December 2016 Observations & Discussions

Was at 64° at 2pm now down to 47°

42.8 here now

40 degrees

39. Frank what caused the winds not to be much of anything compared to how models were show img near warning level winds 36 hrs ago? Trying learn why these wind events never pan out. Breezy once in a while right now but Def no 40mph gusts. And it was also supposed to be in the morning. Was the front slower?

33* black ice forming in spots.

jmanley32 wrote:39. Frank what caused the winds not to be much of anything compared to how models were show img near warning level winds 36 hrs ago? Trying learn why these wind events never pan out. Breezy once in a while right now but Def no 40mph gusts. And it was also supposed to be in the morning. Was the front slower?

Jman, take a look at the image below, which is the sounding for OKX from tonight:



Look at the region that I have circled in neon green.

The red line shows the temperature profile through the atmosphere while the green line shows the dew point. The level of the atmosphere is denoted by the horizontal black lines labeled with the numbers on the left side of the graph, which are labels in hPa/mb. In the area of the temperature/dewpoint lines that I have circled, notice how the red (temperature) line takes a sharp turn to the right between the 1000 and 850 hPa levels (so at approximately 925 hPa), and then less significantly at the 850 hPa level. Now take a look at the numbers along the bottom of the graph; those are temperatures in °C. So, where the temperature line turns sharply to the right, that means that there was a sharp increase in the temperature in the layer where it first made the turn through where it reversed course. That's known as an inversion, because you have temperature increasing with height when it should decrease, as well as colder air beneath warmer air (colder air below the 925 hPa level with a sharply warmer layer between 925-850 hPa). When cold air is below warm air, especially when the cold air is at the surface, that is a highly stable situation because cold air is dense and warm air is not, so it acts to stop any vertical motion (why would it want to allow vertical motion, which works to achieve stability, when it is already stable?). Therefore, even though the winds at 850 hPa were close to 50 knots, because the lower atmosphere was stable, (thanks to the inversion), they could not be mixed down to the surface. That inversion essentially acts as a barrier that won't allow anything to move through it until it is eroded.

Make sense?

Just as an interesting aside, if we were looking for severe weather, that same inversion would be known as a "cap", because it would essentially be putting a lid on the convection, not allowing any to develop from surface-based air parcels (until it was eroded, in which case you would then achieve explosive convection assuming conditions were favorable for severe weather).

35° at Stony Brook........to make the ° symbol on your key board hold down the "Alt" key and then key in the numbers 0176.

From and iPhone or iPad keep your finger on the number 0 you'll see a ° pop up above it slide your finger to it to select it.

rb924119 wrote:

jmanley32 wrote:39. Frank what caused the winds not to be much of anything compared to how models were show img near warning level winds 36 hrs ago? Trying learn why these wind events never pan out. Breezy once in a while right now but Def no 40mph gusts. And it was also supposed to be in the morning. Was the front slower?

Jman, take a look at the image below, which is the sounding for OKX from tonight:



Look at the region that I have circled in neon green.

The red line shows the temperature profile through the atmosphere while the green line shows the dew point. The level of the atmosphere is denoted by the horizontal black lines labeled with the numbers on the left side of the graph, which are labels in hPa/mb. In the area of the temperature/dewpoint lines that I have circled, notice how the red (temperature) line takes a sharp turn to the right between the 1000 and 850 hPa levels (so at approximately 925 hPa), and then less significantly at the 850 hPa level. Now take a look at the numbers along the bottom of the graph; those are temperatures in °C. So, where the temperature line turns sharply to the right, that means that there was a sharp increase in the temperature in the layer where it first made the turn through where it reversed course. That's known as an inversion, because you have temperature increasing with height when it should decrease, as well as colder air beneath warmer air (colder air below the 925 hPa level with a sharply warmer layer between 925-850 hPa). When cold air is below warm air, especially when the cold air is at the surface, that is a highly stable situation because cold air is dense and warm air is not, so it acts to stop any vertical motion (why would it want to allow vertical motion, which works to achieve stability, when it is already stable?). Therefore, even though the winds at 850 hPa were close to 50 knots, because the lower atmosphere was stable, (thanks to the inversion), they could not be mixed down to the surface. That inversion essentially acts as a barrier that won't allow anything to move through it until it is eroded.

Make sense?

Just as an interesting aside, if we were looking for severe weather, that same inversion would be known as a "cap", because it would essentially be putting a lid on the convection, not allowing any to develop from surface-based air parcels (until it was eroded, in which case you would then achieve explosive convection assuming conditions were favorable for severe weather).

This actually helped me. So thanks Ray.

At the end of the day, it's not about what wind speeds models show between 925mb and 850mb, but rather are conditions conducive enough for those wind speeds to mix down to the surface. Normally precipitation helps do that but the rain was very light today. Practically drizzle.

Wow, dropped from 50.2 down to 17.9 now! 72%, 30.37 R

Got maybe an inch or two of snow on the property but prospects for a White Christmas look dim with temps Weds and beyond reaching the low 40's each day.Snowpiles, maybe.Anyway, Christmas forecast 44, much better than last years torch.

21.0°, about 2" or so survived yesterday's high of 44.7 and light rain... pattern looks bleak for the next few weeks

Frank_Wx wrote:

rb924119 wrote:

jmanley32 wrote:39. Frank what caused the winds not to be much of anything compared to how models were show img near warning level winds 36 hrs ago? Trying learn why these wind events never pan out. Breezy once in a while right now but Def no 40mph gusts. And it was also supposed to be in the morning. Was the front slower?

Jman, take a look at the image below, which is the sounding for OKX from tonight:



Look at the region that I have circled in neon green.

The red line shows the temperature profile through the atmosphere while the green line shows the dew point. The level of the atmosphere is denoted by the horizontal black lines labeled with the numbers on the left side of the graph, which are labels in hPa/mb. In the area of the temperature/dewpoint lines that I have circled, notice how the red (temperature) line takes a sharp turn to the right between the 1000 and 850 hPa levels (so at approximately 925 hPa), and then less significantly at the 850 hPa level. Now take a look at the numbers along the bottom of the graph; those are temperatures in °C. So, where the temperature line turns sharply to the right, that means that there was a sharp increase in the temperature in the layer where it first made the turn through where it reversed course. That's known as an inversion, because you have temperature increasing with height when it should decrease, as well as colder air beneath warmer air (colder air below the 925 hPa level with a sharply warmer layer between 925-850 hPa). When cold air is below warm air, especially when the cold air is at the surface, that is a highly stable situation because cold air is dense and warm air is not, so it acts to stop any vertical motion (why would it want to allow vertical motion, which works to achieve stability, when it is already stable?). Therefore, even though the winds at 850 hPa were close to 50 knots, because the lower atmosphere was stable, (thanks to the inversion), they could not be mixed down to the surface. That inversion essentially acts as a barrier that won't allow anything to move through it until it is eroded.

Make sense?

Just as an interesting aside, if we were looking for severe weather, that same inversion would be known as a "cap", because it would essentially be putting a lid on the convection, not allowing any to develop from surface-based air parcels (until it was eroded, in which case you would then achieve explosive convection assuming conditions were favorable for severe weather).

This actually helped me. So thanks Ray.

At the end of the day, it's not about what wind speeds models show between 925mb and 850mb, but rather are conditions conducive enough for those wind speeds to mix down to the surface. Normally precipitation helps do that but the rain was very light today. Practically drizzle.

Wow I learned me a little something as well.  And Frank ironically this was likely one reason, if not THE reason,  why there was nothing but a little light rain to drizzle for most of us as the front ran through the coastal plain where this inversion layer resided.  As Ray mentions this inversion layer created stability between 1000mb-925mb.  So as the front pushed through, the precip essentially "dried up" relative to areas N&W of the coastal plain.    Despite the heavier winds above this inversion layer as Ray points out in the soundings, no heavy down pours, then no mixing the mid level winds down to the surface.  

Here is the 3KM Total precip before the front, and after the front.  Notice the line of higher precip totals from SW to NE (A line through Central PA, NW NJ, N HV, NW CT, and into Mass) essentially stops as it reaches the coast, again likely due in large part to the inability for air to rise with any gusto due to the "capping" effect of this inversion layer between 1000-925mb; therefore, no burst of heavy down pours that typically comes with a cold frontal passage.  And Ray I am going to assume that during early spring and summer months this is also a reason why I typically see nice summer thunderstorms literally fizzle out as they head out over LI.  The cool marine layer at the surface creates a similar inversion.  FYI the sounding from OKX that Ray refers to above is from the Upton station out on LI.  

BEFORE THE FRONT:



AFTER THE FRONT:

18 degrees at 7 am this morning. Snow melted yesterday off grass then froze on the driveway overnight...a sheet of ice this morning! Lots of wind last night and of course there was a precipitous snow melt with the rise in temps yesterday. Almost makes no sense...ying and yang thing.

No worries, Frank!! I didn't mean to steal your thunder, but I just happened to see the question and it sparked my own curiosity. Once I found out why, I figured I might as well just put it up.

And Scott, that is very likely a big reason, although LI and the coastal plain also experience sea breezes, which set up their own meso-scale circulations that play a role as well.

rb924119 wrote:No worries, Frank!! I didn't mean to steal your thunder, but I just happened to see the question and it sparked my own curiosity. Once I found out why, I figured I might as well just put it up.

And Scott, that is very likely a big reason, although LI and the coastal plain also experience sea breezes, which set up their own meso-scale circulations that play a role as well.

No such thing as stealing thunder here. You read a question where you feel you can provide input, answer it. Semplice! ("simple" in Italian).

Frank_Wx wrote:

rb924119 wrote:No worries, Frank!! I didn't mean to steal your thunder, but I just happened to see the question and it sparked my own curiosity. Once I found out why, I figured I might as well just put it up.

And Scott, that is very likely a big reason, although LI and the coastal plain also experience sea breezes, which set up their own meso-scale circulations that play a role as well.

No such thing as stealing thunder here. You read a question where you feel you can provide input, answer it. Semplice! ("simple" in Italian).

Thats why I love this board, it is an oasis of reason and respectability, folks with an interest of sharing and studying the science of meteorology for others to learn.You guys are the best!!!!

16.8, 68%, 30.43 R

docstox12 wrote:Wow, dropped from 50.2 down to 17.9 now! 72%, 30.37 R

Got maybe an inch or two of snow on the property but prospects for a White Christmas look dim with temps Weds and beyond reaching the low 40's each day.Snowpiles, maybe.Anyway, Christmas forecast 44, much better than last years torch.

Still 8 degrees above the normal Christmas high temperature of 36 but beggers can't be choosers. Compared to last year it will feel arctic.

Ok, it's cold.

Another day of 30's tomorrow then temps rebound to slightly above normal rest of this week into Christmas.



Christmas Eve

Christmas Eve and Day look dry. If there's rain, it will come late Christmas Day into Monday.

Ice rink frozen baby been on it since Friday, last three years negative on this. 
May be ome a babynpol.once again by the end of the month but 4"of rock solid ice takes a while days on end for it to all melt.

If we aren't going to get much snow, at least we can keep it for a few days. Still have snow on the ground, probably about an inch or so left!

6 degrees, 82%, 30.38R.

rb924119 wrote:

jmanley32 wrote:39. Frank what caused the winds not to be much of anything compared to how models were show img near warning level winds 36 hrs ago? Trying learn why these wind events never pan out. Breezy once in a while right now but Def no 40mph gusts. And it was also supposed to be in the morning. Was the front slower?

Jman, take a look at the image below, which is the sounding for OKX from tonight:



Look at the region that I have circled in neon green.

The red line shows the temperature profile through the atmosphere while the green line shows the dew point. The level of the atmosphere is denoted by the horizontal black lines labeled with the numbers on the left side of the graph, which are labels in hPa/mb. In the area of the temperature/dewpoint lines that I have circled, notice how the red (temperature) line takes a sharp turn to the right between the 1000 and 850 hPa levels (so at approximately 925 hPa), and then less significantly at the 850 hPa level. Now take a look at the numbers along the bottom of the graph; those are temperatures in °C. So, where the temperature line turns sharply to the right, that means that there was a sharp increase in the temperature in the layer where it first made the turn through where it reversed course. That's known as an inversion, because you have temperature increasing with height when it should decrease, as well as colder air beneath warmer air (colder air below the 925 hPa level with a sharply warmer layer between 925-850 hPa). When cold air is below warm air, especially when the cold air is at the surface, that is a highly stable situation because cold air is dense and warm air is not, so it acts to stop any vertical motion (why would it want to allow vertical motion, which works to achieve stability, when it is already stable?). Therefore, even though the winds at 850 hPa were close to 50 knots, because the lower atmosphere was stable, (thanks to the inversion), they could not be mixed down to the surface. That inversion essentially acts as a barrier that won't allow anything to move through it until it is eroded.

Make sense?

Just as an interesting aside, if we were looking for severe weather, that same inversion would be known as a "cap", because it would essentially be putting a lid on the convection, not allowing any to develop from surface-based air parcels (until it was eroded, in which case you would then achieve explosive convection assuming conditions were favorable for severe weather).

I get the general idea, yeah thats very interesting and my question taught some good info to everyone so it worked out well all around. Funny enough it was windy as heck this morning and colddddd. I forgot what it was like to be cold in December lol. I believe my car said 25 at about 11:30. Not sure what it is now, cannot wait till one day I can have a weather station when I have my own property.

Frank_Wx wrote:Christmas Eve and Day look dry. If there's rain, it will come late Christmas Day into Monday.

As long as it doesn't snow on the 24th, 26th or 28th, both days I will be traveling in CT (family).

7.3°, 68%, 30.29 S - coldest morning so far this season

Will this be our last coldest night of the year looks like it .now we have to wait until Jan for the cold and snow .had a morning low of 20*

1.4 degree, 81%, 30.30 R

That little snowpack left, calm winds must have accentuated radiational cooling up here.Also at 700 feet up.