Ralph Wiggum Posted January 18, 2019 Share Posted January 18, 2019 Ha! RGEM insistent on mid 50s here Sunday morning still. Leading the way with other guidance ticking towards it. Unreal. Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 Looking more and more like a plain rain event now for 95. Maybe a few flakes to start. Even up towards allentown and lehigh valley it may be mostly sleet and possibly change to rain. I'd expect totals even up in the pocono's to take a hit due to sleet as well. Terrible trends in close, this winter blows. Looking forward to arctic temps for 2 days followed by another rain storm.... 1 Link to comment Share on other sites More sharing options...
zenmsav6810 Posted January 18, 2019 Share Posted January 18, 2019 NWS claim 3-6.5" imby Link to comment Share on other sites More sharing options...
mikeosh Posted January 18, 2019 Share Posted January 18, 2019 MT Holly just expanded the WSW to include upper Bucks and western Montgomery. They are thinking colder Link to comment Share on other sites More sharing options...
Rockem_sockem_connection Posted January 18, 2019 Share Posted January 18, 2019 Non event for me and I'm not mad. FRZ isn't fun. All the rain will freeze after the fact though, interested in seeing how that plays out. Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 GFS continues to think 50s sunday with the RGEM. Cut snow totals region wide...almost everyone changes over at some point. Link to comment Share on other sites More sharing options...
Stormman96 Posted January 18, 2019 Share Posted January 18, 2019 5 minutes ago, mikeosh said: MT Holly just expanded the WSW to include upper Bucks and western Montgomery. They are thinking colder Yea what are they looking at. Showing 4-8 for upper bucks an has temps staying below freezing entire event Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 3 minutes ago, Stormman96 said: Yea what are they looking at. Showing 4-8 for upper bucks an has temps staying below freezing entire event I'm thinking they are basing it off climo too. Alot of times the CAD is severely under forecasted right up to the event. Their discussion is actually a really good read. But yeah almost no models have that anymore. Link to comment Share on other sites More sharing options...
JTA66 Posted January 18, 2019 Share Posted January 18, 2019 Looks like the GFS takes the low right over Philly up to Boston. Link to comment Share on other sites More sharing options...
Stormman96 Posted January 18, 2019 Share Posted January 18, 2019 2 minutes ago, The Iceman said: I'm thinking they are basing it off climo too. Alot of times the CAD is severely under forecasted right up to the event. Their discussion is actually a really good read. But yeah almost no models have that anymore. No question this is turning out to be one of the worst winters in a very long time. I knew that November snow was going to kill our winter an some pros told me that wasnt true back in November an said that only applies woth October snow. Obviously that is incorrect. Looks like more rain late next week. We are going to have to hope for the snowiest February in history in order to save this winter. A lot of outlooks look to be going up in flames Link to comment Share on other sites More sharing options...
penndotguy Posted January 18, 2019 Share Posted January 18, 2019 Im just gonna let this play out, not giving up just yet but yeah expectations are low at this point. I still think the flash freeze we have may be the more intriguing thing to me Link to comment Share on other sites More sharing options...
JTA66 Posted January 18, 2019 Share Posted January 18, 2019 Followed up by another southern slider next weekend (although Redsky may cash in on that). Link to comment Share on other sites More sharing options...
mikeosh Posted January 18, 2019 Share Posted January 18, 2019 I guess the 3 1036 highs over Canada and Maine aren't enough to keep cold air at surface? Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 interestingly I don't think we come anywhere near the forecasted high. Currently 33 at noon with a high of 40 expected. With the cloud cover hanging tough, may limit how warm we get today. Interesting to see if this has any effect. Almost all guidance busted on this. Link to comment Share on other sites More sharing options...
zenmsav6810 Posted January 18, 2019 Share Posted January 18, 2019 1 hour ago, Stormman96 said: Yea what are they looking at. Showing 4-8 for upper bucks an has temps staying below freezing entire event clinging to the NAM... I thought only amateurs did that. NAM 3k is solid cold through surface-mids-uppers down through virgnia. What does the Euro say? Link to comment Share on other sites More sharing options...
mwiecz01 Posted January 18, 2019 Share Posted January 18, 2019 1 hour ago, hurricane1091 said: Non event for me and I'm not mad. FRZ isn't fun. All the rain will freeze after the fact though, interested in seeing how that plays out. that's a concern i have. I'm supposed to travel back from eastern long island to chester county on Sunday afternoon. no way to know for sure but wondering about the potential for a significant flash freeze between before 6pm? i'm hoping to cold stays off long enough to get back home safe Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 Flash freezes are so rare. 2005 or 2006 was the last one we've had. Agree the potential is there but a lot of times these never come to fruition so I'll believe it when I see it. Link to comment Share on other sites More sharing options...
ChescoWx Posted January 18, 2019 Author Share Posted January 18, 2019 Latest Wxsim with 12z models still showing a front end thump with a little earlier arrival of snow for NW Chester County PA - here is the rundown Light snow arrives by 130pm / Mod Snow at 3pm / Heavy Snow at 5pm continuing thru 830pm with 5.0" of snow by that time. Mix of Snow and heavy sleet through 1130 pm with 2" to 3" of sleet (Total snow/sleet 7-8") before a brief change to ZR and then rain by 1230am continuing till 7am with 1.00" of rain with temps reaching 37 before starting to fall late AM Link to comment Share on other sites More sharing options...
zenmsav6810 Posted January 18, 2019 Share Posted January 18, 2019 21 minutes ago, The Iceman said: Flash freezes are so rare. 2005 or 2006 was the last one we've had. Agree the potential is there but a lot of times these never come to fruition so I'll believe it when I see it. Burbs had one after 2016 blizzard Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 hmmm 12z hi res wrf-NSSL is very interesting. Here is the warmest panel I could find. Looks like we wet bulb and surface temps hang tight in a classic CAD formation. 95 stays at or below freezing the entire time. Could it be on to something? It is the only model that has nailed the temps today being in the low-mid 30's as opposed to low 40's... Link to comment Share on other sites More sharing options...
specialsk Posted January 18, 2019 Share Posted January 18, 2019 Breaking updates on Winter Storm Harper Link to comment Share on other sites More sharing options...
Bosswx Posted January 18, 2019 Share Posted January 18, 2019 The only threat I have left from this storm is a flash freeze. Oh well, onto the next. Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 another WRF meso model keeps SE PA all frozen...here's the warmest panel...could the meso models be keying on the CAD better? Would not be the first time. Very interesting developments. Link to comment Share on other sites More sharing options...
zenmsav6810 Posted January 18, 2019 Share Posted January 18, 2019 Here's the formula for CAD detection, . From Wikipedia: "This algorithm is used to identify the specific type of CAD events based on the surface pressure ridge, its associated cold dome, and ageostrophic northeasterly flow which flows at a significant angle to the isobaric pattern. These values are calculated using hourly data from surface weather observations. The Laplacian of sea level pressure or potential temperature in the mountain-normal—perpendicular to the mountain chain—direction provides a quantitative measure of the intensity of a pressure ridge or associated cold dome. The detection algorithm is based upon Laplacians () evaluated for three mountain-normal lines constructed from surface observations in and around the area affected by the cold air damming—the damming region. The "x" denotes either sea level pressure or potential temperature (θ) and the subscripts 1–3 denote stations running from west to east along the line, while the "d" represents the distance between two stations. Negative Laplacian values are typically associated with pressure maxima at the center station, while positive Laplacian values usually correspond to colder temperatures in the center of the section.[13] Map of the labeled weather stations in the Southeastern US that are suitable for use in the CAD detection algorithm" I'm sure there is a model out there somewhere to look at just this Link to comment Share on other sites More sharing options...
Lady Di Posted January 18, 2019 Share Posted January 18, 2019 13 minutes ago, The Iceman said: another WRF meso model keeps SE PA all frozen...here's the warmest panel...could the meso models be keying on the CAD better? Would not be the first time. Very interesting developments. I suppose it's a possibility. I mean we have everything from the 50s (that I can't see happening) and this map. Split the difference and that moves the snow/rain/mix line a little further south? Even though the low is riding the PA.MD boarder? Interesting though. Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 Another Hi-res WRF keeps SE PA all frozen Link to comment Share on other sites More sharing options...
Ralph Wiggum Posted January 18, 2019 Share Posted January 18, 2019 25 minutes ago, zenmsav6810 said: Here's the formula for CAD detection, . From Wikipedia: "This algorithm is used to identify the specific type of CAD events based on the surface pressure ridge, its associated cold dome, and ageostrophic northeasterly flow which flows at a significant angle to the isobaric pattern. These values are calculated using hourly data from surface weather observations. The Laplacian of sea level pressure or potential temperature in the mountain-normal—perpendicular to the mountain chain—direction provides a quantitative measure of the intensity of a pressure ridge or associated cold dome. The detection algorithm is based upon Laplacians () evaluated for three mountain-normal lines constructed from surface observations in and around the area affected by the cold air damming—the damming region. The "x" denotes either sea level pressure or potential temperature (θ) and the subscripts 1–3 denote stations running from west to east along the line, while the "d" represents the distance between two stations. Negative Laplacian values are typically associated with pressure maxima at the center station, while positive Laplacian values usually correspond to colder temperatures in the center of the section.[13] Map of the labeled weather stations in the Southeastern US that are suitable for use in the CAD detection algorithm" I'm sure there is a model out there somewhere to look at just this Dude this is exactly what I was just thinking to myself! Link to comment Share on other sites More sharing options...
The Iceman Posted January 18, 2019 Share Posted January 18, 2019 18z nam has a big thump in the front end for a lot of areas. 2-4"+ for most in SE PA. Link to comment Share on other sites More sharing options...
Hurricane Agnes Posted January 18, 2019 Share Posted January 18, 2019 Governor Wolf just declared a state of emergency here in PA. A number of restrictions have been imposed for the weekend - https://6abc.com/weather/gov-tom-wolf-declares-state-of-emergency-for-pa/5095938/ Quote A commercial vehicle ban will be in place between 12 p.m. Saturday and 12 p.m. Sunday on all interstates and the Pennsylvania Turnpike, except for Interstate 95 in southeastern Pennsylvania to allow snow plow crews to have a clearer route. The ban will also be imposed on the U.S. 22 expressway in the Lehigh Valley and the Pennsylvania Route 33 expressway in Northampton and Monroe counties. State officials urge motorists to use caution during the storm, postpone travel if possible, reduce speeds and be aware of the potential for rapidly changing weather and roadway conditions. Speed limits will be restricted to 45 mph on the interstates and expressways as the storm progresses. Link to comment Share on other sites More sharing options...
penndotguy Posted January 18, 2019 Share Posted January 18, 2019 Warnings just issued, 5-11" 0.10 Ice We shall see. Link to comment Share on other sites More sharing options...
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