wdrag

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.

Yes... looks a little drier than normal through the 17th, after, all bets off... So anything we get this week in CP adds to the 7.23" so far. GEFS starting to show more and more TC options. The one in GMEX-HAT around the 8th-9th is not for us, I dont think, unless abrupt upper level changes develop with the approaching Great Lakes trough middle of next week. So not counting on that but monitoring. After the 17th might be something that allows trop PW this far north, but it seems it will have to come from GMEX. Added CPC week 3-4, issued once weekly on Fridays.

There should be showers or sprinkles Sunday morning and then if the 06z/4 HRRR is to be believed late day I95 east, and then possibly later Sunday night whatever survives with the frontal passage from the west. I dint have much to add this morning...models differ. Nora contribution impact this morning from CO to MO, attached. Use the legend for a little more assistance.

So when the topic started, anticipated a rather warm first week of Sept - overall it will not be. TC moistures were anticipated and both are going to occur, however in a huge reverse order with IDA almost 5 days sooner than originally expected and Noras leftover PW about 4-5 days later than expected. Worthy I think to pay attention to developments after the 17th in the western Atlantic to Gulf Coast. Maybe this is premature so I'll follow with probably no GMEX TC related thread post for at least a week. Finally, at the behest of WPC-NWS, they prefer all of us on the same page and not naming these TC's up here as remnant (despite IDA being half to 65% of what it was striking Louisiana). Any future TC posts from myself will somehow migrate over to Post TC or TD. That will take that issue off the table as a hindrance to messaging, if indeed it was significant.

Well, I don't know yet what to believe, but the potential exists for anywhere from a trace to isolated 1" rains Sunday early Monday. Minor in comparison to IDA impact here. In my mind Nora's PW has influenced the weather in in the central Rockies-into central Plains and we'll see a piece of it by Labor Day. I think it's worth tracking tropical PWATS as we do Atmospheric Rivers across the Pacific for the western USA in winter. We'll see what happens. It obviously is not major but it to me appears to be coming with 850 MB wind core and an increasingly favorable 500MB jet core diving down to 40N to sweep the PWAT east toward Delmarva/NJ/LI.

While this remnant TC moisture plume is probably hard to discern and am sure most if not all are reluctant to ascribe the coming Sunday-early Monday shower event to Nora's RH, I will. The initial burst is Sunday morning and how much elevated convection remains as it crosses the area is debatable but have to think there will be some showers in the associated instability burst (850 MB sw speed max crossing PA-NYS). 500 MB winds are not favorable for a large event here. There could be another burst of showers in the leftover moisture late Sunday or Monday morning. All totaled, as per WPC, probably less than 1/4". Should be a non player in leftover receding waters of Post Trop IDA.