but not yet hot) Gulf of Maine. Look for highs ranging from the upper 60s/low 70s north to upper 70s/low 80s south.
A “cold front” is struggling to push east across the region this morning as a storm moving through Quebec tries to push drier air in our direction while tropical moisture begins streaming north ahead of Isaias. Dew points currently in the upper 60s to low 70s should fall off into the lower 60s or even upper 50s in western parts of the region by this afternoon. The humidity will linger a bit more along the coastline. Winds behind the boundary this afternoon will be from the west-southwest which is favorable for warm temps, especially along the coastline. With that in mind, expect highs ranging from the mid 70s up north to the low 90s along the coastal plain.
Skies will feature a mix of sun and clouds today as various disturbances drift overhead and leftover low-level moisture clears out. The best chance for cloud-cover will be up in the mountains while the coastal plain will see more sunshine. No precipitation is expected until late tonight in advance of Isaias.
Speaking of Isaias, the system is still expected to impact our area as a tropical storm tomorrow. The track has shifted a bit to the west since yesterday’s update which means that more of us will be on the windy side of the storm rather than the rainy side.
Flash flooding will still be possible in the mountains where the heaviest rain (2-5″ localized 6-8″) will fall. Most of us though will end up with a brief round of showers and storms that could drop an inch or two of rain. That will be welcome news for parched lawns and gardens, but generally isn’t much of a flooding concern (except for the usual poor drainage spots that flood every time we get a thunderstorm).
The bigger story for most of us will be the strong winds. As the storm passes to the west, we’ll see southeasterly winds pick up during the day tomorrow. Currently, most coastal spots should expect gusts to 45-55 mph with a few 60 mph readings not impossible in embedded stronger thunderstorm cells. Inland, winds should top out around 35-45 mph. This is enough to knock down trees and powerlines, especially given that these gusts will be from the southeast. As we learned in October 2017, our area is particularly vulnerable to tree damage from southeasterly winds because they don’t happen very often (but when they do, they’re usually quite strong). So be prepared for a bit of time without power tomorrow night and Wednesday. Unless the storm really pulls itself together today, I’m not expecting widespread major issues. This is about as strong as one of the stronger non-tropical storms we might get in late fall.
One last note is that the environment will be favorable for tornadoes as Isaias passes just west of the region probably tomorrow night (this storm has been really frustrating to figure out timing). By virtue of tornadoes being spatially confined phenomena, the odds of one striking your house is extraordinarily small. That said, you should have a way to get warning information from our friends up at NWS Gray if they issue a tornado warning for your area. Remember that the best place to be during a tornado is in your basement or an interior room on the first floor with no windows. We very rarely have to worry about tornadoes up here, but tropical cyclones are one good way to produce them. The last time we had a tropical cyclone pass to our west (Fay earlier in July), we also had a tornado (EF0 near Sebago Lake).
Here’s a timelapse I took of that storm looking WSW from Hackers Hill in Casco.
I’ll have another update on Isaias tomorrow morning at the usual time, or perhaps this evening if there are significant changes to report.
Today will feature continued warmth and increasing humidity as southerly winds continue ahead of a storm developing in the Great Lakes. A bit of weak lifting ahead of that storm will team up with our warm and humid airmass to produce a few showers this afternoon/evening. As per usual, the best shot at some rain will be in the mountains. High temps will range from the upper 70s up in the mountains to the upper 80s in southern NH.
Skies are sunny for most of us as I write this a little before 6 AM, but clouds are rapidly increasing from the west ahead of the aforementioned storm system. I’d expect mostly cloudy skies for the rest of the day once these clouds arrive, though a few sunnier patches are possible especially farther east.
In news relating to Isaias, the storm has been plagued by dry air and wind shear as it has been drifting through the Bahamas over the past couple days. The upshot for us is that the storm is unlikely to approach the Carolinas as a strong hurricane, which means it won’t make it up to Maine as a weaker (but still intact) hurricane.
As a result, the threat for widespread damaging winds and destructive storm surge is now quite low. This is especially good because we haven’t had a hurricane since Bob back in 1991, and therefore there are plenty of folks in Maine and New Hampshire who have never seen what a hurricane can do up here (and Bob wasn’t all that bad of a hurricane in our area all things considered).
We will still get some impacts from Isaias, but they will be more in the form of breezy conditions, higher humidity, and heavy rain. The heavy rain may actually cause some flooding issues, especially if the storm tracks along the coast (putting the mountains on the western/rainy flank of the system). For most of us though, Isaias will pass with little impact outside of some grateful gardens. Remember, most of our region is still experiencing drought conditions, so a widespread soaking rain is welcome news!
I’ll continue to keep an eye on the forecast for Isaias, especially if it were to change and become more impactful.
Today will feature another day of mostly sunny skies and mild temps, though with winds shifting around to the south, we’ll tack on a few degrees to our high temps today over yesterday. Dew points will also start to creep upwards especially this evening. Expect highs to range from the mid/upper 70s in the far north and right along the Midcoast to low 90s in southern NH. Skies will be mostly sunny today after some very patchy fog burns off in the next couple hours.
Just like the past couple days, afternoon cumulus will pop up in response to daytime heating. At the moment, there’s no indication that more than one or two of these will be able to produce a couple raindrops. As always, the best chance for a very brief shower is up in the mountains.
As I’ve been mentioning for a few days now, Hurricane Isaias remains worth watching closely as it moves through the Bahamas. Thankfully for the entire East Coast, the storm has continued to struggle over the last 24 hours due to some dry air and strong winds about 25,000 feet above the ocean south of Florida. This means that as the storm recurves up the coast, it will do so as a strong tropical storm rather than a strong hurricane. What’s the upshot for us here in Maine? If current forecasts hold, Isaias has a good shot at smashing the last of our drought. The setup here favors persistent rounds of heavy rain starting Tuesday morning and ending midday Wednesday (roughly). When all is said and done, we could be looking at a widespread 3-6″ rain event with locally higher totals possible. If your location is susceptible to flooding, you should start thinking about what you’d need to do to prepare for high water. If you’re high and dry, this storm is likely to feel like just another rainstorm.