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February 21st - 23rd Winter Storm Part 2


Powerball

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Cyclone, I can't explain why, but I can tell you I've seen it time and time again, in top down saturation cases like this the p-type will start out as sleet despite the entire column being below freezing. I'd love for someone smarter than me to explain to me how this is physically possible, but I honestly cannot count how many times I've seen it happen and I even talked with my co-workers on Sunday about that being the case for this event. 

My guess is that it has to do with the increase in pressure as the snowflakes fall through the dry column...the water solid/gas line "leans" left below 0 C at temperatures >1013 MB, meaning ahead of surface lows, flakes are falling into air at pressures of 1014-1016 Mb or higher as they near the surface, so even if the surrounding air is less than 0C, the flakes can melt, due to pressure not heat. However, melting itself is an endothermic process that sucks heat from the surrounding air..which would cause that air to cool.

If that indeed is what happens, I see it as a negative feedback loop where in the beginning the flakes melt and refreeze as sleet but eventually the negative feed back of the endothermic melting causes the near surface air to cool to the point that melting never takes place and the snow falling remains snow all the way to the surface. The only limiting factor to this theory would be the timing, I.e. at the terminal velocity of snow does it have time to make the change as it falls from the 1013.25 MB height to the surface...vertical and horizontal wind shear would certainly also play a role..

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few lightning strikes detected down by IKK.

 

Hmm, I'll have to call the parents later to see if they saw saw/heard anything. 2:15am and 2:55am obs at IKK.

 

METAR KIKK 220815Z AUTO 11014G17KT 1 3/4SM TSUP OVC005 M03/M03 A2989 RMK AO2 LTG DSNT SE T10281035

 

METAR KIKK 220855Z AUTO 10011KT 2SM -VCTSSN BKN007 OVC013 M03/M04 A2987 RMK AO2 LTG DSNT SE T10301037

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I never said they will be wrong, I'm agreeing that they are going to be more accurate with totals than most on here. I think GRR, DTX, and IWX have a good handle on accums.

I sense major wish-casting with some and that's fine. Everyone on this thread is entitled to their opinion, right? After all it is a public forum and we are all meteorological enthusiasts.

I'm not asking anyone to agree or disagree with me, I'm not trolling. I'm throwing my two cents out just like the rest of you.

Harry, I knew from looking at radar that we were going to get more than an inch or two. It has been snowing heavily here for the past four hours, not one. 4 hours of 1 inch rates equals at least 4 inches.

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LOT, ORD, and RFD reports.

 

 

0701 AM     SNOW             OHARE AIRPORT           41.98N 87.90W02/22/2013  M2.7 INCH        COOK               IL   OFFICIAL NWS OBS

 

0701 AM     SNOW             ROCKFORD AIRPORT        42.20N 89.10W02/22/2013  M2.7 INCH        WINNEBAGO          IL   OFFICIAL NWS OBS

 

0701 AM     SNOW             ROMEOVILLE              41.65N 88.09W02/22/2013  M3.4 INCH        WILL               IL   OFFICIAL NWS OBS
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LOT, ORD, and RFD reports.

 

 

0701 AM     SNOW             OHARE AIRPORT           41.98N 87.90W02/22/2013  M2.7 INCH        COOK               IL   OFFICIAL NWS OBS

 

0701 AM     SNOW             ROCKFORD AIRPORT        42.20N 89.10W02/22/2013  M2.7 INCH        WINNEBAGO          IL   OFFICIAL NWS OBS

 

0701 AM     SNOW             ROMEOVILLE              41.65N 88.09W02/22/2013  M3.4 INCH        WILL               IL   OFFICIAL NWS OBS

 

 

I had 2.9 at ORD

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