purduewx80 Posted December 19, 2018 Share Posted December 19, 2018 The pattern change across eastern North America from today to Friday is phenomenal, notably so from the Southeast to the Lakes but especially so over the Canadian Maritimes. 500mb anomalies there shift from ~250m below normal today to something off the charts late Friday. Also note how the western Atlantic ridges flexes once again, as we've seen time and time again in 2018. Positive temperature anomalies will also be impressive, and it is likely that record warmth will occur in parts of New England. NYC's 65F from 2013 may be hard to beat but BOS could easily reach or exceed 1957's 62F reading. As the +EPO-driven Pacific jet currently bringing thunderstorms to the Seattle area dives into the Southern Plains the next couple of days, deep meridional flow will develop in the eastern US. This unusual south-to-north flow at all levels of the atmosphere will draw Caribbean and Gulf of Mexico moisture due north along the East Coast, setting the stage for a heavy rain and wind event in the Northeast. As @bluewave has alluded to, nearly all model guidance forecasts record precipitable water in the region Friday - both for meteorological winter and perhaps the entire cold season. We shall see if OKX and CHH set an impressive record. What is certain is that heavy rain will occur in the Northeast as a result of the anomalous warmth, moisture and 60-80KT+ low level jet. Mesoscale details probably will not be known until Thursday or even early Friday, but the synoptic drivers seem to favor much of the region experiencing a convective squall of sorts in the WAA regime Friday morning. Widespread 1-2" amounts will be common, but any areas that get stuck under the conveyor could see upwards of 4" in short order. Lapse rates favoring convection may allow the shallow inversion to be penetrated in parts of the region. While I don't expect widespread thunderstorms with wind damage, parts of NJ, Long Island and southern New England could see this jet mix down in the heaviest of showers. Anyone flying in or out of the Northeast Friday may want to consider alternate plans. Given this system is occurring on one of the busiest travel days of the year, delays could get out of hand in a hurry. 10 Link to comment Share on other sites More sharing options...
gravitylover Posted December 19, 2018 Share Posted December 19, 2018 Damn, one of my kids is up in VT skiing with a group from her college and will be leaving there Friday afternoon to head home in the school van. Sounds like some wonderful traveling conditions. Link to comment Share on other sites More sharing options...
purduewx80 Posted December 19, 2018 Author Share Posted December 19, 2018 11 hours ago, gravitylover said: Damn, one of my kids is up in VT skiing with a group from her college and will be leaving there Friday afternoon to head home in the school van. Sounds like some wonderful traveling conditions. should be a lot of snow melt and river flooding up in northern new england. some of the rivers have ice, so the quick melting and potential for heavy rain may cause more flooding than we'd otherwise expect w/ a quick mover like this. Link to comment Share on other sites More sharing options...
gravitylover Posted December 19, 2018 Share Posted December 19, 2018 Yeah the fact that all of the drainages are frozen and are also already bankfull will be a problem especially considering how much of the snowpack is still soft and will degrade very quickly. Link to comment Share on other sites More sharing options...
purduewx80 Posted December 19, 2018 Author Share Posted December 19, 2018 Aside from the 12km NAM, the latest guidance is suggesting LI and CT have the greatest risk for rainfall amounts over 2 inches. Various pieces of both global and hi-res guidance are painting >4" amounts in CT. Link to comment Share on other sites More sharing options...
Gravity Wave Posted December 19, 2018 Share Posted December 19, 2018 I have a friend going on a ski trip starting Thursday, he should probably think about packing some water skis as well. 1 Link to comment Share on other sites More sharing options...
LurkerBoy Posted December 19, 2018 Share Posted December 19, 2018 How warm do we get Friday! Link to comment Share on other sites More sharing options...
purduewx80 Posted December 19, 2018 Author Share Posted December 19, 2018 59 minutes ago, LurkerBoy said: How warm do we get Friday! 60ish. Upper 50s near the water, no higher than 65 if low clouds scatter out. Mid-60s look more likely in interior New England. Link to comment Share on other sites More sharing options...
purduewx80 Posted December 19, 2018 Author Share Posted December 19, 2018 Interestingly, the past few RPM runs are mixing the core of the LLJ down through the inversion Friday morning. It has temps maxing out at 67 for EWR, 65 at NYC and LGA, and 62 at JFK - all records for the 21st. Could see high wind warning criteria met on LI if that verifies, especially where the convective precip ends up. 2 Link to comment Share on other sites More sharing options...
wdrag Posted December 20, 2018 Share Posted December 20, 2018 Is this also going to serve as the obs thread (1+ inch rain/> 45 MPH wind gust) for the coming substantial rain event 6P/20-6A/22? Or should we begin another OBS only thread. Whatever you prefer. I'll check back Thursday morning. Thanks, Walt 1 Link to comment Share on other sites More sharing options...
Rjay Posted December 20, 2018 Share Posted December 20, 2018 8 minutes ago, wdrag said: Is this also going to serve as the obs thread (1+ inch rain/> 45 MPH wind gust) for the coming substantial rain event 6P/20-6A/22? Or should we begin another OBS only thread. Whatever you prefer. I'll check back Thursday morning. Thanks, Walt Right here is perfect for an obs thread 1 1 Link to comment Share on other sites More sharing options...
SnoSki14 Posted December 20, 2018 Share Posted December 20, 2018 Really potent bugger, chances of more widespread 3"+ amounts are increasing. Could see a moderate risk upgrade for river flooding. 1 Link to comment Share on other sites More sharing options...
Mark McIntyre Posted December 20, 2018 Share Posted December 20, 2018 GOES-16 water vapor loop already getting better by the minute Link to comment Share on other sites More sharing options...
Snowlover11 Posted December 20, 2018 Share Posted December 20, 2018 should be a fun ride friday morning. Link to comment Share on other sites More sharing options...
LongBeachSurfFreak Posted December 20, 2018 Share Posted December 20, 2018 If we are going to have a major apps runner let’s go all out. The tropical moisture plume is about a legit as you can get. The radar should lit up like a Christmas tree Friday morning. It’s been a while since we have had HWW Se winds. Probably since Sandy and those were more of a ESE. 1 Link to comment Share on other sites More sharing options...
Snowlover11 Posted December 20, 2018 Share Posted December 20, 2018 uptons point and click has 2-4” of rain 1 Link to comment Share on other sites More sharing options...
NJwx85 Posted December 20, 2018 Share Posted December 20, 2018 I’m all in on this one. Have liked this threat for sometime. Link to comment Share on other sites More sharing options...
LibertyBell Posted December 20, 2018 Share Posted December 20, 2018 14 hours ago, purduewx80 said: Aside from the 12km NAM, the latest guidance is suggesting LI and CT have the greatest risk for rainfall amounts over 2 inches. Various pieces of both global and hi-res guidance are painting >4" amounts in CT. Based on upslope and the storm tracking to the west of us, the rainfall maxima should be in the mountains of NW NJ and the Poconos. Link to comment Share on other sites More sharing options...
LibertyBell Posted December 20, 2018 Share Posted December 20, 2018 5 hours ago, LongBeachSurfFreak said: If we are going to have a major apps runner let’s go all out. The tropical moisture plume is about a legit as you can get. The radar should lit up like a Christmas tree Friday morning. It’s been a while since we have had HWW Se winds. Probably since Sandy and those were more of a ESE. How high are the winds going to be? I was thinking more like Wind Advisory rather than High Wind Warning Link to comment Share on other sites More sharing options...
Rtd208 Posted December 20, 2018 Share Posted December 20, 2018 Link to comment Share on other sites More sharing options...
weathermedic Posted December 20, 2018 Share Posted December 20, 2018 3 hours ago, LibertyBell said: How high are the winds going to be? I was thinking more like Wind Advisory rather than High Wind Warning Wind advisories up for the area. Gusts up to 45 mph expected late tonight through Friday night. Eastern Massachusetts has a high wind watch up. 1 Link to comment Share on other sites More sharing options...
bluewave Posted December 20, 2018 Share Posted December 20, 2018 This developing storm system will produce one of the most negative 500 mb height anomalies for the Gulf in December at -6.37 sd. Just goes to show the extreme amount of tropical moisture getting tapped. OKX could see close to the highest December PW reading on their sounding Friday morning. We will have to monitor the short term trends as to where the best training sets up across our area. 1 Link to comment Share on other sites More sharing options...
purduewx80 Posted December 20, 2018 Author Share Posted December 20, 2018 1 hour ago, bluewave said: This developing storm system will produce one of the most negative 500 mb height anomalies for the Gulf in December at -6.37 sd. Just goes to show the extreme amount of tropical moisture getting tapped. OKX could see close to the highest December PW reading on their sounding Friday morning. We will have to monitor the short term trends as to where the best training sets up across our area. Thanks for posting the anomalies...the original ECMWF image I shared was supposed to loop and show this but it's not animating. Also...well said on the short-term trends tomorrow. Models not handling convection in FL very well this morning so it's likely none of them have it pegged here tomorrow either. 1 Link to comment Share on other sites More sharing options...
purduewx80 Posted December 20, 2018 Author Share Posted December 20, 2018 6 hours ago, LibertyBell said: Based on upslope and the storm tracking to the west of us, the rainfall maxima should be in the mountains of NW NJ and the Poconos. Very well could be but it entirely depends on where the conveyor belt sets up and if it remains stationary tomorrow. There will continue to be variability in the modeling given the mesoscale nature of the event. Link to comment Share on other sites More sharing options...
Juliancolton Posted December 20, 2018 Share Posted December 20, 2018 Events like this really make me miss the old SPENES messages. Those discussions were always such a pleasure to read and study. Link to comment Share on other sites More sharing options...
NJwx85 Posted December 20, 2018 Share Posted December 20, 2018 The high res models, especially the 12z NAM and RGEM have trended towards stalling the LLJ over the region tonight into Friday afternoon. If correct this is going to lead to some serious flooding. It's these widespread 3-4" storms that tend to cause the most problems. Link to comment Share on other sites More sharing options...
ForestHillWx Posted December 20, 2018 Share Posted December 20, 2018 The Passaic River in Lincoln Park is just below bankfull. 3-4" will flood the low parts of that and many other low lying towns in north jersey. Link to comment Share on other sites More sharing options...
gravitylover Posted December 20, 2018 Share Posted December 20, 2018 While the temps are pretty well above freezing the clouds have inhibited ground thawing so it's still frozen here. At least in the beginning of the storm I expect a fair bit of the rain to just run off which will make any flooding problems worse. As the ground thaws we'll get down to the mud and thoroughly saturated ground and whatever new falls will have nowhere to go. It's going to be a mess. Link to comment Share on other sites More sharing options...
NJwx85 Posted December 20, 2018 Share Posted December 20, 2018 Some decent low level shear late tonight into early tomorrow afternoon on most models. Mostly non-directional but I wonder if it's enough to give someone a weak spin up given the other parameters. Link to comment Share on other sites More sharing options...
bluewave Posted December 20, 2018 Share Posted December 20, 2018 https://mobile.twitter.com/SERCC/status/1075813030565421058 Wettest December Day on record for Sarasota Bradenton International Airport (SRQ) with the 3.96 that has already fallen today 1 Link to comment Share on other sites More sharing options...
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