Roger Smith

Some rather extreme looking solutions on RGEM and GFS 18z, makes me think this storm may join the elite memorable storm category but probably more for what it does in PA than any other state, however NJ, MD and NY could have some of the historical mentions. Each run seems to drop the central pressures (at comparable times) a couple of mbs. Very interesting to watch this unfold (and let's face it almost 0% of this storm has actually happened yet).

GFS apparently just caved to the RGEM but then said, listen since you rented the room, I'll pay for an extra night. Danger is more with mixing than total QPF if these coastal long-duration scenarios work out. Severe mixing may intrude into se NJ but what about PHL? Thinking maybe 20% loss to sleet? If these scenarios actually happen, if more like NAM/Euro then total QPF a lot lower anyway. Seriously, a little north of metro PHL could get buried 1888 style if these maps pan out. I live in a high snow area myself so you might catch up to me by Tuesday (snow on ground 32" here).

8-50" would be a good call at this point.

Some monster snow potential in e PA and quite a bit of NJ also if the North American models are correct, in particular the RGEM, very tight frontal boundaries will be shoved up against the cold trapped over e PA, with a coastal making a bit of a retrograde motion later Monday. Euro solution more like 15-25" max. I suppose that makes it the more likely to verify just on probability alone, but if there's more of a curl to the circulation, look out, some place in e PA could top 40" like BGM did in the December storm. If I had to guess where the jackpot will be, would say Pottstown to Easton. Would not expect much today, all unfolds with the coastal rapid deepening phase.

Based on 18z obs the primary low has deflated to 1003 mb in n KY but the circulation is very flabby within 100 miles of the center, indicating that the coastal transfer is starting to develop. The wave formation near the coast is most evident near SAV, when an impulse now forming near the AL-GA border catches up to this coastal wave that should initiate the coastal as a separate circulation around 00-02z. Models seemed to be struggling with multiple coastal vortices that suddenly jump forward towards NJ, in reality there would probably be something more organized by 12z east of Hatteras. What this looks like is analogous to the blizzard of 1888 only aimed more at NJ/PA than LI/CT. There will quite likely be some enormous snowfalls in eastern PA and the contours around those maxima would be quite impressive even into MD, DE and NJ. Local amounts of 40" or even higher would not be surprising given the curved moisture feed aimed at one region for 24h.

Not as pessimistic as some here after looking at 12z guidance and current analysis. The GEM and GFS both show quite a strong curved trajectory towards ACY for the coastal and still hint at a stall if not a loop. While this would obviously jackpot e PA, last time I looked there are no states between PA and MD and that jackpot is only 30-50 miles into PA so would expect at least the northern tier of MD counties to approach 20" snowfalls -- the higher this jackpot goes, the better MD does, there would be no physical rule to say that the more snow falls in PA then less would fall in MD. Also the dynamics of this are quite unusual, especially if the CMC is right and they do after all have as good a set of the data input over the current complex upper pattern as any rival model would have. Looking at 12z analysis, the low in the Midwest is not stacked but has an unusual C-shaped vertical profile from 500 mb in nw IN to surface in se IN (at that time) with 700 and 850 back in IL. That will distort over 24h into the coastal setup and the hook will then be rotated about 90 deg (counter-clockwise) anchored by a 500 mb low over VA, to a surface low bombing east of Delaware. I think with these unusual dynamics there could be more wrap around effect than you might expect with a more standard Miller B. As to bust calls at this early stage, most of the potential of this storm is Monday-Tuesday, I would not write it off anywhere in the mid-Atlantic and especially not in ne MD or n DE. It could be a 60h storm with an interruption later today, so even if 40 of those hours only produced 0.2" inch snowfalls that's still 8.0" and some of these hours tomorrow into Tuesday will produce considerably more, would expect at least moderate snow in some of the bands extending into MD (S+ obviously possible and will be widely reported in PA and NJ, NYC). Another consideration is that if a lot of very mild air dams up against a wall of cold south of Long Island while the low is stalling or looping, then some of that will be entrained west across NJ and PA and around the circulation which may create a warm seclusion, which is probably that feature on some models that rotates back across MD in latter stages of the storm. Anyway, bottom line is this will turn into an intense coastal almost without a direct parallel and do its own thing with memorable results, and you have a front row seat, enjoy.

The 06z RGEM begins to hint at explosive development off the coast by late Monday, looks like bad news for LI and se MA snow potential but possibly returning a stronger potential for MD-DC-VA as a lot of Atlantic moisture is going to be forced aloft and uppers are still marginally favorable (more than a few miles from the shore at least). Some place in PA will probably top four feet at this rate. If that's not too far from the PA-MD line then some place in MD could top three feet. This could get very interesting.

A little to the west of Columbia MO, center is 997 mb and went over Whiteman AFB around 0030z. Rain-snow dividing line roughly DSM to LAF. Should be near STL by 03-04z.

Has this been mentioned? ... the 1922 Knickerbocker storm looks very similar on historical weather maps at closest approach to DC, although it was entirely coastal in origin ... upper panels on wetterzentrale are obviously back-cast but look rather similar also. Timing (Jan 28-29) and the sort of otherwise bland winter season are also similar. Just a factoid among many. One other detail that caught my eye in assessing model scenarios is that offshore the warmer Gulf stream water has pooled out around 70W with a fairly cool coastal layer, there's no instant torching of lower levels available from contact with these relatively cold seas. This is why I tend towards accepting the RGEM solution, if I saw a sharper gradient out around the Texas Tower then perhaps more of a Long Ilsland bomb outcome. The 24 hours of east winds will probably advect some warmer surface layers briefly but that may just assist in the loop process and strand a cutoff secondary near the coast.

--4.5 __ --4.7 __ --5.2 ___ --6.0 __ --7.5 __ --3.0 ___ +1.5 __ +2.5 __ +2.3

Clearly a high variance situation in the model suite, but somebody's bound to get 24-36 inch amounts, can't see how se PA is not the most likely place given the factors in play. But sure it could be somewhere else. Looks like a sure 12-18 inch outcome at a minimum, if I were more of a stakeholder I might back down to 18-24 from what I actually think will happen. Good luck -- it all depends on that coastal stall retrograde loop aspect, best location for PHL to max is probably central DE, a bit further south may shift the heaviest snow to n DE and ne MD (which are still going to do very well). Weak or absent coastal loop still makes 12-18 plausible.

No need, check official forecast, they did it for me. Can somebody tell me how Temiskaming Shores (pop 50) gets onto a map and Chicago doesn't? Seriously, I can certainly see how actual amounts will be in the 6-12 inch range but my forecast is based on GEM being best available modelling, have been tracking events in Europe for forecasting that I do, and GEM has been quite reliable all winter when GFS and ECM are not in agreement, when they are in agreement I tend to take that blend and just check GEM for possible deviations -- what's interesting, and this may answer a question asked in the thread by Stormtracker IIRC, what the Canadian model may be picking up is the setting up of blocking from the fairly strong trailing wave that formed in the wake of the Tuesday s.e. VA developing low that then exploded to 952 mbs south of Newfoundland, then was followed by developing low -- also developments over Greenland and Europe are slowly building towards a major blocking episode, GEM seems to have done better with this and I noticed today's ECM 12z run has backed off a very progressive 00z solution in Europe towards at least 50% of the cold advection for Britain and Ireland suggested on GFS and GEM. My forecast scenario could also go wrong if the retrograde loop is further north than GEM shows. This would shift the 24-30 inch outcomes into east central PA entirely, and would probably result in 50-60 per cent validation rates on my amounts for BWI and DCA, IAD. Anyway all my forecast really says is that I feel the RGEM has the best call on development. We'll find out on Monday.

RGEM and to a lesser extent GFS have retrograde loop of coastal, which would explain apparently huge snowfall predictions. Not quite buying that totally but factoring it into second call which follows first call (which was 17-23 widespread, 25-30 local). DCA 16.5 IAD 20.5 BWI 24.5 nMD/sePA local 30-35 15" snow line n/c DE to near Annapolis to Quantico mixing zone mainly from that contour to Ocaen City-Richmond (5" snowfalls). Blizzard-like storm for many areas of c, ne MD and e PA, s/c NJ Winds not being discussed much but with the retrograde loop, gusts to 70 mph quite possible in a zone from n/c DE to central Chesapeake, probably 35-45 cities along I-95. Just a relatively brief interval of those winds, associated with retrograde phase mid-day Monday. Further afield, predicting 30" PHL, 20" NYC, 12" BDR, 14" BOS, only a medium sized snowfall for much of inland New England as they get a weaker phase of the evolution. Max snowfall from storm somewhere like Pottstown PA 36"

You know things are going well when (a) you wonder if the 4 inch QPF would be all snow or just mostly snow (b) you wonder why that guy in BC always underpredicts snowfalls

GGEM has an exceptional look for this region, 15-25 inch potential with about 24h of continuous moderate to heavy snow potential as the coastal slowly develops in an ideal location, while the primary slumps southeast to eliminate dry slot and transient warmth. GFS is almost as good. ECM appears to be drifting into the same outlook. Based on that, first call from me: widespread 17-23 inch totals, local 25-30. mixing issues confined to central, southern DE, southeast MD, VA s/e of RIC.

This seems like a good set of model signals with GFS very good, GEM perhaps a bit warmer solution than ideal, ECM now trending a bit suppressed, my guess is that a very large storm is likely and this divergence represents those developing signals coming into the mix -- in fact this could turn out to be a monster storm with the long interval of coastal development and signs that the center wants to set up very close to the Delaware coast. My hunch is we're looking at 20-30 inch amounts with this one.

Won't be me starting any storm contest threads, the winter seasonal contest is probably basically this storm plus 5" anyway.

Predict the temperature anomalies (F deg) relative to defined normal period (expect this to remain 1981-2010 for a few more months yet) for these nine locations ... DCA _ NYC _ BOS __ ORD _ ATL _ IAH ____ DEN _ PHX _ SEA The deadlines and late penalties now in force are as follows: enter by 0600z 1st, no late penalty enter by 1800z 1st a late penalty of 1% enter by 00z 2nd, late penalty of 2% enter by 03z 2nd, late penalty of 3% enter by 06z 2nd, late penalty of 4% after 06z 2nd, late penalty increases to 1% per 2h interval. It increases further to 1% per hour at 06z 3rd. __________________________________ These late penalties will be assessed unless participants supply a valid health-related reason for being late and also stipulate that they have seen no useful guidance since 0600z 1st. The late penalty is designed to offset advantages gained from later guidance rather than being punitive just for lateness alone.

Final scoring for Jan 2021 These scores are based on the final anomalies in the previous post. FORECASTER _________________DCA_NYC_BOS__east_ ORD_ATL_IAH__cent_ c/e___DEN_PHX_SEA__west___TOTALS DonSutherland 1 _______________ 70 _ 56 _ 48 __ 174 __ 96 _ 92 _ 94 __ 282 __ 456 __ 72 _ 84 _ 66 __ 222 _____ 678 RodneyS _______________________ 76 _ 86 _ 86 __ 248 __ 50 _ 62 _ 52 __ 164 __ 412 __ 64 _ 88 _ 96 __ 248 _____ 660 BKViking _______________________ 90 _ 96 _ 98 __ 284 __ 20 _ 66 _ 72 __ 158 __ 442 __ 44 _ 84 _ 88 __ 216 _____ 658 Roger Smith ____________________88 _ 80 _ 70 __ 238 __ 26 _ 98 _ 92 __ 216 __ 454 __ 74 _ 28 _ 86 __ 188 _____ 642 ___ Consensus __________________88 _ 96 _ 88 __ 272 __ 28 _ 62 _ 66 __ 156 __ 428 __ 48 _ 84 _ 80 __ 212 _____ 640 wxallannj _______________________88 _100_ 88 __ 276 __ 28 _ 76 _ 48 __ 152 __ 428 __ 12 _ 98 _ 80 __ 190 _____ 618 hudsonvalley21 _________________76 _ 70 _ 62 __ 208 __ 48 _ 64 _ 72 __ 184 __ 392 __ 48 _ 78 _ 98 __ 224 _____ 616 Scotty Lightning ________________78 _ 76 _ 70 __ 224 __ 06 _ 62 _ 88 __ 156 __ 380 __ 46 _ 78 _ 64 __ 188 _____ 568 wxdude64 ______________________80 _ 74 _ 76 __ 230 __ 22 _ 54 _ 66 __ 142 __ 372 __ 26 _ 94 _ 58 __ 178 _____ 550 so_whats_happening __________ 100 _ 58 _ 38 __ 196 __ 46 _ 60 _ 42 __ 148 __ 344 __ 48 _ 92 _ 48 __ 188 _____ 532 RJay ___________________________98 _ 74 _ 50 __ 222 __ 56 _ 42 _ 58 __ 156 __ 378 __ 66 _ 48 _ 28 __ 142 _____ 520 Tom ___________________________ 66 _ 74 _ 76 __ 216 __ 00 _ 38 _ 64 __ 102 __ 318 __ 32 _ 94 _ 62 __ 188 _____ 506 ___ Normal _____________________48 _ 56 _ 60 __ 164 __ 00 _ 42 _ 58 __ 100 __ 264 __ 36 _ 98 _ 64 __ 198 _____ 462 ____________________________________________________________________________ EXTREME FORECAST REPORT High score must go to either the extreme warm or cold forecast, or second most extreme, for a station to qualify. ORD _ DonSutherland1 (+5.0) was a lot closer than anyone else to the confirmed outcome (+5.4). ATL _ Roger Smith (+3.0) wins here as ATL finishes on +2.9 or higher. IAH _ Don Sutherland (+1.8) has a win as IAH finished +2.1 ... Roger Smith (+2.5) has a loss by two points. DEN _ Roger Smith (+4.5) took a win here (DEN confirmed +3.2). (PHX narrowly missed out with third coldest forecast high score) The results in total are records of 2-0 for DonSutherland1 and 2-1 for Roger Smith. Four months qualified, all on the warm end of the forecasts. __________________________________________ Congrats to DonSutherland1 and all the crew after quite a close first month generally speaking, narrow range of scores. (note _ edit on March 3 was to correct small addition mistakes in scoring revealed by work on annual scoring after Feb)

Can we switch to snow on the ground outside one's house, because that way, I win ...

Since we're comparing snow pictures ... I live about 20 paces left of this photo (taken a week ago, the trees have lost that snow cover from the windstorm last week, snow on ground is about the same today as then after a bit of a thaw and a bit more falling) -- this is a normal look for here in mid-January.

I think the first half of February will deliver the goods. There are some similarities to 2010, and if you recall, no sign of winter at all in January 2010, until the last few days anyway. Western Europe is in a very similar pattern to Jan 2010.

Do you perceive two different kinds of cold regime down there, like the anticyclonic type and the advection from far north type? This far north, we tend to do these two types simultaneously, either there's cold air of northern origin trapped over us, or we're in a mild Pacific flow. This winter, it has been relatively mild (I'm only a few miles north of the 49th parallel here) but at my elevation a fairly decent snowfall. Quite a contrast locally, at my elevation 20-25 inches on the ground, down in the Columbia valley a few miles east of here, almost no snow, just partial cover and 2-4 inches where any at all. We just had some very strong winds from that low that came in off the ocean Tuesday night, a few large trees close to us coming down at daybreak.

First and second editions of the anomaly tracker, for 10 and 20 days ... with final anomalies added on Feb 1st. ______________________ DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 11th _ (10d anom) ___ +4.7 _ +3.6 _ +4.2 __ +7.1 _ +2.9 _ --1.5 __ +3.6 _ --1.1 _ +3.5 21st _ (20d anom) ___ +4.7 _ +5.4 _ +5.7 __ +6.9 _ +1.7 _ --1.2 __ +4.1 _ +0.9 _ +3.4 11th _ (p20d anom)__ +2.5 _ +1.8 _ +2.0 __ +2.5 _ +1.0 _ --2.0 __ +0.5 _ --1.5 _ +1.5 11th _ (p27d anom) __ +1.5 _ +1.0 _ +1.0 __ +1.0 __ 0.0 _ --2.5 ___ 0.0 _ --1.5 _ +1.5 21st _ (p31d anom) __ +3.0 _ +2.5 _ +2.0 ___+4.5 _ +1.5 __ 0.0 ___ 0.0 _ +1.0 _ +1.5 Feb 1st _(31d anom)_ +2.6 _ +2.2 _ +2.0 ___+5.4 _ +2.9 _+2.1 __ +3.2 _ --0.1 _ +1.8 __________________________________________________________________________________ snowfalls to date ____ 2.6 __ 12.6 __ 23.1 __25.4 _DTW19.5_BUF44.0 _ 20.1 _ 0.5 _BTV34.5 ____________________________________________________________________________________ 11th __ A mild start to January except in the southwest and Gulf coast where slightly below normal. The projections are based on the assumption of a modified cold pattern, not exceptionally cold, but somewhat below average in most regions for the rest of the month to the 27th at least. Despite the widespread below average temperatures, not a lot of snow on offer other than perhaps lake effect and a few transient 1-3" events. 21st __ The milder pattern continued anyway in the east, modified cold became modified mild with no snow on the ground near the coastal plain. Similar comment for DEN and to a lesser extent (with no snow expected) PHX and SEA. Forecasts for the southeast fared better though. The end of month forecasts are based on the assumption of near normal averages in most places across the south now to 31st, trending to around -4 average anomalies closer to the Canadian border. Snowfall contest amounts are updated above also. Many of those had added almost nothing until late January. Current totals are valid end of day Jan 31st. Provisional scoring will follow using the end of month projections generated. 27th _ ORD adjusted from +3.0 to +4.5 as cold end of month not as deep on current charts. 31st - 1st Feb _ Monthly final anomalies have been added.

Table of forecasts for January, 2021 Apologies, a bit late getting this together ... welcome back to the new contest year. FORECASTER ___________________ DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA __ bias DonSutherland 1 ________________+4.1 _ +4.4 _ +4.6 __ +5.0 _ +2.5 _ +1.8 __ +1.8 _ +0.7 _ +3.5 __ +1.86 hudsonvalley21 _________________+3.8 _ +3.7 _ +3.9 __ +2.6 _ +1.9 _ +0.7 __ +0.6 _ +1.0 _ +1.9 __ +0.93 so_whats_happening ___________ +2.6 _ +4.3 _ +5.1 __ +2.5 _ +0.9 _ --0.8 __ +0.6 _ --0.5 _ --0.8 __ +0.24 RJay ___________________________ +2.5 _ +3.5 _ +4.5 __ +3.0 __ 0.0 __ 0.0 __ +1.5 _ +2.5 _ --1.8 __ +0.24 BKViking _______________________ +2.1 _ +2.0 _ +2.1 __ +1.2 _ +1.2 _ +0.7 __ +0.4 _ +0.7 _ +1.2 __ +0.44 wxallannj _______________________+2.0 _ +2.2 _ +2.6 __ +1.6 _ +1.7 _ --0.5 __ --1.2 _ --0.2 _ +0.8 __ --0.30 ___ Consensus __________________+2.0 _ +2.0 _ +2.6 __ +1.6 _ +1.0 _ +0.4 __ +0.6 _ +0.7 _ +0.8 Roger Smith ____________________ +2.0 _ +1.2 _ +0.5 __ +1.5 _ +3.0 _ +2.5 __ +4.5 _ +3.5 _ +2.5 __ +1.06 wxdude64 ______________________ +1.6 _ +0.9 _ +0.8 __ +1.3 _ +0.6 _ +0.4 __ --0.5 _ --0.4 _ --0.3 __ --0.81 Scotty Lightning ________________ +1.5 _ +1.0 _ +0.5 __ +0.5 _ +1.0 _ +1.5 __ +0.5 _ +1.0 __ 0.0 __ --0.47 RodneyS ________________________+1.4 _ +1.5 _ +2.7 __ +2.7 _ +1.0 _ --0.3 __ +1.4 _ +0.5 _ +2.0 __ +0.13 Tom ____________________________ +0.9 _ +0.9 _ +0.8 __ --0.2 _ --0.2 _ +0.3 __ --0.2 _ +0.2 _ --0.1 __ --1.03 ___ Normal ______________________ 0.0 __ 0.0 __ 0.0 ____ 0.0 __ 0.0 __ 0.0 ____ 0.0 __ 0.0 __ 0.0 ___ --1.30 ____________________________________________________________________________________ ____________________________________________________________________________________ Color coding shows warmest and coldest forecasts. Normal is colder than all forecasts at DCA, NYC, BOS. New feature this year, "bias" is your average departure from consensus. (not an average of absolute difference, but an average of the nine anomalies vs consensus -- could help you figure out your tendencies). With eleven forecasters and consensus being the median, that will be the 6th ranked forecast. ------------------------------------------------------------------------------------------------------------------------------ Review of scoring rules For most forecasts, the scoring is 100 minus two points per 0.1 deg error in outcome. When an outcome is more than 5.0 deg above or below normal, a smaller decrease is applied, at either end of the scoring zone between 0.0 and the outcome, where equal portions near 0.0 and the outcome lose only one point per 0.1 error. Example, outcome is 7.0, zones from 0.0 to 2.0 and 5.0 to 7.0 lose one point, a forecast of 3.5 which would normally score 30 gets 50 points because it loses 30 points 3.5 to 5.0, and 20 more 5.1 to 7.0. You always score some points by being on correct side of normal. Back in March 2012 we had an outcome greater than 10.0 (DCA +12) and scored that on a totally sliding scale from 0.0 to +12.0. The only other scoring rule is that the maximum raw score must be 60 or greater, when it is not, then all scores are adjusted on a "minimum progression" basis with the closest forecast scoring 60, and the rest eligible to score at intervals ... with eleven forecasts, there would be nine more scores at intervals of six, and then a bottom score of zero. However, any raw score that is higher than the minimum progression score is used instead. If the raw scores were clustered from 20 to 50, then in my example, 30 might be the lowest boosted score and the lower ones (24, 18, 12, 06, 00) would be higher raw scores instead. These are by the way the scoring rules that I have been applying for about ten years now. As to late penalties, I have been trying to balance fairness with fun, as we can see in the larger picture, this is not very easy to do. The late penalties kick in at 0600z of the 1st, and amount to one per cent reductions for each six hour interval (or fraction) that you are late, up to 36h (1800z 2nd, late penalty by then is 9%) and would increase by 1% per hour thereafter although we rarely get forecasts much later than 12-18 hours after deadline. I have been lenient in 2020 on health-related late situations. My philosophy on late penalties is not to be punitive but just to try to level the playing field in case guidance improves in some situations by the time a late entrant makes a forecast. If guidance improves, a 5% scoring reduction might offset the advantage gained. Anyone has the right to submit a late revision for one or more stations, and those would be scored by the relevant late penalty. It would not be applied to forecasts unchanged from on-time submission.