December obs/disco/short range

[MN Transplant]

If you like pina coladas

and getting caught in warm rain...

You and I found different soundings for IAD. That's weird. Got mine from Wyoming.

[das]

ImageUploadedByTapatalk1417527062.340281.jpg

 

Here's a better image:

 

[WxUSAF]

You and I found different soundings for IAD. That's weird. Got mine from Wyoming.

They look about the same from what I can tell.  Notice that -9.3C dewpoint at 917mb.  

 

Here's the link for mine:

 

http://climate.cod.edu/flanis/analysis/raob/index.php?type=conus-current-current-text-KIAD-0

[mappy]

i had a nice coating of sleet at the house, on the deck and car. driveway/roads were wet. but it definitely sleeted quite a bit overnight and this morning

[Ji]

what a failure this winter is so far

[CAPE]

what a failure this winter is so far

Get used to it. You have at least 2 more weeks of failure. For most of us, its been fine and realistically we dont expect any real winter weather until the end of December, or later.

[usedtobe]

IAD morning sounding:

 

Current filename: /home/data/upa/2014120212.upa.cvt

Date: 1200Z 2 DEC 14

Searching for KIAD...

Searching the city database file for: KIAD ...

Date:1200Z 2 DEC 14

Station: KIAD

WMO ident: 72403

Latitude: 38.95

Longitude: -77.45

Elevation: 98.00

-------------------------------------------------------------------------------

LEV PRES HGHT TEMP DEWP RH DD WETB DIR SPD THETA THE-V THE-W THE-E W

mb m C C % C C deg knt K K K K g/kg

-------------------------------------------------------------------------------

SFC 1024 98 1.8 -0.0 88 1.8 1.1 20 5 273.1 273.7 273.0 283.2 3.73

1 1021 120 1.6 -0.8 84 2.4 0.6 22 7 273.1 273.7 272.7 282.7 3.53

2 1019 135 1.8 -1.0 82 2.8 0.7 24 8 273.5 274.1 272.8 282.9 3.48

3 1000 279 0.4 -2.2 83 2.6 -0.6 40 18 273.5 274.1 272.5 282.4 3.25

4 985 400 -0.9 -3.8 81 2.9 -2.0 51 19 273.4 273.9 272.0 281.4 2.92

5 953 663 -2.1 -4.0 87 1.9 -2.8 80 21 274.8 275.3 272.9 283.0 2.98

6 951 680 -2.3 -5.4 79 3.1 -3.4 81 21 274.8 275.2 272.4 282.2 2.68

7 939 781 -2.7 -5.6 80 2.9 -3.7 90 23 275.4 275.8 272.8 282.8 2.68

8 931 849 -1.5 -7.5 64 6.0 -3.6 96 24 277.3 277.7 273.3 283.8 2.33

9 929 866 -2.7 -8.7 63 6.0 -4.7 97 24 276.2 276.6 272.4 282.2 2.13

10 925 900 -1.9 -7.9 63 6.0 -4.0 100 25 277.4 277.8 273.3 283.8 2.28

11 917 969 -2.3 -9.3 59 7.0 -4.6 101 23 277.6 278.0 273.2 283.5 2.06

12 909 1039 -2.9 -7.9 68 5.0 -4.6 102 20 277.7 278.1 273.6 284.3 2.32

13 899 1127 -3.3 -7.9 70 4.6 -4.8 103 17 278.2 278.6 273.9 284.8 2.34

14 897 1144 -2.9 -5.3 83 2.4 -3.8 104 16 278.8 279.3 275.0 286.8 2.87

15 888 1224 -3.1 -4.7 89 1.6 -3.7 107 13 279.4 279.9 275.6 287.9 3.03

16 880 1296 -1.9 -2.5 96 0.6 -2.1 126 11 281.4 282.0 277.4 291.5 3.61

17 876 1333 -3.7 -4.5 94 0.8 -4.0 135 10 279.8 280.4 275.9 288.6 3.12

18 871 1378 0.6 0.1 96 0.5 0.4 147 9 284.8 285.5 280.1 297.3 4.42

19 864 1443 1.8 1.3 96 0.5 1.5 164 8 286.7 287.5 281.5 300.5 4.86

20 858 1499 -0.5 -0.5 100 0.0 -0.5 179 7 284.9 285.6 280.0 297.0 4.30

21 850 1575 3.0 2.7 98 0.3 2.8 220 8 289.3 290.3 283.4 304.9 5.47

22 834 1729 4.0 3.8 99 0.2 3.9 235 14 291.9 293.0 285.1 309.3 6.03

23 831 1759 4.0 3.9 99 0.1 3.9 238 15 292.2 293.3 285.2 309.8 6.10

24 830 1769 2.6 2.6 100 0.0 2.6 239 16 290.8 291.8 284.1 306.8 5.56

25 801 2057 2.4 2.4 100 0.0 2.4 245 19 293.6 294.6 285.4 310.1 5.68

26 766 2417 0.2 0.2 100 0.0 0.2 245 21 295.0 295.9 285.2 309.9 5.07

27 765 2427 0.0 0.0 100 0.0 0.0 245 21 294.9 295.8 285.1 309.6 5.00

28 743 2661 -0.5 -0.5 100 0.0 -0.5 238 24 296.8 297.7 285.9 311.5 4.97

29 740 2694 -0.5 -0.5 100 0.0 -0.5 237 24 297.2 298.1 286.0 311.9 4.99

30 700 3137 -2.5 -2.6 99 0.1 -2.6 250 32 299.7 300.5 286.5 313.3 4.51

31 681 3355 -3.5 -3.6 99 0.1 -3.6 256 29 301.0 301.8 286.7 314.0 4.30

32 680 3367 -3.7 -3.8 99 0.1 -3.7 256 29 300.9 301.6 286.6 313.7 4.25

33 557 4916 -12.7 -13.2 96 0.5 -12.9 261 33 307.9 308.4 287.3 315.8 2.48

34 543 5110 -14.1 -14.7 95 0.6 -14.3 260 35 308.5 308.9 287.3 315.7 2.25

35 541 5138 -14.3 -15.0 94 0.7 -14.5 260 35 308.6 309.0 287.3 315.6 2.20

36 532 5265 -15.9 -17.1 90 1.2 -16.3 260 36 308.1 308.5 286.8 314.2 1.88

37 529 5308 -16.7 -19.2 81 2.5 -17.4 260 36 307.7 308.0 286.3 312.8 1.58

38 528 5322 -16.7 -19.3 80 2.6 -17.4 260 36 307.8 308.1 286.4 312.9 1.57

39 512 5553 -17.5 -17.9 97 0.4 -17.6 257 38 309.6 309.9 287.3 315.5 1.83

40 505 5656 -18.7 -19.5 93 0.8 -18.9 256 38 309.4 309.7 286.9 314.6 1.62

The 4C temp in the elevated warm layer is all you need to see.  About 2.5 degrees warmer than yesterday's 12Z run if I remember correctly. 

[Ji]

The 4C temp in the elevated warm layer is all you need to see.  About 2.5 degrees warmer than yesterday's 12Z run if I remember correctly. 

guess that 18z Nam was a bit off

[mitchnick]

The 4C temp in the elevated warm layer is all you need to see.  About 2.5 degrees warmer than yesterday's 12Z run if I remember correctly. 

Euro was right all along with the warmer progs.

[mitchnick]

guess that 18z Nam was a bit off

you're new here, aren't you?

[usedtobe]

guess that 18z Nam was a bit off

 

If you look at the 00 hr NAM from this morning you'll  see it is way off too.   It has max warm layer temp at 2C and it's 4C.  That's a pretty big difference.   The 12Z GFS also had a sleet sounding so none of the models had the warm layer warm enough. 

[usedtobe]

Euro was right all along with the warmer progs.

 

Did you actually see full resolution soundings from the euro?  

[The Dude]

Found a few pellets of ice on the grill cover this morning.  

[smokeybandit]

If I had musical talent and started a band, I'd name it "33 Degrees and Rain"

[T. August]

I received a bit more sleet than I thought I would. Little piles are sitting on the gutters and on the deck from where it slid off of the roof. I'll never know exactly how much it accumulated because it melted, but if I had to guess, I'd say .3".

 

By chance did anyone in SE Harford County measure the sleet accumulation lol?

[mitchnick]

Did you actually see full resolution soundings from the euro?  

saw the skewts off the Accuwx site and they always were warmer than NAM, GFS and Canadian

as of 2 days ago, it was essentially a non-event on the Euro as we are seeing today

[I-83 BLIZZARD]

Some sleet and snow flakes mixed leaving a coating on the deck. As of 8:30 just some light sprinkles at the house. Non event even there. Some moderate showers in downtown Baltimore. Cold rain basically everywhere.

[usedtobe]

Here's how model sounding can sometime bite you because we usually only see the forecast temperatures every 50mb or every 25mb depending on which site we're getting the sounding from  The actual sounding for IAD is shown below. The bold numbers to the left are the pressure levels and the bold numbers to right are the wet bulb tempertures at that level.  Note that at 834mb, the wet bulb temperature is 3.9C.  Such a warm wet bulb temperature usually will completely melt the snowflake so when it fall through the cold layer below 850 mb, the melted snowflake cannot refreeze.

 

 

21 850 1575 3.0 2.7 98 0.3 2.8 220 8 289.3 290.3 283.4 304.9 5.47
22 834 1729 4.0 3.8 99 0.2 3.9 235 14 291.9 293.0 285.1 309.3 6.03
23 831 1759 4.0 3.9 99 0.1 3.9 238 15 292.2 293.3 285.2 309.8 6.10
24 830 1769 2.6 2.6 100 0.0 2.6 239 16 290.8 291.8 284.1 306.8 5.56
25 801 2057 2.4 2.4 100 0.0 2.4 245 19 293.6 294.6 285.4 310.1 5.68

 

Now let's look at the NAM model sounding for the same time this morning.  The forecast by the model for 00 hrs where we're only looking at temperatures every 50mb.  Note that the temperature at 850mb and 800mb are both a tad warmer than the actual sounding but that the model sounding would still argue for sleet as the maximum wet bulb temperature in the warm layer is only 2C. Usually at 2 degrees the snowflake only partially melts so it will refreeze when it falls through the cold layer.

3  900  1116  -3.0  -4.9  87  1.9  -3.7 109  17 278.4 278.9 274.9 286.6  2.944  850  1571   1.1   1.0  99  0.1   1.1 159   7 287.3 288.2 281.8 301.1  4.845  800  2061   2.0   2.0 100  0.0   2.0 225  22 293.3 294.3 285.1 309.4  5.54

I also looked at the model sounding every 25mb and even that failed to catch the strength of the warm layer.  at 825mb the wet bulb temperature was only 2.6C.  That is still a sleet sounding. While model sounding are still the best way to determine precipitation type, they still can lead you astray on occasion even if the model forecast is not that bad.

[Ian]

guess that 18z Nam was a bit off

It kinda sorta got the heavier stripe idea right.

[Sparky]

i had a nice coating of sleet at the house, on the deck and car. driveway/roads were wet. but it definitely sleeted quite a bit overnight and this morning

yeah, I had at least a quarter inch of crust on the grass, deck, car, trashcan etc.

[ravensrule]

 

Here's how model sounding can sometime bite you because we usually only see the forecast temperatures every 50mb or every 25mb depending on which site we're getting the sounding from  The actual sounding for IAD is shown below. The bold numbers to the left are the pressure levels and the bold numbers to right are the wet bulb tempertures at that level.  Note that at 834mb, the wet bulb temperature is 3.9C.  Such a warm wet bulb temperature usually will completely melt the snowflake so when it fall through the cold layer below 850 mb, the melted snowflake cannot refreeze.

 

 

21 850 1575 3.0 2.7 98 0.3 2.8 220 8 289.3 290.3 283.4 304.9 5.47

22 834 1729 4.0 3.8 99 0.2 3.9 235 14 291.9 293.0 285.1 309.3 6.03

23 831 1759 4.0 3.9 99 0.1 3.9 238 15 292.2 293.3 285.2 309.8 6.10

24 830 1769 2.6 2.6 100 0.0 2.6 239 16 290.8 291.8 284.1 306.8 5.56

25 801 2057 2.4 2.4 100 0.0 2.4 245 19 293.6 294.6 285.4 310.1 5.68

 

Now let's look at the NAM model sounding for the same time this morning.  The forecast by the model for 00 hrs where we're only looking at temperatures every 50mb.  Note that the temperature at 850mb and 800mb are both a tad warmer than the actual sounding but that the model sounding would still argue for sleet as the maximum wet bulb temperature in the warm layer is only 2C. Usually at 2 degrees the snowflake only partially melts so it will refreeze when it falls through the cold layer.

3  900  1116  -3.0  -4.9  87  1.9  -3.7 109  17 278.4 278.9 274.9 286.6  2.944  850  1571   1.1   1.0  99  0.1   1.1 159   7 287.3 288.2 281.8 301.1  4.845  800  2061   2.0   2.0 100  0.0   2.0 225  22 293.3 294.3 285.1 309.4  5.54

I also looked at the model sounding every 25mb and even that failed to catch the strength of the warm layer.  at 825mb the wet bulb temperature was only 2.6C.  That is still a sleet sounding. While model sounding are still the best way to determine precipitation type, they still can lead you astray on occasion even if the model forecast is not that bad.

 

Thanks for the great explanation Wes.

[StudentOfClimatology]

34/32..once CAD gets going here it's really hard to get rid of. Unfortunately it's just turning a cold rain into a colder rain attm..mehtastic thus far

[T. August]

It's been 36F all day. It got to 35F early this morning, and I guess that's when it was sleeting pretty good.

[Eskimo Joe]

 

Here's how model sounding can sometime bite you because we usually only see the forecast temperatures every 50mb or every 25mb depending on which site we're getting the sounding from  The actual sounding for IAD is shown below. The bold numbers to the left are the pressure levels and the bold numbers to right are the wet bulb tempertures at that level.  Note that at 834mb, the wet bulb temperature is 3.9C.  Such a warm wet bulb temperature usually will completely melt the snowflake so when it fall through the cold layer below 850 mb, the melted snowflake cannot refreeze.

 

 

21 850 1575 3.0 2.7 98 0.3 2.8 220 8 289.3 290.3 283.4 304.9 5.47

22 834 1729 4.0 3.8 99 0.2 3.9 235 14 291.9 293.0 285.1 309.3 6.03

23 831 1759 4.0 3.9 99 0.1 3.9 238 15 292.2 293.3 285.2 309.8 6.10

24 830 1769 2.6 2.6 100 0.0 2.6 239 16 290.8 291.8 284.1 306.8 5.56

25 801 2057 2.4 2.4 100 0.0 2.4 245 19 293.6 294.6 285.4 310.1 5.68

 

Now let's look at the NAM model sounding for the same time this morning.  The forecast by the model for 00 hrs where we're only looking at temperatures every 50mb.  Note that the temperature at 850mb and 800mb are both a tad warmer than the actual sounding but that the model sounding would still argue for sleet as the maximum wet bulb temperature in the warm layer is only 2C. Usually at 2 degrees the snowflake only partially melts so it will refreeze when it falls through the cold layer.

3  900  1116  -3.0  -4.9  87  1.9  -3.7 109  17 278.4 278.9 274.9 286.6  2.944  850  1571   1.1   1.0  99  0.1   1.1 159   7 287.3 288.2 281.8 301.1  4.845  800  2061   2.0   2.0 100  0.0   2.0 225  22 293.3 294.3 285.1 309.4  5.54

I also looked at the model sounding every 25mb and even that failed to catch the strength of the warm layer.  at 825mb the wet bulb temperature was only 2.6C.  That is still a sleet sounding. While model sounding are still the best way to determine precipitation type, they still can lead you astray on occasion even if the model forecast is not that bad.

 

Excellent summary...thank you Wes for the insight.

[CAPE]

36F, total rainfall 0.42".

 

Lots of cold rain lately. Looks pretty wet for the end of the week and weekend as well. When the pattern finally does flip to cold, we will be due for some dry weather.

[HighStakes]

a cold and nasty 33 degrees.

[NoVaWx]

Great practice for the rest of winter

[WVclimo]

I have been at 32.5 degrees +/- 0.3 degrees since 10:00 this morning. Drizzle and occasional light rain all day, but no icing on any surfaces or even trees. Now steadier more moderate rain has moved in, but temp hasn't budged.

[CAPE]

I have been at 32.5 degrees +/- 0.3 degrees since 10:00 this morning. Drizzle and occasional light rain all day, but no icing on any surfaces or even trees. Now steadier more moderate rain has moved in, but temp hasn't budged.

The classic 33 and rain.

[MN Transplant]

Was the euro actually dry? 0.73" and counting.