Friday/Saturday rain could be heavy
Showers today, tonight and Wednesday could drop more than an inch of rain in some locations across Central Maryland. But forecasters are looking ahead to what could be some heavy rains late Friday into Saturday.
Once the low-pressure system darkening our skies today and Wednesday moves east and away from the mid-Atlantic coast, our skies will clear as high pressure moves in. Temperatures have been falling all night, and won't get much higher today than they are this morning. By tomorrow we'll be looking at highs again in the 50s. Sunshine returns Thursday, but the blue sky will be short-lived.
By Friday night, the high pressure will be moving off, and the next storm system will be cranking up over the Midwest. As that low intensifies, it will draw what forecasters are calling "copious amounts of Atlantic/Gulf of Mexico moisture" into our region. Sterling says it's still too soon to say precisely where the rain will be heaviest, or how much will fall. But you can plan on your Saturday being wet.
Sunday, at least, looks partly sunny and cool, with a high in the 50s.
Jeff Halverson, associate professor of georgraphy and environmental systems at UMBC, says the storm is a classic "cut-off" low.
"A cut-off is a large, cold, upper-level cyclonic vortex that has broken free from the westerly jet stream ...It's a bit of a rogue whirlpool, and it moves sluggishly, and can even become stationary overhead," he said. This particular cutoff will gain strength from a powerful surface low over the Great Lakes, and another low expected to develop over the mid-Atlantic.
"Because of the cold air aloft (an unstable atmosphere) and a good tap on Atlantic/Gulf of Mexico moisture in a southerly flow ahead of the front, heavy periods of showers w/embedded thunder are a good bet Saturday-Saturday night-Sunday AM."
(SUN PHOTO: Frank Roylance, April 11, 2011)