March 10 - March 11 Redux Event

[bluewave]

This might be old news for most, but I found the new Ensemble-forecasting page for river forecasts. Here's Pine Brook's page.

http://www.erh.noaa....html/PINN4.html

That's a really high end event forecast there for sure.

http://water.weather.gov/ahps2/crests.php?wfo=phi&gage=pinn4

[LocoAko]

This might be old news for most, but I found the new Ensemble-forecasting page for river forecasts. Here's Pine Brook's page.

http://www.erh.noaa....html/PINN4.html

That's a really high end event forecast there for sure.

http://water.weather...=phi&gage=pinn4

Yeah, definitely. Just for reference,

GEFS:

NAEFS:

SREFS:

[gravitylover]

Yeah the Saw Mill/Taconic pretty much suck if it rains which makes some places very hard to access. There is always a closure just past the 287/87 interchange that gums things up. Hutchinson and Bronx River Parkways are also hazardous when heavy rains occur in the County, especially with the repeated moisture like we've had this season with 25" snowpack melting and then three major rainstorms in a row.

Route 9 and the Thruway stay in good shape though, which means you're never totally screwed around my area of SW Westchester. It does become extremely hard in the eastern sections of the County to commute since there aren't a lot of options to the Bronx River/Hutch except for always crowded 95.

My daily commute is Taconic/Sprain/BRP and into the city on the FDR. I've had it take me as much as six hours when the roads in Westchester are closed for flooding. I've also had it become a 130 mile ride home (instead of the regular 55) when everything is closed and I have to go through CT and take a tour of SW CT making my way home in a very roundabout way eventually going through Danbury then heading back south. I fear that tomorrow night will be one of those. A few years ago I figured it would happen so I took the train. Bad idea when Metro North stops in North White Plains and you then have to hitchike the rest of the way.

[Brian5671]

My daily commute is Taconic/Sprain/BRP and into the city on the FDR. I've had it take me as much as six hours when the roads in Westchester are closed for flooding. I've also had it become a 130 mile ride home (instead of the regular 55) when everything is closed and I have to go through CT and take a tour of SW CT making my way home in a very roundabout way eventually going through Danbury then heading back south. I fear that tomorrow night will be one of those. A few years ago I figured it would happen so I took the train. Bad idea when Metro North stops in North White Plains and you then have to hitchike the rest of the way.

you must have some serious miles on your car @ 110/day....

[gravitylover]

35k a year. That includes a bunch of ski trips and regular mt bike excursions though. Try needing a set of tires every year and new snow tires every two seasons

[nzucker]

18z NAM not that impressed with the rain for NYC metro. Total QPF only 1-1.5" or so for the 2-day storm:

[CT Rain]

I'm interested to see how the monster convection over the SE US impacts the eventual outcome of this storm

[IsentropicLift]

Once again, the text soundings are much higher for KMMU than the 60hr accumulated total would indicate - 3.80" of rain

110310/0700Z 25 10013KT 33.1F RASN 0:1| 0.0|| 0.0 0.004|| 0.00 0.00|| 0.00 0.00|| 0.00 70| 0| 30

110310/0800Z 26 10013KT 32.9F SNRAPL 0:1| 0.0|| 0.0 0.008|| 0.01 0.01|| 0.01 0.00|| 0.00 14| 43| 43

110310/0900Z 27 10012KT 33.1F RAPL 0:1| 0.0|| 0.0 0.008|| 0.02 0.00|| 0.01 0.00|| 0.00 1| 41| 58

110310/1000Z 28 10012KT 33.3F RAIN 0:1| 0.0|| 0.0 0.008|| 0.03 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/1100Z 29 10012KT 33.4F RAIN 0:1| 0.0|| 0.0 0.016|| 0.04 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/1200Z 30 10012KT 33.8F RAIN 0:1| 0.0|| 0.0 0.020|| 0.06 0.00|| 0.01 0.00|| 0.00 0| 0|100

----------------------------------------------+----++-------------++--------------++-------------++-----------+---+---

110310/1300Z 31 09014KT 34.2F RAIN 0:1| 0.0|| 0.0 0.031|| 0.09 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/1400Z 32 10014KT 35.1F RAIN 0:1| 0.0|| 0.0 0.035|| 0.13 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/1500Z 33 10014KT 36.5F RAIN 0:1| 0.0|| 0.0 0.055|| 0.19 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/1600Z 34 10014KT 37.9F RAIN 0:1| 0.0|| 0.0 0.059|| 0.24 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/1700Z 35 10013KT 39.6F RAIN 0:1| 0.0|| 0.0 0.055|| 0.30 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/1800Z 36 10014KT 40.8F RAIN 0:1| 0.0|| 0.0 0.055|| 0.35 0.00|| 0.01 0.00|| 0.00 0| 0|100

-------------------------------------------------------------------------------------------------------------------

Date/hour FHr Wind SfcT Ptype SRat|Snow||TotSN QPF ||TotQPF Sleet||TotPL FZRA||TotZR S%| I%| L%

-------------------------------------------------------------------------------------------------------------------

110310/1900Z 37 11015KT 42.3F RAIN 0:1| 0.0|| 0.0 0.055|| 0.41 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/2000Z 38 11015KT 43.0F RAIN 0:1| 0.0|| 0.0 0.055|| 0.46 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/2100Z 39 11017KT 43.7F RAIN 0:1| 0.0|| 0.0 0.079|| 0.54 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/2200Z 40 11016KT 44.2F RAIN 0:1| 0.0|| 0.0 0.055|| 0.60 0.00|| 0.01 0.00|| 0.00 0| 0|100

110310/2300Z 41 11016KT 44.8F RAIN 0:1| 0.0|| 0.0 0.130|| 0.73 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0000Z 42 11017KT 45.0F RAIN 0:1| 0.0|| 0.0 0.185|| 0.91 0.00|| 0.01 0.00|| 0.00 0| 0|100

----------------------------------------------+----++-------------++--------------++-------------++-----------+---+---

110311/0100Z 43 11018KT 45.5F RAIN 0:1| 0.0|| 0.0 0.217|| 1.13 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0200Z 44 11019KT 45.9F RAIN 0:1| 0.0|| 0.0 0.169|| 1.30 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0300Z 45 11019KT 45.9F RAIN 0:1| 0.0|| 0.0 0.150|| 1.45 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0400Z 46 12018KT 46.4F RAIN 0:1| 0.0|| 0.0 0.217|| 1.67 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0500Z 47 12019KT 46.9F RAIN 0:1| 0.0|| 0.0 0.205|| 1.87 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0600Z 48 12019KT 46.9F RAIN 0:1| 0.0|| 0.0 0.154|| 2.02 0.00|| 0.01 0.00|| 0.00 0| 0|100

----------------------------------------------+----++-------------++--------------++-------------++-----------+---+---

110311/0700Z 49 12020KT 47.1F RAIN 0:1| 0.0|| 0.0 0.134|| 2.16 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0800Z 50 12019KT 47.7F RAIN 0:1| 0.0|| 0.0 0.217|| 2.37 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/0900Z 51 13019KT 48.0F RAIN 0:1| 0.0|| 0.0 0.209|| 2.58 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/1000Z 52 13019KT 48.6F RAIN 0:1| 0.0|| 0.0 0.094|| 2.68 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/1100Z 53 13018KT 48.7F RAIN 0:1| 0.0|| 0.0 0.075|| 2.75 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/1200Z 54 13015KT 49.3F RAIN 0:1| 0.0|| 0.0 0.311|| 3.06 0.00|| 0.01 0.00|| 0.00 0| 0|100

----------------------------------------------+----++-------------++--------------++-------------++-----------+---+---

110311/1300Z 55 14010KT 49.3F RAIN 0:1| 0.0|| 0.0 0.476|| 3.54 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/1400Z 56 14009KT 48.7F RAIN 0:1| 0.0|| 0.0 0.213|| 3.75 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/1500Z 57 13009KT 48.2F RAIN 0:1| 0.0|| 0.0 0.043|| 3.80 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/1600Z 58 12009KT 48.9F 0:1| 0.0|| 0.0 0.000|| 3.80 0.00|| 0.01 0.00|| 0.00 0| 0| 0

110311/1700Z 59 15006KT 50.2F RAIN 0:1| 0.0|| 0.0 0.004|| 3.80 0.00|| 0.01 0.00|| 0.00 0| 0|100

110311/1800Z 60 19005KT 50.0F RAIN 0:1| 0.0|| 0.0 0.004|| 3.80 0.00|| 0.01 0.00|| 0.00 0| 0|100

----------------------------------------------+----++-------------++--------------++-------------++-----------+---+---

110311/1900Z 61 24009KT 50.2F 0:1| 0.0|| 0.0 0.000|| 3.80 0.00|| 0.01 0.00|| 0.00 0| 0| 0

110311/2000Z 62 26011KT 47.7F 0:1| 0.0|| 0.0 0.000|| 3.80 0.00|| 0.01 0.00|| 0.00 0| 0| 0

110311/2100Z 63 27010KT 47.8F 0:1| 0.0|| 0.0 0.000|| 3.80 0.00|| 0.01 0.00|| 0.00 0| 0| 0

[IsentropicLift]

No real changes with the GFS

[nzucker]

As mentioned by someone in the PHL forum, radar looks anemic at this point.

[CooL]

As mentioned by someone in the PHL forum, radar looks anemic at this point.

i knew people would start saying this and i really hope this is the last lol, its going along just as modeled..The low will continue to strengthen up the apps, combined with the strong high to the northeast setting up a convergence zone right over eastern PA and NJ with heavy rain. When every model has atleast 2" of rain within 12 hrs of start time that is a really good hint, especially since they have been locked in on this event for days

[IsentropicLift]

well said...............model spread is actually quite low and has been for days.

[CooL]

http://ruc.noaa.gov/rucnew/from_jet/ruc7t/full/2011030923/totp_sfc_f24.png

ruc 24 hr precip and its still raining

[IsentropicLift]

You can see the precip starting to fill in now over PA, it's just a matter now of how quickly it gets here

[nzucker]

i knew people would start saying this and i really hope this is the last lol, its going along just as modeled..The low will continue to strengthen up the apps, combined with the strong high to the northeast setting up a convergence zone right over eastern PA and NJ with heavy rain. When every model has atleast 2" of rain within 12 hrs of start time that is a really good hint, especially since they have been locked in on this event for days

No one is saying the banding is not going to intensify; you can already see signs of it strengthening on radar. We'll have to see if the primary banding over E PA/NJ trains over one area or just washes west-east as it weakens, that could make a substantial difference. But the two-part nature of this event and modest QPF from the 18z NAM tells me this event probably isn't going to cause historic flooding. Major flooding in isolated areas where 3" rain falls on heavy snowpack, sure. But widespread historic flooding with 4"+ rain verifying? Not likely in my opinion.

[Mr Torchey]

We shall see, but many a convective burst over the se has put an arrow thru the heart of snow weenies over the years. Time will tell, but in my humble opinion those looking for big rains.......god knows why they would under these circumstances.........should be a little concerned about the major convective eruption over the southeast thats heading east.

[CooL]

No one is saying the banding is not going to intensify; you can already see signs of it strengthening on radar. We'll have to see if the primary banding over E PA/NJ trains over one area or just washes west-east as it weakens, that could make a substantial difference. But the two-part nature of this event and modest QPF from the 18z NAM tells me this event probably isn't going to cause historic flooding. Major flooding in isolated areas where 3" rain falls on heavy snowpack, sure. But widespread historic flooding with 4"+ rain verifying? Not likely in my opinion.

strongly agree, 4"+ is way out there and will be lollipop at best imo,

[IsentropicLift]

The models have been consistent for days. We got a briefing from OEM earlier. 2" of rain would put the Pompton River where I am at about what it was last March. 4" of rain would cause historic flooding. Were forecasted by every model to recieve at least 2" of rain.

It's not just about the volume of water, you also need to look at whats going on downstream.

The Passaic River at Little Falls is still well above flood stage. The Ramapo and Pequannock Rivers flow into the Pompton River in Pompton Lakes and then the Pompton River flows into the Passaic River at Two-bridges on the border of Fairfield and Lincoln Park.

When the Passaic River is already high, it creates a natural resistance to the Pompton River. The best example is to take two hoses, flow one at 150GPM and a second at 90GPM. Then try to bisect the 150GPM flow with the 90GPM flow, it's not going to happen. The 90GPM will just get redirected. So.....when the Passaic River is really flowing, the water coming down the Pompton has no place to go and it creates almost a natural dam. In extreme cases, it can cause reverse flow.

My thoughts are, as the Pompton River begins to rise, it will get to the Two-bridges area and begin to back up since the Passaic River is well above normal flow. That also has the effect on the Ramapo and Pequannock Rivers. The flooding on Monday was stricktly based off of volume. This has the potential to be both volume and backup based.

Luckily, the Passaic River itself doesn't have any resistance, so eventually the volume decreases enough to allow for it to take some of the water from the Pompton and relieve some of the flooding first in Pompton Lakes and then in Pompton Plains and Pequannock. The last places to see relief are Pine Brook, Lincoln Park, Fairfield and Little Falls.

[nzucker]

strongly agree, 4"+ is way out there and will be lollipop at best imo,

The rain also occurs gradually which means you aren't talking about getting 4" in 90 minutes as you could with intense thunderstorms/convections in summer. Most places are probably looking at 2.5" rain over 36 hours, a pain in the butt but not life-threatening. Even though the water table is still high, the ground has dried some from a few days of March sunshine, which is strong with no vegetation in place particularly. Everything goes into drying the surface of the ground, allowing it to absorb more water.

[IsentropicLift]

The rain also occurs gradually which means you aren't talking about getting 4" in 90 minutes as you could with intense thunderstorms/convections in summer. Most places are probably looking at 2.5" rain over 36 hours, a pain in the butt but not life-threatening. Even though the water table is still high, the ground has dried some from a few days of March sunshine, which is strong with no vegetation in place particularly. Everything goes into drying the surface of the ground, allowing it to absorb more water.

You really have to live where the flooding takes place to know how the system works. In the middle of the summer when the water levels are low, sure it's going to take a massive amount of rain in a short period to cause flooding. This time of year is different. Just look at the hydrographs from Sunday and Monday and see what 3" of rain can do.

[CooL]

New nam with 3-4" in NE PA and NW jersey, with gradually less to the east towards nyc, we'll see if this sharp cutoff verifies

[IsentropicLift]

NAM looks like it's coming in wetter west of the city. Also doesn't have much of a lull as prior runs. We shall see what the text soundings look like.

[mgerb]

The rain also occurs gradually which means you aren't talking about getting 4" in 90 minutes as you could with intense thunderstorms/convections in summer. Most places are probably looking at 2.5" rain over 36 hours, a pain in the butt but not life-threatening. Even though the water table is still high, the ground has dried some from a few days of March sunshine, which is strong with no vegetation in place particularly. Everything goes into drying the surface of the ground, allowing it to absorb more water.

The amount of drying of the ground over the past few days is almost negligible. In fact, the fact that there is no vegetation means that runoff will be even more efficient. If you're talking flash flooding, then yes, the threat is not the same as you might find with summertime convection, but the river flood threat in this situation is significant.

[CT Rain]

The amount of drying of the ground over the past few days is almost negligible. In fact, the fact that there is no vegetation means that runoff will be even more efficient. If you're talking flash flooding, then yes, the threat is not the same as you might find with summertime convection, but the river flood threat in this situation is significant.

Especially given the fact some rivers in N NJ will be above flood stage when the rain begins!

Here in CT the only concern is the Housatonic River if snowmelt in the hills of W CT and W Mass starts getting out of hand like it did Sunday night.

I do think NE PA is in for some trouble.

[rgwp96]

actually started out as snow and some sleet here, temp 35

[nzucker]

New nam with 3-4" in NE PA and NW jersey, with gradually less to the east towards nyc, we'll see if this sharp cutoff verifies

I am worried about NNJ and NE PA as there is a signal for training and perhaps elevation enhancement as well, so we could see some significant rainfall amounts. For places farther east, it'll be hard to have widespread life-threatening/historic flooding since all the models seem to be weakening the band after it dumps on NJ and PA. Looks like a routine but annoying early spring rainstorm for NYC, Westchester, SW CT, and LI. The 2" we got with the last storm was enough to close down the Saw Mill Parkway for quite a while, so we'll see what another 1.5-2.0" does. NAM shows 5" of rain near the I-80 corridor in PA, which would be very damaging. Should be interesting to see how that band either trains in one area or moves along as it develops, will be fun to follow.

BTW, I'm not mocking your thoughts, Noreaster, I understand there are grave concerns in some areas. I just doubt this event will be "historic" or "life-threatening" for most of NYC metro....it could be in isolated areas, however, like where you live. I do think you're prone to exaggerate threats though, such as mentioning how the snowpack had 9" of liquid last year in March. Was probably more like 6-7" in most of the highest elevations, with 2-3" liquid at lower levels. This area is accustomed to heavy rainstorms in spring so we're not talking about a novel situation here; New Yorkers know how to handle the rain as we receive on average 45-50" liquid per year.

[nzucker]

actually started out as snow and some sleet here, temp 35

I am at 36/31 and wondering if I might see some -SN tonight at the start. 850s are warming quickly however, so the precipitation needs to get in soon.

That's the temperature downtown so I might be a tick cooler in the wooded hills. HPN at 400' is at 35F with E winds at 9mph. However, it's not so much a boundary layer issue as a mid-level warming problem, in terms of starting as frozen. I think snow will be limited to the hilly suburbs, though, as boundary layer temperatures are too warm in NYC proper, with Central Park sitting at 39/31.

[MikeS]

I have a little light snow and sleet mix falling right now here in Wayne

[rgwp96]

temp falling still,down to 34 with light snow

[ag3]

Yup. Snow/sleet mix here in Queens also.