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Jan 20/21 Snow Threat


snowNH

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Wow... the NAM is pulling the Messenger special of cutting back and shaving QPF just hours before a storm. I remember last winter it did that every single time.

I'm pretty sure the NAM has the worst precip score of any model past like 36 hours. If people actually try base a forecast off of it when it differs from the Euro/GFS/SREF precip drastically, then that is poor forecasting.

It was showing over half an inch of qpf here a few runs ago while the Euro has been pretty steady for the last 3-4 runs.

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I'm pretty sure the NAM has the worst precip score of any model past like 36 hours. If people actually try base a forecast off of it when it differs from the Euro/GFS/SREF precip drastically, then that is poor forecasting.

It was showing over half an inch of qpf here a few runs ago while the Euro has been pretty steady for the last 3-4 runs.

Yeah... it was awful up here during the event prior to MLK weekend. We were supposed to get that SW flow slug of precip which led folks to think 4-7" and most of northern VT ended up with 2-3" and only 0.2" of liquid vs. a NAM 0.6" forecast, lol.

EURO has been impressively steady based on the posts here of a consistent 0.3-0.4" QPF.

I still think all of you get into the 3-6" range... solid Advisory event. That radar doesn't look all that bad, I mean no one was expecting a major storm and it really doesn't need to look like much on radar to get a fluffy 4, 5, even 6". Just think back to yesterday, radar didn't look that impressive coming across NYS... you never would've known that it would produce 4-6" totals in parts of SE MA.

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Yeah... it was awful up here during the event prior to MLK weekend. We were supposed to get that SW flow slug of precip which led folks to think 4-7" and most of northern VT ended up with 2-3" and only 0.2" of liquid vs. a NAM 0.6" forecast, lol.

EURO has been impressively steady based on the posts here of a consistent 0.3-0.4" QPF.

I still think all of you get into the 3-6" range... solid Advisory event. That radar doesn't look all that bad, I mean no one was expecting a major storm and it really doesn't need to look like much on radar to get a fluffy 4, 5, even 6". Just think back to yesterday, radar didn't look that impressive coming across NYS... you never would've known that it would produce 4-6" totals in parts of SE MA.

I'll be interested to see the flake quality...if we are getting efficient dendrites, then it won't take much to get 4-5" amounts. But I'm not totally excited by upstream obs...usually good dendritic growth will yield a lot more 1/2 mile obs or less...but who knows, good dendrites can do pretty good damage even with 3/4 mile vis.

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Little pins here ...the kind of stuff you get when it is extremely cold and dry. It is 9 degrees after all.

Radar shows some 20 dbz stuff trying to finally extend northeast from BGM and at the same time the back edge is sinking to the west ...maybe we'll get a couple hours of decent snow before it just starts to taper off. LOL

I'll be interested to see the flake quality...if we are getting efficient dendrites, then it won't take much to get 4-5" amounts. But I'm not totally excited by upstream obs...usually good dendritic growth will yield a lot more 1/2 mile obs or less...but who knows, good dendrites can do pretty good damage even with 3/4 mile vis.

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Little pins here ...the kind of stuff you get when it is extremely cold and dry. It is 9 degrees after all.

Radar shows some 20 dbz stuff trying to finally extend northeast from BGM and at the same time the back edge is sinking to the west ...maybe we'll get a couple hours of decent snow before it just starts to taper off. LOL

NEEDLES!!!!!!!!!

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Concerning signs:

- Obs from Philly / southern NJ area are consistent with colder 6Z NAM, ie., drier for SNE

- Dewpoints are around 4-5F in SNE... at least several degrees colder than 0Z NAM and GFS MOS

Meanwhile...

Congrats AmericanWx... From Upton AFD:

.NEAR TERM /THROUGH TONIGHT/...

BANDS OF LIGHT TO MODERATE SNOW ARE FILLING ACROSS THE ENTIRE CWA.

INITIAL REPORTS VIA SPOTTERS...AMERICANWX.COM AND ASOS OBS

INDICATE 1-2 INCHES OF ACCUMULATION FROM NYC WEST...AND A

COATING TO AN INCH FARTHER EAST. COASTAL FRONT HAS SET UP JUST S

OF LONG ISLAND...AND NE FLOW SHOULD KEEP SFC TEMPS WELL BELOW

FREEZING FOR THE DURATION OF THE EVENT. 06Z NAM HAS ALSO TRENDED

COLDER ALOFT...WITH NEARLY ALL SNOW AND JUST A BRIEF MIX WITH

SLEET IN THE AFTERNOON FOR LONG ISLAND. ITS QPF IS ALSO

LOWER...BUT ITS HIGHER SNOW RATIOS OF 12-15 TO 1 DURING PDS OF

MODERATE SNOW SHOULD KEEP AMTS SIMILAR TO PREVIOUS FCST.

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Wow... the NAM is pulling the Messenger special of cutting back and shaving QPF just hours before a storm. I remember last winter it did that every single time. It was atrocious in that event before MLK weekend with QPF, too... it was way too high up here, showing a slug of over 1/2" and we got like 0.2-0.3". Not sure what it is with that model.

nam_namer_024_precip_p24.gif

Shouldn't come as a suprise to anyone....it always initially overestimates qpf by at least 1\3.

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Well the amounts I threw out after the 12z runs came out yesterday are going to be too high I think given the trends. Hopefully 2-4 for BOS. 4.7 probably is not happening although 3-5 was the range i was thinking. That's why we have ranges, for things like this.

Ranges allow us "careful space".

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NAM does show frontogenesis increasing between 900mb and 700mb across southern and southeastern areas. I do think this will help wring out some extra snow.

Ratios won't be too great either... snow growth isn't too exciting. Looks like at least so far best lift is under the DGZ.

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NAM does show frontogenesis increasing between 900mb and 700mb across southern and southeastern areas. I do think this will help wring out some extra snow.

Ratios won't be too great either... snow growth isn't too exciting. Looks like at least so far best lift is under the DGZ.

Could be above it too. There was some lift at 500mb.

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First flakes started about 2 miles into my run and by mile 5 it was coming down nicely. Rds already snowcovered. Perfect winters day . I was in all my glory running..Tunes banging, snow falling, temps in the mid teens. I had this huge smile on my face half the time. Radar looks good for a nice solid 3-6.

I know, I was out walking the dogs.perfect winters moring, work cancelled. Getting good snow growth now and hey watch Thursday bro.

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NAM does show frontogenesis increasing between 900mb and 700mb across southern and southeastern areas. I do think this will help wring out some extra snow.

Ratios won't be too great either... snow growth isn't too exciting. Looks like at least so far best lift is under the DGZ.

Nice growth here now. Not sure what you were expecting with all the Debbie posts but this is sweet this winter.

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