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11/7 Noreaster Thread


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I think it accounts for it because verbatim the GFS drops close to an inch of QPF, factor in some melting & sleet at the end and seems about right.

Depends on how much of that QPF the GFS actually qualifies as falling as snow. Most model sites will just output the standard 10:1 ratio because, as far as I know, the GFS just uses a binary yes/no for snow QPF water equivalent and doesn't calculate a ratio. It would be up to the programmers of each individual site to add in a calculation for ratios.

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This was mentioned in the NYC thread... but I think how cold it was today has a lot to do with these forecasts evolving into snow. The cold wasn't supposed to be this persistent, its definitely noticeably colder now back there than it was expected to be several days ago.

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How does Hurricane Schwartz concentrate on his job with Sheena Parveen working next to him...I envy him & pity him LOL...

I asked earlier, does this storm have a chance to beak the all-time Nov snowfall for 24hrs in Philly?

http://www.americanwx.com/bb/index.php/topic/37634-117-noreaster-thread/page__st__700#entry1850525

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This was mentioned in the NYC thread... but I think how cold it was today has a lot to do with these forecasts evolving into snow. The cold wasn't supposed to be this persistent, its definitely noticeably colder now back there than it was expected to be several days ago.

you still locked in for your 8-12 loli's to 16?

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Top 5 November Snowstorms in Chester County (don't think any of these will be approached with this one)

1) 11/15/1906 - 9.5"

2) 11/6/1953 - 8.6"

3) 11/26/1938 - 7.0"

4) 11/4/1910 - 6.6"

5) 11/15/1908 - 6.3"

Wondering what was reported for the 1987 Veterans Day storm and the 1989 Thxgvg Eve storm?

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This was mentioned in the NYC thread... but I think how cold it was today has a lot to do with these forecasts evolving into snow. The cold wasn't supposed to be this persistent, its definitely noticeably colder now back there than it was expected to be several days ago.

I was wondering the same...had a high of 44 today, currently 33, forecast low of 27

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I have just a brief question/ concern about the combination of wind and snow. We are looking at a high wind warning along our coast with about 50% of the leaves on the larger mature trees, especially oak. If the wind stays N or NNW during the height of the storm, then I believe even we would eventually go over to snow. I doubt it would take more than a half inch of heavy wet snow to bring down limbs and trees with warning level winds. The ground is still very soft from 8"+ rains last week and the morning rains will not help. Just a concerned fire captain here, thanks all for the great reads!

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Well, the thing about high winds is that it actually tends to decrease the overall accumulation of snow on trees. The prettiest snows are where it just snows and sits, the snow just keeps building up. With significant wind, the snow tends to blow off.

Ratios will also make a big difference as far as how much it takes to bring down branches... A relatively high ratio snow (10:1 or 12:1) will require many more inches than a low ratio 3:1 or 5:1. And yes, those low ratios are what may happen tomorrow.

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HPC discussion - sounds like it does not reflect 18z

MID ATLANTIC...

THE 12Z GUIDANCE NUDGED BACK WEST TOWARDS THE COAST...BUT

INDIVIDUAL MODELS OFFERED A VARIETY OF SOLNS OF QPF AND THERMAL

FIELDS. TENDED TO PUT MOST WEIGHT INTO A COMPROMISE OF THE 12Z

GFS AND ECMWF...ALTHOUGH ASSUMED THAT THE CENTRAL PRESSURE OF THE

LOW PRESSURE CENTER WILL BE SLIGHTLY UNDER 990 MB BASED ON

DISCUSSIONS WITH HPC MODEL DIAGNOSTICS. THE PROBABILISTIC MAPS

CLEARLY DEPICTED A STRIPE OF SLIGHT RISK OF 4 INCHES MAINLY ACROSS

NJ AND SE PA...AND FELT THAT WAS ADEQUATE GIVEN THE UNCERTAINTY IN

TRACK. FORECAST SOUNDINGS FROM BOTH THE NAM AND GFS WERE NOT

TERRIBLY FAVORABLE FOR SNOW UNTIL THE AFTER 07/21Z IN THIS AREA.

NORMALLY WOULD HAVE THOUGHT THE WINDOW OF OPPORTUNITY FOR 4 INCHES

WOULD BE LIMITED BY THE SHORT DURATION BUT THIS AREA IS IN THE

FAVORED DEFORMATION ZONE AND HAS MAXIMUM OF VERTICAL VELOCITIES IN

THE DENDRITIC GROWTH REGION IN A FEW OF THE MODELS...SO DID NOT

FEEL A SLIGHT RISK OF 4 INCHES WAS UNREASONABLE.

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It's one of those things where you know mesoscale banding will hook someone up in a narrow area, but if you are not under that band, it will be tough to accumulate. 15-20 DBZs won't cut it.

would make sense and be ......intelligent to mention that in the advisory i would think .

why not mention 1-2 inches with higher spots where meso scale banding sets up "which is difficult to pin down" ?

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