Friday, March 25, 2011

Rare late season snow becoming more likely--

March 30 2003-- a heavy rain switches to a driving heavy wet snow. Roanoke to Blacksburg had 4-8 inches. Lynchburg had 5+ inches fall, but only a 2 inch max depth. At my Forest home-- we had an inch, a lull which allowed it to melt and another 2 inches that accumulated.

This is the last latest snow in our region. In April 2007 we barely missed a late season snow that coating the ground from NE NC-- Mebane NC had a coating.

Same set up as before-- The cold has been trending a smidge colder, but the models do want to punch a warm later through between 7 and 10k feet. This is a tremendously cold air mass so even when this happens, the snow would partially melt and fall as snow grains rather than pure sleet. When I examine the layers of the atmosphere and see that in theory Roanoke and Lynchburg are supposed to change to sleet before Richmond-- usually this indicates this warm air push is not only very likely, but often will occur sooner than modeled.

Brutally cold day Sunday for LATE March-  temps may struggle to reach freezing once the snow starts, even with a strong late day March sun.

My best guess now is start time between 10 PM far west to 2 AM far east overnight Saturday into Sunday.

Martinsville to Danville-- rain, mixing with sleet. Sleet could coat the ground.

Blacksburg, Roanoke, Lynchburg-- could have a little rain to start, but snow-- changing to snow grains and sleet ending as flurries.  (Snow grains look like rice) 1-3 inches.

Jackpot-- Lexington to Hot Springs to Harrisonburg to Waynesboro into Charlottesville-- 2-5 inches, best accumulations at the highest elevations. Would not be shocked to hear a 6-7 inch total from Afton Mt or some other elevated location.

We are about 48 hours out from this event-- so it has some wiggle room to change. I'm always leery of the "north trend" the models often display. In terns of wiggle room-- we don't have much because Danville starts as rain and changes to sleet as modeled now well into the event. 60 miles isn't much of a jog in 48 hours. Having said that-- there has been remarkable consistency in the models for days now. Still, I've seen the north trend OVER and OVER in years past-- sometimes the models never even show it, but it takes place anyways.

As a result, I'm in full storm mode-- blog updated 2x a day until this event passes by.

Thursday, March 24, 2011

Sharply colder weather on tap-- with a side of white ??

Crazy to think that we've had some great weather the past couple weeks and in the blink of an eye we MAY be looking at a late season snow/sleet event. But, alas-- spring time.

Reality, we've been playing with fire a while because there's been plenty of cold air on our side of the globe, just no blocking to force it south. Enter the block and we've got a legit shot at something over the weekend and MAYBE again next week.

This is a quick heads up, but I will elaborate later. Cold front drops through or region and stalls to our south as a storm forms along it. If the cold air settles as far south as the NAM/ EC we'd have a good shot at some snow/sleet and rain--  Timing looks to be Saturday night into Sunday. This could be a wet system-- but with the warm ground and sun  angle -- a slushly inch or two is likely the best we can do. Some data also has hinted as sleet being the predominant precipitation type. We've got about 60 hours until game time.

Friday, March 11, 2011

So, you're telling me there's a chance??

If something does come of this-- it will be a million to one.

The model data has been all over the place. ( Putting aside that guidance showed between 2-3 inches of rain in Lynchburg with the storm Wednesday and Thursday and we got a meager .65 inches or so)-- there has been SOME event hinted at on the data for a week or so.

Some days, there has been NO storm, some days-- Models made a MAJOR storm.

Slowly, it seems there will be a storm.

Could it be SNOW??
Well, I don't usually blog that much over rain, so YES-- but I highly doubt it. Since this blog is often used to speculate I don't mind throwing this out there.

Basically,  HP is sliding to an ideal spot for our location and a short wave consolidates at the about best time and fires up a decent event. The forcing is supplied from the closing off upper air low and a sinking cold front. If you've been reading me a while-- lift= precipitation.

Temps are very marginal and its still 3 days out.

My gut says we get a storm but its about 100 miles north of shown-- and temps are warmer. Waynesboro, Harrisonburg and those places may see a decent late season snow.

For the record-- some data I just checked out showed between .5 and  1.25 inches of liquid over our region with a decent path of 1-5 inches of snow in that. Temps are horrible the last 2k feet or so-- hence the lack of snow from all that precipitation. Ironically, the storm putters so slow because there isn't much of a jet stream speed wise as of now-- that it actually warms up aloft as the storm unfolds. So, if some places do see snow, it may end as rain.

As of now, anywhere below 2k feet-- expect rain. Those higher elevation places COULD get a get something-- rain switching to snow. We've got plenty of time to watch this event--

Tuesday, March 8, 2011

Flood Watches Hoisted again--

Another late winter storm will impact our region starting Wednesday. The rain will begin Wednesday afternoon and will be rather heavy overnight into early Thursday morning. Region wide totals-- 2-3 inches, with maybe a few spots ending up with more.

With the good rain over the weekend, rivers still running high from the rain on Sunday, and likely more rain falling this time a more potent flood event could unfold. Again, the highest prone regions will be along the rivers and the low lying areas.

Wednesday night will be a pretty raw, nasty night with temps in the low to mid 40's and a breeze out of the NE.

The great issue is that we certainly need the rain. As we predicted in our winter outlook, this was a rather dry winter and any rain is needed.

Monday, February 28, 2011

Tornado Watch starting at 1 PM

First of the year---

Pretty powerful set up, especially this "early" in the year. Meteorological spring does begin tomorrow--

I expect a powerful line of storms to approach our far west regions by 2 PM and begin to move east. This could be impacting the area between 3 and 6 PM. The Watch is currently in effect until 4 PM-- looking at some data, I suspect this will be extended, especially areas to our immediate east and south, guessing until 7PM.

Keep your ears and eyes open to local media and the NWS for the latest updates.

Sunday, February 20, 2011

So close, yet so far away

Extreme temperature gradient-- Common in late winter-- especially in La Nina winters.

I've been watching a storm for about a week that is another two part event. Part one is underway-- from MN to NY a big swath of snow with some sleet and ice. Max snow will be over a foot in some places. This is riding along an arctic front that is sliding DUE north to DUE south. A second piece of energy rides along and some of the latest data pushes snow ALL the way down to Charlottesville-- maybe a couple inches, while at the same time NO layer of atmosphere here is even below freezing.

I'm not sold yet on the extreme far south, but if you recall this photo--- if that 500MB low is a little SW, this is very plausible.

I'm glad I'm not forecasting from DC to PHILLY-- some places in that region have a shot of 6-8 inches of snow and some may get none. The model data is split..but the ECMWF has consistently been south. As a result, I'd bet that much of the DC metro region gets 2-5 inches of snow with someone making a run at 8 inches. (Maybe Leesburg??) This is not set in stone and some fluctuation in the data is likely.

Friday, February 18, 2011

Get these clouds out of here!

I'm hoping we max out today temp wise, which would be mid 70's--- looking at the skies which are somewhat cloudy as of 9 am-- it isn't a good thing. Winds are out of the west and this should help with the temps, but ideally we want these clouds out of here FAST. Clouds o' plenty to our west, so I'm a little concerned the clouds hold us ONLY into the upper 60's.


Looking into the future-- the word will be gradient. There is plenty of arctic air up in Canada, but we also have a strong ridge to our south. Ridging to our south often means WARMTH while the pattern is allowing the cold to come dangerously close to our area.  My idea of a snow event near the Mason Dixon line Monday night and Tuesday is on the table-- every once in a while the computer models will push that system south and try to make it snow here.

I don't expect this to happen--- but I can't totally pull if off the table. I'm attaching a map where I've labeled the pieces of the storm. For the next two weeks-- we are going to be caught in this battle between a decently strong south east ridge, but plenty of cold air in Canada and some physical mechanisms to get it close to our region.
My initial hedge is we stay on the warm side mostly--- but this will have to be watched.