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Forgot to add the radar appearance quote from mweisenfeld. Not Birds: AP with temperature inversion developing near or after sunset. Shows some nearby non-moving targets near radar and not too distant hills. Here is more information below. Extracted from sensAgent.com The position of the radar echoes depend heavily on the standard decrease of temperature hypothesis. However, the real atmosphere can vary greatly from the norm. Anomalous Propagation (AP) refers to false radar echoes usually observed when calm, stable atmospheric conditions, often associated with super refraction in a temperature inversion, direct the radar beam toward the ground. The processing program will then wrongly place the return echoes at the height and distance it would have been in normal conditions.[2] This type of false return is relatively easy to spot on a time loop if it is due to night cooling or marine inversion as one sees very strong echoes developing over an area, spreading in size laterally, not moving but varying greatly in intensity with time. After sunrise, the inversion disappears gradually and the area diminishes correspondingly. Inversion of temperature exists too ahead of warm fronts, and around thunderstorms' cold pool. Since precipitation exists in those circumstances, the abnormal propagation echoes are then mixed with real rain and/or targets of interest, which make them more difficult to separate. Anomalous Propagation is different from ground clutter, ocean reflections (sea clutter), biological returns from birds and insects, debris, chaff, sand storms, volcanic eruption plumes, and other non-precipitation meteorological phenomena. Ground and sea clutters are permanent reflection from fixed areas on the surface with stable reflective characteristics. Biological scatterer gives weak echoes over a large surface. These can vary in size with time but not much in intensity. Debris and chaff are transient and move in height with time. They are all indicating something actually there and either relevant to the radar operator and/or readily explicable and theoretically able to be reproduced. AP in the sense of radar is colloquially known as "garbish" and ground clutter as "rubbage". Doppler radars and Pulse-Doppler radars are extracting the velocities of the targets. Since AP comes from stables targets, it is possible to subtract the reflectivity data having a null speed and clean the radar images. Ground, sea clutter and the energy spike from the sun setting can be distinguished the same way but not other artifacts.[2][3] This method is used in most modern radars, including air traffic control and weather radars.

Ap possibly incomplete preliminary wrap-up of two day totals... (MARFC radar-sensor for NJ is complete), but CoCoRaHs may update further later. Added AHPS SR two day radarCT/LI age 333PM. Have not taken the time to add up some of the wunderground two day obs for southern LI.

WU reports after midnight only are attached... (early this Friday morning). Decent leftover's near Brookhaven. Usually I don't see these appended to NWS posts, but the data is valuable=useful, if checked against surroundings and radar. Part two (all of last night) ended up less than anticipated in the page1 posts on this topic, due to the main band being south of LI instead of over LI. Still, the two day amount graphic posting late this morning will be fairly impressive in NJ/LI - well above normal for the entire week two period. I don't plan on any further topic posts for the next 5 days... awaiting the eventual tropical cyclone northward feeds. NCEP model guidance transmission appears to still have the past two days of timely delivery issues. Thank you for all of your posts-comments/impressions. Will add more around 11A. 755A/11 (818A update--just cleaned out all my attachments up through Aug 29, 2020 to make room for the future)

Have seen all model guidance shift to the southeast on heavy rainfall band. I'm reluctant to give up on it, due to instability, proximity of the front and PWAT over 2" through at least 3AM Friday BUT... I have to give up on the outside chance additional amounts for s LI that adding up to 1 ft near Copiague. I did append a MAX rainfall graphic that indicates isolated 4-5" might occur in 1 or 2 locations (this graphic begins at 8PM tonight)... if we get a nice period of training between 6PM and 3AM. If that were to occur where 4+ occurred this morning, then there would be additional overnight flood problems with a couple more reports of entire event totals over 7" on southern LI. Again, uncertainty on overlap. Elsewhere...bands developing now and so by 3A Friday... expecting a couple of 3-5" in NJ s of I80 and maybe the CT coast. That would possibly result in a couple new FFW's by midnight? Offline til 5P. Thanks for all the posts and support for this topic.

This Copiague NY data looks a touch high but has a valid zero base line. This is one of at least 8 5+ inch reports this morning s LI.

Am not quite as concerned about Sunday... not ruling it out but I think Sunday's event will be less on LI... faster flow and not quite as extensive PWAT. Potential yes, needs to be monitored. I think late today-tonight is the key for me. IF the next big band occurs s of LI...that will be the best solution. Copiague near Amitityville is our largest amount that I can find so far (7+"). By the way, there was very little or no lighting associated with the event so far on our land area, at least to my knowledge. Also have my doubts right now about the 12z NAM HRRR solutions. Need to reevaluate at 230P.

909A/10 update. Added CoCoRAHS past 24 hours and WX underground totals midnight-9A. SPCHREF MAX Rfall graphic of 7" "was" a good starting point on max rainfall. Already 4.5-7.5" parts of s LI. One foot max not impossible by 9A Friday if a number of the models are correct about training event on LI in PWAT of 2.2" tonight. The launch of this last potential prolific band seems to be centering near I78 in e PA mid afternoon and then training east this evening. HRRR and HRDPS not in agreement but prior experience from reliable sources... light north wind just north of a boundary in high PWAT can yield prolific rainfall. We shall see if that includes LI tonight... I'd prepare for flooded roads and basements there tonight, where ever 4+" occurred this morning, and methods to evacuate water should these equally big rains develop tonight. Wantage NJ-this part..0.41" now. Nothing compared to other parts of NJ and LI.

Good Thursday morning all, Radar continues to underestimate rainfall amounts. .06 here in Wantage and OKX/DIX radar did not detect any accumulation here. Added two maps of midnight-630A rainfall. one from nw NJ where you can see some of the cities. The other with a 3.06" centered on Oceanside NY (w LI).

It looks like some big numbers are coming to the I95 corridor (pockets of 3+ inches--iso 6-7"?). Digital Storm Totals from DIX and OKX are too low this Wednesday evening in s NJ. Already 1/2-1.2" amounts in parts of southern Ocean County(see attached weather underground). Look at the radar loop and you can see if that intensity comes overhead, torrential rain will occur. Long ways to go. HEAVIEST rainfall may come in two bands---one at sunrise NJ-LI, and then 3P-10P for ne NJ-CT/LI and extreme se NYS with good frontogenesis probably yielding some 1.5"+ amounts in 1 hour. 952P/9

Some of new 12z/9 guidance is in: This may be a fairly serious brief and small areas of short fuse FF for parts of NJ/NYC area, Thursday, keeping in mind previous FFG. 12z/9 SPC HREF 24 hr MAX rainfall potential. It's increased somewhat in NJ. I see 7" flagged here for 2 successive cycles in ne NJ. We'll see what happens. ICON/GGEM are pretty decent as well. 226P/9

Jut added last nights 00z/9 SPC HREF 24 hour Max rainfall graphic ending 8PM Thursday. Legend decodes the 8 member ensemble attempt at prediction.With a PWAT of 2.3"...these numbers are possible, if thunderstorms occur. Something to monitor tomorrow. Also, added the probability of 2" or more of qpf per the 00z/9 NAEFS by 8PM Monday...showing a50+% chance of 2+" on LI (back up from a few days ago). mPING may be helpful tomorrow. 931A/9

Have attached relatively high 6 hour FFG, plus the first week of Sept departure from normal rainfall, and the ~Aug 30 NAEFS 52 member D8-14 pattern that suggested near or above normal rainfall along the east coast for week two of Sept, that was posted on p2 of the Sept thread... with a cooler pattern nations midsection abutting a warmer than normal western Atlc temperature pattern. Now we're in the shorter term and modeling consensus has increased the front end of the probable two part R+ episodes -Thursday- and Sunday-Monday(13-14). 00z/9 model guidance is suggesting widespread showery conditions Thursday in the NYC forum, with some thunder. PWAT may rise to 2.3". Have seen a little ensemble guidance suggesting max rainfall of 5-7" in eastern NJ and possibly near NYC. There is enough wind that one or 2 clusters of thunderstorms might produce a wet microburst of severe weather in NJ or even LI on Thursday. My expectation is that everyone in the NYC forum receives a minimum of 1/4" and then in NJ/LI there should be several reports of 3+" with isolated 5" possible. Some of the showers may creep into the southern part of the NYC forum late this afternoon or evening but the main show is Thursday-Thursday night. There could be a couple of leftover showers leftover after daybreak Friday on LI. Normal rainfall in our area for a week period in September seems to be around 1-1.1" though our climate specialists may have other differing information. In any case, have not added Sunday-Monday to this topic... that too could be pretty heavy, though 00z/9 modeling has a slightly less extensive band of 2" PWAT over our area and a couple of models have most of the convection to our east. Would like to see the GGEM operational on board for Sunday. 726A/9

Good morning this Labor Day 2020, Yesterday: no showers late afternoon evening s of I84... a few just n of I84 in se NYS and sw CT. No thunder per lighting archive. The week from Tuesday through Monday the 14th. Less chance for 2+" rains (near out above normal qpf), per the Rockies cutoff slowing and opening up late, but not yet a done deal for less. This coming Wed-Thu, and Sunday and Monday still may see significant qpf production around here. We seem to be more on the northern edge of decent qpf but some room for modeling error exists. PW rises to near 2" with pairs of days. Any showers outside those 4 days would appear to be an unexpected bonus. 634A/7

For next week: No change in overall modeling posted from the NAEFS since Sunday the 30th, supported by other forum participants looking at varying guidance. It's looking like normal or above normal QPF for much our our area between Tue and next Monday the 14th. With PWAT near 2" late Tue through next weekend... some places will have 2+" inch totals... conceivably much heavier, but, overlapping daily or every other day rains are not guaranteed and so no numbers offered above 2" at this time. Sunday (tomorrow) not only has a decent shower threat along and north of I80 in the afternoon, there could be low top isolated thunder. 3P/5

Pending any more data... there was 1 report of SVR in our NJ part of the forum last evening (added graphic) and added the CoCoRaHS 24 hour totals ~6A/3-6A/4

Next week continues of interest, as it appears the ensembles are slowing the central USA trough and building a strong ridge along the e coast...with lots of southerly component. 00z/4 NAEFS reflects... showers develop Monday night or Tuesday (inverted trough early-mid week) and continue intermittently through Monday the 14th. Presuming some days will be rain free... Haver added a week long graphic that now has an ensemble 40-50% probability of 2" Long Island. It's also becoming a little clearer, that one axis of heavy precip will be west of the Apps, and another along the USA east coast with a relatively low qpf expectation between. Finally-Sunday the 6th...still to me looks like isolated or sct showers about the NYC forum area per KI pooling in weak WAA? 1023A/4

Looks like no svr: despite helicity. Max rainfall I think was just s of NAM axis as posted in this topic. I see spotty 1.5" plus in that axis. Probably just didn't have enough CAPE, instability.

I'll be away for a large portion of this time frame so creating a possible avenue of posts, IF SVR materializes. Have seen a few models with a separate more northerly strong shear zone near I78 to southern LI early tonight. Added a couple of graphics. This matches the SPC D1 Slight Risk. While I think most of the SVR will be south of our forum, needed to cover for a possible potent developing event. You'll know by 7PM what's moving through and/or near KABE. Keep alert on your radar data. IF a supercell develops...real good chance of 1-3" in 30 to 60 minutes. Again, low prob for our area but could not ignore some of the modeled guidance.

Poured here in Wantage between 11P-2A but wifi power interruption prevents accurate accounting. At least 1.1" at that time and Digital Storm Total shows some nr 2" amounts around here in nw NJ. No topic on SVR today, at least not yet. Most of the activity in our forum should be 6P-midnight with the bulk of svr just s of of our forum. If any SVR, think it's mainly Ocean County. Not enough CAPE imo. Will rereview early this afternoon. As an aside, many talking about rain free weekend...not so sure about Sunday. Seems like more clouds and a pooling of KI across our area. My guess there will be a couple of showers around in the afternoon. Monday is the warmer beach weather day (safely distanced). Trough evolution central USA next week seems more positively tilted but Wed--Fri, should rain decently in parts of our area with potential for 2" totals somewhere. 652A/3

So, I'm aware of the watch just to our sw. I expect a combo of the HRRR and HRDPS to handle timing-coverage. RE: SVR? I doubt in our area but cant rule it out. My guess is a broken line of showers with embedded thunderstorms... a few of which will produce .25 to 1" of rain in 1 hour and maybe a G40-45 MPH. These storms should be decaying as they enter NYC 1A-3A Thursday. Will reevaluate Thursday evening, around 645A Thursday. May post again, if its surprisingly big here in Sussex County toward 11P-mid tonight. Otherwise... this is my last post of today.

Just a brief note to ensure all know mPing has returned this afternoon. We'll need to reload the app (delver then add). Its is valuable information-ground truth check on radar. It works. Apparently it returned last evening.

Is it true... mPing has returned? I think it has... here is a twitter report. NOAA NSSL @NOAANSSL · 1h Get your phone ready - mPING is back! Download the updated app to report the #wx near you! Already have the app? Redownload the app for the latest updates. https://mping.nssl.noaa.gov

1.00" in Wantage NJ so far, since 5AM. No SVR topic planned, so far. SPC D2 afternoon update said this about it's Marginal for our area. ...Hudson Valley into Southern New England... There may be some potential for strong/gusty winds to occur north of the more robust convection across the Mid-Atlantic Thursday evening/night. Low-level warm advection would be the main forcing mechanism. However, most 12Z guidance does not suggest strong storm development across the Hudson Valley into southern New England late in the period. Have therefore trended the Marginal Risk southward a bit, but still including the NYC metro and far southern New England in case convection develops a little farther north than currently forecast.

0.97 so far... since 5A. Not well modeled. Surprised HRDPS missed this on its very short term forecast.

Wantage NJ... 0.69" so far since 5A.. beneficial!