Apr 20, 2015 8:09 PM
NH1 Weather Insider with Joe Joyce: April 21, 2015
NH1 Chief Meteorologist
We are waking up this morning to the sound of a few early morning downpours, and even a thunderstorm. These storms brought severe weather across NY and PA last night, and even triggered a few tornado warnings! This energy is moving through this morning in a weakend state. A cold front will provide the necessary lift to still trigger some locally heavy rain in time for the morning commute. Showers will linger through the mid-late morning before pulling away by the midday. Rivers are running high and are swollen. They will likely rise during the day on Tuesday, so some minor flooding should be expected. The combination of snowmelt, and rainfall is making for a high water table so many of us have the sump pump going to help save the basement. Most of us will escape with out too many problems as total rain fall estimates are about .50-1.5". That we can handle. Rainfall of 3-5" would be much more problematic!
Drier air will follow in behind the passing front with a wind shift to the west. Temperatures will warm into the Lwr-mid 60's if we break into any sunshine. If the clouds hold, we will all be stuck in the 50's. I am leaning towards a nicer Tuesday afternoon! Wednesday may start off with a little sunshine, but it won't last long. Clouds will quickly build ahead of another cold front which will push through during the afternoon and trigger a few more scattered showers. Winds will still be from the SW so we will try to hold onto somewhat milder air for as long as possible.
The pattern this week is being controlled by a HUGE upper level low pressure system in the upper levels of the atmosphere. It is a cool pool of air aloft which adds instability. As the ground warms from the sun, the warm air rises into the cooler air where it eventually cools, condenses, and can form big building clouds. The upper level low also rotates pieces of energy into the Northeast like spokes in bicycle wheel. Each piece provides enough lift to help trigger cloud formation or periodic showers. This huge cool pool of air will be drifting over our heads starting Wednesday and will pretty much stay in place right through the weekend, and likely right to the end of April. This will help to suppress any spring warmth and keep temperatures seasonally cooler for late April standards. It will also make for plenty of mixed skies, with periods of sun, times of clouds...and mostly cool and dry conditons...despite the hit or miss shower from time to time.