wdrag
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Good Sunday morning everyone, it is a cold January 16 and likely to be even colder for a day or two between the 23rd and 30th. What follows is my own expectation. Please follow updates on all NWS warnings-statements-forecasts for todays storm. Uncertainty on when the snow mixes with or changes to sleet/ freezing rain or plain rain. Two hours error can mean a snowfall forecast error of 1-4". Baltimore-Philly-NYC: an hour or two of snow begins 4P-8P changing briefly to sleet-freezing rain, then to heavy rain by 10 PM with 3 hours of 45-55 MPH easterly wind gusts sometime sometime between 11PM and 4 AM . Untreated surfaces possibly slippery for a couple of hours late today-this evening. Power outages possible because of the wind later tonight. Snowfall probably a trace to around an inch. The rain washes it away overnight. However, there could be a half inch of snow showers between 11A-11P Monday, probably minor impact at worst. Yes I can see 60 MPH gusts NYC, but I think the 60-70 is better reserved for where the NWS has the warnings. It is definitely a short wind of opportunity. I84 corridor from the Poconos-northwest NJ through interior northeast MA. Snow begins 630PM-10PM, probably accumulating an inch an hour, for an hour or two before changing to sleet and freezing rain by 4 AM Monday, and then to a bit of rain Monday morning daylight hours. It goes back over to snow showers Monday afternoon - evening where slippery conditions might redevelop on untreated surfaces with an additional inch of snow possible. Significant travel problems tonight, especially Poconos extreme northwest NJ (Sussex County) into the hills west of Hartford between 830PM this evening and 6AM Monday with delays or cancels for Monday morning activities, especially the Poconos. Minimum snowfall 1.5" with generally 2-5" in the I84 corridor, possibly 8" parts of the Poconos, Catskills, Litchfield Hills. Scattered wind gusts of 45-50 MPH between midnight and 4 AM may cause power outages. SNOW REMOVAL: those with heart issues, be alert for the heavy wet soaked snow tomorrow morning. Even if only 2" of slush, it might effectively be 1" of rain soaked weight. Get some help to remove by 6PM Monday as the slush starts to refreeze. Attached: The National Weather Service 5AM snowfall map. Please use the legend for your area of interest. Big snow western NYS down the Appalachian rim. Remember: it's not perfect but gives a good idea of what is coming. Posted 657AM/16
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For what it is worth: Will begin the 21st-22nd thread around 8AM pending more review. No guarantees on that one for us but certainly potential in a strong baroclinic zone. Maybe ATL-ILM will get 4+"? and we miss? or..... not another LaNina inside runner?
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No change to this thread. Will replace with an OBS-NOWCAST thread around 11A. I think the thread title suffices and 38+ pages of discussion notes all the elements, disappointments but I'm sure you'll be busy by 8PM with winter obs and then early Monday with the damaging wind e LI and wind advisory power outages elsewhere, heart attack snow-slush removal I84; then back side 0.1-1" snow showers 11A-11P Monday. Something like that. Follow NWS statements-warnings (despite what I might suggest in my expectations). Il'l also begin the 21-22 thread around 8AM pending more review. No guarantees on that one but certainly potential in a strong baroclinic zone. Maybe ATL-ILM will get 4+"? and we miss?
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I dont see wind advisory criteria NYC til the 2A-5A time frame. seems like gusts below 40 knots thru 1A. I could be wrong. I checked HRRRX 80 meter winds and they don't reach 40 kt til 1A and the window of opportunity is about 3 hours, best around 2 or 3A. I can see G 50KT NYC but I would not forecast this. I think pressure falls will help concentrate the action as the storm occludes in e PA Monday morning. Soundings don't look unstable to me for transfer. E LI I think best chance gust 50-55kt.
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I can understand... Wind advisory may suffice. Not clear cut to me about warning level, and where tho I agree e LI looks best.
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I would say advantage meteorologists who KNOW post-processed data known errors. Also, a slight advantage meteorologists who study the models, almost every cycle, learning biases, which may change every model iteration. Meteorologists may rely too heavily on pattern recognition, not study the model detail or just too easily toss guidance that doesn't fit their expectations (disadvantage consumer-wishcasting). That's where self control-realization that models are only as good as the data and the understanding of the model capability. (GFS handling of boundary layer temps or the NAM ability to sense warm layers aloft better than some other models) We have a whole lifetime to learn our own biases and make an effort to reduce those biases and see the primary guidance. I also think some meteorologists may not understand FGEN-banding, and what drives the big precip (jet cores), or favorable patterns aloft for Cold Air Damming. Also some meteorologists are probably not using all the available tools... TSections, Soundings to the forecast advantage, or hourly data platform information. Fortunately the models steady improvement raises the performance of all ships-forecasters Humility is a best practice and knowing in advance that our attempts at forecasting reality will be in error, at least to some extent.
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Considerations: I84 corridor, hope HRRR and HRRX are too cold. Otherwise quite a snow/ice problem with power outages That's what Im getting hints of in the 18Z cycle...and the HRRRX is consistent with its 12z cycle. So, the bias is probably too cold and am looking for warmer cycles, especially the 00z. I am thinking the warming above 32F-scouring at the surface high valleys I84 corridor may not complete til after sunrise. If that happens, combined snow/ice will be a warning impact for at least some of this area. Pressure falls inflow will tend to turn the surface wind ne-or ene despite se isobars, at least in the interior. As of this mornings WPC cycles: am thinking the freezing rain risk is being underplayed n off I78 and w of I287 (ne NJ/se NYS and ne PA) Modeling is weakening the coastal flood threat NJ/NYC... onshore 40-50kt winds too short and pass by, by 12z..however low pressure in the 985 MB range gives a decent surge. So flooding possible but more than minor?? Have my doubts but reserve the opportunity to rereview tomorrow morning. Modeling also seems to trending to run a little east with the storm in the Carolinas then turns due north to DC-CXY to co-locate with the 850-500MB closed lows. Modeling also tending to offer only a 6-12 hr period of too warm for snow, suggesting any back side showers will fall as wet snow Monday, certainly the interior hills of w NJ and ne PA (closed low and colder thicknesses with the cold pool moving ne from DCA-CXY-which will make for steep moist lapse rates it crosses our area). No thread title adjustments now, but will re-review in the morning. I think it continues yes to serve reasonably well.
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I looked at 12z NAM/3K. The wind windowg45-60 MPH is about 3 hours. I'm not changing anything on the thread headline yet. It's been left open to a host of possibilities. Coastal flooding is not a lock for anything more than minor in our area. Why? Because max inflow has departed to the east by the time of high tide. Only the low pressure in the 980's is the reason for continued big positive surge. Also EKMAN transport onshore ie better on east-northeast surface winds than southerly for our shores. Need further scrutiny but timing is critical.
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What I am projecting based on modeling through 6AM. I've added 3 graphics. Note yet changing the headline. May lower the snow impact to interior and hype the wind a bit more but for now, until certitude, I'm staying with the headline. NYC: seems like an hour of snow begins 7P-830P Sunday changing to sleet-for a little while, then to heavy rain by midnight Sunday with 3 hours of 45-55 MPH easterly wind gusts sometime sometime between 1AM and 7AM Monday. Untreated surfaces possibly slippery for a couple of hours Sunday evening. Power outages possible because of the wind early Monday. Snowfall probably a trace to an an inch. NYC might see a slight accumulation of snow Monday evening with the trough aloft passage and temperatures falling back below freezing. That Monday evening backside may be a small travel problem. I84 corridor from the Poconos-northwest NJ-southeast NYS-W CT. Snow Sunday night should begin 7PM-10PM, probably briefly heavy changing to sleet and freezing rain by 5 AM Monday and then to a bit of rain Monday morning daylight hours. It goes back over to snow showers Monday afternoon or evening where slippery conditions might redevelop on untreated surfaces. I see significant travel problems, especially Poconos extreme northwest NJ (Sussex County) into the hills west of Hartford between 10PM Sunday and 7AM Monday with delays or cancels for Monday morning activities, especially the Poconos. Snow amounts uncertain due to how fast the snow changes to ice. I lowered the minimum snowfall 1.5" because of my concerns for snow to change to tick-tick-tick (sleet) about 3-5 hours after it starts snowing. My guess is generally 2-5" before the change. There might be another 1/2-1" of snow late Monday on the backside of the storm, but that is manageable by exercising a little caution. The main problem is midnight to 6AM Monday morning when snow-ice should be heavy for a time, and scattered wind gusts to 45 MPH could cause a few power outages. Appended the NWS snowfall forecast as of 5AM; the NWS ensemblechance of 4+" and the experimental winter storm severity index. I may work on that thread headline as early as 2PM. Have a day.
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Tomorrow morning what watches will post, will be out and and then i can make any headline adjustment at that time. Have a good night. Walt
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Might see gusts around 45 MPH near sundown.
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Added 10z/14 ensemble chance of 1" and 4+" of snow: both by 7AM Monday. More careful details and graphics post this evening. The NWS GIS snowfall was only thru 7PM Sunday as of this writing so useless to post.
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Basic thread headline looks acceptable to me still well in advance of the Sunday night-Monday morning storm. I'll rereview everything this event and possibly improve the headline but I just don't want to lock out possibilities yet. I know it says Noon Sunday start. I'm protecting at a slightly faster forward motion. And it looks like very little snow LI/coasts (less than 2", if that but it still could be messy for an hour or two, especially if cold air damming even holds sway along the coast for a little while. Have a good day: will revisit this evening.
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on SREF reliability, I don't think it would to exist in NCEP USA model suite, if it wasn't a helpful tool. It can be stellar, and sometimes miss completely but wherever the core axis... it's pretty darn good.
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SREF too early. 09z run is conservative on snowfall w NC and I like that. As multi above - wait to refine and cant rule out an ene turn once the storm gets near BWI. Out to sea, think the chance of that is less than 5%. Better chance of a miss all wet than out to sea no qpf.
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My own view having reviewed most of the modeling through 06z/13. The Sunday-Monday morning storm, still has track uncertainty. The USA model is more snowy-icy than the European. Solutions below lean a little to the warmer less snowy scenario but not with high confidence of being correct. If you need to travel Sunday-Monday morning, please follow later forecasts from your reliable sources. Baltimore-Philly-NYC: seems like a short period of snow near or just after sundown Sunday changing to sleet-freezing rain for a little while, then to heavy rain overnight Sunday with gusty east winds, possibly to 45 MPH near or after midnight. Untreated surfaces possibly slippery for a few hours. I84 corridor from the Poconos-northwest NJ through interior northeast MA. Snow Sunday night, should be heavy for a time changing to sleet and freezing rain by dawn Monday and either ends as rain or snow midday Monday. I see significant travel problems, especially Poconos extreme northwest NJ (Sussex County) into the hills west of Hartford. Snow amounts uncertain due to how fast the snow changes to ice. Also, wind gusts in the ridges may reach 45 mph near sunrise Monday and if trees iced, that's a power problem=uncertainty on ice amounts. Graphics: The ensemble chance of 3" of snow or a significant combo of snow-sleet Sunday 7am through only 7am Monday. An incomplete first glance at potential impact from this storm, only through 7AM Monday. The orange area is a start. The new 06z EC OP (rather gross 10 to 1 snow-sleet conversion) for snowfall ending 7PM Sunday - slightly faster and a bit further east than the previous 00z/13 op for comparison. Sleet is high bias problem with these 10 to 1 ratio's, and I think too for the positive snow depth change products.
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My only comment on all that is posted. Think ensembles mxd precip & sleet is counted as snow 10 to 1 ratio. Therefore be cautious where mixed precip can occur and think se EDGE might be way too high??? Gradients are always a problem. All modeling has se 850 inflow till late Monday morning= Cold Air Damming for the interior. In the meantime, I will probably wait til 6 hours before the period of snow (and possibly rain) that I think is going to occur LI/CT/MA, especially east sections of all, with small accumulation possible Friday. Not enough members covered for a thread except possibly OBS-NOWCAST. Will reevaluate all by 720AM Thursday.
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Sort of agree but, I don't think we have another way, unless we look at clustering. ?? I thought this appended site would cease, but alas we still have it. GEFS... plume clustering if you will. I've taken a look back and the GEFS has been having LGA at 3-4" the last 4 cycles. Does not imply it's correct. Like all here, I could see it much less, but I think we need to think about a turn-redevelopment to the ENE off NJ. Just my thinking based on 06z ensembles. I could be wrong but I just dont see this storm up to ALB... the upper air I do not think supports that track. Again I could be wrong so I dont want to provide useless hope, but this is why I'm waiting another 24 hours before any further commitment one way or the other. Probably my last post til this evening or tomorrow morning. By the way, I see the NAM is coming west with qpf on FRI morning. Watching that carefully for E LI to BOS.
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06z GEFS of interest on 2" snowfall: it cuts w of BWI-PHL, then turns ene across LI. What I'm seeing via the 06 GEFS is a tendency to close off the 500 short shortwave as it crosses LI Monday. I think interest in snowfall NYC north and west should be continued til future modeling closes the door. 5 days to go.
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Good morning again, No thread e LI/e CT/E MA this morning for Fri morning of 1/14. Models basically dry. Still not convinced there won't be a band of snow in the FGEN zone, as added below. Also, I keep looking at the GEFS and impressive attempt at cold shot after the 22nd and continues cold looking through at least the 28th.
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Looking periodically very cold here 21st-28th, my guess is colder than what occurred yesterday the 11th or this Saturday the 15th. Could be two more significant storms here, around the 21st and 25th and our coldest of the winter may arrive after one of those. Yesterdays CPC threats in the LR are added.
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5AM Wednesday Jan 12: title and tags adjusted to drop Saturday, focus late Sunday-Monday morning for what appears to be an 18 hour storm of snow-rain-snow. Heaviest snow tends to be modeled west of the I-95 corridor but ensembles still warrant continued concern for the axis of heavy snow including I95. At this point far too uncertain but where it snows for 12 hours, widespread 6+" seems likely. Also a 6 hour period of potential 50 kt inflow gusts is possible for the coasts Sunday morning and if it occurs with the dawn Monday high tide, would result in coastal flooding, magnitude unknown. This does not appear to be a long duration storm (24 hours+) but it should be intense for a few hours Sunday night or Monday morning. Again track uncertain, and sensitive to the intensity of the surface low. There still is opportunity that this will track too close to our area for much snow but there are several days to adjust the track and resultant precipitation type. It does appear there will be a general inch to 1.5 inches of qpf with this system, maybe thunder too. A big storm with large scale impacts entire east coast-Appalachians. The only reason I didn't highly stronger wording for impact, is that this will occur later Sunday and the following Martin Luther King Jr Holiday. Added the overnight WPC ensemble thinking of 3+" of snow, which does not include the new 00z/12 GEFS/EPS/GEPS. So this favors Appalachian Rim, NYS to just west of of I95. Unknown but potential for a good sized fast moving storm is at hand, maybe KU?
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Unsure if anyone posted but CPC has some interesting possibilities for 19th-22nd including a chance of heavy snow basically Chicago to New Haven northward and a high prob of very cold air invading the upper Midwest.
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HI! Glad there is still a ballgame for the weekend. Will post an updated thread title at 8am Wednesday when I know I have the time. Will do a a semi thorough review at 1030pm but not attempt a successful adjustment til 8am Wed. Suspect will also start the Friday morning thread at 8am Wed. Everything needs to be on the table in advance in the forum we learn from each other. Fwiw, the 17z WPC D4-6 do not have the 12z ensembles incorporated. Tonight’s 5z issuance should be, Ithink a little further west and confident of a substantial event near ATL to interior N.C. VA. more as time allows overnight or Wed AM. On call. Walt
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Having passed 24 hours of modeling, the diverse modeling/ensemble opinions remain undecided. On the table, too many shortwaves, or not enough separation. Am leaving the thread as is... my thinking is to grow this into something substantial but I may be wish casting. So keeping conservative. 14th morning: I think e LI, e CT and e MA will see a period of snow (1/2-3") Friday morning followed by scattered midday north wind gusts near 45 MPH. What I think we'll see is the 12z NAM be much deeper at 78-84 hours which a much tighter gradient and shoots a period of snow up the FGEN zone on the northwest side of the bombing ocean storm. I will wait til sometime this evening to start that thread if the modeling looks more acceptable for this NAEFS scenario. The weekend-Monday affair looks like a moderate or greater snow event from near ATL to interior NC and VA. This is only my opinion. LOW PROB follows: What I'm thinking is that the two shortwaves crossing the central-eastern USA this weekend early next week merge-phase. The lead short wave sets the stage ATL-NC to NJ Sunday with the following short capturing the stewing low off NC. NAEFS is marginal risk here in NYC. To have TWO bombing lows off our coast within 3 days is unusual and not the likely scenario, except that modeling a couple days ago was going for it and we seem to be in extremes cold season starting with the TORS in KY, w USA snows in Dec, I95 snows so far in JAN. Attached 06z EPS for Sunday morning...a westward shift. Offline til sometime this evening.
