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March 20th-22nd Suppressed, Fish, Not Coming Threat

Rjay

By Rjay,
in New York City Metro

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The Iceman

The Iceman

Posted
Posted
1 minute ago, tempestatis014 said: 

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Complex storm system consisting of multiple coastal lows are
expected to impact the region on Tuesday and Wednesday. The
extent of the impacts are yet to be determined...

Forecast models continue to exhibit poor run-to-run continuity
as they struggle to handle the complex interactions between the
train of shortwave troughs ejecting from western North America
(there are at least four distinct disturbances seen on water
vapor satellite imagery that will come into play).

There continues to be disagreement with the idea that the
midweek event will consist of two distinct waves of precip
(round 1 Tuesday-Tuesday night and round 2 Wednesday) with
enough separation distance between the two coastal lows to
allow for a break in the precip late Tuesday afternoon and
night.

Round (1)- Tuesday and Tuesday Night...

The latest trends point toward a favorable synoptic pattern for a
big winter snowstorm for our region. However, there are several
factors working against that notion at least for the first part of
the event:

(1) A high sun angle in late March and marginally cold surface
temperatures (especially I-95, S/E) will make it very difficult for
snow to accumulate effectively during the day time unless the rates
are moderate to heavy. Aside from the initial band of overrunning
precip that targets the southern half of the forecast region Tuesday
morning-early afternoon, the consensus from the 00Z guidance is for
the precip to be light through Tuesday night.

(2) A key ingredient in this event in the position of the high,
which is forecast to be located over northern Ontario and a bit
farther northwest than what is ideal for an all snow event,
especially along and S/E of I-95. Consequentially, warm air aloft
wrapping cyclonically around the system should advance into the S/E
portion of the region. This would imply mainly rain in SE PA, C/S DE
and E MD (along and south of the Delaware Bay) through at least
Tuesday evening with a mix of rain/sleet/snow nosing close to
Philadelphia (especially its S/E suburbs).

(3) While areas farther N/W of the city favor snow Tuesday and
Tuesday evening, precip amounts quickly taper off as there should be
a sharp cutoff on the northern edge of the precip shield.

Accordingly, snowfall accumulations are around an inch or less for
Tuesday; same for Tuesday night. The exception is the higher
elevations (above 400 ft) in SE PA and Cecil County, MD where 1-2"
of snowfall is possible each period. A Winter Weather Advisory
may be needed for these areas.

Round (2)- Wednesday...

This is the period of greatest concern for a potentially significant
snowfall is Wednesday. This is also the period of greatest
uncertainty. The 00Z ECMWF and UKMET have shifted considerably
toward a high-impact event with warning-level snowfall accumulations
and windy conditions as the second coastal low takes a track closer
to the coast. The NAM and GGEM showed a similar snowy scenario but
the latest 00Z runs have backed off from that idea. The GFS is
somewhere in between but generally shows a minor event. There
continues to be a large spread among the GFS, ECMWF and GEM ensemble
prediction systems. All this equates to is a high degree of
uncertainty. We`ve seen models trend northwest closer to the event
with several significant snows in recent years, so it`s a bit
premature to rule out this scenario. Given the uncertainty, the
probabilistic snowfall graphics (available on our winter webpage)
provide much more value than any deterministic forecast. IF the high-
end snowfall scenario were to verify, extensive tree damage and
power outages could occur once again.

NWS in Mt. Holly still being negative with this thing, although they upped the totals to 3-5 for the region

After last march's massive bust for them, I don't blame them at all for playing this one conservative. They looked awful during that storm downgrading from 16-24" to 4 to 8" two hours before the event was over and was clearly busting huge hours before that update. Their current graphic is perfect for the uncertainty this far out. I doubt they forecast huge totals until the event is under way and it's clear the conservative forecast is too low. Too many variables in late March to be confident in widespread big totals.

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Animal

Animal

Posted
Posted
1 minute ago, The Iceman said:

After last march's massive bust for them, I don't blame them at all for playing this one conservative. They looked awful during that storm downgrading from 16-24" to 4 to 8" two hours before the event was over and was clearly busting huge hours before that update. Their current graphic is perfect for the uncertainty this far out. I doubt they forecast huge totals until the event is under way and it's clear the conservative forecast is too low. Too many variables in late March to be confident in widespread big totals.

Great write up imop.

there may not even be a storm 2

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CIK62

CIK62

Posted
Posted

The expected for NYC is 4" and the 10% mark is virtually the same at 5".  Looks like they have (NWS) little confidence with this double talk.  Again, as with all these storms, they give us a 90% chance of beating 0".

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SnowGoose69

SnowGoose69

Posted
Posted

The timing of the event may prevent it from being as big as it could if it occurred at night.   It’s colder than the previous events but this time of year you need 27-28 or colder during the day to really avoid melting on pavement and even on colder surfaces as well 

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MJO812

MJO812

Posted
Posted
1 minute ago, SnowGoose69 said:

The timing of the event may prevent it from being as big as it could if it occurred at night.   It’s colder than the previous events but this time of year you need 27-28 or colder during the day to really avoid melting on pavement and even on colder surfaces as well 

We still don't know yet how big this storm will be.

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sferic

sferic

Posted
Posted
5 minutes ago, SnowGoose69 said:

The timing of the event may prevent it from being as big as it could if it occurred at night.   It’s colder than the previous events but this time of year you need 27-28 or colder during the day to really avoid melting on pavement and even on colder surfaces as well 

Was April 1982 in NYC 20's or did persistence  of high rates overcome ground resistance?

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purduewx80

purduewx80

Posted
Posted

09Z SREF mean is not all that different from the 03Z. Still a huge spread, but QPF in the NYC area is near 1.2" on the mean with snow totals on either side of 6". It did trend slightly colder but plenty of members have mixed precip types, which is why snow is only half of QPF.

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purduewx80

purduewx80

Posted
Posted

plumes are a nice way to look at the trends and to find any clusters:

SREF - http://www.spc.noaa.gov/exper/sref/srefplumes/

GEFS - http://www.emc.ncep.noaa.gov/gc_wmb/tdorian/gefs/EMCGEFSplumes.html

Still a lot of spread on both, as you'd expect, but the GEFS mean nearly doubled snowfall at LGA from the 00 to 06Z run. There is a substantial cluster in the 7-9" range.

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larrye

larrye

Posted
Posted

So I get that the models have trended northward over the past 24-48 hours. But has anyone taken a look specifically at surface temps in NYC + precip intensity + the amount of progged snowfall during the day vs. night (at least as progged currently) to see if the precip is likely to accumulate? SnowGoose69 makes the point that this time of year, you really need low surface temps + we all know that sun angle and ground level warmth play directly into the forecast.

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Stormlover74

Stormlover74

Posted
Posted
Just now, larrye said:

So I get that the models have trended northward over the past 24-48 hours. But has anyone taken a look specifically at surface temps in NYC + precip intensity + the amount of progged snowfall during the day vs. night (at least as progged currently) to see if the precip is likely to accumulate? SnowGoose69 makes the point that this time of year, you really need low surface temps + we all know that sun angle and ground level warmth play directly into the forecast.

The gfs and Euro have temps in the 30 to 32 range so this is considerably colder than 2 weeks ago. We still need good rates of course but this airmass is a lot better

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Stormlover74

Stormlover74

Posted
Posted
6 minutes ago, tempestatis014 said:

12z should be coming out within the next hour correct?

Add an hour for dst

time model starts to run

 

GFS: 10:30; 4:30 (AM/PM)

GEFS (Eneembles):   12:00, 6:00 (AM/PM)

NAM: 9:00, 3:00  (AM/PM

SREF:  8:20, 2:20 (AM/PM)

RGEM: 10:20, 4:00 (AM/PM)

GGEM (CMC):  11:00 (AM/PM

UKMET:  10:40 (AM/PM)

ECMWF (Euro/ECM):  12:45 (AM/PM)

ECM ensembles:  3:00 (AM/PM)

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SnowGoose69

SnowGoose69

Posted
Posted
15 minutes ago, NJwx85 said:

The number 1 & 2 analongs over the East at 48hrs are 2/17/03 and 2/11/83 respectfully. 2/6/10 is number 5.

http://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=EC&fhr=F048&rundt=2018031900&map=thbCOOP72

The first piece has 03 similarities while the 2nd is more similar to 83.  The first one has that relatively weak low with an overrunning signal while the 2nd piece is basically a non phaser self amplifying shortwave similar to 12/09 and 2/83.

The whole setup combined though may be closest to December 2003 

 

 

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