wdrag

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.

CP at 7.25" as of today. More to come this week and maybe late this weekend?

Wed-Thu ould produce anywhere from .05 to 1" NYC-CP. It's add on, whatever it is.

Raining out here in Wantage NJ without any radar echo our way. .04 for the day. everything wet. Also, am seeing steady rains entering s NJ from s PA. to me, looks like going to be widespread 0.1-0.7" amounts southern LI down to near I78 between now and 10AM Monday.

I see CP has added .01 today to far.

Am not sure what will change the pattern? MJO i suppose or some huge tropical exchange with the polar region. All i see is another year of warmer than normal as represented by sea breeze summer cooler NYC data...7 of the first 8 months of 2021. I aw the 00z/5 MEX MOS guidance for NYC this morning and it starts at or above normal for many days... beginning the 6th. I'm not sure about Wed-The but warmth is apparently coming. Later, Walt

So even though amounts are miniscule, it is wet and not too sunny. 0.02 here in Wantage NJ at 1121AM. Two things about this minor (so far) event, it's trackable and I sort of wish those that are showing 10 day forecasts, would look at PWAT changes and ensembles to minimize these optimistic longer range outlooks. Basically it rains a bit, every 3 days. Therefore if its not, we need to be sure about ridging and no instability -moisture encroachment. For now much of nw NJ, nePA and distant interior se NYS have measured .01-.05 a bit more along the northern fringe of the NYC subforum. This day is far from over, and modeling continues to spew a narrow 1/2+ stripe somewhere in our NYC subforum by tomorrow morning. PWAT axis looks a little larger to the south of I80 so I suppose it can miss the region north of us, but there is likely to be a little bit of convection rolling across parts of I84 tonight.

Yes, you're probably going to be right... that would fit the opportunity for our NYC attempt at 10+.

So we dawn this Sunday with leftover Nora's showery moisture approaching from the west giving sprinkles in some areas by daybreak Monday, while others have 0.1 to possibly isolated 1". See WPC qpf for the general coverage today-tonight in 2 or three bands of 1/2-3 hours duration. It is what has been trackable for many-many days, obviously far removed from its Baha source region, having been clipped a bit by the Rockies, but will affect haying-corn retrievals here in nw NJ the next 24 hours.

Looks like warming w respect to normal begins to normal... whether its continuous or interrupted by the next trough midweek, unknown but overall September looks to be heading to the warmer than normal side of the ledger by mid month. Continue to look to the period after the 17th for opportunity for possibly more significant TC moisture. For now, am seeing the midweek tropical moisture in the se USA just passing se of us. So Larry's swells-rip current impact is the apparent biggest TC related action this week for our asubforum, with Nora's moisture contribution noticeable today-tonight but small.

Processes will be improved including modeling a 2 hour window of potentially overwhelming-excessive rainfall and then it's up to us to get the message out out 2 hours in advance, not within it's occurrence for which i'm afraid entrapment was occurring on roads near creeks and near overwhelmed drainage basins. Scary in that situation, and what to do becomes a problem.