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Monitor NWS products including NHC and local offices from OKX and PHI. This Topic doesn't guarantee anything but serves as a platform for comment. Suggest starting with actual 5+" rainfalls, or unusual flooding. Note: WPC is already bullish on Tuesday's rainfall. Tropical Debby remnants-east coast trough-RRQ upper level jet related pattern this week had WPC intermittently forecasting 7+" of rain in NJ and possibly coastal CT/LI. PA and se NYS may also be involved in big rain. PRE conditions may??? exist late this week (Fri-Sat?) but uncertain in our NYC subforum. Added a few graphics. WPC overall has been advertising 5+ in its graphics for our area since 06z/4. Below is the WPC 7 day rainfall forecast based on ensembles etc. Sampler past 3 days rainfall via CoCoRaHs. Machine ECMWF EFI, Machine GEFS ARI and UFHS, WPC D2 excessive and their D5. You'll note the GEFS machine tools extend beyond D5. This weeklong accumulative event may be over by Sunday the 11th. FFG is very dry south of I80, so far. This could. change radically by Friday night. Ensemble river stage products right now are conservative but highlight I95 corridor in our area. FFG for now is most vulnerable I80 northward in NJ. What to do? Just think of what you may??? need to alter in your plans due to flooded roads/streams, cellars. Potential doesn't mean it occurs. 727A/5 Initial title Potential POCKETS 5-12" of rain by 18z Sunday. Suggest OBS Tue-Sunday only when exceeding 5".123411

454AM 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. --- At this 6-7 day lead time 8PM Sunday Jan 9 issuance, options are fairly wide open. For now, a light or moderate event 'seems' likely but absolutely not a lock, nor is a heavy event excluded. This event still could be demolished to zero by what happens off New England on the 14th, or what follows between the 19th-22nd. However there already has been discussion the past several days for the coming weekend. Ending 12z/9 the past 6 cycles of the ECMWF op, the last 4 cycles of the CMC GGEM [LI 3 cycles, I84-4 cycles] have some sort of snow event, especially I84. Maybe the GFS via it's 18z/9 cycle is shifting snow emphasis on the 16th for our area instead of bombing off the coast on the 14th? Having reviewed ensembles: 12z/9 EPS/GEFS/NAEFS all have some sort of frozen event is coming to the northeast USA, along and north of I80 including LI. Have added the broad coverage low chance WPC D7 issued at 17z/9, the EPS 24 hour qpf ending 12z/17 and the 12z/EC 850 MB low (GEFS so far has nothing, still favoring the 14th but not as far south and west as previous). NAEFS products for 00z/17 are added including previous 24 hr qpf, 00z sfc temp in C, and the sfc pattern. There will be quite a few model changes-conflicts and this could end up having been a wasted effort... but it seems worthy of further scrutiny as our next possible significant snow or ice event for at least a portion of the NYC subforum.

637AM Sunday: : headline updated to Major near blizzard and added power outages. Major near blizzard Nor'easter coming. I would not plan on driving anywhere on Monday in northern NJ, ne PA, se NYS and ditto CT Monday afternoon-night, MA Monday night. NYC my guess is a foot, possibly more before mixed Monday night. Otherwise, amounts between 1-2 feet from I78 northward with lesser 8-18 inches CT and MA where rain/sleet invades later Monday night. Isolated 30" possible nw NJ, or ne PA into the Catskills by the time this storm ends early Wednesday.. Drifts 3-4 feet. Power outages possible Monday afternoon and night from northern NJ northeastward to CT and Boston from a combination of heavy wetter (heart attack for the hear tcondition vulnerable) snow and northeast wind gusts of 40-55 MPH. Snow starts central NJ around 3 PM, northern NJ-ne PA 6-10P, CT around dawn Monday. Worst of the storm NJ/PA sunrise Monday-midnight Monday night, CT Monday afternoon-night. Coastal flooding may be major near the midnight Monday high tide cycle? Follow NWS. ---- 615AM Saturday: Imperfect probably messy big snowstorm is coming, imperfect in that modeling the past 24 hours is drifting north and suggesting a dry slot late Monday will allow enough warming for sleet (rain LI) to I80 including all of I95 Monday night so that the stratiform burst of 1-2"/hr Heavy snow during Monday, especially afternoon, becomes bands of snow in the interior late Monday night-Tuesday, some areas probably recovering Tuesday with several hours of no precip. So, my own single forecaster point of failure but use of ensembles could be too pessimistic about the sleet/rain intrusion. For NYC... I'll start with 6" with possibly as much 1/2" late 31. Hope that its mostly snow after 00z/2 but even if, snow ratios may be down to 7 or 8 to 1?? I dont' want to cap NYC since am uncertain about dry slot. Sleet/rain/freezing rain may be getting involved Philly to Toms River during Monday morning. There may be a period of near blizzard conditions on LI centered Monday afternoon? BUT, I don't want to call it a blizzard for fear of easily missing criteria. The point of this paragraph, is that I think Monday, especially afternoon should be the worst period of travel and if models continue this, in future cycles through Sunday morning, then I think it would be a recommended no travel for that 6-12 hour period to limit accidents and allow plows to maintain passable-less slippery conditions for first responders. Snow may be wet on LI/Monmouth-northern Ocean Counties in NJ if 6" at 32-33F, we would have power outages... still too early to be sure. CT I84... continue to notice some multimodeled lesser snowfall there, so while I think a big snow there, cautioning myself. Coastal flooding: see NWS statements/flood watches already posted and no change from yesterday with the late Monday evening high tide cycle most favored for flooding (within 2 hours either side of the time of high tide) Graphics are the 00z/30 EPS as a base amount, the 00z/30 EC IR prediction for 06z/Tue showing the dry slot penetration, and the NWS 09z/30 prob for 6" or more of snow by 12z Tues. That's the reasoning basis for this update.

726PM/15: Our forum is well aware that the recent few days of modeling is favoring a developing -NAO (Greenland Block-anomalously warm 500MB heights) that probably won't fully activate until Thanksgiving and beyond. One sharpening-negative tilt trough is multimodeled to drive southeast from central Canada Sunday the 21st and close off somewhere over New England Tuesday the 23rd, then possibly lodge near Labrador (50/50) Thanksgiving while following shortwaves try to organize a trough near the east coast by next weekend. The latter initially associated clipper low ??may??redevelop far enough south to become a significant impact player in our weather BY next weekend. For the past couple of days modeling has favored early next week (22-23) for a possible rapidly intensifying low pressure system somewhere along the mid Atlantic or New England coast. This event still has many undetermined outcomes (as of this Monday 11/15 writing), with the 12z/Monday Nov 15 EPS favoring wet weather (0.25-1.5" of rain) possibly ending as a period of wet snow or flurries even to the coast late Tue or Wed. That wetter and slightly colder solution is not yet shared by the 12z or 18z/15 GEFS, which has development later and further northeast. The NAEFS QPF is not very robust either. In fact I cant find any ensemble modeling with an 850 LOW south of Massachusetts. However, of interest beyond the probably quiet Thanksgiving day, is the likelihood of a little colder air in place ahead of the next strengthening short wave. Depending on how far south the core of that short wave (VORT MAX) tracks, it could permit coastal development near LI/Cape Cod late Friday. A long shot now, but the NAEFS as of the 12z/15 cycle has a bit more qpf for the NYC forum, especially CT, than for the earlier event. In summary, the bombogenesis near LI shown on recent GFS/EC OP models is of interest but it is not (yet?) the preferred ensembled solution...just a possibility. If it eventually occurs, the tags and title of this thread will update and reflect a much stormier scenario. The potential exists but far too early for me to express confidence (despite the anomalously warm SST's near our coasts that would energize sfc development). I am as interested what might happen next Friday-Saturday, with colder air in place and what at this issuance looks like an ordinary frontal passage, might develop into something with a bit of wintry interest, for the forum. If this becomes a non consideration in a few days, I'll admit it. 545AM/16: Title added HIGH to impact. Changed wind event to Damaging Wind. No other changes at this time. Bombogenesis with associated variable but high impact weather across the subforum. Wraparound snow potential continues for a portion of there subforum. Snow event, at least for the interior seems to be shaping up for the I84 region, sometime between the 26th-28th. Will rereview sometime this evening and again early Wednesday. Potent pattern for one or two travel HIGH impact events NYC subforum Thanksgiving week: Mon-early Wed 11/22-24; & Fri-Sun 11/26-28. 540AM/24: The above was the headline issued on the 15th, having added HIGH to impact and changed wind to damaging wind, Thread now refocuses headline on part TWO 26-28, w possible extension to 29 in the future. Part ONE failed due to modeling leading up to the 15th issuance being too deep aloft, too quick. Ended up further east and we were dry with a chill gusty wind. Tags: dropped heavy rain, and changed damaging wind to wind event. Modeling beginning with the cycles of Tuesday the 23rd have increasingly hinted at a possible wind advisory event for part of the area later Friday into Saturday morning followed by some sort of snow or flurry event Sunday - possibly lingering into Monday. Questionable outcome but we do know the modeling is digging a 3rd strong short wave trough into the northeast USA late this coming weekend. Therefore, while the first on the 23rd didn't produce hazardous weather, the second may generate a bit of a wind event in the wake of the cold frontal passage late this Friday, and the 3rd may allow some sort of coastal low to develop Sunday, departing Monday the 29th. Uncertainty exists.

Please follow NWS (SPC/local offices) for additional information on the late Thursday afternoon-evening SVR threat. Confidence on SVR late today is less than a CAA wind event for late Friday. Used HRRR/EC/3KNAM for main guidance, Richardson # projects strongest wind transfer of a descending jet Friday evening, after sunset. Whether that occurs? However lapse rates do increase substantially with the arrival of the cold pool aloft allowing opportunity for damaging wind gusts late Fri-Fri eve. No time for graphics-please follow up as you think best. This thread should serve as the thread for any damage reports.

HRRR and 3KNAM offer a squall line of sorts in the warm sector 6P-10P, accentuating NJ s of I78 where the Significant Tornado parameter and Supercell composite indices are notably large. This is on the tail end of of 75kt 850 sw jet over LI, just ahead of a cold front with marginal CAPE. (That 850 jet initially causes the midday deluge's in parts of our area with possible flood advisory for poor drainage flooded roads). Should not be much hail, if any. Max Updraft helicity 2-5KM has some swaths across much of the region. Not saying it will happen but should at least have gusts near 40 kt with the line as per HRRR/EC gust algorithms. HRRR prior to 09z/28 has isolated G50-60KT. R# looks more permissive than for this past Fridays wind advisory event . I think most of any severe should be NJ shore but could extend east. Even a small chance of G40-45KT in the strong southerlies for LI, well ahead of the squall line., NWS OKX has a wind advisory posted for the OKX forecast area later this evening-Monday. That should verify with scattered G40kt, especially 3AM-Noon Monday, associated with the cold core arriving (CAA) and pressure rises.

548A/17: Advisory situation may be coming to a portion of the forum-not a lock, for the Friday morning commute, despite probable less than official criteria amounts NYC/LI due to sharply falling temps to between 25-30F with sleet to snow in the 5A-8A time frame and gusty n-ne wind of 30-40 MPH. Snow ends sometime late morning-midday with temps recovering above freezing in the afternoon. Wind gusts for a few minutes between midnight and 8A could reach 50 MPH in parts of the area. Added wind event to the thread. Snowfall for NYC-LI T- at most 2", while a bit heavier seems likely I84 corridor extreme nw NJ of 1/2 to possibly 3". Think the best chance for 2+" in our subforum is CT. If the precip ends more abruptly, then we escape the advisory and amounts will be under 1" with the lesser snowfall of the 00z/17 cycle ICON, UKMET, 12K NAM considered. Note: as the transition to snow occurs, the first hour or two may be melting on most surfaces and certainly pack down to snow ratios less than 10 to 1, possibly closer to 7 to 1 or something like that. Some of the modeling has complications not only Friday, but also next Monday. For Friday, there could be two bands of halfway decent accumulative snow, one across I84 and the other just south of I78 across central or s NJ? TBD. Then, next Monday: the 00z/17 EPS and GEPS want to form a deep cyclonic circulation off the mid or south Atlantic coast this weekend and drift it north or northeast early next week, spreading rain back into the area. Depending on latitude of formation, will determine how much warming aloft occurs. ENS have 850 temps in the +3/+4C range next Monday, too warm for snow, provided all the excessive height rises and warming aloft that is modeled in the northeast occurs. If that shifts north, then there is a real long shot (very low chance) we might be looking at some marginal thermal profiles for a bit of wet snow in CT. At this time, I wouldn't be promising mostly clear skies and dry weather for Sunday afternoon-Tuesday morning. Added the 0841z/17 NWS ensemble prob for >1" of snow Friday. You can see the concern for going too heavy. --- Strong cold high pressure approaching Quebec Friday-Saturday will combine with an eastward moving and opening closed low in the Ohio Valley, to permit a period of wet snow here on Friday. Duration and intensity are uncertain along with resultant amounts (T-2"?) and will be related to the proximity of the positive tilt 500MB trough. For now, this could be considered a back-back system, modeled way back as early as the 00z/7th modeling cycle, that could provide as much snow to the parts of the forum, as whatever occurs late 16-17. The fresh influx of colder BL air from the north may even allow measurable snow into NYC? Most of the modeling favors a few hours of snow Friday morning with marginal accretion temps. Still, for an event at the tail end of winter for NYC, it could provide a little fun? This especially if the GEPS-NAEFS solutions of keeping the low close enough to continue significant qpf going into early Saturday. Then we would be talking about some potentially plowable snow to near NYC, but this is an outlier possibility for now and best at this time (D5) to favor conservative ,minor impact, at worst. Finally, if this storm system does hang around nearby to our south all weekend (low chance), it might make a northward drift into the CT/LI part of the forum Monday the 22nd, but by that time, the snow temp profiles have warmed to rain (probably exhausted the snow profile cold air supply).

Monday morning March 1 625AM Update: Good to see the sleet obs yesterday in our distant nw suburbs. Below restates what is obviously modeled and discussed in prior days updates: I moved the timing up an hour and changed the title to add OBS-NOWCAST as well. Will have summary maps of rain, any snowfall, and possibly wind gusts 45+ in tomorrow's (Tuesday) 10AM wrapup-review. Tonight 7PM/1 -3AM/2. Turning sharply colder with bands of flurries and snow showers causing a few areas of hazardous travel as temps fall from near freezing at 7PM to between 5 and 15 above by dawn Tuesday I84, and near 20 NYC, along with gusty northwest winds 35-45 MPH and wind chill down just below zero. Most areas only flurries, but a half inch of snow is possible a few locations ne PA, extreme nw NJ and especially se NYS, CT and maybe even e LI. A wind advisory is posted with NYC wind chill close to zero at sunrise Tuesday. ---- 650A Sunday/28: Ttile dropped snow from the snow to rain scenario. Significant 21 hour rainfall (1/2" I84 to 3/4-1.5" NJ/LI) this afternoon into Monday mid morning with snowmelt but not enough for a problem. Could see the need for something water related a part of urban ne NJ by Monday morning? Dense fog possible tonight with mild moist air over chilly ground. I think there will be spotty icing highest peaks of the Poconos/Catskills/Litchfield Hills this afternoon-tonight but no significant treated road problem. Small chance that rain ends as wet snow forenoon Monday I84 high terrain with little or no impact, if it does end as snow. Monday evening from roughly 8P -4A Tuesday, flurries likely to near NYC with a band or two of snow squalls CT/NYS/ne PA and possibly extreme nw NJ that could coat roads with a hazardous 1/2" accumulation in 30 minutes, along with gusty northwest winds to near 45 MPH, a few minutes of reduced visibility under 1/2mile and icy roads due to temps plummeting from near freezing at 8PM to the teens by dawn Tuesday (20-22F NYC?) and wind chill near zero CT/NYS/PA. We'll see if the models back off but from what i can tell, the early GFS op (V15) has been onto this from many days ago, much more so than any other model. NYC either no snow or a Trace of flurries. Some of the modeling suggests a band of squalls crosses from CT through e LI later Monday night. --- 655A Saturday/27: Coming to the end of this thread... that may end with a noticeable bang. Definitely a significant rainfall (1/2"or more) Sunday into Monday morning with snowmelt but not enough for a problem. Dense fog possible Sunday night with mild moist air over chilly ground. Chance that rain ends as wet snow forenoon Monday I84 high terrain with minuscule impact. However, Monday evening from roughly 8P -4A Tuesday, flurries likely to near NYC with a band or two of snow squalls CT/NYS/ne PA and possibly extreme nw NJ that could coat roads with a hazardous 1/2-1" accumulation in an hours time, along with gusty northwest winds to near 45 MPH, a few minutes of reduced visibility under 1/2mile and icy roads due to temps plummeting from near freezing at 8PM to the teens by dawn Tuesday (20-22F NYC?) and wind chill near zero CT/NYS/PA. We'll see if the models back off but from what i can tell, the early GFS op (V15) has been onto this from many days ago, much more so than any other model. Bluewave detailed elsewhere in the March thread. --- Good Friday morning everyone, Feb 26: Focus is mainly the I84 corridor. The Adirondacks are reserved for the last pgh. 1201AM-10AM Saturday (27th). A 1-4 hour period of showery wet snow-sleet will probably occur from the Baltimore area northward across the I-84 corridor early Saturday. There even could be spotty freezing rain? Minor-short duration impact, at worst, reserved primarily higher terrain where an inch or 2 is possible in the Poconos. Elsewhere for the I84 corridor, inclusive of nw NJ, expect a Trace-3/4"; Baltimore-Phildelphia urban centers a Trace. A quick change to rain occurs shortly after onset, except that change to rain in the Poconos and northwest hills of CT may not occur til ~ 10AM Saturday. Melting all surfaces once the change to rain has occurred. Most may not notice the snow if sleeping. Late Sunday the 28th-Monday March 1: I84 corridor. Uncertain but probably not a significant problem. Complex rain (spotty ice) possibly end as snow event. Any icy weather Sunday evening the 28th is reserved for the Poconos. Precipitation may end briefly as snow the rest of I84 corridor Monday morning March 1? So far, models say proceed with normal life with significant wintry weather unlikely. Monday night March 1 I-84 corridor---near midnight: A strong cold frontal passage may be accompanied by a dusting to 1/2" of snow. If this occurs, the sudden drop in temps with the snowfall would make it slippery. March 3-6: Uncertain modeling continues to suggest a wintry event that may include several inches of hazardous snow for the I84 corridor northward? Some models have no storm, so nothing to be sure of. Adirondacks: Please follow local forecasts: snow showers or flurries this morning. A period of snow Saturday changes to rain. A period of rain or ice is possible Sunday. Then, a refreshing of accumulative snow late Monday followed by a polar plunge Monday evening. March 3-6--- uncertain but seems like a period of snow in there somewhere. The second week of March, especially after the 7th... looks rather mild. 615A/26 Friday 517PM/26 update: 517PM Friday: seems to be getting slightly more interesting for ice and snow distant nw-ne suburbs. First: GFS v15 looks like, (barring a complete fade within 4 days) the winner regarding the intensity of this cold shot Monday night. Second: Unclear to me whether it warms much above freezing high terrain near I84 Sunday and I can see smidge of ice there. Third: Chance of dense snow eating fog late Sunday? Fourth: Modeling from both the GFS V15 and 16 has started showing more minor snow shower/flurry action Monday, on the backside of Sundays rain (and dense fog by night?). And 18z/26 GFS modeling is moving flurries down to near LI sound later Monday night with the strong polar cold front that looks like it may have gusts near 45 MPH drilling sharply colder temps into NYC. Will revisit Sunday morning. --- Friday 638AM update: Am still not convinced that this event will be insignificant but it's heading to a possibly wrongs-wasted thread. We do know it's going to rain and potentially pretty hard for a time on Sunday with precipitation lingering into Monday morning. Evolution has not yet permitted cold enough air to return, allowing for precip to change to snow Monday. Of concern to all who favor the GFSv16 implementation, is the still far different modeling between the V16 and the current operational V15. V15 in my opinion seems to have a pretty good chance of prevailing with it's polar cold frontal passage Monday night, flurries or snow showers possible down to NYC with plunging temps well down into the 20s in NYC (maybe ~22?). Meanwhile late Sunday the 28th-Monday March 1: I84 corridor. Uncertain but probably not a significant problem. Complex rain (spotty ice) possibly end as snow event. Any icy weather Sunday evening the 28th is reserved for the Poconos. Precipitation may end briefly as snow the rest of I84 corridor Monday morning March 1? So far, models say proceed with normal life with significant wintry weather unlikely. --- Thursday morning (25) 659AM update: Modeling and WPC is coming up on qpf for Sunday and there may be lingering Monday morning at the least. I have not crossed this thread off as a bust for the I84 corridor. No excuses. I still think it's on the boards and what I do think I know is that decent qpf is coming the 28th. Late Sunday the 28th-Monday March 1: I84 corridor. Uncertain but probably not a significant problem. A complex rain (spotty ice) possibly change to snow event. Any wintry weather Sunday evening the 28th is reserved for the Poconos. It could spread across the rest of I84 corridor by Monday morning March 1, but for now models say proceed with normal life. As you know, GFS modeling is drifting away from its excessive cold outbreak Monday night and leaves the door open for a little more than meets the eye (so far). I might be completely wrong for this period, regarding a wintry event occurrence but the door for me, is not yet closed. --- Wednesday morning 655 AM update: Title remains unchanged. May need to add a bit of ice for the interior in future reviews. Multiple model ensemble reviews of the 00z/24 cycle and 06z/24 GFS and V16 op reviews. Late Sunday the 28th-Monday March 1: I84 corridor. Still uncertain. A complex potential significant rain to snow event. Any wintry weather Sunday evening the 28th is reserved for the Poconos. It could spread across the rest of I84 corridor by Monday morning March 1 with significant hazardous high terrain accumulations of several inches I84 itself northward, while much less impact in the valleys below 700 feet elevation (Hartford, Poughkeepsie, Scranton). A shot of notably cold air follows Monday night (but not the GFS op ferocity which doesn't have much support). This for me is the 00z/24 consensus from NAEFS and 06/24 V16. Definitely not buying the GFS powerful cold shot preempting an event. I could be wrong but I see enough cold air seeping into the backside of whatever comes out of the Ohio Valley to make for a snow risk. It could even snow down to LI/I78 at the tail end (low chance for now, but a window that needs to remain open). It's complex and details remain tbd. It's possible I've read too much into this thread?? Considerations include WPC continues rather dry and very little wintry weather risk. --- 624A/23 - Tuesday: Incorporates modeling of ensembles through 00z/23, and op models through 06z/23. Maintain patience. A significant event is probably coming including some snow for I84 and possibly to NYC's immediate n/w suburbs. EPS/GEFS trending a fairly significant decline in AO/NAO first couple of days in March (think this an EPS concession to the GEFS, as i recall). GEFS has significant snow for the Virginias on the 2nd. That is a sign something is coming, with latitude axis of snowfall in doubt. I favor further north, per NAEFS. Also, the 06z/23 GFS op not given any weight in my thinking since its prediction for the NYC 1000-500MB thickness 06z/2 is 240 m less than the V16. (504 op vs V16 528 for NYC). Sensitivity between northern southern stream interactions is probably messing up solutions and so uncertainty. It either snows a bit late 28, or what i think is more likely is some snow late March 1-morning 2. EC wants to snow the 3rd. Therefore, no change in thread. --- 646A/22: May extend the title to 3P March 2 in the updated post tomorrow morning, otherwise, despite some dry modeling, I think we're on track for a significant event, some of it wintry, especially I84 corridor. Details TBD but it looks to me like a warmer wet prelim event late 28-early March 1, then some cooling and a change to snow from north to south late March 1 or early March 2. If its the standard CFP with low north of our forum, then no snow LI, but if it's two waves of low pressure, then the fun of the challenging forecast. I can definitely see 4" of snow in the northwest part of the forum for this complicated event. Not saying 4" will happen but definitely potential. --- 550A/21: No change to thread (for me). Model variability. By and large looks too warm for more than 1" of snow/sleet NYC-LI-s of I78, if any at all. Modeling does have an option for heavy qpf, snow/sleet/freezing rain to rain, end as snow especially I84 corridor. Not saying that will happen, but I think that option is realistic instead of the all warm-wet Great Lakes inside runner scenario. It's complicated and if necessary in a day or two may need to change the primary end date to March 2, as optioned in the initial thread. Also, for now no flood threat due to snowmelt/qpf, if that warm heavy qpf option comes to pass as the primary reality. That flood threat insert for me, has to wait 3 more days before throwing in the towel on my primary concern for wintry elements. Finally, that closed low option continues (06z/21 V15 ballistic, V16 not). Will monitor successive GEFS 6 hour member cycles as seen on http://www.meteo.psu.edu/~fxg1/ENSHGTAVGNH_0z/ensloopmref.html Any questions and I can guide us thru this. Just use your cursor to slide over the hours from L to R and not only monitor the mean, but the spaghetti, which for me is crucial to understanding future model options. ---- 330P/20: 12z/20 EPS GEFS diverge with the Canadian GEPS favoring too warm for snow I80 south but that can change in 9 days. What does seem apparent is that there will be strong WAA into the top of the ridge, which can allow snow at warmer than expected 1000-500MB thicknesses due to marginal column temp for phase change to rain. Also, there have been some GEFS members trying to close off a low over the forum (too little-too late & too far north?). While that type of deepening is not predominant now, it seems worthy of monitoring daily trends. One of my concerns is that LR modeling in the 6-10 day range has yielded colder results recently, than what we would have thought beyond D5. 12z/20 modeling also indicates a healthy qpf event of 1/2 to possibly 1". This event is focused on the 28th-1st, but not impossible to see it begin late 27 or end on Mar 2. . Only 1 graphic for a couple of days.

This topic for Friday-Sunday dual event is posted with much lower issuing confidence than the topics of 11/11-15, and 11/30-12/01. There may be several verifiable flood (not flash flood) warnings for rivers-small stream in northern NJ-northwest of I95 by Sunday morning from a widespread 1-2" rainfall, isolated 3" possible. There is a small chance for 45+ MPH gusts. It appears the best chance of verifiable hazards will be along the I84 higher terrain where ice or snow can occur. The ice or snow amounts 3-4 days in the future cannot be counted on to be more than 1 tenth inch glaze or more than 3" of snow, though the option exists for heavier snowfall north of I84. Lead precipitation Friday afternoon and night is associated with a reinforcing cold front. Rain NYC. However the I84 corridor may see some wet snow Friday night? mPING. Saturday: Chilly rain most of the NYC forum, heavy at times with 1-2" general, isolated 3". I84-best chance that there could be some ice Saturday before cooling thicknesses and the rapidly developing low change precipitation to some snow before it ends Saturday night or Sunday morning. mPING may be quite helpful. Winds: Depends how fast the storm develops. If a 998MB low is south of Islip Saturday-then brief northeasterly gusts 40-50 MPH Saturday would be possible on LI and the NJ coast, otherwise I think there may be a better chance of northwest wind gusts 45-50 MPH Saturday night or Sunday morning as the storm moves rapidly past Boston. After further review, I don't think tidal flooding will be a significant threat Saturday. Starter graphics: 6 hr FFG..shows the vulnerable areas. Once yesterdays wave off rising river waters passes Wednesday night, I'll add some small stream guidance-if it applies. Added the 12z/1 GEFS prob of 1". Yellow is up around 75-80% chance. The 12z/1 EPS also has 1-1.5" as does the 12z/1 NAEFS. Final starter graphic is a 52 member NAEFS blend of where the sfc low will be and it's intensity Saturday evening. You'll note the yellow color northeast of the center... that implies greater variability of the pressures there..and could mean that the surface low will be further northeast by Saturday evening. Good luck with this... I hope this topic will produce some verifiable NWS hazards. 521P/1

Per this afternoons NWS issuance of a wind advisory for Monday, have split the difference in the timing to keep it simple for our AMWX NYC forum. Confidence is somewhat less than yesterday to see more than isolated 46MPH advisory criteria reports and associated power outages from downed tree limbs, aided by many trees still partially leaved. Appears best chance for downward transfer of 45-max 60 MPH gusts is 6A-Noon, especially ne PA and I84 ridges through se NYS and CT in CAA with a gradual decrease in wind probable during mid and late afternoon. E tip of LI may also be more prone to gusts past 46MPH aided by the warm surrounding SST's. Positives are the Richardson # briefly "nearly" solid 0.25 (red) to 825MB and the associated steepest lapse rate with a decent nw flow gradient between deepening near 980MB low pressure in the Maritimes and 1035MB high pressure to our southwest. in the lower Mississippi Valley. Negatives: My experience that the FOUS displayed synoptic scale BL wind needs to equal or exceed 27kt on the coastal plain (LGA so far is modeled to be hovering with a max of BL wind of ~25-26kt), and a lack of strong pressure rises-subsidence-rapidly rising sfc based LI. Even the Richardson # is starting to show breaks. 12z/1 SPC HREF, 12z HRRRX, 18z HRRR and and 12z EC gusts seem predominately below 46 MPH, except the ridges. Added graphics to this topic a couple of 3KM NAM 18z/1 LGA time section graphics for Monday (Richardson #, Temperature and wind and RH tsections)... and a 3K NAM 18z/1 modeled sounding focused on 16z.

Prior modeling steep lapse rates momentum transfer prompts on the forum, the wind advisory issuance by OKX for LI/se NYS/CT, the marginal risk for SVR by SPC skirting the northern fringe of the forum, all are contributing to this topic. CAA aloft steepens lapse rates this afternoon as intensifying low pressure crosses northern Maine this evening. Winds at 850 MB will be 40 to possibly 50 knot and so there is a chance to latch onto some of the 40 knot gusts. Best chance for spotty gusts 46 MPH or greater appears to be se NYS, CT, e LI. Appears to me most of the wind gusts will be 40-45 MPH but gusts 50-60 MPH are possible, especially e LI. Gust algorithms from the 00z/7 cycle EC, and SPC HREF are generally a bit weaker than the early morning HRRR, tho SPC HREF MAX gusts do offer the potential. Evaporating sewd moving showers may add to the transfer. 657A/7