wdrag

Have no changes to previous days outlooks and as highlighted in the thread headline through the 12z/30 op data and 123z/30 GEFS/EPS qpf data. Do have to account for some non GFS/EC modeling south, but for now the ENS dictate the concerns. PLEASE follow NWS watches/warnings/statements, especially RIVER/small stream/basement flooding that is likely for portions of our area. Wind gusts still an unknown so not playing that up. Tomorrow morning, if everything is on track will highlight MODERATE to possibly ISOLATED Major impact. We will have seen worse in the past decade. PRE: I think is likely though it may stray slightly from the 1000KM 24 hr separation requirements. I still need to recheck those requirements in a PPT that I haven't yet found, on line. AND we need a 4+" requirement, which am unsure will be met-am not following local data there along the OHIO River. Still, i see guidance that successfully pointed to what I think is a PRE near the OHIO River (slightly further s of where i thought this morning, but do see there attached). It should reform in southern PA tomorrow and drift into NJ by 4AM Wednesday, drifting ene from there. Whether it colocates with the subsequent TC torrential rainfall???

EXPERIMENTAL from WPC for Wednesday... Extreme precip monitor... recurrence interval. Let's see what happens for this D3 issuance at about 09z/30. Unsure whether this is issued twice daily? Generates from WPC QPF, therefore, if we miss the qpf, we miss the ARI. Please read the background for this.

No basic changes from my perspective using multiple guidance from the 00z/30 model cycle. Appears to me to be moderate to spotty major impact event due to antecedent ground saturation. Title will probably upgrade to MODERATE-iso MAJOR tomorrow morning but for now I like the 2-8" swath. You can see the HPC 4-6" yellow swath attached. FFA for NJ and points southwest. My guess i s OKX issues later today. I can see them waiting, to deal with whatever the results of the afternoon convection that will produce spotty 1" amounts in our area today. I think we'll see a PRE in the upper Ohio Valley today near the Ohio River... (may already be forming), then that redevelops across southern PA Tuesday, into NJ Wednesday morning, then the TC rains in earnest Wed night-Thursday morning. For now staying with 2-8". It is my expectation that there will be some large rivers that reach moderate FS, but that is solely dependent on 3"+ averaged over the ENTIRE river basin, so too early to be sure where, though I focus on NJ, PA. Wind: keeping tropical gusts for now...could see iso 50 kt but think it best to focus on rain. IF 50 kt were to occur, that would enhance the potential for widespread power outages--a fickle forecast, dependent mainly on wind gusts exceeding 40 kt. Think it best to keep this part lower visibility for now. The second graphic added is the 00z/30 6 HR SPC HREF MAX qpf for Tue afternoon, showing a focus near I76...where I think a PRE will reform. I did not examine the multitude of 00z/30 GEN/WAA products. A PRE is not guaranteed, nor a PRE rainfall swath of 3+" not guaranteed to be colocated with the primary 4+ swath later on. 534A/30.

48 hr HRRR example for PA PRE? May be starting there???

My next more thorough eval at 6A Monday. Noting the 18z GFS op qpf seems to have a PRE trying to form I76 Tuesday. I'll be keeping an eye on this. Doesn't take much to triple the yield in this subtle situation that models tend not to forecast very well.

I’m out of touch w anything on NWS terminology changes 2018 onward. Other than EF2 or bigger I’m of the opinion that big wind is big wind. Many of these wind events are highly concentrated meso or miso scale. Bottom line if you’re in the general warning. No surprises. Just be smart safe. In advance I know most disagree. IMO Just too darn hard to get much useful and reliable lead time on the Majority of small hurricane related tors m. Knowing the best 2 hour window of opportunity can be useful.

I doubt very very much if NWS locally is Ignoring National centers NHC and WPC. Both have our area nailed fir a sizable event!

Thanks. I think of major in terms of Public impact. WPC Noon update has widespread 2+. This is not Irene Lee combo. Someone correct me if I’m wrong. The places that exceed 6. will have big problems starting w basin and small stream. We can’t be wrong about Major. I think that is coming for a few spots but can’t determine for another day. That would be my take if I were briefing.

I don't have a screen shot for that hour, but you can use this site to go back and put in the zulu hours (09z for 5am, 10z for 6AM and the correct date for the OKX radar and you should see what you're looking for. Thanks, Walt Walt

Here is what I'm expecting for our area, excludes anything happening in our subforum prior to 2PM Tuesday August 31. 06z/29 3K NAM and to some extent the 00z/29 EC are suggesting a PRE develops in the central PA mountains Tuesday afternoon-evening, on the north edge of the 2"PW axis, in 850-700MB weak FGEN, WAA; and then spreads east into our sub forum by 4AM Wednesday. These PRE's are composted 24 hr separate events from the TC rainfall, can last 6 hours and dump 3+" rainfall in a narrow stripe (I do not think NYC last Sat night was a PRE since it occurred with 15 hours Henri landfall). Have added a little composite information...just shift it west a bit. Then presuming the EC OP is correct about the heaviest rain occurring Wednesday night -midday Thursday, we should have a a general 2-8" rainfall by Thursday night, max axis unknown since modeling is tending to shift slightly north directly across our area. IFFF a PRE does occur in our area, I can see iso 10" rainfall. I expect more flooding (possibly MAJOR for a couple of forecast river stages) than the ensembles are posing for some of the forecast rivers. Just a little too early to highlight but as in Henri, the ensembles did not capture the stage rises that occurred in NJ. FF potential I think is pretty high, based on 6 hr FFG, and attached departure from normal precipitation. Wind: I can see gusts 50 kt, but that will be in part dependent on IDA intensity and combined high pressure gradient on the north side of the storm, with the presumption IDA crosses NJ. No further comment from myself til tonight. Have a good day. Finally added the graphics at 739A/29--sorry for the overnight. Remember, this is not gospel but what I'd be briefing EM's as a stand alone briefer with NHC/WPC guidance and ensemble/operational model support.

You're probably correct. I do think its going to take a some 40-50 kt gusts to make this a big player. That is possible in northeast flow Thursday the 2nd. IFFFF IDA goes north of us, then southerly gusts. Potential exists...just need to be careful about overping so far in advance. I'm more worried about a PRE--some model signs in PA late Tuesday moving east overnight Tue night.

Am not ignoring NORA potential for enhancing rainfall potential ~ the 5th-6th. More on NORA Monday morning.

Have to walk the dogs, and so an update of words ~7-730A. A general moderate impact, possibly spot major (areas of considerable flooding, mayybe pockets of wind/soft ground related power outages??) .

12z EC, as mentioned two posts by Stormlover, EC a slam but not necessarily a dunk, yet. Would like the GGEM to come north. Also the 12z/28 EC op rudimentary wind gusts of 40-50 kt may end up lower than modeled, ala Henri. Does look interesting for our area along the lines of 3-6" FFA, FFW, G 35kt. ON a PRE: IF this slows down it's track toward us, then I'd go for a PRE. Right now, need to wait.

Also, folks don't like to be wrong and get over amped. (unreliable). 16z/28 WPC average qpf forecast. New 12z/28 GEFS confirms.

When I get home I’ll comment further including a graphic but WPC with its 1525z Ish D4-5 issuances has virtually all of our forum 1.5 to 3”. I agree with this. I think you’ll see the media etc start the awareness later today. To me, If we get a PRE, Then our problems will be further magnified. I just don’t have an answer on a PRE. In the meantime, spot 6” appear realistic. Can’t post much today. More tomorrow. Walt

CoCoRAHS data at 922AM this morning. Some pretty good gradients between NIL and 1"+.

Mon and possibly Tue seem to have decent chance of 90+ EWR. Also, I see a potentially quick heating up around the 3rd-4th, albeit brief), though it may remain just in upper 80s???

512P/3 hitttled topic header to the 5th-6th. Further topic update Saturday morning. NORA's life as TC will end as it nears AZ late next week, but its vorticity and PWAT infusion can be tracked across northern Rockies then northern USA, near and north of I80 (near and north of latitude 40N). The associated 500MB wind max appears to track across our area late on the 4th, but the moisture infusion is stretched to possibly lay out arross our area the 5th-6th. If the cold front stalls in our area, then the moisture release could be of 3" interest. Just need to wait a few more days to figure out if its just 1/4" convective showers or a stripe of 3" rainfall somewhere in our subforum. If the front does not stall passing through our area, then the impact will be nominal-all of this presuming the model track of NORA's remains is reasonably accurate. So, am not guaranteeing big impact but I do think this merits monitoring in our wetter than usual summer pattern. IF this does come into better focus as a significant player here, headline and tags will be upgraded.

Thursdays thread continues. I probably should hit the title harder but for now... I am expecting 3-6" across at least a part of the area with FF watches, and more warnings if more than 3" occurs. Still unclear to me whether IDA passes north of I84 or just s of I78. I think we've opened ourselves to a PRE Tuesday evening the 31st if the front stalls just south of us near I78-I95-476 with the primary rainfall in a 6 hour period Wednesday afternoon into Thursday morning. This I'm pretty sure is going to be a problem storm for us due to the antecedent wet conditions. Squall gusts of 35 kt possible. There is a low chance that IDA closes off as slower moving upper low just south of us Thursday the 2nd. Latest EPS (00z/28) and GEFS (06z/28) have widespread 1-2" 24 hr qpf across our area by 18z Thursday. More attempts at info will post Sunday.

NORA thread starts by 9AM Sat 8/28. Impact may be low but if the front drags its way through, more important impact.

August CP total 10.32 through 8AM/28. Just so you know how difficult it is... Newark T past 24 hours, so far. So, I know some want to state it was a gimme... but not in my mind. Convective qpf has very large gradients over just a 1000-5000 feet. Now, how much more before Sept 1? Please see IDA thread. I've added digital storm total data for this event through 606AM, and note the black areas of no qpf up against the rainy areas. To illustrate further, at 922AM I added the CoCoRAHS data...note in NNJ the 1.61" and the Trace very nearby. Click CoCoRaHs map for greater clarity.

NORA... think you may want to look at PW tracking, 850 vt tracking and just basic GFS QPF tracking of NORA's remains out of Baha. Looks like a CFP with decent amounts in the northeast around Sept 5-6??, a time when CF's tend to dry out as convective temps decrease.

Good Friday evening, No change in expectations on my part for IDA, despite12z/27 EPS and WPC shunting to our south. Too much RRQ of the upper level jet to our ne... I think this could be nice event up here but need more agreement of the models. Room for error continues but no change for me.

So all who had it as a gimme and or 1-4" etc...you're winners. I'll check some more data tomorrow. So, what this means to me... we've had a unique two consecutive months in our NYC CP history, seldom seldom recording two 10+'s in a row. Can our two month total exceed 1983's two consecutive months (see top of thread) 24.55"? Need 3.16" or thereabouts. Finally, long-long-long shot, but might we try for a third totally unique 3 consecutive months. Seems like we have to get a dose of IDA (RRQ of se Canada trough and inflow at 850 from IDA). That could be in the 3-6" range... (or miss us?). I may be starting a NORA contribution thread tomorrow, as I'm pretty sure RH is going to come out of Baha and cross the Rockies and join an approaching CF here ~ the 5ht or so. Then after the 7th??? There may be more? Repeating trough looks okay to our west if we get some more TC up w of 80W Longitude.