Don't look at the radar, it's almost impossible to tell what's going on. convergence cause by the coastal low and a system to our west has promoted the growth of snow showers around the region. The focus of the convergence has just shifted into the DC metro from the west. Snow will fall tonight 1-3 inches expected. Due to cold temperatures, any moisture will freeze, possibly resulting in icy spots.
School forecast:
- Delay: 67%
- Closing: 30% (Snow totals are a bit iffy and we need to verify on the high side to get off)
- Nothing: 3% (somewhat arbitrary number but you get the point: low)
1/26/2015 6:00PM Update:
Hope has returned. Light to moderate snow has entered MoCo. Could be the beginning to a decent bit of snow. Things are looking up again.
1/26/2015 5:00PM Update:
The energy transfer is complete and so clipper is dead and the coastal low has started strengthening. The remnants of the clipper will help extend an area of low pressure to the west of the storm called a Norlun Trough. Precipitation and position of Norluns are almost impossible to forecast with complete accuracy. One can only blanket the general area and say you're at risk for snow, not sure how much though. The NWS has kept a broad area of 2-3 inch forecasts to reflect this. Some will get less, some may get more. In any case, precip has started to move west over the bay towards us while some precip is also approaching from the west. What happens in the next few hours will be interesting. Let's see if we can score some heavy snowfall.
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| Dover Delaware radar shows precip pivoting in our direction and trying to expand across the bay |
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| Radar over the DC region shows precip movement in all directions. Quite unusual. A small bit of precip is moving towards DC from both west and east. |
1/25/2015 11:15 PM Update:
This is the explanation for why we don;t have a simple 5-8 inch cold powdery clipper system, but instead a convoluted and in some ways, ironic, mess.
Before Two days Ago...
All we knew was that a clipper was coming after the wet coastal storm on Saturday. I wrote it off as trending north and a non-event. We all wished that it would dig south. Lo and behold, it did. We were happy.
Two days Ago...
We were set for a decent event. The GFS and the NAM agreed on dropping 5+ inches of powder over the DC area and although the Euro gave less precip, it had the same general idea too. New England wasn't going to get anything. Temps weren't an issue as the clipper (primary low) would zip to our south and northerly winds on the backside would draw in cold air. The models were relatively consistent with their solutions. It could stop digging now. But it didn't.
Last Night...
The Canadian short term model, the RGEM, dug the storm way south, but the low was so strong, that southerly flow ahead of the storm ruined our temps. It also killed off the primary low before it got east of us, this leaving no northerly flow to cool us until the coastal low got going, which by then, was too late. This was worrying. The other models also decided that a coastal low was the way the storm would do. This coastal low would have a western extension, bringing us snow. We were now depending on a dying clipper and a moody unpredictable "teenage" coastal low to bring snow.
What was worse was that the Euro came in with a screwjob too. A different one. When the primary low died to the west of us, the precip shield would also die just to the west too. Then energy would transfer to the coastal. which would bomb out and clobber the NE. The moral of the story is be careful what you wish for. We wanted south and it went south. Too far south...
However...
Fortunately the GFS has held fast to it's idea of snowbands off the coastal low. Hope we can cash in on this storm. The short term models seem to like it too. And the Euro like overamping storms and making the too strong. Just keeping it optimistic here.
1/25/2015 9:55PM Update:
The last model run before the storm (00z model suite) has started. The NAM came out first. not the most reliable model. But still worth a look due to its higher resolution. Until you see that it comes out worse. 1-3 inches for most of us, not including melting. Also screws over NYC. I guess that's a plus. Or an indicator that something is wrong.
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| The NAM gives counties just NW of us 3-6 but gives us 1-3 and NYC around 10-15 inches of snow. |
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| NYC snow forecast: 2-3 feet of snow. |
1/25/2015 8:40PM Update:
Percentages for closing tomorrow lowered to 45%, chance of early release raised to 12.5% and chance of nothing raised to 40% on the account that the primary low is weakening too rapidly, temperatures are too warm, and the coastal low will travel too far to the east to give us much.
Snow forecast language altered to reflect long duration. Totals will not be reached it coastal low skips to the east.
Original Text:
Well, here we go again. Another complicated setup in which we may get a decent snow... or get screwed over. It is almost painful to watch the models spit out feet of snow in the Northeast while we get only a few inches at best. Hurts even more to see a near perfect clipper system for us 2 days ago turn into a monster snowstorm for someone else which in turn screws us over. Just another winter in the Mid-Atlantic region I guess. We get a dying clipper and they get a historic blizzard.
Take, for example, the forecast for New York City.
- Snow with widespread blowing snow. The snow could be heavy at times. Some thunder is also possible. Low around 21. Wind chill values between 5 and 10. Windy, with a north wind 22 to 32 mph, with gusts as high as 46 mph. Chance of precipitation is 100%. New snow accumulation of 11 to 17 inches possible.
- Tuesday Snow with widespread blowing snow. The snow could be heavy at times. Some thunder is also possible. High near 24. Wind chill values between zero and 5. Windy, with a north wind 34 to 37 mph, with gusts as high as 49 mph. Chance of precipitation is 100%. New snow accumulation of 10 to 14 inches possible.
Ok. Rant over. We actually have a chance at some decent snow despite the fact that half the models say no and the rest say meh. This will be a drawn out event. However, everything will start out as rain. It's a race between cold temperatures and the dying low. If our temps don't drop fast enough, our precip will all be rain and little to no snow. Currently, models depict changeovers in the early morning. After that, we get light precip for a day or so as the primary low dies and a new one forms to the east of us. That low will be what gives the NE a blizzard.
Snowday forecast for MCPS:
Chances of
- Delay-2.5%
- Early Release-
2.5%12.5% - Closing-
65%45% - Nada-
30%40%
- Upcounty
- 3-6 inches of snow by Tuesday night
- Changeover to snow between 3AM and 5AM Monday morning
- Downcounty
- 2-4 inches of snow by Tuesday night
- Changeover to snow between 5AM and 7AM Monday morning
Maybe calling this a screwjob was too harsh. Compare to the NWS Sterling forecast. Pretty similar.
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| I guess the NWS has finally learned it's lesson on the urban heat island. The went out of their way to make sure DC is forecasted to get less than the surrounding region. |
