Yesterday's downpours gave us a glimpse into why the desert southwest flash floods so often. After just 12 days without rain, our soil here in Maine had changed in composition...it was no longer able to absorb moisture effectively. Just 0.3" of rain in downtown Portland created rivers running downhill, collecting into huge murky puddles of rain, asphalt, grass, mulch, cigarette butts and discarded indie-rock bumper stickers.
Now that we've broken the seal (ahem, so to speak) in most spots, the precipitation we deal with this weekend should drain in a more reasonable way. After all, we actually NEED the rain.
Today: The sunshine most of us experienced earlier is now driving some instability based showers that are popping up rapidly over the foothills and mountains. These showers will slowly drift eastward toward the coastline bringing downpours and isolated small hail (the hail is a result of a very cold pool of air aloft. Remember hail is essentially supercooled water droplets turned into ice, so the more cold air aloft, the easier it is to produce hail). Not everyone will get hit with one of these showers, but look for a general increase in cloud cover regardless. High temperatures are all over the place; from mid 50s in Rockland to mid 70s in Sanford and Berlin. In general the farther from the ocean you are, the warmer.
Tonight: The daylight driven showers will settle down by 9-10 PM and the rest of the evening will feature cloudy skies and some dense fog. The fog, although thick in spots last night, will be quite widespread this evening, pushing farther inland. There will be a few showers drifting around the state, but for the most part the heavier rain will hold off until Saturday.
Saturday: With a cold front rapidly approaching, look for showers by early morning over western and southern Maine. Meanwhile central and eastern Maine will start the morning with fog and low cloud cover. Slowly the front will drift eastward through the day, bringing the shower activity to an almost statewide level by noon. Now, there WILL be periods of time when it's not raining due to the more scattered nature of the precipitation. The problem is that the showers will be so widespread and random it will be hard to plan anything outside with confidence. High temperatures will stay in the low 60s along the coastline, mid 60s farther inland. (The immediate coastline will likely deal with some drizzle, so that keeps temperatures down).
Showers continue Saturday night with dense fog once again returning.
By Sunday morning the cold front will be racing eastward into Downeast Maine. The result will be some morning showers along the coastline but then drying by mid morning. The low level moisture could be tough to scour out so I'm going to call it mostly cloudy until noon...after that look for gradual breaks in the cloud cover leading to partly sunny skies from 1 PM to 4 or 5 PM.
By late afternoon there will be a secondary cold front swinging through, so a late day sprinkle is a possibility, especially away from the coastline.
In short: If you have plans for Mother's Day that involve outdoor activities, I'd shoot for the middle of the day because the morning and late afternoon look a little sketchy.
We turn much cooler for Monday and Tuesday as an airmass rushes down from Canada. Highs will stay in the 50s in many spots but the trade off will be mostly sunny conditions for both days.
Have a fantastic weekend.