Possible Weekend Snowstorm: Some Quick Thoughts

[donsutherland1]

Some quick thoughts...

1) I believe somewhere along the East Coast will likely see a 6" or greater snowstorm (with potentially more).

2) Past consistency in the modeling with a focus on the Mid-Atlantic makes me suspect that this area (probably such cities as DCA, BWI, and PHL) will probably have a relatively higher risk at seeing 6" or more. This does not rule out the possibility of a significant snowfall for southern and even central New England.

3) I'm not ready to buy into last night's run of the ECMWF, though it's an argument that might have merit, especially if the Euro locks into it.

4) Past analogs supported far more snowfall in January than has occurred in DCA to NYC and help give some credence to the idea that a significant storm might occur.

• Almost 85% of analog years saw more than 1" in DCA and 1/4 saw 6" or more.
• Almost 75% of those analogs saw NYC receive 2" or more in January and 47% saw 10" or more.

January snowfall to date has come to 0.5" in NYC and Trace in DCA.

Thus given the weight of analogs, I'd be extremely surprised if either of these cities finished close to where they're currently at.

This does not mean that extreme snowfall is likely though each city did have a few extreme outliers among the analogs.

FWIW, the February ideas also look snowier than normal in these cities and I'll be interested to see whether the picture holds together when the ENSO data for the week of January 12 becomes available.

5) Things can still go wrong. But I would be suprised if no one on the East Coast saw a significant snowfall from the weekend event.

Who gets how much is still quite uncertain for me. Others might have a firmer grasp on that.

Hopefully--and this is my preference and not any kind of forecast--cities that have been starved for snow, not just this winter but also over the past two winters i.e., Richmond, Washington, DC, Baltimore, and Philadelphia, will all enjoy a significant snowfall of 6" or more.

[adelphi_sky]

Significant for me is 8" or more. Though DC usually shuts down and goes stir crazy from just 4".

[Lowpressure]

Don , we are looking at 1-3 tomorrow with the clipper, thoughts are on the lower side. NWS D.C. says it is debating WWA if trends continue to support a stronger solution. A dusting Thursday and then the POTENTIAL for a more significant storm over the weekend into Monday. They are not willing to commit to anything IRT the weekend system yet. Temp profiles would seem to keep it all snow North of RIC. At least as of this run. D.C. has been trending downwards for several runs now.

[Rainband]

Brrrr

[adelphi_sky]

Don , we are looking at 1-3 tomorrow with the clipper, thoughts are on the lower side. NWS D.C. says it is debating WWA if trends continue to support a stronger solution. A dusting Thursday and then the POTENTIAL for a more significant storm over the weekend into Monday. They are not willing to commit to anything IRT the weekend system yet. Temp profiles would seem to keep it all snow North of RIC. At least as of this run. D.C. has been trending downwards for several runs now.

Trending downwards as far as temps or precip probabilities?

[jimvb]

I agree with Donsutherland1 that the weekend storm seems headed to Washington to NYC. The 06Z and 12Z GFS runs both show the L of the storm to move farther northward, to the VA-NC border, with the 0 line going through Fredericksburg.

But Donsutherland1 seems to be saying that because NYC and DCA has not received much snow this year, that they must therefore get a lot of snow now. This is like the argument that because after flipping a coin 10 times and getting 9 heads and 1 tail, that the coin is now much more likely to fall tails, to get the averages right. But the coin does not know about averages, and the chances for getting a tail are still 50%. The same with the weather; it does not know averages. It seems to me this area may get the snow because at least one model (GFS) seems to indicate it, not because of any averages.

[Alexm89]

What does 0 line mean because I live in Fredericksburg Virginia.

[vbhoutex]

I agree with Donsutherland1 that the weekend storm seems headed to Washington to NYC. The 06Z and 12Z GFS runs both show the L of the storm to move farther northward, to the VA-NC border, with the 0 line going through Fredericksburg.

But Donsutherland1 seems to be saying that because NYC and DCA has not received much snow this year, that they must therefore get a lot of snow now. This is like the argument that because after flipping a coin 10 times and getting 9 heads and 1 tail, that the coin is now much more likely to fall tails, to get the averages right. But the coin does not know about averages, and the chances for getting a tail are still 50%. The same with the weather; it does not know averages. It seems to me this area may get the snow because at least one model (GFS) seems to indicate it, not because of any averages.

I think you misread Don's post. He was basing his thinking on the analogs for this winter, not the fact they have had little snow.

[krysof]

the gfs keeps seesawing with every run, once it has little snow or moisture than it has a lot of moisture.There us a good chance of a snowstorm this weekend. It's only tuesday so no promises yet but if the system continues to verify, I will be posting snowfall maps on Thursday or even Wednesday night if the chances of a snowstorm continue to increase.

[SouthernWx]

But Donsutherland1 seems to be saying that because NYC and DCA has not received much snow this year, that they must therefore get a lot of snow now. This is like the argument that because after flipping a coin 10 times and getting 9 heads and 1 tail, that the coin is now much more likely to fall tails, to get the averages right. But the coin does not know about averages, and the chances for getting a tail are still 50%. The same with the weather; it does not know averages. It seems to me this area may get the snow because at least one model (GFS) seems to indicate it, not because of any averages.

Don is utilizing his knowledge of snowstorm climatology. A knowledge of climatology is just as important to the forecaster as the ability to interpret model data. Don and I both utilize climatology as well as model data and another often overlooked asset in forecasting....common sense.

A forecaster who utilizes model data, climatology, and common sense will usually be an extremely accurate forecaster (as both Don and I are

PW

FYI...Alex: the 0 line (or 0° C) simply means the freezing line at 850 mb (5000' feet above the ground). In most circumstances, the heaviest snow falls near or just north of the 850 mb 0° isotherm. Just south of the 0° line is where many times heavy accumilations of sleet and freezing rain occur, especially here in the southeast U.S.

[jimvb]

Don, I think I see what you mean. Compare this winter with others with similar patterns to see what may happen. Sometimes I do that with hurricanes. Applying that to the coins (comparing the run to other runs that may come from fair or biased coins) may lead to the conclusion that the next flip is more likely to be HEADS - maybe the coin is biased.

Also - that was a good explanation of the 0 line in the GFS 6 hour precip maps. What you are saying is that the GFS seems to indicate that central and southern VA could get sleet and freezing rain. I sort of had this in the back of my mind when looking at the GFS. The 850 line represents what's 850 meters above, and what's on the ground could be colder. Is there any way of finding the ground temperature with any of these models, especially since temperatures vary between night and day? And does the 540 line mean the same thing?

[donsutherland1]

Jimvb,

I'm not arguing that becuase NYC and DCA have not seen much snow this year, therefore they are due. I stated that a strong number of analogs pointed to far more snowfall for January than has occurred. Now, if the analogs offer reasonable guidance, then one would expect that the snowfall deficit between what has occurred so far in January and what the analogs suggested would close.

The model guidance continues to keep DCA through NYC in the game for possible significant snowfall. There is still uncertainty. Yet, I do believe that analogs can offer some guidance and at this time they support what most of the modeling is indicating.

These analogs are not necessarily about flipping coins so to speak. They are constructed based on past ENSO regional patterns, the QBO, etc. There's no guarantee as to the outcome but given the strong cluster (75%-85%) pointing to given outcomes, I believe one should take such outcomes seriously. Moreover, there is good model support for a significant snowstorm (amounts, actual locations still debateable) so I don't believe the analogs are necessarily pointing to a dead-end.

BTW, the analogs for Boston suggested overwhelming support for at least 10" and good support for at least 15" for January. So far, 11.9" has fallen there this month. Given the modeling and the idea that the analogs did not prove clueless with regard to Boston, I think having some confidence in the analogged ideas concerning DCA and NYC is not a stretch.

[donsutherland1]

Thanks Perry.

Very well said. It will be interesting to see how this storm ultimately evolves.

[krysof]

New gfs models came out showing a stronger storm than the last run and a further north snow event. This could be intense for Philly, NYC, and/or Boston.

[Matt31388]

They're calling for 1 to 3 inches here in Eastern KY, how good of chance do we have that amount will increase by Saturday?

[DS]

Has anyone ever heard of a theory that the GFS is much better beyond day 7 and within day 4? This, I think is a classic case of such an argument. From day 7 to 10, the GFS had a consistent storm track WAY farther south than now. Now, (day 5, 6), it is going bonkers and going WAY farther north. I do agree with its swath or precip, but I believe that the redevelopment of the 2nd low will be much stronger and further south, showing that the GFS's progs from day 8, 9, 10 were better, again.

[krysof]

The 18z run of the gfs shows the secondary low spinining of the jersey shore or so. This is as north as I want the gfs to go with it because I'm getting nervous that if the north trend continues, that I will get ice or rain here in north central nj. I want the storm to be much stronger and a little further south. A stronger storm will spread snow up and down the east coast no matter if its much further south.

[wxguy25]

Some quick thoughts...

1) I believe somewhere along the East Coast will likely see a 6" or greater snowstorm (with potentially more).

2) Past consistency in the modeling with a focus on the Mid-Atlantic makes me suspect that this area (probably such cities as DCA, BWI, and PHL) will probably have a relatively higher risk at seeing 6" or more. This does not rule out the possibility of a significant snowfall for southern and even central New England.

3) I'm not ready to buy into last night's run of the ECMWF, though it's an argument that might have merit, especially if the Euro locks into it.

4) Past analogs supported far more snowfall in January than has occurred in DCA to NYC and help give some credence to the idea that a significant storm might occur.

• Almost 85% of analog years saw more than 1" in DCA and 1/4 saw 6" or more.
• Almost 75% of those analogs saw NYC receive 2" or more in January and 47% saw 10" or more.

January snowfall to date has come to 0.5" in NYC and Trace in DCA.

Thus given the weight of analogs, I'd be extremely surprised if either of these cities finished close to where they're currently at.

This does not mean that extreme snowfall is likely though each city did have a few extreme outliers among the analogs.

FWIW, the February ideas also look snowier than normal in these cities and I'll be interested to see whether the picture holds together when the ENSO data for the week of January 12 becomes available.

5) Things can still go wrong. But I would be suprised if no one on the East Coast saw a significant snowfall from the weekend event.

Who gets how much is still quite uncertain for me. Others might have a firmer grasp on that.

Hopefully--and this is my preference and not any kind of forecast--cities that have been starved for snow, not just this winter but also over the past two winters i.e., Richmond, Washington, DC, Baltimore, and Philadelphia, will all enjoy a significant snowfall of 6" or more.

I pretty much agree however 6"+ in RIC is looking more in jeopardy w/ each Euro run and the GFS is now beginning to come around to that idea though its going to take a few more runs to begin to cement any kind of consensus.

WRT DCA-PHL 6"+ seems a pretty good bet unless it gets to the extreme of the 12z ECMWF.

NYC is in good shape regardless.

[stormman]

question, you say 6+ for philly unless its gets to the extreme of the 12z euro? If the 12z euro were to verify what would that mean?

[Chris the Weather Man]

Yes, west of NYC do look good....... Historic? well, that remains to be seen....