Monday, March 2, 2015

Very Active Next Few Days

(Posted 3/2 5pm)

After super nice weather today, it looks like a very active next few days.  Keeping an eye on a few things:

1)  Minor Winter Weather Event Tuesday AM: Areas of light wintry precipitation will be possible late tonight into Tuesday as a warm front lifts north through the region.  Although quite scattered, best chances will be across western portions of the state.  Not everyone gets in on the action but certainly something to keep in mind for your morning commute.

Tuesday Forecast

2) Rain Showers + Snow Melt Tuesday PM through Wednesday PM:  Precipitation will change to all rain Tuesday afternoon and continue off and on into the overnight.  Right now it looks like heaviest rains fall to our west. Parts of West Virginia, Kentucky, and western Maryland will see 1" to as much as 3" of rain on top of melting snow leading to flooding.  This may become a bit of a concern here as well with  heavier, steadier rains working in Wednesday afternoon.  On the bright side, most areas hit 50 Wednesday before the frontal passage.

Snow Water Equivalent...Heavy Rain on top of the 4-6" of Liquid Tucked into that WV Mountain Snow Pack = Flooding Concerns

3) Changeover to Snow on Backside: After the frontal passage, cold air surges in Wednesday night changing many over to snow.  Accumulations depend on just how quickly this occurs.  It's usually difficult here to see significant snows behind a frontal passage without a well-defined area of low pressure forming and riding up the gradient (for example the Thanksgiving storm last year).  While there are signs a weak wave develops and scoots over the Carolinas, this seems more a matter of cold air catching up to frontal precipitation.  While this leaves me a bit skeptical, every major computer model insists this ends up a significant (5+") snowstorm for the entire Shenandoah Valley. A few other factors to consider:
  • It'll be in the 50s Wednesday afternoon....requiring quite the drop Wednesday night
  • Snow following rain with marginal temperatures typically takes a bit longer to start sticking
  • Cold air may get hung up on the western side of the mountains for a time...think of this as a kind of reverse cold air damming
  • Models may be overdoing the amount of precipitation on the back side of the cold front
Summary:  For the Shenandoah Valley (taking everything into consideration)...I think there will be snow, but I'm not sold on much more than a few inches (1-3 or so).  Higher amounts may be found across western mountain areas and the far northern Valley.  This is a bit of a compromise between my brain (higher) and my gut (lower).  Be sure to check back tomorrow as this is very subject to change. 

Set-Up for Thursday's Snow Potential

No comments:

Post a Comment