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The Accuracies and Inaccuracies of Forecasting Light Snow

January 27th, 2015 at 11:49 pm by under Uncategorized, Weather

The first picture is my final snowfall prediction from Monday night’s forecast. The second (blue-ish) picture is a radar estimate/depiction of the snow that actually fell; the darker the blue…the heavier the snow.

2Radar
I spoke about this a couple of times on the air today. I basically talked about the accuracies, but also the shortcomings of snowfall forecasts. The snow forecast for last night and this morning can be considered a pretty good one; We generally got the areas of heaviest snow in the right places. And we didn’t see any big surprises. In other words, no bigger than expected snow amounts. The prediction was for a dusting to two inches for the vast majority of the area (see 1st picture) and that’s pretty much what we got.

The only real tangible mistake on the forecast was that I predicted 2″ to 3″ of snow for much of the Eastern Shore…and that just didn’t happen. To understand my thinking from last night regarding heavier snow for the Eastern Shore, look to that area over the water…in the lower Bay (2nd picture). At the time that the forecast was put together, I was concerned about a heavier slug of snow (2″-3″) for the Eastern Shore. It was close, but no cigar! Only about a half mile west of Cape Charles over the water…but that part of the snowfall forecast was indeed a little off. The Eastern Shore generally got 1″ to 2″ of snow and NOT the 2″ to 3″ that was predicted.

There’s one other thing to note. On the forecast graphic you will note that snow totals are a bit more “broad-brushed” than the reality shown in the second graphic. This reflects the realities of forecasting snow…especially relatively lighter amounts. We simply cannot predict all the smaller details and variabilities that you see on the second graphic. It is simply the “state of the art”.

All in all, though…I was pretty happy with the snow forecast. A big thanks to meteorologists Tiffany Savona and Jeremy Wheeler for their collaboration and hard work. I hope that you were able to make good use of the snow forecast!


Short Update On Upcoming Snow

January 25th, 2015 at 8:41 pm by under Uncategorized, Weather

The forecast models have come into better agreement as to the snowfall for Monday night into Tuesday. As you’ll see, the models are not in complete agreement quite yet…but it is reasonable to expect that we will see accumulating snow into the region. Virginia’s Northern Neck and Accomack County on the Eastern Shore are likely to receive the most snow (possibly 5″ in northern Accomack). Areas along the western and southern shores of the Chesapeake Bay are likely to receive 1″ to 3″ of snow. We’ll be able to fine-tune this a bit better as the storm draws closer tomorrow. As I mentioned yesterday, this is not likely to be “the big one”, but there is likely to be enough snow to affect traffic and may close businesses and schools.

Yesterday, the EURO model was predicting huge amounts of snow for the Eastern Shore (7″-9″!) and more significant amounts for the Hampton Roads cities, too. In my blog post yesterday, I had pointed out that the EURO was an outlier–predicting too much snow–and shouldn’t be taken too seriously. Well, today the EURO backed off considerably for our part of the world. Here are two screen-grabs of the EURO…one fairly local and another for the Northeast U.S.:

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E COAST_EUROYou will note that the New York and Boston areas are just gonna’ get hammered with snow (24″+).

Here’s a look at the GFS model on a regional, then East Coast scale:

GFS18GFS_EASTYou will note that the GFS has a greater concentration of snow for areas west of I-95 and on into the Charlottesville area. It also has less snow for the Eastern Shore. The wider view shows Boston getting hit with heavier snow (18″-24″), but New York getting around 8″ to 10″.

While the forecast models are not yet in total agreement, they do agree on a couple of things:

(a). We’ll see some accumulating snow.

(b). For the vast majority of us, the total accumulated snow will be a relatively small amount (dusting to 2″).

That’s still enough to “shut us down”, though. Stay tuned!


Now Comes Monday Night And Tuesday…

January 24th, 2015 at 6:49 pm by under Uncategorized, Weather

Well, we made it through Saturday with just a few sleet pellets mixing in with the rain. Sunday promises to be a much nicer day. Sunshine, light winds, and afternoon temperatures in the low to mid 50s.

Monday looks to be a cooler day with highs around 48. Scattered light rain is likely.

Monday night into early Tuesday, we’re looking at measurable snow into the region. At least a light accumulation of snow is likely. However, the forecast models present a great deal of variability (thus uncertainty!) as to how much snow we’ll actually get. There’s everything from a light dusting…all the way up to enough snow to shut down the northern portions of our area!

Here’s the worst case scenario first from the European model:

Screen Shot 2015-01-24 at 6.03.05 PM

It’s showing anywhere between a dusting in North Carolina…to 2.5″ to 3.5″ near the Bay (Hampton Roads cities)…all the way up to over 9″ for the Eastern Shore. It’s a good forecast model, but likely overdoing the snowfall amounts substantially! Don’t believe it yet, but keep it in mind as we work our way through a few other models.

GFS18ZThe above is a screen-grab from the new GFS model initializing (gathering 1:00 PM data) at 1:00 PM Saturday. A color code is not needed here…because the light pink color is obviously indicating the lightest snow over our area (.50″-1″ at most) while keeping heavier areas of snow well to the north.

Here’s the Navy model (GEM) initialized at 7:00 AM:

gem12It likewise shows very light snow into most of the area. It does however, show a bulls-eye of 1″-2″ over Accomack County on the Eastern Shore.

Finally, here’s the NAM which initialized at 1:00 PM:

NAM18The color-coding on this one shows a dusting to a half inch in the light pink area…and a half inch to one inch in the darker pink area. Northern Accomack County again gets more snow…in the 1″ to 1.5″ range.

The models do have a very general agreement in that they intensify a low pressure center off the Eastern Shore, thus drawing in cold air and moisture (snow!) on the west side of the developing storm. But the one outlier here is the Euro showing greater intensification of the storm and just as importantly, holding the storm just off the Eastern Shore for a greater period of time.

The chances of at least a light dusting of snow are very good. But beyond a light dusting, the forecast models are just not coming together on a common solution regarding snowfall amounts. You’ll want to watch the situation over the weekend and into Monday (especially if you live near the Bay!). Forecast snowfall amounts will gradually become more apparent. The time frame for snow right now looks to be from after midnight on Monday night through around noon or so on Tuesday.


No Snow For The Snow-Lovers…Sorry

January 22nd, 2015 at 11:12 pm by under Uncategorized, Weather

A couple of pictures here. The first shows a time-line of what we can expect for Friday and through the overnight hours into Saturday morning.
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Temperatures on Friday will likely top out at around 42 to 45. Rain begins toward the dinner hour on Fri. evening with moderately heavy rain from Friday evening off & on through around 4:00 AM Saturday. We’ll also see stronger southerly winds on Friday night which could actually warm things up to around 50 overnight. On Saturday, we’ll see a few scattered lighter showers mainly during the morning. It’ll be cool again with highs in the low 40s.

The second graphic shows the amount of rain that we’re likely to get between Friday evening and Saturday. Again, most of that rain should fall between Friday evening and Saturday noon.

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Frozen Roads Not Likely To Be A Problem

January 14th, 2015 at 10:16 pm by under Uncategorized, Weather

The last of the light rain moved off by around 6:30 PM. Temperatures have not dropped significantly (or at all!) through the region. So there’s not a good likelihood of wet roads re-freezing. Additionally, the wind is still blowing from the north at about 10 to 15 mph. That wind also helps to dry out the roads.

Here’s a look back at what we predicted for Tuesday night into Wednesday morning. That general area of freezing rain was of greatest concern. For the most part, that area of freezing rain was correct. However, we did get a little more than expected (~.25″) for the Middle peninsula. Basically though, the forecast was pretty good.

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Here’s a map of the actual reported amounts through the region. It’s from here:

24HR_Mixed_Precip_Jan14_2015


Rain’s Gone…

January 14th, 2015 at 10:12 pm by under Uncategorized, Weather

The last of the light rain moved off by around 6:30 PM. Temperatures have not dropped significantly (or at all!) through the region. So there’s not a good likelihood of wet roads re-freezing. Additionally, the wind is still blowing from the north at about 10 to 15 mph. That wind also helps to dry out the roads.

Here’s a look back at what we predicted for Tuesday night into Wednesday morning. That general area of freezing rain was of greatest concern. For the most part, that area of freezing rain was correct. However, we did get a little more than expected (~.25″) for the Middle peninsula. Basically though, the forecast was pretty good.

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Here’s a map of the actual reported amounts through the region. It’s from here:

24HR_Mixed_Precip_Jan14_2015


Biggest Wintry Weather Threat So Far This Season!

January 13th, 2015 at 10:53 pm by under Uncategorized, Weather

As of 11:00 PM, we’re seeing a lull in the precipitation. By 1:00 or 2:00 AM, the rain (& everything else!) begins again. Here’s a time line through noon tomorrow:

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Snow is obviously the usual concern for any winter storm, but this time freezing rain is a much bigger concern:

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Jeremy will be on the air a half hour early (4:00 AM) for WAVY News Today. At that hour, we’ll likely be right into the heart of the wintry weather!


State Line And Southward Into North Carolina…

January 8th, 2015 at 10:50 pm by under Uncategorized, Weather

Forecast models are not “in lockstep” on this one. But there is some indication that we could see some drizzle into the area near sunrise.

This is a picture from one of the forecast models that actually does paint a little light rain into the area at 8:00 AM. Our temperatures are likely to be around 28 degrees at that time. Additionally, the ground is likely to to be well-below freezing.

Sooo…we could see a few patches of freezing drizzle close to the state line and southward. It should warm to well-above freezing by around 11:00 AM, thus putting an end to any frozen precipitation. Check in with Jeremy Wheeler on WAVY News 10 Today at 4:30 AM.

Weather Map Tomorrow_full


Coldest Temperatures In A Year!

January 7th, 2015 at 10:50 pm by under Uncategorized, Weather

It’s been a year since we’ve had weather this cold, so we might forget a few common sense things that’ll make us more comfortable, save money, and protect ourselves and our families. I’ve been “harping” on this one for a few days now; drip your faucets!

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The temperatures on the above graphic were updated with current (11 PM) trends in mind. I’ve put together a few other cold weather tips that you may or may not have thought of. Be safe!

Weather Map TodayWeather Map Tomorrow


It Really Is Likely To Be THAT COLD

January 6th, 2015 at 10:55 pm by under Uncategorized, Weather

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You know your own house better than anyone. And you probably know how exposed your pipes might be affected by temperatures in the teens. Take precautions, if need be!

The colder temperatures start moving in on Wednesday afternoon…and it’ll be at its coldest on Thursday morning.