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February 11 -12 Winter Storm Threat


NEG NAO

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Very nice discussion from the NWS-Philly office...

National Weather Service Mount Holly NJ
356 PM EST Sun Feb 10 2019

NEAR TERM /THROUGH MONDAY/...
High pressure located off the Middle Atlantic coast this afternoon
will continue to drift southeastward tonight and Monday. Weak warm
advection on the back side of the high is expected to affect our
region tonight. Arctic high pressure sliding from Ontario to Quebec
should begin to nose down into our area on Monday.

Light precipitation approaching from the Ohio River Valley is
expected to overspread our region late this evening. We are
anticipating light snow in eastern Pennsylvania, and in northern
and central New Jersey. Snow, sleet and freezing rain are expected
for northeastern Maryland, Delaware and southern New Jersey. The
mixed precipitation should change to all rain in the Maryland
counties of Talbot and Caroline, the southern half of Delaware and
Cape May County in New Jersey toward morning.

The precipitation is forecast to end on Monday morning across most
of eastern Pennsylvania, and northern and central New Jersey. The
light wintry mix should linger during the morning in parts of
northeastern Maryland, Delaware and southern New Jersey.

As broad low pressure begins to approach from the west, the
precipitation will begin to spread back to the north on Monday
afternoon, with light snow returning to eastern Pennsylvania, and to
northern and central New Jersey. A light wintry mix, favoring rain,
should continue in our southern counties.

The expected snow totals in the northern half of our forecast area
for tonight do not warrant an advisory. We will keep the Winter
Weather Advisory in place for the southern half of our region from
1000 PM this evening until noon on Monday. We have expanded the
advisory to include the Maryland counties of Talbot and Caroline,
and Sussex County, Delaware (except for the beaches) due to the
expectation of a light glaze of ice in parts of those counties.

Low temperatures for tonight should favor the 20s and lower 30s with
a light and variable wind. A northeast wind around 5 to 10 MPH is
forecast to develop on Monday. High temperatures will likely be in
the 30s.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
This portion of the discussion will focus on the 2nd of the one-two
punch.

Synoptically...The period starts with a warm front well to our south
and high pressure centered well to our north. The front will be
attached to a low west of the Mississippi. This low will track
northeast and be positioned near the Great Lakes 24 hours later, on
Tuesday evening. At this time, a secondary low will develop near the
coast of NJ and track northeast Tuesday night.

Impacts...This event will cross the Tuesday morning commute as well
as the Tuesday evening commute. For the I95 corridor, the morning
commute will experience the most impacts. Further north and west,
the morning commute will be a snowy one and the evening one could be
a mixed bag of snow, ice and freezing rain.

Headlines...Winter Storm Watch posted for the southern Poconos and
NW NJ to account for both the snow and ice.

Snow/sleet amounts...Ranging from 5 to 8 across the Southern Poconos
and NW NJ, 3 to 5 across Berks and the Lehigh Valley, then 2 to 4
down to I95. 1 to 2 when you cross the river into NJ and also for
northern Delmarva. An inch or less south and east of there.

Freezing rain...Tricky here at this point and depends on the
strength of the low-level warm nose. For now, have .2/tenths of
ice across the Southern Poconos and NW NJ, .1 to .2/tenths
across Berks, the Lehigh Valley and Morris County in NJ, a trace
to a .1/tenth down to the urban I95 corridor, and then a trace
south of there. Cape May county and Sussex county may not see
much snow or ice at all.

For the Poconos and NW NJ, it`s not out of the realm of
possibility of receiving more ice. Some of the forecast
soundings over the last two runs have up to .4/tenths.

Rain...Not sure the Poconos will ever go over to all rain. The
Lehigh Valley and Berks are forecast to change over late Tuesday,
and the urban corridor around midday Tuesday.

QPF...This is not a weak/dry system. Total QPF, when all said
and done will be between 1.00 and 2.00 inches. Where the ptype
is mainly liquid, expect minor flooding in the most prone areas.
Even across locals that get accumulating snow, moderate to
heavy rain is possible after the changeover.

Transitions...As stated, the frozen/freezing may never change over
across the far north. For the Lehigh Valley, going with all snow
Monday night into Tuesday morning and transitioning to all rain
Tuesday afternoon. Across the urban and I95 region, going with snow
Monday night to a mix by daybreak Tuesday, followed by all rain in
the afternoon. The Tuesday morning commute looks nasty for this
area. Across the coastal plain and our southern Delmarva zones,
going with snow to rain on Monday night. Looks like all rain here
Tuesday and Tuesday night.

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6 minutes ago, Snow88 said:

It's either going to be all snow ending as sleet or all rain with some sleet.

It’s hard to see the second scenario playing out given the high and how consistently the Euro has been.  We aren’t seeing any major warming trend like we did as we approached the last event  

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11 minutes ago, snowman19 said:

The new RGEM is showing a mid-level furnace all the way up to Albany. Way different than what the GFS is showing. https://www.tropicaltidbits.com/analysis/models/?model=rgem&region=neus&pkg=T700&runtime=2019021018&fh=54

1) It's the warmest model right now

2) It's at hour 54 which is at end of it's range

3) Its not a furnace for a large portion of posters north of city. I am right on zero line at 7pm Tuesday after about 6-8 hours(or more) of snow. 

4) stop speaking in absolute terms. There is so much that is undetermined at this point with thermal profiles. 

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20 minutes ago, snowheavyattimes said:

Maybe they’re including sleet.

Seems to be at odds with the Mt Holly discussion RU posted at least near I95 corridor; unless they are expecting an intense 2-4 before a changeover, which they state will happen shortly after dawn....either we sleet all day, which at least one red tagger here doubts, or we go to rain. The only certainty I come away with is that it will rain at some point. This looks like every storm of the early 90's. And there's talk of flooding. ugh.

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4 hours ago, SnowGoose69 said:

The setup was nowhere near as good.  High wasn’t a one piece anchored high.  It was a sprawled our high with the neck positioned too far west across Quebec so you just didn’t get the proper CAD signature.  Also the air mass wasn’t as good in place ahead of the storm

Exactly I'm a realist and usually lean toward cautiously pessimitic but even I can see this setup is different

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1 hour ago, Snow88 said:

It's either going to be all snow ending as sleet or all rain with some sleet.

I don't think it's either of those, definitely going to be snow, sleet and rain but the question is which precip type we get the most of. My guess is rain for the city on SE but I do think this is not a non event on the frozen side during the day on Tuesday.

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35 minutes ago, snowman19 said:

The new RGEM is showing a mid-level furnace all the way up to Albany. Way different than what the GFS is showing. https://www.tropicaltidbits.com/analysis/models/?model=rgem&region=neus&pkg=T700&runtime=2019021018&fh=54

It totally blew the MLK storm doing the same thing.  I’ve noticed that the RGEM along with the UKMET have been bad this winter 

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5 minutes ago, Snow88 said:

Radar looks very good for tonight

 

I have no clue how this is going to miss but everything misses this winter.

Yea it seems that the immediate NYC region and LI (and further up to Boston) have been the real snow losers of this winters pattern with either being cold but too far north due to dry air / confluence or being too warm per the storm track. 

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This is a 'learning winter', where we all learn humility.

Fact is no model set has performed either consistently or reliably this winter, at least for the NYC area.

Given that there is plenty of computer power available to throw at these problems, it suggests that there are real shortcomings in the models the forecasts are based on. Hope that the folks at NOAA and elsewhere recognize this and try to rework these fundamentals, because until that happens, things will not improve.

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1 minute ago, etudiant said:

This is a 'learning winter', where we all learn humility.

Fact is no model set has performed either consistently or reliably this winter, at least for the NYC area.

Given that there is plenty of computer power available to throw at these problems, it suggests that there are real shortcomings in the models the forecasts are based on. Hope that the folks at NOAA and elsewhere recognize this and try to rework these fundamentals, because until that happens, things will not improve.

The 80's were " learning winters"...we learned how to survive with almost no snow...

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3 minutes ago, etudiant said:

This is a 'learning winter', where we all learn humility.

Fact is no model set has performed either consistently or reliably this winter, at least for the NYC area.

Given that there is plenty of computer power available to throw at these problems, it suggests that there are real shortcomings in the models the forecasts are based on. Hope that the folks at NOAA and elsewhere recognize this and try to rework these fundamentals, because until that happens, things will not improve.

This isn’t a static system. People think that the models are ‘static’. You build them and they work. That’s not the case. They are always changing and improving. The problem is the environment is also always changing. It is is like trying to hit a bulleye when the dart board is moving. The further you stand from that dartboard represents the longer range, meaning it is very hard. They will definitely use all seasons as learning experiences to improve the models. 

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15 minutes ago, Snow88 said:

Radar looks very good for tonight

 

I have no clue how this is going to miss but everything misses this winter.

Meteorologist Jeff Smith did mention the snow struggling to get into our region due to dry air. Maybe we'll be pleasantly surprised overnight. I'm so snow starved I would sign up for an inch. How depressing.:(

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