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Central PA - Early/Mid December 2016


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1 hour ago, AllWeather said:

No, you're correct. Backside snow southeast of the mountains almost never happens. Downsloping (warming) winds either dry things or warm it up (or both). I've personally never seen cold air catch up in an anafrontal situation to change over to snow SE of the high terrain of C PA. 

It usually takes a pretty strong frontal passage and/or a negative tilt to the 500 trough with perhaps a bit of secondary development to get much precip to hang back behind a frontal passage for any appreciable changeover situation. The frontal passage is fairly strong, but trough is quite positive in it's orientation. Western PA from perhaps just off the Allegheny Front westward likely sees a brief late changeover that delivers a T-1 to cover up whatever mess is left on the ground Sun afternoon...probably mainly in the Laurels. But I certainly wouldn't expect much toward the Sus Valley. Saving grace from this being an all out ice storm in a lot of the region may well be the QPF itself. The first wave that will deliver the snow and wintry mix hasn't looked particularly wet QPF wise, with models like the Euro and GFS showing much more with the wave associated with the frontal passage (which should be all rain). The GFS in particular has shown a pretty big weakness in QPF with the first wave (downsloping with the more westerly component to the flow). Total QPF in this mornings run (6z) only had 0.1-0.25" in the LSV/South central through 51 hours. 12z coming in looks pretty similar. Probably why CTP didn't jump on warnings like PBZ did, as you figure with a good depth to the cold air early in the event (up to 925mb level) sleet could be a predominant transition p-type in most of the region for a period of time. Wouldn't rule out warning ice in some places though, will have to see what kind of precip coverage/intensity we're dealing with once things move in early tomorrow. 

1 hour ago, pasnownut said:

and furthermore....any annafrontal snow stuff some are holding onto....fugettaboutit.

if were lucky a few mood flakes possible to T up whats left of your crotch after tommorow's mess....

It often teases us on the models, but rarely ever comes to fruition.  Believe me, I hope I'm wrong.  At least there is some energy scooting SE w/ the frontal passage that may give it a shot as temps crash back towards normal.

All good.  At least were trackin....(although I just saw an add for a cheap toaster.....:weep:)

Nut

 

That we are, this time last year we were tracking the prospects of a 70 degree Christmas. I literally posted this on this exact date last year:

Quote

 

Wow the Euro lol, todays 12z out at the end of its range has ridiculous temperatures. Broad area of 15-20ºC (!!!) 850 temps that move into PA and 65 to low 70s for surface temps Christmas Day in the commonwealth. 75-80 in sections of KY, TN, WV. Absolutely insane if that comes anywhere close to fruition.

I have noticed that the GFS and Euro have been diverging a bit the last couple runs. The GFS runs a system and a front through by Christmas day and having much different temps (close to seasonal). Euros sending an energy depth charge into the west and building our Christmas in July (or should I say July in Christmas) ridge in the east. GFS more progressive with it. I'm sure the answer lies somewhere in between, the Euros probably driving and holding into the western states too much. Oh, and the GFS has a fantasy range significant mid-atl snow storm... so that in itself is progress haha. 

 

 

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When comparing the QPF forecasts (time and amounts) from WPC againsts the skew T plots for Harrisburg using the GFS, I feel that either a WSW or an ISW would be more appropriate for at the very least Cumberland, Dauphin, and Lebanon Counties at this short range.  I'm not 100% sure of the criteria of said warnings...

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1 hour ago, Blizzard of 93 said:

Most models have trended colder today & snow amounts around Harrisburg are in the range of 3-5 inches of snow before the changeover to ice. It will be interesting to see how it plays out in the next 12 hours or so.

Could you be more specific as to the model(s) you are using that are projecting these snowfall accumulations?  On Pivotal weather's site, using this afternoon's 18Z runs, the NAM gives zero measureable snow to MDT, and the GFS gives less than 1.0".

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14 minutes ago, sauss06 said:

I agree, i just brought extra wood in just in case

as did I.  although the cooler trends are being noticed, it will only help for ice.  850's are still burnin up and at best, we hang onto pingers for a while longer.  

For me ice is meh....so I'll just take it and skate....

Careful all.  Going to my sons fire company for breakfast tomorrow.  I better eat lots, cause I'm guessing traffic will be light.

Nut

 

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yeah, as I alluded to a couple days ago, and the models seem to be finally latching onto, even though there is warming aloft, it usually underpreforms at the surface, ala 3k NAM 2m temps as per above for Saturday.  I think we wake up Sunday morning 10-15 deg warmer than same time Saturday.  at least the warmup for those who get snow, is short lived and with cold ground temps, some may hold onto snowcover into mid week.  JMO's

Nut

 

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22 minutes ago, Blizzard of 93 said:

I just reviewed the both the 0z NAM & High-res NAM Weatherbell maps & it still shows 3-4 inches of snow for the LSV. 

yeah, i just saw that.  Looks like best lift comes in while we still have a couple hours before we flip.

I hope we can scrounge a couple inches.

Nut

 

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3 minutes ago, Blizzard of 93 said:

0z RGEM has 3 inches in LSV.

0z GFS has 5 inches for Harrisburg area.

It is interesting to look at the current Winter Weather Advisorys for neighboring forecast offices. CTP has a coating to 2 inches across the LSV. Mount Holly has 2-4 inches for Berks & western Chester counties that border the LSV. 

I must say that that LSV "bullzeye" has been rather consistent on the models.  While I find the odds stacked against us, just like I referenced the Christmas miracle of 03', i guess we could hang onto the snow longer.  This one has always oozed overreaching ice potential to me.  As stated earlier, would love to be wrong.

Everyone swings at an outside curve once in a while....

Headed to bed for a couple hours, then I'm getting up to watch the snow.

Night all.

Nut

 

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