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Pittsburgh, PA Thread: Winter '14-'15


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never did switch here.

Still light to moderate snow.

Picked up another inch this afternoon.

4 total.

Looks like a nice burst about to move into Allegheny County.

I hope everyone can switch back to snow.

I picked up maybe a quarter inch before switched over to drizzle \ rain. Puts me at 2.75. Elevation must be helping you out just enough. I was hoping to get into a heavy band with those giant wet flakes. :cry:

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never did switch here.

Still light to moderate snow.

Picked up another inch this afternoon.

4 total.

Looks like a nice burst about to move into Allegheny County.

I hope everyone can switch back to snow.

I guess the rain/snow line cut Allegheny County in half again as it tends to do. Probably by the time it switches back over down here, the moisture will be just about gone. That's what usually happens.
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Had some fat flakes a few minutes ago, mabey we get one last burst before the best lift and moisture leaves the region.

This line of rain must go right through the city as I am about 10 miles north of the city and I have stayed straight snow.

5 inches total. 3 this morning and 2 more this afternoon.

The snow had lightened up but with this next batch it is coming down moderate again.

I know I am at a higher elevation and that does seem to come into play.

I feel bad for the people south and east of here who have switched to rain. It seems to never fail.

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This line of rain must go right through the city as I am about 10 miles north of the city and I have stayed straight snow.

5 inches total. 3 this morning and 2 more this afternoon.

The snow had lightened up but with this next batch it is coming down moderate again.

I know I am at a higher elevation and that does seem to come into play.

I feel bad for the people south and east of here who have switched to rain. It seems to never fail.

 

Used to live in West View, but now live in Avalon. NEVER had the issues that I have with changeovers in West View I have here.

 

Funny, I think that the forecast verified at most higher elevations..KPIT north, but lower elevations lose out. Will be interesting to see final total at Kpit.

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Well, the GFS at least did show a break in between vort maxima:  http://mp1.met.psu.edu/~fxg1/AVNEAST_0z/avneastloop.html It shows up in the 3-hourly QPF product.  It also shows the sequence of vort maxima moving over the region in southwesterly flow.  AFAIK  this dry slot hasn't been really bad...i.e. yes MGW had 2 hourly reports with no precip, but thus far precip has not stopped at PIT.

 

As far as p-type goes, 540 dam 1000-500 hPa thickness + soundings signaled to me that MGW would be having p-type issues:  540 line progged north of MGW signaled that a layer was going above 0C, and then soundings showed that the warmest layer would be close to the surface.  Result:  rain.  It is possible that if the warm layer was shallower, snow could still be falling w/ 2 m temp of 37F.

 

Thanks for the information.  You'll have to forgive me, though, as I'm not sure what I'm looking for in regards to "vort maxima" (nor do I know what exactly that means).  The dry slot has likely felt a bit worse because we changed to rain shortly after 11.  It really did look like, at one point, that almost all of PA was dry.  Maybe there were less than stellar radar returns.

 

I also knew we'd switch to rain at some point.  That was accounted for in almost every model I saw except the NAM (which went nuts as usual).  I've lived in and around the MGW since the Fall of 2010, and there really is a bit of a microclimate here.  All I can think is it must be due to our relative position to the Allegheny and Appalachian mountains.  We're basically a valley heatsink of sorts.

 

The only way we can stay all snow in this area is with a massive amount of confluence from a well-positioned high in NY or southern Canada, or if the low manages to stay well suppressed to our south.  In any other occasion, we automatically will flip precip types and most, if not all, models will underdo the strength of the warm influence in our particular sector.  I believe a good number of models gave us ~10 hours of snow.  In reality we had about half that; as I said, the changeover occurred not long after 11 AM.

 

I've been here long enough to know to adjust my own forecasts, but this is something NWS Pitt still doesn't account for (for whatever reason).

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3 products issued by NWS for: Pittsburgh PA


Freezing Rain Advisory
URGENT - WINTER WEATHER MESSAGENATIONAL WEATHER SERVICE PITTSBURGH PA815 PM EST SAT FEB 21 2015PAZ007>009-013>016-020>023-029-031-073-075-220915-/O.CAN.KPBZ.WS.W.0005.000000T0000Z-150222T0300Z//O.NEW.KPBZ.ZR.Y.0011.150222T0115Z-150222T1100Z/MERCER-VENANGO-FOREST-LAWRENCE-BUTLER-CLARION-JEFFERSON PA-BEAVER-ALLEGHENY-ARMSTRONG-INDIANA-WASHINGTON-GREENE-WESTMORELAND-FAYETTE-INCLUDING THE CITIES OF...GROVE CITY...FRANKLIN...TIONESTA...NEW CASTLE...BUTLER...CLARION...BROOKVILLE...BEAVER...PITTSBURGH METRO AREA...KITTANNING...INDIANA...WASHINGTON...WAYNESBURG...GREENSBURG...LATROBE...UNIONTOWN815 PM EST SAT FEB 21 2015...FREEZING RAIN ADVISORY IN EFFECT UNTIL 6 AM EST SUNDAY......WINTER STORM WARNING IS CANCELLED...THE NATIONAL WEATHER SERVICE IN PITTSBURGH HAS ISSUED A FREEZINGRAIN ADVISORY...WHICH IS IN EFFECT UNTIL 6 AM EST SUNDAY. THEWINTER STORM WARNING HAS BEEN CANCELLED.* ICE ACCUMULATIONS...A TRACE FROM FREEZING DRIZZLE. ALSO ANY  MELTED SNOW WILL REFREEZE QUICKLY THIS EVENING.* ICE BEGINNING...FREEZING DRIZZLE WILL COMMENCE IMMEDIATELY  SUBSEQUENT TO THE END OF SNOWFALL.* ICE ENDING...FREEZING DRIZZLE SHOULD END BEFORE SUNRISE.* IMPACTS...DANGEROUS TRAVEL CONDITIONS ARE EXPECTED DUE TO ICY  ROADS.PRECAUTIONARY/PREPAREDNESS ACTIONS...A FREEZING RAIN ADVISORY MEANS THAT FREEZING RAIN WILL CAUSETRAVEL DIFFICULTIES. BE PREPARED FOR ICY SURFACES AND USE CAUTIONWHILE DRIVING.  REPORT ICE ACCUMULATION TO THE NATIONAL WEATHERSERVICE BY CALLING 412-262-1988...POSTING TO THE NWS PITTSBURGHFACEBOOK PAGE...OR USING TWITTER @NWSPITTSBURGH.&&$$
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Got home around an hour ago. Had a great family day out. Hard to tell what we got here. Up at Blue Knob it stayed pretty much all snow, but was never really came down heavy. Prob got 4" up there would be my guest

Guess PIT didn't get 8"

Sent from my iPhone using Tapatalk

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Looks like a general 3-6 across western PA. Not the worst ever, but was really thinking we would go over 6. Local Mets got it mostly spot on, so good call.

 

However, the 1-3 calls were really off, and I guess some people must have been "shocked" there were multiple reports of 5 or more.

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Well around 6 we left the house since it had been raining for the past 3 hours and roads were ok. I got a half mile from my house and it was pouring snow to get on route 28 to head to the Pittsburgh Mills Mall. It was snowing there like crazy too. The elevation difference isn;t much maybe a couple hundred feet but I am pretty close to the river too so that probably doesn't help. I need to move about 10 miles North or East and I think I'd avoid this warm tongue. lol

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Thanks for the information.  You'll have to forgive me, though, as I'm not sure what I'm looking for in regards to "vort maxima" (nor do I know what exactly that means).  The dry slot has likely felt a bit worse because we changed to rain shortly after 11.  It really did look like, at one point, that almost all of PA was dry.  Maybe there were less than stellar radar returns. [...]

What vorticity maxima means -- vorticity is basically the spin that a parcel of air has.  This spin is due to changes in the flow in space.  The spin can be induced by speed differences, directional differences, or both.  A vorticity maximum is where the parcel is spinning counterclockwise relatively more than the surrounding area.  It can commonly be seen on 500 hPa plots, i.e. http://mp1.met.psu.edu/~fxg1/AVNEAST_12z/avneastloop.html. The greater vorticity values are shaded red.  A maximum is denoted by an X.  Geopotential height is contoured in black.  Parcels travel roughly parallel to the geopotential height contours, through the vorticity maximum and then out of it.  Downstream of the vorticity maximum, parcels spin at a slower rate and spread out horizontally, a process called horizontal divergence.  Below the divergence is upward vertical motion, and interesting weather.  The opposite occurs upstream of the vorticity maximum.

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I know its impossible to call this but I think we see maybe 2 more storms. Probably the 2-4 variety. The pattern seems to want to break down with the PNA wanting to tank. Only thing in our favor is the EPO.

Yeah, with the PNA going in the tank cutters will start to be the favored storm I think. We can always get lucky with a thread the needle type storm but after this week climo will really start to work against us.

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Yeah, with the PNA going in the tank cutters will start to be the favored storm I think. We can always get lucky with a thread the needle type storm but after this week climo will really start to work against us.

only thing I can say is working for us is the fact wave lengths are shortening. It won't take much for us to get a storm. For some reason we always do alright in march if its cold.
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