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October Discussion: Bring the Frost-Hold the Snow


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20 minutes ago, wxeyeNH said:

Question....  has any "official" reporting station in New England or for that matter the Northeast reported a 32F for a low yet.  I know a few weather stations like Alex's  31.9F have had a touch of frost but anything official?

 

CAR had their first frost (36F or lower) on 9/29, and CON had theirs on 10/1, but no freezes yet. Gonna be an easy frost/freeze program this year for the New England WFOs because by the time we have first frosts and freezes the growing season will officially be over. After this week all but 4 of the 22 climo sites in CT that have published frost/freeze normals will be past their average first freeze date, so I imagine northern New England is weeks behind schedule.

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1 minute ago, CoastalWx said:

36 counts as a frost?

I mean you have to pick a 2m temp threshold since actual frosts aren't tracked officially. I guess 36F at 2m means a few degrees colder at ground level where plants might be? I've always assumed the 36/32/28 thresholds for which they publish normals were the frost/freeze/hard freeze thresholds for climate tracking purposes and weren't just randomly selected temp thresholds.

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Just now, snowman21 said:

I mean you have to pick a 2m temp threshold since actual frosts aren't tracked officially. I guess 36F at 2m means a few degrees colder at ground level where plants might be? I've always assumed the 36/32/28 thresholds for which they publish normals were the frost/freeze/hard freeze thresholds for climate tracking purposes and weren't just randomly selected temp thresholds.

Maybe we should clarify 32 or lower if people are thinking that when talking frost. I think that's what most people mean. I get what you are saying. I never knew 36 was the temp when considering frosts. My personal observations are that you may get a few whites shingles on the roof at those temps. But me personally....I don't really think of it as a first frost.

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10 minutes ago, snowman21 said:

CAR had their first frost (36F or lower) on 9/29, and CON had theirs on 10/1, but no freezes yet. Gonna be an easy frost/freeze program this year for the New England WFOs because by the time we have first frosts and freezes the growing season will officially be over. After this week all but 4 of the 22 climo sites in CT that have published frost/freeze normals will be past their average first freeze date, so I imagine northern New England is weeks behind schedule.

Interesting about the growing season will be officially over.  I never thought of that but even if we got there I feel they should issue a frost/freeze since although the farming growing season will be over many people keep houseplants out.  I had envisioned that once we get later in the season than this when the first cold snap comes they will have to issue a warning  from the Canadian border to the South Coast of New England, basically all of New England at one time.

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Just now, CoastalWx said:

Maybe we should clarify 32 or lower if people are thinking that when talking frost. I think that's what most people mean. I get what you are saying. I never knew 36 was the temp when considering frosts. My personal observations are that you may get a few whites shingles on the roof at those temps. But me personally....I don't really think of it as a first frost.

We usually can frost the grass and cars at like 35F here on rad nights.

I know the NWS BTV climo looks at 36> as frost and 32> freeze.  I think the advisories are listed that way too.

Frost Advisory when expecting 36F or lower, Freeze Warning for 32F or lower.

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1 minute ago, wxeyeNH said:

Interesting about the growing season will be officially over.  I never thought of that but even if we got there I feel they should issue a frost/freeze since although the farming growing season will be over many people keep houseplants out.  I had envisioned that once we get later in the season than this when the first cold snap comes they will have to issue a warning  from the Canadian border to the South Coast of New England, basically all of New England at one time.

I know...the NWS I believe goes by Climo dates for that (Ocean St can correct me if I am wrong)...but in reality people will sort of base plants on the current wx regime. 

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2 minutes ago, powderfreak said:

We usually can frost the grass and cars at like 35F here on rad nights.

I know the NWS BTV climo looks at 36> as frost and 32> freeze.  I think the advisories are listed that way too.

Frost Advisory when expecting 36F or lower, Freeze Warning for 32F or lower.

Yes...but I think in general people consider first frosts in their minds as 32 or lower. 

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Just now, Damage In Tolland said:

Not really. A freeze is upper 20’s

No it’s not though lol.  That’s technically a “hard freeze” I think they call it at 28F or lower.

The freezing point is 32F but remember it’s at 2-meter. Your grass and garden surface is colder than the 2-M temp on calm nights.  If you put the sensor right on the grass blades you would see it like putting your dew sensor in the mulch bed in the summer.

 

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1 minute ago, CoastalWx said:

Yes...but I think in general people consider first frosts in their minds as 32 or lower. 

Interesting.  I’ve always seen frosts around here in that 32-36F range with clear skies.  If we hit 31F it’s just full on frozen/freeze.  Like scraping the inside of your car windows lol.

Maybe it’s the rad valley affect.  A hilltop with breeze at 34F maybe not?  Clear dead calm 34F here is definitely a good healthy white frost on the yard.

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3 minutes ago, powderfreak said:

Interesting.  I’ve always seen frosts around here in that 32-36F range with clear skies.  If we hit 31F it’s just full on frozen/freeze.  Like scraping the inside of your car windows lol.

Maybe it’s the rad valley affect.  A hilltop with breeze at 34F maybe not?  Clear dead calm 34F here is definitely a good healthy white frost on the yard.

For instance, Joe Schmoe sees frost on his car or grass. He says hey it must be 32 out!! He's probably close to being correct. If he looks at his thermo and sees it is 35 with nice signs of frost...I don't think he'll get excited about saying he had his first frost. I think there is a difference in a field that is subject to radiational cooling for sure as you said. Objects on a clear and calm night will act to be cooler than the ambient air temp. 

 

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9 minutes ago, wxeyeNH said:

Interesting about the growing season will be officially over.  I never thought of that but even if we got there I feel they should issue a frost/freeze since although the farming growing season will be over many people keep houseplants out.  I had envisioned that once we get later in the season than this when the first cold snap comes they will have to issue a warning  from the Canadian border to the South Coast of New England, basically all of New England at one time.

I don't know what the rule is, but it happens every now and again where you'll never see a frost/freeze advisory/warning even if it's the first one, and the discussion always refers to the growing season being over even if not in reality. I'm not sure what cut off they use though for when they end the growing season. I doubt it's the 50th percentile (average) date, so maybe they take the 75th or 90th percentile date and call the season over at that point meaning no need to issue any sort of advisories.

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8 minutes ago, CoastalWx said:

For instance, Joe Schmoe sees frost on his car or grass. He says hey it must be 32 out!! He's probably close to being correct. If he looks at his thermo and sees it is 35 with nice signs of frost...I don't think he'll get excited about saying he had his first frost. I think there is a difference in a field that is subject to radiational cooling for sure as you said. Objects on a clear and calm night will act to be cooler than the ambient air temp. 

 

Yeah it’s probably very based on location.  Like maybe DIT doesn’t even see frost until 20s because it’s breezy on a hilltop?

I do agree that Joe Schmoe sees frost outside he thinks it’s 32F outside, whether it is or not.  He’s telling his friends it got to freezing even if he had a Davis and it had a min of 34.4F but his grass, car, and neighbor’s roof is white.  My wife thinks it’s freezing, then I tell her the low was 34F and she’s confused… so I just say yeah must’ve been freezing :lol:.

Experiences all cloud our opinions, a suburban neighborhood, a mixed hilltop or a radiational area will all see it slightly different.

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17 minutes ago, powderfreak said:

Yeah it’s probably very based on location.  Like maybe DIT doesn’t even see frost until 20s because it’s breezy on a hilltop?

I do agree that Joe Schmoe sees frost outside he thinks it’s 32F outside, whether it is or not.  He’s telling his friends it got to freezing even if he had a Davis and it had a min of 34.4F but his grass, car, and neighbor’s roof is white.  My wife thinks it’s freezing, then I tell her the low was 34F and she’s confused… so I just say yeah must’ve been freezing :lol:.

Experiences all cloud our opinions, a suburban neighborhood, a mixed hilltop or a radiational area will all see it slightly different.

I will say in my simple, male mind.....I only care about 32. Like if I see frost on the roof and it's 34 or 35...it means little to me. I always view 32 as the benchmark. 

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27 minutes ago, powderfreak said:

I think the difference is what we each think is what… versus what NOAA/NWS tracks.  

36/32/28 degrees are the official thresholds they track it seems.

Correct. PEople need to distinguish between what "They think" and what the official thresholds are. For NWS tracking, 33-36F is a frost.

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I don’t frost well on the ground here on my hillside so I don’t see frost above 33. At my old place near Massabesic Lake I used to radiate like mad and could frost the ground up at 35/36. You really need a spot where the cold air can drain in and pool. If you fog up at 34-35 you may not even frost up in the valley either since the temp in the fog layer will be somewhat uniform. Either that or you get some dew that turns to frozen dew if you drop down to 32 after it forms. Someone like Kevin who stays well mixed will be less likely to see frost at >32 as well. So a lot goes into it.

To me, a frost is a frost. If you see frosty grass at 35 it counts. But I only track freezes/32 since you can actually track that with remote sensing. You can get a freeze before a frost too in a season like this where you are way later than normal and then a strong cold front comes in and gives you a mixed 30-32 with no ground saturation. 

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