Two Mdt to high impact events NYC subforum; wknd Jan 6-7 Incl OBS, and mid week Jan 9-10 (incl OBS). Total water equiv by 00z/11 general 2", possibly 6" includes snow-ice mainly interior. RVR flood potential increases Jan 10 and beyond. Damaging wind.

[gravitylover]

8 hours ago, Will - Rutgers said:

i love global warming, over the last couple years i take a drink every time i read “record breaking PWATs” in an AFD, really hoping the hospital has a generator and my liver transplant on wednesday doesn’t get cancelled

Did we know? Damn dude. Sign in on Thursday and let us all know how great things are and how well you're feeling! It sounds like we're going to need the good news. 

[wdrag]

SPC HREF under Fire: go to gust potential and make sure you keep it on MIN gust... that will be realistic.  Looks potent at 00z/10 especially Delmarva. The idea is to use conservative predictors far in advance.  

[Will - Rutgers]

32 minutes ago, gravitylover said:

Did we know? Damn dude. Sign in on Thursday and let us all know how great things are and how well you're feeling! It sounds like we're going to need the good news. 

guys i’m really sorry about this but i was just making a joke about taking a drink every time we have huge PWATs, my liver is OK as far as i know.  i actually stopped drinking last year and that’s why my posts are so bad now.  in any case thx for all concerned

anyway friends back to weather

[rclab]

53 minutes ago, Will - Rutgers said:

guys i’m really sorry about this but i was just making a joke about taking a drink every time we have huge PWATs, my liver is OK as far as i know.  i actually stopped drinking last year and that’s why my posts are so bad now.  in any case thx for all concerned

anyway friends back to weather

That’s a relief Will and thank goodness you’re off the buoy. As always …..

[Albedoman]

2 hours ago, wdrag said:

I agree with albedoman post.  I'll be checking my drains today, getting a pool pump out with a hose for extricating water Tuesday night if this comes to pass.  I won't be surprised at a gravity wave that will modulate the heaviest rain zones but also assist wind damage.  The idea, life will have to adjust Tuesday night Wednesday.  

Added a graphic of ensemble predictions of flooding up in our area.   That's just the NWS flood forecast points.  ALWAYS...this is predicated on the ensemble anticipated rainfall-snowmelt.  That ensemble rainfall is 2.5".  Note if another inch occurs next Friday night-Saturday the Passaic at Pone Brook would be in moderate or major flood through next weekend. Again, this is my own take on the modeling and not a NWS warning.  If the rain is less, it's not as dire.

The idea of a gravity wave Walt is exactly what I was thinking as well. Mixing the winds down  through a squall line will yield a tremendous amount of straight line wind damage, especially for those on ridges, hills and deep valleys. The second storm this week on Sat is very concerning as well as their will be absolutely no more stormwater storage in manmade structures and in the soils  and anything that falls will be 100% runoff to the rivers.  Even a 1.5 in of rain event will be create serious flooding. Another thread should be created for this storm event after Wednesday.  The mid atlantic region is experiencing its own atmospheric river right now and the media should be picking up on this fact. Never in my lifetime have I seen so many 2-3+ in rain events occur in less than a month and especially in December and January for our area. If the artic cold was present at each event, we would be talking nearly 100 inches of snow for our region already. 

[MJO812]

The coast is going to get hammered tomorrow with wind gusts over 60 mph.

[Snowlover11]

25 minutes ago, MJO812 said:

The coast is going to get hammered tomorrow with wind gusts over 60 mph.

They want you on harbor patrol tomorrow night

[MJO812]

4 minutes ago, Snowlover11 said:

They want you on harbor patrol tomorrow night

[MJO812]

3K Nam has 80 plus gusts on the south shore od NYC 

[nycsnow]

This wind event is probably going to be more widespread and possibly damaging compared to last one. Longer duration as well

[MANDA]

Final storm stats:

Two day snowfall = 7"

Two day melted = 1.22"

[MANDA]

Always like a visible satellite pic day after a snowstorm.

[wdrag]

1 minute ago, MANDA said:

Always like a visible satellite pic day after a snowstorm.

does that fit snowman19 nada east of I287?  I'm doing cocorahs now.  I need to understand reality.

 

[IrishRob17]

11 minutes ago, MANDA said:

Final storm stats:

Two day snowfall = 7"

Two day melted = 1.22"

I got into some good ratios in that heavy band Saturday night, 13.9" snowfall and the melted down core sample yesterday was 1.26"

[NJwx85]

Biggest difference with this system over the one in December is the wind threat well inland. 55-60 might be marginally notable on LI but it’s pretty serious in NJ, E PA and Southern portions of NY State where there are heavily wooded areas, exposed power lines and saturated grounds. Many areas in NNJ are less than 2 weeks removed from a major flood. Water tables are high and reservoirs are already at capacity. Bad combo to add that with pending rapid snow melt. Reminds me of March 2010 system.

[wdrag]

Jan 6-7 CoCoRaHs rainfall-snowfall data, plus NOHRSC snowfall. Click for clarity if you wish.

 

[wdrag]

Snow water equivalent...alot of this in NJ e PA will melt by Noon Wednesday. Lot of potential water for the rivers wherever 2-3" of qpf occurs on top of that NJ snow water equiv. 12Z/8 Modeling and BOM is favoring I think the I287 area...correct me if Im wrong. 

[Snowlover11]

kinda thankful we didnt get the heavier totals here, rockland is a shitshow when we get heavy rain as is. wednesday’s morning commute will be outrageous all over.

[jm1220]

57 minutes ago, MANDA said:

Always like a visible satellite pic day after a snowstorm.

I’d like it more when I had some of said snow.  

[wdrag]

Added the 12z/8 run for 24 hr qpf...SPC HREF--please reference the legend.  I like this and it matches multiple model bands of heaviest qpf which looks to me like 1.5-3.25" with the heaviest over NNJ.  I checked minimum wind gusts and all generally 50-55 MPH Delmarva-coastal NJ and LI 00z-07z/10.  I dont want to hammer the wind too much more right now. I'm certain of power outages. but how extensive?  I see the NAM BL wind is 45kt at 06z/10... that's very large.  LI and se New England coast should have pretty significant problems. Discuss and add on.  Texas now up to 19000 power outages as the eastward and then northeast ward march of power outages has just started. Is it continuous across multiple states? Smokies should feel this late tonight-tomorrow morning. 

 

[jm1220]

9 minutes ago, wdrag said:

Added the 12z/8 run for 24 hr qpf...SPC HREF--please reference the legend.  I like this and it matches multiple model bands of heaviest qpf which looks to me like 1.5-3.25" with the heaviest over NNJ.  I checked minimum wind gusts and all generally 50-55 MPH Delmarva-coastal NJ and LI 00z-07z/10.  I dont want to hammer the wind too much more right now. I'm certain of power outages. but how extensive?  I see the NAM BL wind is 45kt at 06z/10... that's very large.  LI and se New England coast should have pretty significant problems. Discuss and add on.  Texas now up to 19000 power outages as the eastward and then northeast ward march of power outages has just started. Is it continuous across multiple states? Smokies should feel this late tonight-tomorrow morning. 

 

I wonder how real that upslope aspect to the rains are inland. I know those SE winds will be bringing tons of moisture. If so that'll just add to the huge flood threat. 

[wdrag]

6 minutes ago, jm1220 said:

I wonder how real that upslope aspect to the rains are inland. I know those SE winds will be bringing tons of moisture. If so that'll just add to the huge flood threat. 

Could--

am taking these numbers verbatim more pore less and let reality direct.  We only have a 12 hour winedow. It will pound and fortunately most of the melting should begin during the night but residual runoff Wednesday morning will be impressive. I foresee lots of flooded basements in NNJ.  I am even worried here in SC.  The snow may hold a lot of the water in the interior of NYS/ne PA and prevent major flooding but I'm not betting. Please reference the Snow water equiv map posted earlier...at least 1" of water to melt in NNJ near Passaic County I think. 

[wdrag]

21 hours ago, RU848789 said:

Ahhh, I now see what you meant about the slider bar, which I wasn't using.  I simply clicked on the "entire period" button and up popped the graphic I copied/pasted in this thread, which does say through 1/13/24.  However if one tries to use the slider bar, one only gets the first 3 days to work and it's grey after that.  This is a problem for this page, as users will obtain info they think is for flooding through 1/13, when it's not.  One other minor point: the ensemble river flooding graphic you posted doesn't note anywhere on the graphic what timeframe the graphic is for (it only gives the start time, not the end time).  Again something that should be fixed. 

I send emails to the WFO webmaster a couple of times per year with minor issues like this, since you may not have noticed, but I occasionally dive into deep details, lol (the webmaster is the one they recommend contacting on the NWS-Mt. Holly webpage, but this one might be better sent to MARFC as you were suggesting, since it looks like the office just "hosts" that page from them) and I always get a reply and sometimes an answer. 

I still recall asking in 2016 if they could start doing snowfall forecast and accumulation maps regionally, instead of just maps for each WFO and the reply was they don't do that, but he'd pass the comments along and a few years later they appeared (my guess is more than a few folks made requests like that).  

Hi... you saw my last post of how guidance is posted to answer your questions-impressions.  

Here's the MARFC answer on D4-9. Please accept this. 

 

I hope I've closed the loop on all your concerns. If not, please let me know.  Thanks. 

----

Walt, 

 

The nine day forecast slider is the default and we can't change it. We will still be issuing our usual 3 day forecasts and there are no current plans to change that.

 

 

[cannoliman42]

Am I simply reading incorrectly? Is the 3km NAM showing 90 MPH wind gusts off the Rockaways? It's showing 3 hours of 80+ MPH wind gusts for most of Long Island (Queens and Brooklyn included). I saw a peak of 94 mph off the coast of Jones Beach. Does the hi-res NAM typically overdo winds like this compared to other models like the HRRR?

[justinj]

4 minutes ago, cannoliman42 said:

Am I simply reading incorrectly? Is the 3km NAM showing 90 MPH wind gusts off the Rockaways? It's showing 3 hours of 80+ MPH wind gusts for most of Long Island (Queens and Brooklyn included). I saw a peak of 94 mph off the coast of Jones Beach. Does the hi-res NAM typically overdo winds like this compared to other models like the HRRR?

Way Overdone. Gusts will be 45-50 maybe a 60

[jm1220]

16 minutes ago, cannoliman42 said:

Am I simply reading incorrectly? Is the 3km NAM showing 90 MPH wind gusts off the Rockaways? It's showing 3 hours of 80+ MPH wind gusts for most of Long Island (Queens and Brooklyn included). I saw a peak of 94 mph off the coast of Jones Beach. Does the hi-res NAM typically overdo winds like this compared to other models like the HRRR?

Yes it’s overdone but I could see 60+ mph gusts especially if there’s an organized squall line and/or the inversion breaks. That’ll be enough to knock trees down and power out. 

[SnowGoose69]

Much like last time BUFKIT algorithms do not want to mix winds down really and only indicate JFK maybe gusting 40-42...I would think just before FROPA they could have a stronger gust than that 

[Albedoman]

1 hour ago, wdrag said:

Added the 12z/8 run for 24 hr qpf...SPC HREF--please reference the legend.  I like this and it matches multiple model bands of heaviest qpf which looks to me like 1.5-3.25" with the heaviest over NNJ.  I checked minimum wind gusts and all generally 50-55 MPH Delmarva-coastal NJ and LI 00z-07z/10.  I dont want to hammer the wind too much more right now. I'm certain of power outages. but how extensive?  I see the NAM BL wind is 45kt at 06z/10... that's very large.  LI and se New England coast should have pretty significant problems. Discuss and add on.  Texas now up to 19000 power outages as the eastward and then northeast ward march of power outages has just started. Is it continuous across multiple states? Smokies should feel this late tonight-tomorrow morning. 

 

this map says it all. Notice the precip over the Poconos/LV. The snowpack  will not hold in the precip, its already saturated enough now. The Delaware River will rise ten  feet or more in less than 6 hours on Wednesday morning. The tributaries like the Lehigh River will make the flooding  even worse as the snow pack will be completely erased. Little or no sublimation will take place as a result of this type of snowmelt. Fog would have really helped us out but the warm SE winds will melt the crap out the snow before evaporation can take place. IMHO, that is a major game changer because several times during a winter season, a good fog will slowly destroy a snow pack. This time no such luck. The soil profile horizons are supersaturated completely from  the A Horizon all the way to the C horizons. Springs are really flowing heavily right now (Shale soils especially)  as the ground is frozen only a  few inches and not in feet like it should be. I expect major flooding. Anyone doubt me, I am a NRCS certified hydrologist. Simply stated, there is no room from water to be stored- its all going to runoff. Better get your waders on.

[wdrag]

2 minutes ago, Albedoman said:

this map says it all. Notice the precip over the Poconos/LV. The snowpack  will not hold in the precip, its already saturated enough now. The Delaware River will rise ten  feet or more in less than 6 hours on Wednesday morning. The tributaries like the Lehigh River will make the flooding  even worse as the snow pack will be completely erased. Little or no sublimation will take place as a result of this type of snowmelt. Fog would have really helped us out but the warm SE winds will melt the crap out the snow before evaporation can take place. IMHO, that is a major game changer because several times during a winter season, a good fog will slowly destroy a snow pack. This time no such luck. The soil profile horizons are supersaturated completely from  the A Horizon all the way to the C horizons. Springs are really flowing heavily right now (Shale soils especially)  as the ground is frozen only a  few inches and not in feet like it should be. I expect major flooding. Anyone doubt me, I am a NRCS certified hydrologist. Simply stated, there is no room from water to be stored- its all going to runoff. Better get your waders on.

Hi... I like it.  NRCS?  

 

In any case... my only concern is that mixed temps over the snowpack may not pass 50 or if they do, not be 50+ for more than 6 hours over snow depth 8+... I kind of see that in the plan view guidance before and after midnight. sort of looks to me like where there is 8+ snow cover, we only lose 75% and the remaining 2" hold a lot of water... You're the hydrologist.  My concerns are similar though I dont have any expertise on river rises outside of having produced warnings.

I value what you've said. fwiw... I'm going to have to use NERFC/PHI forecast stages. Temps/qpf will ultimately dictate.

Whatever doesn't go Wed morning, might complete the melting cycle Fri night, but even there mostly chilly temps except for maybe 6 hours?

[wishcast_hater]

8 minutes ago, wdrag said:

Hi... I like it.  NRCS?  

 

In any case... my only concern is that mixed temps over the snowpack may not pass 50 or if they do, not be 50+ for more than 6 hours over snow depth 8+... I kind of see that in the plan view guidance before and after midnight. sort of looks to me like where there is 8+ snow cover, we only lose 75% and the remaining 2" hold a lot of water... You're the hydrologist.  My concerns are similar though I dont have any expertise on river rises outside of having produced warnings.

I value what you've said. fwiw... I'm going to have to use NERFC/PHI forecast stages. Temps/qpf will ultimately dictate.

Whatever doesn't go Wed morning, might complete the melting cycle Fri night, but even there mostly chilly temps except for maybe 6 hours?

And the remaining snow pack is gone by Saturdays cutter.......