Tuesday, January 20, 2015

After Midweek Clipper, Watching the Weekend...Not Biting but Watching

Tuesday 1/20 6am
It continues to look like we're heading into an active pattern...one which will feature plenty of northern stream systems with the potential for the southern jet to get involved time to time.

The once promising midweek clipper now looks like it'll track a tad too north for our area to see much if any accumulating snow.  A few rain and snow showers are still possible throughout the day, especially across the far northern Valley and western mountains where light accumulations are possible. There will be a swath of 1-3" up towards the Maryland-Pennsylvania line.

Attention then turns to the end of the week (Friday PM-Saturday) storm potential.  Another clipper is poised to swing through southeastern Canada while a southern stream system develops across the 4-corners area and tracks east across the Gulf of Mexico and eventually off the southeast coast.  There's plenty of uncertainty regarding how this setup plays out but anytime a system is modeled to take a desert southwest to Gulf of Mexico track...it's definitely worth the watch from there.  A few days ago it looked like this system would stay well south of the area..but has since began to trend north. The 00z Canadian and European operational and ensemble means now both get precipitation of some sort into a good portion of Virginia...and as I'm writing this the 6z gfs just joined the party.   As always...the exact track will effect both the amount of moisture and temperature profiles.  It's worth noting we won't have our typical high pressure over the Great Lakes or southern Canada here (the above-mentioned clipper will be here instead). This could lead to some temperature issues.  Yes we are in the heart of winter so this wouldn't be as big of a deal as say for a system in early December...but true, deep cold air is definitely lacking.  So while worth the watch, not ready to jump all in just yet.  It'll take a pretty strong low capable of generating its own cold air for this to become a good snowstorm...which isn't completely out of the question.  We should at least see some sort of wintry precipitation out of this.  Looking ahead, the northern stream looks to remain active heading into next week.
00z Canadian Setup for Weekend System

Shenandoah Valley Forecast
Today: Partly cloudy.  By far the nicest day of the week.  Highs 49-52.
Tonight: Increasing clouds...a few flurries or sprinkles possible after midnight.  Lows 31-34.
Wednesday: Mostly cloudy with a few rain and snow showers..there could be a coating to an inch  up towards Winchester closer to the clipper passage.  Highs 39-42.
Thursday: Mostly sunny.  Highs 43-46.
Friday: Clouds on the increase throughout the day.  Highs 41-44. 

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