wdrag

Feb 1: Flip-flopping ensemble QPFs. Uncertainty with the 00z/28 NAEFS a diminished qpf for our area, the 00/28z EPS continues with an event, albeit boundary layer accumulation problems for NYC while the 00z/28 GEFS was very conservative on QPF. Proceeding with uncertainty but I expect an event of some sort for Feb 1. Best chance for snow accumulation seems high terrain N and W of NYC. No graphics today due to lack of ensemble consensus. 00z/28 GEFS plumes still have snow acc for NYC and POU but am a little concerned about boundary layer warmth for NYC (melting). Also, phasing if any, seems delayed-further east in the GEFS while the EPS sharpens the trough further west than it did yesterday. Sometimes we have to wait til about 72 hours in advance of the date before the models grasp the sharpness of a short wave and/or any phasing option. I would think the 00z/29 cycle should have a little more consensus. In any case... whatever occurs does not seem to be blockbuster... too fast...only a 12 hour event? Hopeful only notes: am thinking a storm track from the lower Miss Valley into the northeast Feb 7-17 but whether we have enough cold air available and timed correctly? This is based on NAEFS overall changes in N American temp distribution and both EPS/GEFS showing an active southern stream in the 500MB pattern, along with QPF production. Then Don's note on stratwarm potential from late yesterday, tho any stratwarm implications around here might be delayed a month? 608A/28

Good Monday morning (Jan 27), I'm dropping these graphics in for possible future look back. Ensembles (EPS, GEFS, GGEM) continue to suggest an event for our area, tho I think the option for a very close warmer-rainier track exists, unless we lose the potential for a closed low in the northeast. MOS is not that cold but cold enough for snow if the needle is threaded favorably. ?? The first two graphics are GEFS plumes for LGA and POU. The bold line is the mean which is biased higher by several 6+" members. Still it's a start. The 3rd graphic is the 00z/27 NAEFS which now show shows a northward spread of the 5MM (0.2") isohyet and not much variability in the northeast. Finally, one of my favorite charts...the MRF ensemble mean 500 flow, and its members. The white lines on the right are the 00z/GFS(=MRF) member and you can see the many individual blue members at 12z/2 even sharper down here into the northeast. Promising, but quite far in advance. What concerns me is the potential for a second sfc low to our north (NYS) in all that strong vorticity advection. That would potentially warm us up ~850MB, above zero? I wont be posting again til tomorrow morning ~7A, provided ensembles continue with an event. 559A/27

Good Sunday evening everyone, I think Feb 1 has been targeted by the ensembles since ~00z/18. That's why i posted directly to this thread since it's a Feb event thread. The usual questions related to this winter are... does it end up stronger, further north and warmer-rainier, or does the predominantly grazing grouping of both the EPS, GEFS, NAEFS prevail? I'd love to see some blocking in ne Canada or a 50/50 low w blocking in Greenland but that is not likely. I'll post these 18z/26 GEFS plumes here for a possible look back when 18z/Feb 2 rolls around and whatever has occurred. I also added the NAEFS which is the GEFS and GGEM ensemble members combined. It too seems to show a grazer, albeit 12 hours slower (late Feb1-Feb 2). There's also variability in SNE (mm) as you can see from the legend. 759P/Jan 26

Now a wrap on state of the northern tier USA and the past 3 days. Three attachments are: 1) Past 72 hours snowfall...mostly midwest and spotty high terrain 4's n NYS and northern NE through 12z/26. 2) How we stood on snow depth this morning with respect to climo 3) Seasonal snowfall so far

Wantage NJ 923A. Rb ~around 9A. 32.9/30.6. noting ice pellets and freezing reports just northwest Wilkes Barree. Glaze at MPO now .07. This may be one of my last reports on this for Wantage, unless wet bulging permits a slight glaze on something which I doubt at 740'MSL.

Good Saturday morning everyone, I am well aware of the massive failure of wet snow in the northeast today-midwest doing ok. The modeling was correct at least a week in advance targeting a significant event for the ne USA on this date. Model thermal fields this past Monday-Tuesday were far too cold (associated with track of 500MB low being far too far south and slower to track into the ne USA). However, ice is now occurring in parts of ne PA high terrain above 1200 feet. Includes Mount Pocono (.04 glaze so far) and Dingmans-the latter in Pike County with a temperature of ~30F. So, I will add a graphic which is the HREF and best model this morning on ice...bar none that we commonly see (exclusive of EPIC which I dont see). Treated roads will probably be okay in extreme nw NJ and ne PA but a period of glaze is coming to the high terrain there this morning. Rainfall rates will be so heavy that most of it will drip off the trees. Here in Wantage NJ at 740'MSL am holding at 33.3F with a td of 28 and no pcpn yet...a north-northeast wind at 812 AM. (One other note edited in at 830 AM Not sure if anyone was looking in n IL/WI modeled rain snow last night. GFS was too warm in the BL completely missing the change to snow out there last evening RFD/MKE/ORD. Tropical tidbits will still have those runs from 12z/18z-24.

Good Thursday morning everyone (Jan 23), My last post on this thread, unless I get lucky to have an observation of wintry precip Saturday morning in extreme nw NJ. System has once again warmed northward and only a brief period of front side minor accumulative snow ice seems possible Saturday morning around sunrise, above 1500 feet. Need to make the best of a poor winter for snow-ice in these parts. 543A/23.

Good Wednesday morning everyone reading this, (Jan 22). I'll add the NWS graphic (first image) produced probably prior to the 00z/22 GFS and EC portion of the ensembles. It's a little more optimistic than the 00z/22 GEFS/EPS, however, I can see those ensemble probabilities for 3+ inches of snow increasing a bit. If they do not increase by this time tomorrow, then the I84 corridor high terrain snow and some ice would probably be limited to elevations above 1500 feet. In other words, virtually all of the NYC forum (2nd image added, courtesy of our moderators) a non player. Before jumping onto that downside no significant snow event, my thoughts. 1) The ECMWF has been quite varied the past two cycles. I'm not convinced of its (EPS) northerly latitude of the 500MB track, the 00z/22 GEFS being further south. 2) The UKMET, while a little bit odd (see 3rd graphic), does end up with the 500 Low near the GEFS position by 12z/Sunday.... but how it gets there is a little more intriguing...it drives a negative tilt lobe eastward across DC before lifting newd. That would allow for a little more cold air damming of marginally cold enough snow thermal profile (inland terrain). I am just unsure whether the UK is realistic. 3) I 'think' the NAM is backing off a little on its wound up 500 Low over IL at 72-84 hrs and if this later development continues eastward the next 6 forecast cycles, then I think we're looking at a high terrain wet snow event, with impact down to POU and FWN as of course MPO/MSV. GFS extended MOS is still pretty cold. 4) Strong UVM during midday Saturday in the distant nw suburbs (ne PA and extreme nw NJ) may change freezing rain and rain to a period wet accumulative snow. As it stands now, portions of the high terrain in the interior northeast north of I80 in PA northeastward (parts of NYS, northern and western New England) are in position to see 6" of snow while little if any is expected-modeled for NYC. I think its a bit early (4 days in advance) to say this storm won't present significant winter hazards at times this weekend down into the I84 high terrain. 648A/22

Agreed.... just need to be patient. 06z/21 500 ensembles and snowfall in for the GEFS. Just need to be patient and look for negatives. I'd like to see the GGEM become a little snowier again... ditto the EC. Still... fairly impressive snowfall forecast in the raw GEFS/EPS for the region n of I80 later this week and weekend. Have a good day, Walt

Good Tuesday morning everyone, Jan 21. No change from yesterdays originating post with new support graphics added. Still need to root for southeast of current 500-850MB and sfc low tracks, for NYC-LI and south of I80 to get some little amounts. However, right now I dont have much hope for that. For our nw fringe of the NYC forum... I think this is a Saturday event, with focus especially afternoon-evening when some banding may occur. Snow impact is also I think elevation dependent, where it's potentially a 6+" wet snowstorm. There could be some backside banding-wraparound snow down to LI Sunday morning but above freezing temps there probably preclude any accumulation in the city. The images: NWS ensemble graphic produced I think prior to 00z/21 ensemble incorporation. Probs for 3" have increased 20% into far nw NJ since yesterday. Then the EPS probs for 3" and 6+" are included from 00z/21 courtesy the ECMWF and Weather.US ( no major changes there). The fourth image is from Bob Hart's MOE FSU weather page, which allows a vertical profile of temps and upward motion for Sparta NJ. You can see potential for a period of heavy wet snow there and temps cool during the first shot in the afternoon, IF this lift in the snow growth zone occurs. You also get a good sense of the boundary layer temp there and the likelihood for elevation dependent accumulation. I've also checked 00z/21 GFS MOS for MPO/MSV/FWN/BDL (consistent with previous cycles) and all suggest elevations will be near freezing during the precip. Finally the downer. LGA snow plumes... at least a few have biased the bold black line mean higher but the preponderance of this 00z/21 snowfall plume diagram is less than 1". I added the Scranton snow plume which shows the potency in the plumes but with most clusters in the 4 and 6" range there which I think is reasonable start for higher elevations of there I84 corridor. POU snow plumes have ~3" mean with those outlier foot plus also probably related to excessive QPF which is unlikely as this storm for us looks transitory. I may not post tomorrow if there isn't a significant change in the model ensembles, or if I do post, could be delayed til 8AM. 616A/21

For what it's worth... am part of the NYC Forum so I won't split my allegiance. My graphics occasionally include references to I84 which is my briefing group at home. You've got excellent forecasters up there! Regards to all and hopefully winter makes some sort of comeback. Walt

Definitely uneasy this far in advance. What I do like is the tracking of both models ensembles of the 500 low and a shot at se flow at 850 for 6-12 hours down here. Wish somehow we could leave a little more cold air in here in advance. Boundary layer warmth is a potential big problem. Did look at snow growth stuff and while modeled snow growth changes radically from run-run, there is potential, where the BL doesn't change to rain. For now, i have to think northwest of NYC. I wont post again til ~7A Tuesday but everyone here will know prior tk that whether these is still a little hope for close to NYC. The GEFS plumes for LGA--I'd like to see those increase a bit by the time Thursday rolls around. I do remember Don's post from 2 day ago about the statistical snow chance for NYC being pretty low so... am not too hopeful for NYC, certainly not now. I think it's best to think of all the downsides this far in advance.

Good Monday morning (Jan 20) everyone, Am a little uneasy starting this event specific topic since uncertainty exists regarding thermal profile and latitude of the primary-secondary development but I thought it best to get this going since it's a potential national news story from the Ohio Valley-Great Lakes to the interior northeast. Upfront: NYC-LI doesn't look promising at this time for more than 3" of snow , if any snow at all, due to the marginal thermal profile in advance of this system. The GEFS through 00z/20 was north of the EPS. There is still plenty of time-room for adjustment but at face value (00z/20 ensembles), this looks to me to be a primarily a northeast PA, northwest NJ northeastward into nw CT (I84 corridor) wet snowstorm with lots of potential (for a bust=no significant snow). My take is it will snow there for a time and that this event could be substantial impact upon higher terrain. I'm adding some graphics - these should not amp up NYC or points south.... but for me serve as a starter for a winter event. These include the 05z/20 NWS ensemble chance of 3+ inches of snow which is less than 10% for NYC. Then I've added..courtesy of the ECMWF and Weather.US, the 00z/20 EPS probs for 3 and 6" for this event (6 days in advance). I've also added the 00z/20 GEFS snowfall plume for LGA which is very low... most plumes under 2". This all adjusts as we move forward in time. If you want to root for snow, root development south of both ensemble systems 00z/20 positions. Am still concerned this will end up north and warmer (rain) up to I84. 625A/20

No further post from myself yet... would like to see GEFS snow plumes a touch higher for LGA before getting NYC group amped a bit. Lack of cold air in advance is a big concern so that this is a marginal thermal situation. Seems like EPS and GEFS stayed the same or trended down slightly (model noise and insignificant?) on snowfall but this is still a consistent signal for the I84 corridor itself to continue monitoring. Just having doubts south of I80 in NJ. There will be much much better scenarios in future winters, maybe later this winter, but will take what we can eek out from this winter. Will not post again til tomorrow morning 7AM. Later, Walt

Good Sunday evening everyone, The NOHRSC snowfall map for yesterdays 7 hour south-southwest surface flow event is appended. It suggests ensembles are useful... with what I think are the usual mesoscale enhancements-suppressions that for me are impossible to be sure about more than a couple of hours in advance. You can compare this to the ensemble predictions for 3 and 4" as posted on prior days.