DarthDoppler Posted January 3, 2014 Share Posted January 3, 2014 Certainly the models may be warming up the low levels a bit too much. But... we've certainly seen huge turn-arounds before. At TTN a low of 1 on 1/27/1994 turned around to a high of 56 on 1/28/1994. It wasn't that extreme at PHL, 11 to 58. However, ABE was even more impressive, going from a low of -5 on 1/27 to a high of 55 on 1/28. That cold snap near ABE had the roads buckled severely with frost heave. That one day when it warmed to over 50 absolutely destroyed many roads around here! They didn't have potholes, they had craters That was THE coldest air mass I had witnessed with lows of -22 and highs around 0 before that mild -5 morning. So yeah I can see it torching Sunday..... (not that it will) Link to comment Share on other sites More sharing options...
Superstorm Posted January 3, 2014 Share Posted January 3, 2014 Jumping in from the CPA thread...back in '96 I went to bed on the 17th of January with a 30" snowcover. The next morning it was gone. That resulted in part of the Walnut Street bridge in Harrisburg getting ripped apart and slamming into the Market Street bridge downstream. I could not believe that much snow could disappear that quickly...but it did. ...to make matters worse (if it is even possible in such a situation), I believe that a number of the floods in 96 were made even worse by ice dams forming and/or breaking up. Much of that January (and much of the previous December) was cold in the east so many of the major rivers in Pennsylvania (from the Delaware to the Susquehanna to the Monongahela and everything in between) were frozen prior to the late January flood so the ice on the rivers broke up and began rushing downstream as quickly as the snow on the ground disappeared. I forget if that is what happened at the Walnut Street bridge, but I believe in quite a few other places in PA, ice dams forming against bridges and adding to the pressure against them caused a number of bridge failures. Luckily, nothing like that is going to happen this time around, no matter how warm it gets on Monday. The pedestrian bridge was destroyed by the ice and river flooding. Link to comment Share on other sites More sharing options...
Plokoon111 Posted January 3, 2014 Share Posted January 3, 2014 Im my backyard on the neshaminy creek we had this steel palvalion gazebo that was completely destroyed by icebergs getting caught adding pressure creating the loudest racket ever. Link to comment Share on other sites More sharing options...
eastonwx Posted January 3, 2014 Share Posted January 3, 2014 This afternoon's AFD: ALL THE TEMP GUIDANCE SEEMS RATHER QUICK IN BRINGING ABOVE FREEZING TEMPS TO THE AREA SUNDAY...CONSIDERING THE DECENT SNOW COVER WHICH WILL BE IN PLACE. WE HAVE CHOSEN TO SLOW THE TREND OF TEMP INCREASE SUNDAY. THIS WILL CAUSE MORE WINTRY WX ISSUES SINCE THE INCREASING MOISTURE AND APPROACHING LOW/FRONT WILL BRING INCREASING CHC FOR PCPN BY AFTERNOON. WE HAVE USED THE TOP-DOWN WX TOOL FOR THE GRIDS SUNDAY AND THIS RESULTED IN A PERIOD OF FREEZING RAIN FOR AREAS (MAINLY) NORTH AND WEST OF THE I95 CORRIDOR. ADVYS WILL HAVE TO BE CONSIDERED FOR SUNDAY IN UPCOMING FCSTS. A MENTION OF ICY MIX POTENTIAL WILL BE INCLUDED IN THE HWO. TEMPERATURES WILL SLOWLY WARM SUN NIGHT AND PCPN WILL MOSTLY CHANGE TO RAIN OVER MOST AREAS (SRN POCONOS MAY NOT CHANGE OVER). Link to comment Share on other sites More sharing options...
Violentweatherfan Posted January 3, 2014 Share Posted January 3, 2014 Any chance of thunderstorms with this storm? Link to comment Share on other sites More sharing options...
newtownwx Posted January 3, 2014 Share Posted January 3, 2014 I haven't had a chance to look at multiple models in depth, but it seems as though many of the ingredients are in place for a non-trivial event. Even just a slight track to the east will yield a much greater chance of a wintry event in the Philly metro. It will be interesting to see how low we dip tonight as there is a large discrepancy between the GFS and NAM. Link to comment Share on other sites More sharing options...
Violentweatherfan Posted January 4, 2014 Share Posted January 4, 2014 I haven't had a chance to look at multiple models in depth, but it seems as though many of the ingredients are in place for a non-trivial event. Even just a slight track to the east will yield a much greater chance of a wintry event in the Philly metro. It will be interesting to see how low we dip tonight as there is a large discrepancy between the GFS and NAM. I think the surface temps will warm rather quickly and limit any frozen precipitation. Kind shopping for some lighting and thunder sine there will be such a large discrepancy in temps once the Arctic front moves in...wondering if the atmosphere behaves the same in the winter as summer... Link to comment Share on other sites More sharing options...
newtownwx Posted January 4, 2014 Share Posted January 4, 2014 I think the surface temps will warm rather quickly and limit any frozen precipitation. Kind shopping for some lighting and thunder sine there will be such a large discrepancy in temps once the Arctic front moves in...wondering if the atmosphere behaves the same in the winter as summer... Precipitation type will all depend on storm track. As of right now, we start off as rain (WAA at the beginning of the event) and changeover to some sort of wintry precipitation late Monday morning with the surge of arctic air. There are many differences between summer and winter synoptic setups, but one key difference is the lack of daytime heating. We are lacking the thermodynamics, which is one reason why it is difficult to see thunderstorms (or thundersnow for that matter) during winter. Link to comment Share on other sites More sharing options...
Sophisticated Skeptic Posted January 4, 2014 Share Posted January 4, 2014 0z NAM is blowtorchin on Sunday. what the fudge.. Link to comment Share on other sites More sharing options...
Violentweatherfan Posted January 4, 2014 Share Posted January 4, 2014 Precipitation type will all depend on storm track. As of right now, we start off as rain (WAA at the beginning of the event) and changeover to some sort of wintry precipitation late Monday morning with the surge of arctic air. There are many differences between summer and winter synoptic setups, but one key difference is the lack of daytime heating. We are lacking the thermodynamics, which is one reason why it is difficult to see thunderstorms (or thundersnow for that matter) during winter. Good points, forgot about the daytime summer heat. I was just focusing on the temp differences, I read in the mid Atlantic forum someone mentioning thunder sleet...it was directed towards "ji" so it was probably in jest. Link to comment Share on other sites More sharing options...
famartin Posted January 4, 2014 Share Posted January 4, 2014 It would seem there's not much to hold the cold. We can get all the snow we want, but if the pattern isn't conducive for holding the cold... well, as we saw in 1994, we just won't hold it. Link to comment Share on other sites More sharing options...
eastonwx Posted January 4, 2014 Share Posted January 4, 2014 It appears any freezing rain or drizzle will be brief before the warm up Sunday Link to comment Share on other sites More sharing options...
Voyager Posted January 4, 2014 Share Posted January 4, 2014 The 6z NAM and GFS continue the idea of "torching" the area. hr 48 has most of the area in the mid 40's to even low 50's it appears. The one thing about the current cold, and many have posted that we just haven't seen a really good arctic outbreak for a number of years, is how hard it is to maintain a decent snowpack in the region. It seems, more often than not, if we do get a decent storm, we warm up significantly a few days afterward, and lose most, if not all of it, before we get another snow event. Link to comment Share on other sites More sharing options...
ChescoWx Posted January 4, 2014 Author Share Posted January 4, 2014 Latest Wxsim with 12z NAM / 6z GFS continues a colder trend for the NW Philly burbs (though not heavy precip it won't take much) - temps get no higher Monday than 36.3 before the front swings thru around 10am with some snow to follow here is the breakdown Light IP arrives around 10am temp 23.6 ZR during the rest of the day with temps topping out at 30.6 at around 2pm Sunday - temps than fall back into the 20's during the late PM and early evening with ZR continuing temperature at 6pm down to 28.4 Temps slowly rise till they rise above freezing around 1130pm by which time 0.23" of frozen has fallen Another 0.32" or rain then falls with temps above freezing before changing back to snow around 11 or 1130am with 1 inch of snow accumulating and temps dropping back below freezing. Link to comment Share on other sites More sharing options...
windvane Posted January 4, 2014 Share Posted January 4, 2014 this is the most realistic scenario of this storm event Link to comment Share on other sites More sharing options...
KamuSnow Posted January 4, 2014 Share Posted January 4, 2014 The 6z NAM and GFS continue the idea of "torching" the area. hr 48 has most of the area in the mid 40's to even low 50's it appears. The one thing about the current cold, and many have posted that we just haven't seen a really good arctic outbreak for a number of years, is how hard it is to maintain a decent snowpack in the region. It seems, more often than not, if we do get a decent storm, we warm up significantly a few days afterward, and lose most, if not all of it, before we get another snow event. Considering how progressive the pattern's been, I thought having snow on the ground for 2 weeks in December was pretty good. And even with the warm-up tomorrow I'm thinking we'll still have snow on the ground through the end of the week. I do know what you mean, but I am enjoying this winter much more than the last 2! Link to comment Share on other sites More sharing options...
jwilson Posted January 4, 2014 Share Posted January 4, 2014 The 6z NAM and GFS continue the idea of "torching" the area. hr 48 has most of the area in the mid 40's to even low 50's it appears. The one thing about the current cold, and many have posted that we just haven't seen a really good arctic outbreak for a number of years, is how hard it is to maintain a decent snowpack in the region. It seems, more often than not, if we do get a decent storm, we warm up significantly a few days afterward, and lose most, if not all of it, before we get another snow event. I was just thinking about this the other day - I love "snow on top of snow." But thinking back, it is such a rarity in this region to get snow on top of snow. Usually, as you said, we warm up shortly after snowstorms, and even if we don't warm considerably, having another snow event on the heels of one snow event seems extremely rare (I don't know the statistics, unfortunately). Those few days in February of '10 were amazing for that reason, but I don't know if it will ever be seen again in the PHL area. Still, I think my favorite winter events are the table-setter systems followed by the main course 24-36 hours later. I like keeping that fresh snow pack around. Link to comment Share on other sites More sharing options...
RedSky Posted January 4, 2014 Share Posted January 4, 2014 Considering how progressive the pattern's been, I thought having snow on the ground for 2 weeks in December was pretty good. And even with the warm-up tomorrow I'm thinking we'll still have snow on the ground through the end of the week. I do know what you mean, but I am enjoying this winter much more than the last 2! That's life in the MA with snow cover. December was an over achiever with white on the ground. Even 02-03 did not have long periods of snow cover in december and january. I believe the longest we have kept the ground white in recent years was january 2011 and february-march 2007 with the sleet glaciers. March is the hardest month to accomplish the feat i was astonished at how long i kept my lawn white that month it was two weeks plus. Don't think it can be done with snow in march, 3 or 4 inches of Rob's sleet is required Should be cold enough this time to keep 2-3" crunchy crust before the next arctic wave Link to comment Share on other sites More sharing options...
ChescoWx Posted January 4, 2014 Author Share Posted January 4, 2014 Latest Wxsim with 12z data for tomorrow Lite IP arriving by 930a temp 21.4 Lite Freezing drizzle thru 12 noon temp at 31.9 (.03") Lite rain from 1230-330 with temps warming to 32.9 before falling below freezing at 330pm (.04") Freezing rain from 330-10pm (temps between 29.5 and 31.9(0.19") Rain after 1030pm ending on Monday late morning (0.37") The Wxsim forecasts 2.2" of snow to remain on the ground by Monday evening Link to comment Share on other sites More sharing options...
eastonwx Posted January 4, 2014 Share Posted January 4, 2014 Freezing Rain advisories up Link to comment Share on other sites More sharing options...
Pohopoco Posted January 4, 2014 Share Posted January 4, 2014 High of 16 about 3 hrs ago,now at 13...I think the cold will be harder to move out at the surface maybe even to mid levels...I've seen no mention of sleet,but I think up here,even down to I-78 or so it could happen and the Fr.Rain/Drizzle could hang on past the 2PM Advisory,like into the night past....Anyway I'm thinking also the CF crossing could be juicier and whiter than foreseen on Monday...Just my opinion... Link to comment Share on other sites More sharing options...
ChescoWx Posted January 5, 2014 Author Share Posted January 5, 2014 Latest Wxsim with 18z data somewhat better for lack of freezing potential - although I am not clear why it has temps falling during the PM? Here is the breakdown Light IP/ZR between 10 -1130am then above freezing temps till 330pm - temps then fall back below freezing till near 10pm with 0.21" falling as frozen. Then above freezing after that Temps on Tuesday get no higher than 7.8 above zero - temps no lower than 5 above during the period Link to comment Share on other sites More sharing options...
eastonwx Posted January 5, 2014 Share Posted January 5, 2014 high of 25 today, currently 11.7F, DP 8.3 AFD says temps should begin to warm overnight, thinking mainly south of here cold air really likes to hang on up here in these valleys. I guess it'll be a race as to warm air or precip arriving Link to comment Share on other sites More sharing options...
DarthDoppler Posted January 5, 2014 Share Posted January 5, 2014 This is going to sound incredibly dumb and unscientific, but when you look at things from this perspective our weather makes much more sense. This is concerning how easily we thaw out even with snow cover and record cold temperatures in the middle of winter. I was looking at the Daily Arctic Sea Ice maps for the Northern Hemisphere. If you keep clicking through different dates from summer to winter you see how consistent the snow/ice is from the north pole dropping down to about the latitude of the us/can border, around the whole hemisphere. As it drops south during the fall it obviously fluctuates, but eventually most places (barring places like western Canada and Norway due to ocean moderating the climate) get snow cover and ice for months on end. The large mountains of course also get their snow. Where we are, with no real elevation (8,000+ feet) and not being that far north (45 degrees is about mid Maine.....) all we get is the fluctuations in the jet stream allowing us some cold air and possible storms. Of course it WILL lift north from time to time giving us mild air........just think about the entire GLOBE and where we are in relation to this. We are in the temperate or fluctuation zone. The only way we are going to get "real" winters around here is for an ice age to change the dynamic of the entire worlds weather. Simply, a few hundred miles is pretty insignificant in the big picture, so it isn't difficult for air from southern us/atlantic/gulf to literally "rain on our parade". Remember it's not just the sun WE get, it's the fact that it's hitting hard down south where there is no snow and the angle is still pretty decent, it's no more difficult for warm air to melt our snow then it is for arctic air to allow it to snow here. This thinking not only explains our frequent thaws, it makes me at least, a bit less of a snow weenie (in other words enjoy what you get and don't lament over it when it melts or misses you) Link to comment Share on other sites More sharing options...
PAPPG Posted January 5, 2014 Share Posted January 5, 2014 high of 25 today, currently 11.7F, DP 8.3 AFD says temps should begin to warm overnight, thinking mainly south of here cold air really likes to hang on up here in these valleys. I guess it'll be a race as to warm air or precip arriving Well, south of here, temps currently dropping quick....but, looking west, it looks like the warm air is coming in quick, before precip. 17.7F/8DP Link to comment Share on other sites More sharing options...
Rainshadow Posted January 5, 2014 Share Posted January 5, 2014 High of 16 about 3 hrs ago,now at 13...I think the cold will be harder to move out at the surface maybe even to mid levels...I've seen no mention of sleet,but I think up here,even down to I-78 or so it could happen and the Fr.Rain/Drizzle could hang on past the 2PM Advisory,like into the night past....Anyway I'm thinking also the CF crossing could be juicier and whiter than foreseen on Monday...Just my opinion... Forecast soundings (not that they are spot on) pretty much keep all the cold air at ground level. Moistening is really in the lowest 10k. It really does look like 99.4% freezing rain. AVP's 850mb temp right now is suppose to be 0C. Other thing and this happened during some recent warm-ups: the forecast 925mb temps are pretty warm. Usually 1500-2000ft, as you are well aware, hang onto the freezing rain for a long long time. This time it might be the valleys up there. We'll re-access the ending time once the overnight models arrive. Link to comment Share on other sites More sharing options...
bugalou Posted January 5, 2014 Share Posted January 5, 2014 16 here near the AC shore, DP 13. Winds have shifted out of the southwest but are still quite calm. This is certainly not an ideal setup, but with snow pack and a recently record cold air mass, we will see how quickly temps will recover. Things seem pretty fast, but I am rooting for the forecast because even a little ZR is going to be a royal pain. Link to comment Share on other sites More sharing options...
Chief83 Posted January 5, 2014 Share Posted January 5, 2014 Now down to 9 degrees in Worcester. Long way to go to get back to 32 by noon tomorrow? Could be a icy afternoon as well as morning. Link to comment Share on other sites More sharing options...
PAPPG Posted January 5, 2014 Share Posted January 5, 2014 12.3F/6DP SSW@2 Link to comment Share on other sites More sharing options...
KamuSnow Posted January 5, 2014 Share Posted January 5, 2014 12.3F/6DP SSW@2 I just looked and yikes, down to 12 here too. Link to comment Share on other sites More sharing options...
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