NCSNOW Posted February 28, 2015 Share Posted February 28, 2015 Raleigh probably gonna issue an advisory this afternoon, that was thinking in AFD. Also of note is the changeover from rain back to snow for Thursday. We Rollercoaster temp wise, then after Thursday below normal, which isn't that bad in March. Next weekend Into early next week is the chance to get a March winter event imo east of the apps, if we are going to get one that isn't piddl like this Sunday or cold chasing moisture next Thursday. Link to comment Share on other sites More sharing options...
calculus1 Posted February 28, 2015 Share Posted February 28, 2015 The two temperature panels corresponding to the above precipitation panels. The wedge signature is strong, and the 2m temperatures stay cold well into late morning: Link to comment Share on other sites More sharing options...
Cold Rain Posted February 28, 2015 Share Posted February 28, 2015 If the precip comes down adequately enough, Calc, you're correct. Temps will lock in for longer than the forecast has been showing, until latent heat released by the freezing process gets them to/above freezing. Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Isn't RGEM in mm? If so, isn't it pretty much in line with NAM/GFS? TW Link to comment Share on other sites More sharing options...
calculus1 Posted February 28, 2015 Share Posted February 28, 2015 Isn't RGEM in mm? If so, isn't it pretty much in line with NAM/GFS? TW Aha! Yes, it is. #mathfail on my part. Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Precip rates look ideal to freez on trees and powerlines. Temps will struggle to 33. Question is how much precip falls. For now, looks lower than .25 warning, but close in some areas. TW Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Aha! Yes, it is. #mathfail on my part. So there's really pretty solid agreement. TW Link to comment Share on other sites More sharing options...
Cold Rain Posted February 28, 2015 Share Posted February 28, 2015 Precip rates look ideal to freez on trees and powerlines. Temps will struggle to 33. Question is how much precip falls. For now, looks lower than .25 warning, but close in some areas. TW Haven't the trends been to increase QPF? Wouldn't take much more to be a mess. Link to comment Share on other sites More sharing options...
calculus1 Posted February 28, 2015 Share Posted February 28, 2015 So there's really pretty solid agreement. TW For whatever reason, the total precipitation panels are in inches though. Go figure. Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Haven't the trends been to increase QPF? Wouldn't take much more to be a mess. Your exactly right. The NAM has put out some totals over .25 in some areas over the last few runs. TW Link to comment Share on other sites More sharing options...
Lookout Posted February 28, 2015 Share Posted February 28, 2015 I had not paid much attention to this until now but it should be noted the models are a solid 10 to 15 degrees too warm with dewpoints in general. They are just badly under estimated at the moment everywhere i look. I'll say this, if there was a 1044mb high over the mid atlantic...9/10 times that ends in freezing temps well down into ne ga. I know there isn't a lot of precip but it's a little bit of a mystery to me why the models aren't colder. A lot depends on temps today for ga/sc as the models warm us up pretty well. However, there is already a thick cloud cover with virga overhead and in fact nam is showing precip later today..it's hard to picture a lot of warming today with stiff northeast winds and if it stays cloudy with any precip. Wouldn't be surprised to see some sleet or even light snow/flurries if anything manages to reach the ground this morning. Soundings are cold/dry enough that it should be flakes if it reaches the ground. Cloud deck is low enough it looks like it could. Link to comment Share on other sites More sharing options...
Cold Rain Posted February 28, 2015 Share Posted February 28, 2015 I had not paid much attention to this until now but it should be noted the models are a solid 10 to 15 degrees too warm with dewpoints in general. They are just badly under estimated at the moment everywhere i look. I'll say this, if there was a 1044mb high over the mid atlantic...9/10 times that ends in freezing temps well down into ne ga. I know there isn't a lot of precip but it's a little bit of a mystery to me why the models aren't colder. A lot depends on temps today for ga/sc as the models warm us up pretty well. However, there is already a thick cloud cover with virga overhead and in fact nam is showing precip later today..it's hard to picture a lot of warming today with stiff northeast winds and if it stays cloudy with any precip. Wouldn't be surprised to see some sleet or even light snow/flurries if anything manages to reach the ground this morning. Soundings are cold/dry enough that it should be flakes if it reaches the ground. Cloud deck is low enough it looks like it could. Local news just mentioned snow flurries here this morning. They said it wasn't likely, but they did give it a nod. Link to comment Share on other sites More sharing options...
NCSNOW Posted February 28, 2015 Share Posted February 28, 2015 Radar showing snow overhead this morning. Pretty thick low cloud deck made me check. But nothing reaching ground Link to comment Share on other sites More sharing options...
Brick Tamland Posted February 28, 2015 Share Posted February 28, 2015 Looks like this one is trying to sneak up on folks. My son is supposed to have his awards program for basketball tomorrow afternoon. When does the precip look come in around RDU? Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 I think for most of the northern piedmont, it seems to come in around daybreak, give or take an hour. TW Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 12z NAM showing precip making it into the triad by 1 am. TW Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 12z NAM has what looks to be warning criteria ice for parts of western part of NC. Not sure about surface temps yet, but typical CAD areas should hold AOB freezing through at least 1pm. TW Link to comment Share on other sites More sharing options...
Solak Posted February 28, 2015 Share Posted February 28, 2015 There's an impressive 1044 High sitting over MD right now with a decent CAD signature wedged down into N GA. I wonder if this will be a case of precip chasing the cold, or if the wedge can hold in place. Not wishing ZR on anyone, especially with all the power outages this week people have already had to endure. Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Is nobody looking at the NAM? TW Link to comment Share on other sites More sharing options...
Cold Rain Posted February 28, 2015 Share Posted February 28, 2015 Is nobody looking at the NAM? TW Don't need to. You just told us about it! Seriously though, the Nam overdoes QPF routinely. If others are showing the same amount, maybe it'll be time to worry a bit more. Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Well here's my interpretation of the 12z NAM. N & W of a line from Morganton to N Meck to Seagrove to Durham start as freezing rain between midnight and 3 am. They will all gradually change over to rain between 11 am and 4pm. During that time, .25 -.40 qpf will fall. Do the math from there. Triad area to Hickory N&W look like a warning may not be out of the question. Just to our north gets a bit more qpf. TW Link to comment Share on other sites More sharing options...
Lookout Posted February 28, 2015 Share Posted February 28, 2015 Local news just mentioned snow flurries here this morning. They said it wasn't likely, but they did give it a nod. I did manage to see what looked like a cross between a flake and sleet. Was very light and lasted about 5 minutes. I know its minuscule but This makes the 5th time i've seen snow flakes this year here. 12z NAM has what looks to be warning criteria ice for parts of western part of NC. Not sure about surface temps yet, but typical CAD areas should hold AOB freezing through at least 1pm. TW Most certainly. 0.35 to 0.50 liquid with temps below freezing in typical damming areas of nc. I believe it would likely make it down into the upstate as well since the models are missing these dewpoints pretty badly and evap cooling should be quite a bit more than indicated by the models, which show virtually zero since it's dewpoints are as much as 15 degrees too warm on the gfs for areas like gsp. I suspect temps will be in the 20s in western nc so those amounts would certainly make for a respectable event. Question is, is the nam over doing amounts or not. Since this isn't progged to be a big/wet system i think it might be right. The nam did very well with the past few light/weak precip events..far better in fact than the gfs. So it's worth watching from the upstate into nc. Link to comment Share on other sites More sharing options...
packfan98 Posted February 28, 2015 Share Posted February 28, 2015 9z SREF has a 94% prob of freezing rain and a mean of .24 qpf while fzrn is the dominant preci type. This is for Greensboro. Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Thanks Pack. How's rdu looking? TW Link to comment Share on other sites More sharing options...
packfan98 Posted February 28, 2015 Share Posted February 28, 2015 Thanks Pack. How's rdu looking? TW Threat looks minimal for RDU with only an average of .05 when temps are below freezing. Link to comment Share on other sites More sharing options...
mackerel_sky Posted February 28, 2015 Share Posted February 28, 2015 I had not paid much attention to this until now but it should be noted the models are a solid 10 to 15 degrees too warm with dewpoints in general. They are just badly under estimated at the moment everywhere i look. I'll say this, if there was a 1044mb high over the mid atlantic...9/10 times that ends in freezing temps well down into ne ga. I know there isn't a lot of precip but it's a little bit of a mystery to me why the models aren't colder. A lot depends on temps today for ga/sc as the models warm us up pretty well. However, there is already a thick cloud cover with virga overhead and in fact nam is showing precip later today..it's hard to picture a lot of warming today with stiff northeast winds and if it stays cloudy with any precip. Wouldn't be surprised to see some sleet or even light snow/flurries if anything manages to reach the ground this morning. Soundings are cold/dry enough that it should be flakes if it reaches the ground. Cloud deck is low enough it looks like it could. Temps may be a little warmer than forecast today around here. It's mostly sunny and temp is 38 and we were only suppose to reach upper 30s to 40. Mabe the cold is still trying to come in? It's very windy also. Link to comment Share on other sites More sharing options...
WeatherHawk Posted February 28, 2015 Share Posted February 28, 2015 Well here's my interpretation of the 12z NAM. N & W of a line from Morganton to N Meck to Seagrove to Durham start as freezing rain between midnight and 3 am. They will all gradually change over to rain between 11 am and 4pm. During that time, .25 -.40 qpf will fall. Do the math from there. Triad area to Hickory N&W look like a warning may not be out of the question. Just to our north gets a bit more qpf. TW I agree TW with your interpretation, and believe that there will be some icing in our areas then to rain. Just concerned that there could be some issues with increased loads and stress on trees and powerlines. Link to comment Share on other sites More sharing options...
packfan98 Posted February 28, 2015 Share Posted February 28, 2015 Has anyone looked at the 12z gfs? I'm on my phone. Link to comment Share on other sites More sharing options...
packfan98 Posted February 28, 2015 Share Posted February 28, 2015 From NWS Raleigh .NEAR TERM /THROUGH SUNDAY/... AS OF 1015 AM SATURDAY... ...THREAT FOR A LIGHT ICING EVENT INCREASING FOR THE NC PIEDMONT EARLY SUNDAY... TONIGHT AND SUNDAY... LATEST MODEL GUIDANCE HAS TRENDED WETTER LATE TONIGHT INTO SUNDAY. THIS INCREASES THE THREAT FOR A LIGHT ICING EPISODE EARLY SUNDAY...MAINLY ACROSS THE PIEDMONT COUNTIES. TONIGHT...SFC RIDGE AXIS WILL REMAIN OVER THE REGION...MAINTAINING A SUPPLY OF COLD DRY AIR IN THE LOWEST 2-4K FT OF THE ATMOSPHERE. ABOVE THE COLD DRY STABLE LAYER...SLY FLOW WILL BE INCREASING IN RESPONSE TO THE 850MB HIGH DRIFTING OFF THE SE U.S. COAST. THIS RETURN FLOW WILL ADVECT A WARMER...MORE MOIST AIR MASS INTO THE CAROLINAS. THIS RETURN FLOW STRENGTHENS SUBSTANTIALLY AFTER 12Z SUNDAY...THUS EXPECT THE BEST UPGLIDE TO OCCUR AFTER DAYBREAK SUNDAY. STILL...MODELS HAVE A TENDENCY TO BE A LITTLE TARDY WITH RETURN FLOW EVENTS. THUS WILL INTRODUCE A SLIGHT/SMALL CHANCE POP INTO THE FORECAST FOR THE PRE-DAWN HOURS WITH THE HIGHEST POPS CONFINED TO THE SOUTHERN PIEDMONT/WESTERN SANDHILLS. PARTIAL THICKNESS TECHNIQUE INDICATES A TREND TOWARD RAIN BY DAYBREAK SUNDAY AS A DECENT WARM NOSE DEVELOPS ALOFT. HOWEVER MODEL SOUNDINGS INDICATE A SHALLOW SUB FREEZING LAYER OVER MOST OF CENTRAL NC AT DAYBREAK SUNDAY. THUS...ANY LIGHT PRECIP THAT OCCURS PRIOR TO DAYBREAK WILL LIKELY BE IN THE FORM OF FREEZING RAIN/FREEZING DRIZZLE. MIN TEMPS WILL VARY FROM THE LOWER 20S IN THE NORTHERN COASTAL PLAIN WHERE CLOUD COVERAGE WILL INITIALLY BE THINNEST TO THE UPPER 20S ACROSS THE FAR SOUTH-SW. SUNDAY...PRECIPITATION EXPECTED TO BECOME MORE COMMON AFTER DAYBREAK ACROSS THE WEST AS ISENTROPIC UPGLIDE INCREASES. THIS PRECIP FALLING THROUGH THE DRY AIR MASS IN THE SUB CLOUD LAYER WILL LEAD TO EVAPORATIVE COOLING...LIKELY LOCKING IN THE SUB FREEZING SFC TEMPS OVER THE PIEDMONT FOR A GOOD PART OF THE MORNING. DUE TO TIMING UNCERTAINTY...WILL CAP POPS AT SOLID CHANCE ACROSS THE WESTERN COUNTIES TRENDING TO SLIGHT CHANCE IN THE COASTAL PLAIN. IF LATER MODEL RUNS ARE CONSISTENT...AN INCREASE IN POPS WILL BE WARRANTED AFTER DAYBREAK IN THE WEST. THE LOCKING IN OF THE SUB FREEZING TEMPS WILL CAUSE A PERIOD OF LIGHT FREEZING RAIN OVER MOST OF THE PIEDMONT SUNDAY MORNING. AT THIS TIME NOT EXPECTING ENOUGH ICE ACCRUAL TO CAUSE POWER OUTAGES BUT COULD SEE SOME SLICK ROADS...ESPECIALLY BRIDGES AND OVERPASSES. THIS WILL LIKELY WARRANT THE NEED OF AN ADVISORY IN LATER FORECAST ISSUANCE. IN THE MEANTIME...WILL HIGHLIGHT THREAT IN THE HWO. EXPECT PRECIPITATION CHANCES TO INCREASE TO LIKELY SUNDAY AFTERNOON AS UPGLIDE REACHES MAXIMUM. WILL EVENTUALLY SEE FREEZING RAIN TRANSITION TO A COLD RAIN OVER MOST OF THE PIEDMONT BY MID DAY...AND OVER THE NW PIEDMONT BY EARLY AFTERNOON. THE OVERCAST SKIES AND EXPECTED PRECIP WILL LIMIT TEMPS TO THE LOW-MID 30S OVER THE PIEDMONT COUNTIES TO THE UPPER 30S-LOWER 40S EAST OF HIGHWAY 1.-WSS Link to comment Share on other sites More sharing options...
tarheelwx Posted February 28, 2015 Share Posted February 28, 2015 Seems they may be underplaying this in the NW Piedmont as a "light icing event." TW Link to comment Share on other sites More sharing options...
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