As I mentioned yesterday during the noon weather, this snow forecast was one of the toughest snow forecasts I have ever done.  The rain moved into the area on schedule and continued during the evening hours.  The rain changed to snow before ending (while most of you slept).  There was no accumulation on the Southside and only a brief dusting on the Peninsula before quickly melting.  So what happened?

The surface low exploded offshore about 50 miles further east than expected.  This caused the heaviest precipitation to simply miss the area and caused the precipitation shield to move out 3-4 hours earlier than expected.  With the rain/snow line moving through the metro area during the overnight hours, the rain changed to snow but ended so quickly it could not accumulate.

With the precipitation not being as heavy, the temps did not drop as quickly as they could have which kept the snow from accumulating.  Once again a near miss for the Hampton Roads area and humble pie for me and my snowflake.

Meteorologist Jon Cash

Computer models are widely divergent in snow expected for the region. And right now, this storm is not behaving exactly like any of the computer models have predicted.

When you add it up, the coldest air will not likely coincide with the heaviest precipitation over the area. By the time the coldest air arrives, the heaviest precipitation will be mostly out to sea. So if the cold air doesn’t have as much moisture to work with…less snow. However, we’re still very likely to see some areas with snow on the ground Thursday morning.

As of this hour, the coldest air is moving eastward out of the mountains. The heaviest precipitation is within about 40-50 miles of the Virginia/North Carolina coast. The storm itself is rapidly developing near Cape Hatteras and will likely push northeastward…dragging the heaviest precipitation out to sea before the near-freezing air arrives. Additionally, a dry “punch” of air is likely to move northeastward in the wee hours. All of this should serve to shorten the amount of time that snow falls in the area overnight.

The warm, wet ground is another effect that will somewhat lessen the amount of snow remaining on the ground by morning. Temperatures have not dropped below freezing very often over the past several days, so the soil and pavement are nowhere near freezing. So the snow that does fall should melt on contact for much of the area. Certainly, we’ll end up with snow on grassy surfaces, but less to even none on the pavement. The only exception to this would be the possibility of “snow bursts” of heavier stuff which could overpower the effect of warmer soil. I do want to mention that temperatures are not likely to drop much below freezing by dawn, so water freezing on the roads is not very likely at all.

With all that being said…it’s gonna’ snow! In fact, it is snowing across much of the region at this hour. We’re likely to end up with half an inch to an inch across the Hampton Roads cities, 2″-3″ from Williamsburg through the Middle Peninsula, and 3″-5″ for the Northern Neck (& perhaps, northern Accomack county).

Jon Cash will be in for WAVY News 10 at Sunrise. He’ll be with you on-air for the latest updates.

Hello loyal fans.  Just so you know… the reason I haven’t written much lately is due to my wacky yet temporary schedule.  This is a rough blog based off of the latest models and what Don was forecasting earlier this evening.  At the time of this writing, A Winter Storm Warning was in effect for the Northern Neck and Accomack county.  A Winter Weather Advisory is in effect for the rest of the area with the exception of most of northeast North Carolina.  The bottom line is this: a very big/strong area of low pressure is beginning to develop south of here.  A strong upper level low is coming in from the Midwest.  The upper low is going to feed the surface low some energy and turn it into a type of snow hurricane in the Northeast States.  The surface low is expected to stay offshore.  As Jon mentioned at the midday show this is a tough forecast.  The rain/snow line is expected to slowly creep east from Central Virginia tonight at a snails pace.  It may not make it to Norfolk/Virginia Beach by the time the precipitation ends.  Let the races begin.

Chief meteorologist Don Slater gave his latest snowfall forecast this evening.  Before I throw out the numbers, just note that I feel that a lot of this will be on grassy areas and not on the roads.  Surface temperatures will be tough to get down to the freezing mark until morning.  Let alone below freezing.  When the north/northwest winds kick in, then cold air can start to move down.   But that probably won’t happen until Thursday morning.  Anyway, Don had 1-2″ of snowfall for the Southside, Hampton, the Lower Eastern Shore, and from Chowan county N.C. northeastward into southern Chesapeake.  He had 2-3″ for Surry county, Newport News, Williamsburg, the Middle Peninsula (Gloucester/Mathews) and part of Accomack county.  4-6 possible inches on the Northern Neck and up towards Chincoteague.  Again keep in mind that a lot of the lower amounts will be on grass.  Areas north of the metro will see the cold air sooner so may see some on the secondaries.  (IF) your county/city gets a heavy localized snow burst, then that will force enough snow to cover some roads as well.  The National Weather Service mentioned this possibility in their earlier discussion.  Snow may continue into Friday in the Winter Storm Warning area.  Hence the higher amounts forecast there. 

Our futuretrak model had a lot of rain/snow mix over the area.  I think that it may have a pretty good handle on things, and would therefore mean the lower end of the ranges above. 

As the surface low moves towards New England it will bomb out.  I saw 970millibars (mb) forecast on the models.  That is pretty low.  This will produce blizzard conditions over a large area.  For us it means that we’ll see some very strong persistent Northwest winds for a couple of days. We could see some gusts up to 45mph. 

Don may get on here later and blog some more.  He can add more detail.  If not, then Jon will be in early tomorrow I’m sure.  Good night Mrs. Callabash wherever you are. 

Meteorologist: Jeremy Wheeler

A super -tough forecast ahead.  A very strong trough of low pressure is diving out of the Midwest while an area of low pressure develops off of the Carolina coast tonight into tomorrow.  At this point this low will be close enough to bring rain into the area late this afternoon and into the evening.  As the strong trough and colder air associated with it crashes into the area overnight, the rain should change to snow from west to east overnight.  The changeover should be during the evening hours from the Peninsula west and around midnight on the southside into Carolina.

The big question will be how much moisture will be left over with this system once the complete changeover occurs.  The other huge question is the exact position of this large, expanding area of low pressure off the coast.  Any change in forecast position of the storm can have a HUGE impact on snowfall totals.  If the low is just a tad closer…much higher amounts are likely.  If it’s just a tad bit further away lesser amounts are expected.

The timing of the changeover will also affect snowfall amounts…a later changeover means lesser amounts.  If the changeover to snow occurs earlier then more snow will have an opportunity to accumulate.

Temperatures will be key to any accumulations too.  A temperature of 33 with moderate snow will stick to the grass but not the roads.  A temperature of 31 and moderate snow will stick everywhere after an hour or two of steady snow.  Light snow will not accumulate at all (a wet, warm ground initially) but a very heavy snow will accumulate everywhere even with a temperature just above freezing.

Needless to say the amount of variables in this forecast makes it extremely difficult to predict snowfall amounts.  But here is my best guesstimate for now.

2-4″ Ahoskie, Wakefield, Williamsburg, Gloucester and the Northern Neck.

1-3″ for most of the metro area excluding Virginia Beach

0-2″ for Virginia Beach into Currituck County and the Northern Outer Banks

Rain should begin in the area late Wednesday afternoon through the evening hours. Around midnight or so, some of that rain should mix with or change to light snow. That light snow should continue off and on during the overnight hours…tapering off by around 8:00 or 9:00 AM. We could still see a stray flurry or two during the day Thursday, but most areas will not see further accumulation. The exception to this could be the Northern Neck and Accomack County on the Eastern Shore. These areas are closer to the center of the storm (Jersey) and could see slightly more snow.

Most of us will just end up with a light dusting for Wednesday night into early Thursday. Half an inch to an inch accumulation could possibly fall out of the sky. It’s questionable though, how much of that snow will stick!

We’ve had enough warmer weather over the past few days to keep the pavement temperatures above freezing. In fact, most areas won’t see solidly freezing temperatures overnight and into Wednesday morning. These warm ground temperatures mean that when snow does fall, it’s likely to melt on contact…at least, for a while. When (and if) snow does get heavy enough to start sticking, it will tend to stick to the grass, but not as much to the roads.

We should be able to fine tune the snow amount forecast as we draw closer to the event. Stay tuned!

An upper level trough of low pressure will be swinging into the area tomorrow afternoon through Thursday.  This trough will cut off and turn into a large spinning upper level low in the jet stream just north of the region.  This strong upper level system will spawn a surface low off of the Carolina coast tomorrow evening.

The models paint a lot of precipitation just offshore tomorrow night with this system.  The colder air (the rain-snow line) should be moving into the area tomorrow evening as well.  The big question will be how close the heavier precipitation will be to the area with this low off shore and when the rain-snow line gets into the metro area.  Also the precipitation shield’s western edge will be somewhere between Williamsburg and Richmond tomorrow evening.

All this means a very close call tomorrow night….stay tuned!

Meteorologist Jon Cash

In the now time frame, fog is the immediate concern. While widespread fog is likely, I don’t think that widespread dense fog is likely. Actual dense fog will likely be a bit more patchy. However, that’s still a problem and sometimes more of a problem. For example, we’ve all been driving in a relatively light fog and then-in an instant- we’ve driven into zero visibility. Drive carefully out there. Low beam headlights, a prudent speed, and a good distance between the vehicle ahead of you!

Then we turn our attention to late Wednesday night and early Thursday. It is entirely possible that we could see some snow mix in with some rain late Wednesday night. In fact, it could be all snow for a while in the pre-dawn hours. However, the amounts are expected to be light…on the order of a half inch to an inch. Additionally, it is expected that whatever snow we get will likely revert to all rain, thus melting whatever snow we get. Again, I’m not too concerned about snow amounts as of this time. But it’s a little early to really nail it down. Stay tuned!

A very strong upper level low pressure system will move across the Mid-Atlantic region Wednesday afternoon through Thursday morning.  The track of this system will determine how much rain and snow showers we receive.

At this point rain showers appear likely Wednesday afternoon with  snow showers Wednesday night into Thursday morning.  It’s too early to say if there would be any accumulating snows or just scattered snow flurries.  The track of the upper low will determine how much precipitation we receive…a track further north means little to nothing…and a track further south would lead to some accumulations.

Meteorologist Jon Cash

Boy oh boy!  Today was great.  We saw highs in the upper 50s to lower 60s, and sun the whole way through.  I got to wash my car which was long overdue.  If I were to go with the computer models today, then I would have said that highs were going to be in the lower 50s.  They have really been undercutting the daytime temperatures.  So despite more cloud cover tomorrow, I am going for highs near 60.  (We saw some 60s inland today).  Here’s the temperature trend for the next 3 days:

Temperature Trend

I had a great blog written yesterday.  It took me about a half an hour to create.  Then…kablooey!  As I hit publish, it magically disappeared.  So, I’ll try and recreate it as best as I can.  No it didn’t autosave the draft like it was supposed to. 

A while back I wrote a blog about the long range forecast, and it’s time to collect on some bragging rights.  In early December 09′ I wrote a weather blog predicting the snow chances for this Winter through mid January.  Here it is: Old Blog  The forecast is towards the bottom.  Looks like I did pretty good on that. 

There are several reasons why we’ve had the weather that we’ve had.  There has been a significant snowpack over a large portion of the country.  That allows for the cold air to reside longer over a location.  This has even been the case even locally with snow still on the ground up until this week north and west of the metro.  Another factor has been the progressive pattern that we’ve been in.  That means that systems have been moving through rather quickly.  One reason for that is the weather pattern in the Atlantic Ocean called the North Atlantic Oscillation.  It is somewhat similar to El Nino, but is in the Atlantic.  It has been negative for a while, which I believe has promoted that quick moving.  This allowed a lot of systems to move into a cold airmass before any southerly winds could warm us up as in previous years.  Also, I’ve heard a little about the Arctic Oscillation, and heard that it has been negative as well.  Here is a great reference from NASA the explains it for this Winter.  Scroll to the bottom for reading.  This phenomenon is supposed to allow for cold air to keep moving down out of Canada.    The southern branch of the jetstream has been pretty active too.  All of this has added up to help us get snow.  We’ve had 8.3″ of snow at Norfolk so far this year.  Much higher amounts north/west of Norfolk. 

After that paragraph of true nerdiness, here are some numbers.  These are the number of days with high temperatures below 50 degrees for the December, January, February period for the last 4 years. 

2009/2010:          December- 16,     January-20,    February-16*

2008/2009:         December-7,       January-21,     February-11

2007/2008:         December-8,        January-16,     February-8

2006/2007:          December-5,       January-14,     February-18

*Month not over yet.

I got this info from the National Weather Service’s website.  It required a lot of adding, so hopefully I didn’t miscount.  You can see that the last 2 years were noticeably colder, but there was also a cold period in February of 07′.  I remember that power bill.  Whoa!  I also did the number of days below 40 degrees, but maybe that’s too many numbers for this blog.  Just know that There were much more this year compared to 2006-2009. 

Going forward, I think this pattern will keep up for a while.  We’ll probably have the brief warmup this week, and then return to the cold pattern by next weekend.  We easily have more chances for snow until probably mid April.  Remember we have  had chances for snow up through April for the last 2 years.  Maybe 3.  We’ll probably start to see some more large systems as we go into March.  Probably more Nor’easters or coastal runners.  The northern and southern branches of the jetstream will probably phase/merge more often creating these bigger systems.  I expect that overall we’ll stay cool for the next couple of months.  We’ll probably start to get some brief warmups.  More brief than usual.  I’m looking forward to some warmer temperatures.  Highs on Monday will be in the upper 50s in some areas.  We’ll definetely cool down towards next weekend though.  There’s no snow in the 7 day forecast, but we may see a good sized system Wednesday into Thursday.  Wind and rain are forecast, but some far inland sections could see a little snow at the end.  We’ll see. 

Meteorologist: Jeremy Wheeler