wdrag

All good on Don’s post. 7.51 as of 8PM.

CP now up to 7.46 or more

CP makes it to 7.40 so far with .15!at 1030

Quick snapshot of what has happened. incomplete data. Sharpening trough approaching from the west has grabbed a little of the NC coast PW and slow movement of trough presents rain problems for the I95 corridor eastward today.

Wantage NJ-this part of nw NJ 1.06 so far. Complex evolution but NYC/w CT should finally get some rain today, bigger amounts probably eastern LI CT River. 06z NAM must be a little too wound up to the west. late HRRR is decent. Wont be able to comment much til its all over. Will add 2 day COCoRAHS late Fri. The HRRR STP/max 2-5KM UPDRAFT picked out the svr/heaviest rain axis pretty nicely for e central PA/ALB areas.

Sept: last half seems to be setting up ever-so-slowly for plenty of rain here. Ridging developing northern tier, while a weakness evolves Gulf States (wet). I see NYC yesterday only a NORMAL day. Might happen again Friday-Sat, but otherwise me it looks like the warmer than normal pattern here should continue through at least the 23rd.

This may be of interest and may support NWS actions late today, tonight. Take a look. Rainfall needed to trigger FFW in 1 and 3 hour increments. I may off line til 5P. Have a day and add on as guidance-data warrant. Thank you.

did read this prior to post. I still believe I'm correct we have report seek/population bias. # of LSR reports can include hail, ice, snowfall of 1"/hr or greater, storm totals. Eastward trend of TOR environment is understood. Also, having worked 1980s-90's, we just didn't have as much human kind dedication (EM's and spotter coordinators I think are now trained to do some of this for the NWS) to finding every little TOR, or time to do the job correctly. I did read NSW article. Good information.

This may be a little disconcerting to read-hear, but having worked there and other offices. LSR's are dependent in large part on population density combined with SEEKING reports and of course the reports that are received by phone, spotter reporting. The goal when I worked was to verify warnings and do a lot of post event calling, reading newspaper accounts, and in todays day, seeking reports via social media. MPing can also contribute reports. Therefore, other states are lower, in part due to processes of acquiring reports, population density and I think, priorities - available staff. This data probably should have been normalized by population. I see no other way to further normalize this data. Yes, working the I95 corridor DCA-BOS is I think a larger than normal YEAR ROUND responsibility due to population-impacts on commerce, and also the broader array of weather events that impact this region. For NJ, it can range from killer fire weather, to hurricanes, coastal flooding, severe storms, flooding, dense fog, urban heat warnings, freezing spray, ice jams, synoptic scale wind, and last but not least-heavy snow-blizzards. Not every state has this array of events (let's not forget tsunami). So the responsibility, imo, is greater here in the I95 corridor but I do think this data needed to be normalized. The data is out there now as a news story, but I do wish there would be a greater attempt at perspective, as I feel the same on all other events that we watch-warning for.

Here's some guidance to consider: available le at 530AM Sept 8. most of the rain today... NJ/NYS/PA, then tomorrow (after midnight, most of the rain LI/CT as a secondary surge is expected. Below all from 9/8/21 00z-06z modeling cycle SPC D1 outlook WPC D1 outlook WPC D1-2 qpf 06Z HRRR max 2-5KM updraft showing potential till axis of strong thunderstorms, the tmay produce svr wx, including a TOR- the latter which still looks plausible over eastern PA this eve. (also shows something up near ALB) 08Z WPC D! excessive rainfall discussion 06Z SPC SVR discussion

00z/8 HRRR and 3K NAM basically no changes through Wed night. EC is probably going to be correct about a second batch of rain Thursday, esp I95 east. HRRR and 3KNAM looking for a problem svr storm - poss tor-supercell w hail in ne PA. HRRR STP 3KNAM STP for about 00z/9. 2-5KMaxc updraft, note the large hail track identical that follows then HRRR total rain and NAM3K total rain

Am seeing dry forecasts for next Mon-Tue??? Not what the KI from the EC is saying and I'm seeing above normal PW oscillating S-N at 40 N here. Think we need to be thinking qpf on one of those days here.

A problem last Wednesday; NIGHT time... much more difficult to judge-assess, especially in near panic mode of torrential rain and some lightning. Also, I think the upgraded warnings were not NEW issuance but prior warning updates (I will stand corrected if I'm wrong but IEM COW did not show new warnings for me); TRAPPED??? EMERGENCY warnings almost too late as torrents were surcharging manhole-sewer systems and people were getting stuck, abandoning vehicles. Finally for me: how much practice do we get warning the EXTREME RECORD breaking event? Experience breeds confidence. WARNING the EXTREME in real time made me almost always pause and be more conservative because it was so seldom in my lifetime.

Moving forward... CP monthly amount should rise tomorrow between 0.2-0.8" (7.45-8.05 by 18z Thursday). This is my own goal based on multiple ensemble guidance.

Thanks Don... it is my opinion that the EC is fantastic synoptically (cool season especially), but that it lacks on convective qpf (warm season) which results in differing frontal positions and max axis of qpf. What I'm seeing in some of the guidance is dew points (strong northward moisture transport) Wednesday afternoon-night into the front with surface dews likely to exceed 70 in NYC and most of NJ. Probably briefly rises to near 73 in NYC. The TOR threat is still particularly large. Rechecked with no change. I'll update overnight and tomorrow morning by 730AM. Don't know if anyone has noticed the numerous reports in the midwest of both hail/wind including 25 reports of Large hail.

EC was misleading last event, remember it displaced north and there was talk of NYC missing out, as late as mid morning Wednesday? Quite a distraction from USA modeling. Think we need to stay with the NAM3K, HRRR, and SPC HREF. SPC has slight risk out for tomorrow western portion of the subforum.

130PM: A couple of notes. SPC HREF from the 12z cycle added. It's possible parts of our area will escape with 0.1" rainfall but am staying with the vast majority of our NYC subforum receiving a minimum of 0.2" with two areas of max rainfall... just northeast of I95 and also possibly e LI and the CT River. Max rainfall appears headed for e PA, nw NJ or se NYS with max possible 3.5". SPC HREF mean and max rainfall appended as well as 12z/7 HRRR operational rainfall total. Again a narrow stripe over little may be found vicinity NYC- Oxford CT, but I wouldn't count on it being less than 0.1". Looks to me like some spots in e PA/w NJ and possibly se NYS will have a tornado threat 6PM-10P. Value above 1 should be a cue. Guidance appended.

Am considering upgrade to iso max 3.25” and adding more guidance but will wait til about 230PM.

Warmer than normal yesterday at CP and apparently a pretty good chance of warmer than normal daily through the 22nd. Always a chance we can sneak in 1 or 2 cooler than normal. Others may see that cooler than normal episode? Showery rains late Wed into Thu; More rain likely between the 13th-14th and then as I see it, 16th or 17th onward as northern edge of the PW sets up to our north and lays out from the central USA across our area. PW juicing down along the Gulf Coast under the ridge aloft. We lay a cool front nearby, it will get wet again here sometime 16th-17th onward.

No change from my perspective using the 12/6 ENS/op models. Will check on iso SVR for late 8th, tomorrow morning, There will be some CAPE around here late Wednesday. WPC expanded the MARG RISK for excessive a little further south in its afternoon release.

Pattern trying to set up after the 16th-17th for a big rain but nothing to grab onto yet...PW building in the Gulf States with WAR circulation trying to draw this RH northeastward. In the meantime we have rain events prior to, around the 8th-9th and maybe the 12th-13th. Looks basically above normal temperature from today through the 20th in NYC unless someone see an interruption. HI modeled into the mid 90s but that thats D9 EC which can be a little extreme hat far in advance.

So, here is generally what happened via CoCoRaHs reports thru 930A/6 and the muted SRH Rainfall mutisensor estimates which tend to be a little on the low side in the core of the heaviest qpf.

Guidance does not seem to have any more below normal temperatures days in CP from today forward through at least mid month? Is that possible?

123PM Tuesday (7th): Raised iso max amount to 3.5". This thread will serve as OBS for this event as well. 528A Tuesday (7th): added possible iso SVR to the tags. This per some of the guidance with CAPE & decent wind aloft plus the newly added SPC MARGINAL risk across our area. No other changes at this update issuance. Added some information graphics from the NWS issued prior to dawn this Labor Day 2021. The Marginal risk for Wednesday-ear;ly Thursday and it's discussion, plus the Mid Atlantic River Forecast Center 6 hour Flash Flood Guidance (use legend for 6 hour amounts needed to begin flooding). Have checked the available River Stage ensembles and they do not seem to respond with rises, but undoubtedly a few small streams will respond with uncertain to predict rises. 00z/6 EPS rainfall is higher (almost twice) than the GEFS. The EPS does not go into the automated River Stage ensemble response guidance. NWS modifies this guidance for their official river stage forecasts, which generally officially publish daily around 10A-11A. Periods of showers Wednesday into Thursday, with an uncertain timing end to the showers and uncertain location of the max rainfall axis, which could reach 2". Just too uncertain at this issuance time to confidently narrow the range. Intensity will determine amount and runoff response. This WPC discussion from predawn Labor Day was added below. ...Northeast... The progressive shortwave trough and its attendant surface low and associated fronts mentioned in the day 2 period will be tracking through the Great lakes and Ohio Valley region into the Northeast. Additionally, there will be a warm front lifting through the Mid-Atlantic states. PW values will be increasing from as the front approaches from the West, reaching 1.25 inches (+1 standard deviation from the mean) by 06/12Z on the 8th. Much of the Northeast will be in an area with broad forcing for ascent. Initially, low-level winds will be westerly near 15-20 kts but will then become southwesterly, increasing to 35 to 45 kts by 6/12Z as the cold front approaches the region. A fairly narrow axis of QPF is expected to align along/ahead of the cold front from West Virginia to Maine, over a large portion of the region that was hit hard by torrential rains from Ida within the past week. These areas are still recovering therefore any measurable rainfall will have the potential to aggravate ongoing flooding. A Marginal Risk area for excessive rainfall and flash flooding was raised, spanning from eastern Pennsylvania/northern New Jersey to north-central Vermont.

Spotty 1/2" occurred the past 24 hours... CoCoRAHS posts around 10AM.