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IDA remnants-Moderate to isolated Major Impact (esp NJ-LI), general storm total 2-8" rainfall Wednesday-Thursday September 1-2 2021


wdrag
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650A Tuesday Aug 31: adjusted headline with mdi-iso Major impact esp NJ/LI, Dropped PRE since no TC and therefore no criteria. 

 

6AM Sunday August 29 thread title update.  Added general 2-8" rainfall, added possible PRE, and withdrew the ? of direct or indirect. Description of increasingly likely impacts around 7AM Sunday. 

 

This issuance makes the presumption that IDA will be our next Tropical Storm and move north into the Gulf states, shearing out into the Northeast or mid Atlantic states 500MB confluence zone next week.  For now the risk of all the tags above is low, but worthy of monitoring. 

It's possible our first rain (if indeed IDA spreads rain into our NYC subforum?) might arrive late on August 31st. Think at this point, antecedent soil saturation and streamflow conditions will assist determining whether there will be any renewed stream flooding, if indeed IDA does dump a stripe of 3-6" of rain in a portion of our subforum.  Chance of 35+ KT wind gusts is also low with the main contribution of IDA, rainfall, to Septembers total.  Tides are fairly low so am not anticipating any problem with tides, at least not at this Thursday August 26th thread initiation. 

Attached the 12z/26 GEFS 500 MB membership for 12z Wed Sept 1 to show the confluence zone and also the 12z/26 24 hr qpf from the EPS and GEFS.  For now these show a glancing blow to our south with a complete subforum no rain miss still possible, but not likely.  The WPC Day 6-7 forecast issued 1622z/26 confirms the potential for at least some rain. 

 

 

Screen Shot 2021-08-26 at 4.02.09 PM.png

Screen Shot 2021-08-26 at 4.03.20 PM.png

Screen Shot 2021-08-26 at 4.03.45 PM.png

Screen Shot 2021-08-26 at 4.14.59 PM.png

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  • wdrag changed the title to IDA remnants Wednesday-Thursday September 1-2 2021? Direct or indirect?

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. 

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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. 

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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

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1 hour ago, HeadInTheClouds said:

I can't believe this thread is so quiet. Another 3+ inches in the area in a short amount of time to cause some flooding problems especially with what has fallen recently. 

it's quiet because we're still dealing with all the rain from last night lol.  People get interested within 48 hours of an event

 

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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. 

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6 hours ago, HeadInTheClouds said:

I can't believe this thread is so quiet. Another 3+ inches in the area in a short amount of time to cause some flooding problems especially with what has fallen recently. 

I have been posting about this in the other thread lol

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THIS IS THE 12Z EURO FOR NYC:        Winds may be stronger just off shore via the graphic output, not shown.

1630152000-P7AKJN3xFrg.png

I am not sure of the definition of  Wind  Swath,  but IDA seems to regenerate some as it nears our coastal area.

1630627200-KnL4pVIoqx8.png

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4 hours ago, wdrag said:

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. 

60 mph winds and 6 inches of rain for the south shore of Long Island.  Thats horrible

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3 hours ago, Will - Rutgers said:

i feel like the spirit is correct but this will end up overdone--a corridor of 3-inch rains as wide as Jersey is long?

one of the more aggressive post-tropical cyclone forecasts i've seen up here especially for something landfalling so far away.

0z runs

Ukie

405687397_qpf_acc.us_ma(2).thumb.png.63d82f10e3c7b7e464ff0726a56be1d5.png

Euro

1109269678_qpf_acc.us_ma(3).thumb.png.33f4dde4b7e1f72881861a251868b9b9.png

Gfs

308303425_qpf_acc.us_ma(4).thumb.png.0762f56e0e72b89200bf31f885959060.png

Cmc

1393896244_qpf_acc.us_ma(5).thumb.png.daee147fd8fce7cf94d138072ce193fb.png

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  • wdrag changed the title to IDA remnants, possible PRE, general storm total 2-8" rainfall Wednesday-Thursday September 1-2 2021
  • Rjay pinned this topic
1 minute ago, wdrag said:

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??) .

I’m worried about soft ground issues on the island. We had another moderate rain event (2” at the wantagh meso and more over parts of Suffolk) this weekend. Trees are sitting in soup. Add another major rain event and it will not take much wind to cause problems. 

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1 minute ago, LongBeachSurfFreak said:

I’m worried about soft ground issues on the island. We had another moderate rain event (2” at the wantagh meso and more over parts of Suffolk) this weekend. Trees are sitting in soup. Add another major rain event and it will not take much wind to cause problems. 

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. 

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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. 

Screen Shot 2021-08-29 at 5.38.55 AM.png

Screen Shot 2021-08-29 at 5.34.31 AM.png

Screen Shot 2021-08-29 at 7.07.45 AM.png

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Good morning everyone hope you have a blessed Sunday. I have a question can’t find it, apparently hurricane ida is cat 4? But where can I get the latest information on wind speed and cat info? I’d like to keep an eye looks like this thing is still strengthening?! Crazy on the 16th year anniversary of Hurricane Katrina 

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2 minutes ago, RippleEffect said:

Good morning everyone hope you have a blessed Sunday. I have a question can’t find it, apparently hurricane ida is cat 4? But where can I get the latest information on wind speed and cat info? I’d like to keep an eye looks like this thing is still strengthening?! Crazy on the 16th year anniversary of Hurricane Katrina 

https://www.nhc.noaa.gov/#Ida

 

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5 hours ago, LongBeachSurfFreak said:

I’m worried about soft ground issues on the island. We had another moderate rain event (2” at the wantagh meso and more over parts of Suffolk) this weekend. Trees are sitting in soup. Add another major rain event and it will not take much wind to cause problems. 

I dont consider 2" a moderate event, that's a lot of rain

 

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  • wdrag changed the title to IDA remnants-Moderate to isolated Major Impact (esp NJ-LI), general storm total 2-8" rainfall Wednesday-Thursday September 1-2 2021
  • BxEngine unpinned this topic

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