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1/21 Clipper Thread


84 Hour NAM

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This is a tough one. Really going to be tough to determine where good bands set up if they do at all. Could just be some light stuff for a 6-8 period.

I agree.. you can see the hints at banding on all the models. If those materialize, the snow may come down hard enough in a band to slush over roads even at like 1 pm. (The Hi-res NAM is a good deal colder than the GFS at the surface, especially in the northern suburbs.) But outside of the bands, I doubt there will be much impact during the daytime. 

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I agree.. you can see the hints at banding on all the models. If those materialize, the snow may come down hard enough in a band to slush over roads even at like 1 pm. (The Hi-res NAM is a good deal colder than the GFS at the surface, especially in the northern suburbs.) But outside of the bands, I doubt there will be much impact during the daytime. 

I thinnk you've hit on the big forecast dilemma, the location of the band.  

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my point is that they're easy to get wrong and aren't the storms we rely on to get to our season average in a normal season.  i do agree, though, that a little snow is better than nothing...but i also agree with ji's comment that clippers with marginal temps are tough to get excited about it.

 

IMO they're pretty easy to get right...with a good vort pass and supportive temps, forecast 0.5-3" and you'll be right 90+X/100 for typical clippers.  perhaps it's harder to forecast for right on the lee side of the mts as redevelopment is many times not speedy enough to catch them w/ decent LE, but for anywhere east of say Rt 29 in VA it's hard to get more straightforward.

 

shot in the dark:

DCA: 0.0-1", boom 1.3

IAD: 1-2", boom 2.8

BWI: 1-3", boom 3.5

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Marginal temperatures at the surface and at 925-900 mb, mostly light rates during the day... yeah, I'm not expecting too much locally. Probably should have brought the 1-2" contour even further north, but whatever. We'll see how it goes.

 

What's the point of putting out a map with a 40% (or is the shading meant to be less) confidence level?  Why not put out your highest confidence forecast?  It's within 24 hours.

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Question, what is the Canadian HRDPS on WxBell? It shows a nice hit for the clipper, but I'm not sure what it is. 

 

I believe it's an experimental high-resolution regional nest within the RGEM. 

 

https://weather.gc.ca/grib/grib2_HRDPS_HR_e.html

 

I'm not sure how good it is for our area.  The 12z run is weenie-bait if you're under one of the big bands.

 

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You have explained your reasoning and, I think, given the nature of clippers, it is very prudent. We are only talking about a few inches. My expectations are low. Nice to see flakes for a few hours., we can agree on that.

We had flakes here this afternoon. It wasn't that thrilling.

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I believe it's an experimental high-resolution regional nest within the RGEM. 

 

https://weather.gc.ca/grib/grib2_HRDPS_HR_e.html

 

I'm not sure how good it is for our area.  The 12z run is weenie-bait if you're under one of the big bands.

 

 

I haven't looked at it enough to know how good it performs for the area but you are right regarding what the HRDPS is - its basically an experimental high-res regional model within RGEM.  I think it even ingests the same data that the RGEM does, IIRC.

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