OT: Snow Thread For Feb 6th & 7th Super Bowl Sunday
- Thread starter Tango Two
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When my parents moved to New Brunswick at the end of the 50's, the phone numbers were KI5 and a lot of businesses put Kilmer5 on their stationary and such.
Mt. Holly and Upton still have all their warnings, but they trimmed snowfall back to the bare minimum that could ever justify warnings, i.e., 3-6" for the NJ counties along the 95 corridor in NJ/EPA from Wilmington up through SE Bucks/Montco and Mercer/Middlesex/Somerset (for Mt. Holly, where 4" is the criterion for a warning for counties S of 276/195, i.e., Philly-Burlington-Ocean and south) and the warnings are for ~6" of snow for NENJ (Union up to Bergen)/NYC metro/Nassau and 5-8" for Suffolk/E CT.
Would love to know if they saw the 6Z NAM before issuing, as the 6Z NAM is back to where the 18Z was ,showing the 6" line running right up the Delaware from Philly to Trenton and then to NYC and 4-6" for 20-25 miles NW of there and 6-7" SE of there. But the RGEM showed a general 1-3"/2-4" event still at 6Z and the GFS is still 2-4" for most, so who knows. NWS-Philly's discussion is below. Ok, back to sleep, lol.
National Weather Service Mount Holly NJ
305 AM EST Sun Feb 7 2021
NEAR TERM /THROUGH TODAY/...
Summary: A quick hitting winter storm will impact the area today,
with most of the precipitation confined to the daylight hours.
Meteorological Overview: Latest sfc. analysis depicts an area of
weak (but deepening) low pressure off the South Carolina coast,
while on water vapor a mid-lvl shortwave trough was evident upstream
of this feature over southern Tennessee. This low is progged to
quickly move NNEwrd during the day today, with the low intensifying
significantly as it moves underneath the right-entrance region of a
strengthening UL jet. To highlight both the rapid intensification
and quick forward speed of the low, by this time tomorrow it is
progged to have a central pressure around 975 mb, and be located in
the Canadian Maritimes. Precipitation will overspread the area from
SW-NE this morning, as ascent increases in association with the
incoming shortwave, the UL jet, and finally (and most importantly) a
region of 600-700mb FGEN associated with the axis of the 700mb wave.
Current observations: A deck of thick cirrus blankets our area, with
light winds and temperatures ranging from around 20 in the Poconos
to the low 40s in Delmarva. Of importance to ptypes, sfc. wet-
bulb temps range from the low teens in the Poconos to the mid
30s in Delmarva, with most of the area seeing Tws in the mid 20s
to low 30s. As of 2 AM, Rain has (based on ASOS obs and mPING
reports) nearly reached the MD/VA border, with snow being
observed in western Virginia and North Carolina. Some radar
returns (aloft) are approaching southern Delmarva, but these
will likely just be virga initially due to the dry low-lvls
Forecast:
Timing... In general the system`s timing looks very similar to what
was advertised in previous forecasts, with precipitation entering
our area early this morning and moving out of the area between 5-
7PM. The heaviest precipitation looks to impact the area from mid-
morning to early afternoon.
Precipitation Types... Very similar to thinking to previous
packages, i.e. almost all snow NW of I-95, mostly snow but some rain
mixed in during times of lighter precip rates near I-95, and then a
messier rain/snow mix likely towards the coast.
Precipitation & Snow Amounts... Forecast QPF amounts were heavily
based towards the 00Z HREF Probability-matched mean and WPC
guidance, resulting in a forecast of 0.2-0.5 inches of water from I-
95 northwestward and 0.5-0.9 inches of water from I-95 to the coast
with the QPF gradient oriented SE. These amounts are about 25% lower
than the previous forecast, and physically this reduction primarily
stems from the consensus low position being a bit further east/less
amplified, which keeps most of the "prime" FGEN forcing confined
near the coast, with weaker (more synoptic-driven) lift NW of I-95,
along with perhaps some compensating subsidence on the cool side of
the boundary. All that being said, our fcst QPF is still about 50%
higher than most of the coarser guidance (which generally have about
0.1-0.5 inches of total liquid) as suspect these are underplaying
the heavier rates present in the FGEN band.
All the above discussion leads us to the most important forecast
element of the day... snow amounts. The reduction of QPF naturally
did contribute to a reduction of snow amounts across the board.
Generally have 3-6 inches along and near I-95, with the axis of
higher amounts tilting SEwrd a bit to account for the FGEN band`s
positioning towards the Coast. Amounts are largely 2-3 inches I-78
and northward, and a sharp gradient remains present near the coast,
due to the ptype concerns there. These snowfall amounts are still a
bit above consensus... probably a nearer to the 75th percentile
outcome than the 50th. The general reasoning for leaning on the high
side is that the potential for locally heavy snowfall does exist,
particularly near or just SE of I-95 where the mesoscale lift
associated with the FGEN band will be favorably placed within the
DGZ. Heavy rates associated in this zone would result in better
ratios and accumulations despite the marginal temperature profiles.
All that being said, would not be shocked to see this being a mostly
2-4 inch event near I-95, with some total "shutout" potential in
Delmarva and along the NJ Coastal Plain if rates never get high
enough to compensate for the poor thermal setup. Up north, QPF looks
to be the main limiting factor, but typically in these events
(provided there is not a dry arctic airmass in place), the
precipitation shield extends a bit further northward than progged.
Therefore am not totally gutting amounts up there despite some
models having only about 0.1 inch of QPF.
Despite lowering amounts, have no plans to significantly modify
headlines as the heavier rates may make up for (from an impact
perspective) total snow amounts potentially being under official
warning criteria.
Woke up to light snow and a coating at 8:50 am to 1" by 9:20 am - that's about 3/4" in the past 30 minutes. Literally pouring huge gorgeous supersaturation-driven dendrites right now. Down to 32F with roads covered. Looks like this could overperform vs. the 0Z models last night. The NAM has been verifying well to our south, so if it's correct, the NWS made a good call in not dropping the warnings for most. We'll see
Absolutely. Snow ratios must be 12-15:1 right now, which will get us to 6" in 4-5 hours at this rate and if the ratio is maintained (which is not a given). On a serious note, many people think snow ratios are a product of temperature. Wrong, they're mostly a product of conditions in the dendritic growth zone 10,000 or so feet up, i.e., ratios are made in the clouds not at the ground. When one has a decent level of supersaturation in the DGZ, driven by strong vertical lift of warm/moist parcels of air from far below, and the DGZ is at the perfect -10 to -20C temperature, that will absolutely lead to heavy vapor phase deposition on seed snow crystals (and even pure nucleation without seeds) and fast crystal/flake growth and high ratios. FWIW, I have a few crystallization patents on organic molecules and crystallization is basically crystallization, whether in a flask or a cloud.
Started at about 9am on the nose here in Little Falls and is sticking to untreated surfaces immediately. Fairly strong. Don't think the streets will hold it off for long.
Most of the models had light snow north of the Raritan right now. They're wrong. This could easily meet the NWS forecasts (at this rate).
As of 9:50 am we have 1.75" on the ground, which is 1.5" per hour rates and it's down to 31F. Snowing moderately to heavily now (smaller flakes, so probably lower ratios now).Woke up to light snow and a coating at 8:50 am to 1" by 9:20 am - that's about 3/4" in the past 30 minutes. Literally pouring huge gorgeous supersaturation-driven dendrites right now. Down to 32F with roads covered. Looks like this could overperform vs. the 0Z models last night. The NAM has been verifying well to our south, so if it's correct, the NWS made a good call in not dropping the warnings for most. We'll see
This post won't age well. Par for the course.
Just do the walk, I don't have any pedestrian walkways in my area as it's all small farms. But it's an icy pothole(where it didn't melt) mess now.
Anyway it just changed over to snow here in Howell not even a dusting on the ground as it's all melting. I'm hoping for either a change back to rain or a quick end.
the pavement is litted with cotton balls..almost 2 inches in the last hour alone
better rates than last storm for me
better rates than last storm for me
The HRRR has this winding down maybe around 3
of course these snowfall rates will not be sustainable the entire time and some will be substinence and some will see rain toward the coast
of course these snowfall rates will not be sustainable the entire time and some will be substinence and some will see rain toward the coast
As of 10:20 am, we're up to 2.5" OTG, which continues our 1.5" per hour rate and it's still 31F. While the ratio is decent with good dendrites, the snow is wet enough to pack well, so it's almost snowman time, lol.
A friend on FB is reporting 5" in Flemington. They did have that very heavy band out there...
1 foot possible?????? Just measured. 4ninches in Hillsborough. If this goes to 4pm no doubt 10 to 12 inches possibe.
The HRRR has been awful for this storm, never showing more than 2-3". I also am not sure we'll see that much subsidence, since this storm seems to have a more homogeneous precip field and less banding than last week's storm.
If it snows at 1.5" per hour until 3 pm, I'll have 10" on the ground. Unlikely, but possible. I'm thinking my original call for 6" in Metuchen will now verify - wasn't confident of that last night at all. It is back to puking huge flake heavy snow here.
