Pittsburgh PA ❄️ Winter 2017-2018

[MikeB_01]

4 hours ago, Rd9108 said:

So I see this and my question is this says on average we get a 8-12 storm every 2 years. When was our last 8-12 storm. I remember maybe one in April a few years ago but nothing really sticks out. 

I think the late January of 2015 had a nice set up. I remember that it was a big one that we were tracking for a while. It gave D.C. almost 3 ft of snow and some people south and east of us 2 ft. I also remember it over performing a little for us from what the models predicted. I was expecting 4-6 and got 9 in my backyard.

[MikeB_01]

14 minutes ago, MikeB_01 said:

I think the late January of 2015 had a nice set up. I remember that it was a big one that we were tracking for a while. It gave D.C. almost 3 ft of snow and some people south and east of us 2 ft. I also remember it over performing a little for us from what the models predicted. I was expecting 4-6 and got 9 in my backyard.

Sorry it was January of 2106

[Mailman]

12z Euro seems to have on and off snow chances for the next 10 days (some changeover events in there).  No big events, but I'll take it in December!  

[Rd9108]

1 hour ago, MikeB_01 said:

Sorry it was January of 2106

I got like 4 or 5 inches in the city from that one. We usually atleast get one or 2 of those a year and it just seems lately that we struggle to get one. 

[north pgh]

looking like a general one inch or less of blowing snow showers tomorrow.

Wed eve and Thurs morning looking more interesting on NAM. Could be a nice 1-3 swatch across all areas.

Either way will nice to get the ground white and snow in the air. 

[Rd9108]

1 hour ago, north pgh said:

looking like a general one inch or less of blowing snow showers tomorrow.

Wed eve and Thurs morning looking more interesting on NAM. Could be a nice 1-3 swatch across all areas.

Either way will nice to get the ground white and snow in the air. 

Any sign of lake effect showers possible?

[Mailman]

Thursday looking solid.

[CoraopolisWx]

The NWS in their AFD this afternoon, even mentioned Thursdays system as having the potential to provide snow to those who don't get much tomorrow.

It almost sounded like something we would say. Lol

[Rd9108]

Gfs actually looks good for a change. Won't play out what it's showing but atleast we have some things to track. It's boring when there's nothing to track. 

[RitualOfTheTrout]

2 hours ago, Mailman said:

Thursday looking solid.

Good track for us, now to get greedy and hope it slows down a bit and gets a little juicier.

[CoraopolisWx]

54 minutes ago, Rd9108 said:

Gfs actually looks good for a change. Won't play out what it's showing but atleast we have some things to track. It's boring when there's nothing to track. 

This is a bit OT, but the TT GFS temp and snow maps seem to over do the urban heat island here in Pgh.

I think the UHI is more pronounced in the summer, but in the winter, snowfall is more elevation dependent.

[RitualOfTheTrout]

Great discussion by NWS:

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Surface low pressure is currently departing the northeastern
reaches of the area. Cold advection has already started quickly
with its passage. Thus, most all areas have seen their highs
for the day with a slowly falling temperature trend this
morning, folloed by a remarkably quicker decline this afternoon
as a secondary frontal boundary surges through the area.

Large scale deformation around the surface low tracking through
is spreading snow across areas north of its track this morning
largely in line with previous expectations, even if the snow got
started a bit later than previously projected. Temperatures in
the deformation zone quickly fall toward and below freezing with
precipitation onset, and given weak snow-to-liquid ratios
through the start of the snowfall that have always been
expected, snow accumulations from the system itself this morning
should largely be relegated to areas north of Pittsburgh.

Things rapidly change as the Arctic boundary pushes into the
area as the last vestiges of deformational ascent depart to the
east. Rapid cold advection will work to quickly destabilize the
column and saturate the dendritic growth zone. This is
evidenced by the linear band of snow activity pushing southeast
of the Michigan/Ohio border, and it will continue southeastward
through our area today. As it passes, a burst of snow in a more
unstable dendritic growth regime will be likely and rapidly
cooling temperatures along the much stronger wind gusts will
follow in its wake. This boundary would seem likely to drop up
to an inch in just about every location in the lower elevations
it passes, but the calculus looks to change dramatically as it
intercepts the terrain.

As boundary layer moisture gets progressively sandwiched into
the terrain with the incoming boundary, rapid cooling aloft and
upslope WNW flow will mean a drastically increasing snowfall
intensity late this morning. A period of heavy upslope snow
showers is likely as the -18C isotherm falls toward the
ridgetops and wind gusts increase toward 40 mph. It is possible
that local blizzard conditions will result, particularly in
Garrett/Preston/Tucker Counties, however the duration of heavy
snowfall should only continue through the afternoon as once the
immediate post-frontal instability effects are exhausted, flow
looks to be too westerly for a decent moisture feed toward the
terrain. Thus, the winter weather advisory has been maintained,
even with high snow rates expected through the daytime today, as
they should fall off tonight. Fries

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
Right as the moisture into the ridges starts to become
exhausted, yet another mid-level short wave tracks southward
across Lake Erie, which will turn our eyes farther north for the
overnight hours. An increase in inversion heights and
reorientation of the flow over basically all of the Great Lakes
starts to occur tonight. A multi-lake fetch from Lake Huron over
eastern Lake Erie is probably the moist poignant feature to
follow. In this area, with inversion heights running up over 11
kft and lake-induced troughing downstream from the lake
increasing boundary layer friction effects, a single dominant
band is suggested by both large scale and meso-models that
tracks into the northern CWA overnight into Wednesday morning.
The models are showing good consistency with this feature, and
previous discussions and headlines have captured the threat
quite realistically with the meteorology being rehashed ad
nauseum. Timing on tongiht`s runs is similar, and thus tonight
still looks like the highest accumulation period for
Venango/Forest/northern Clarion.

Elsewhere tonight, again two other bands seem to be showing up
in large scale model guidances with remarkable persistence such
that incorporating them into the forecast became a bit more
necessary. The first and probably most impactful of these is a
Superior-northern Michigan-western Erie band with a trajectory
over northern Ohio toward Columbiana, Beaver, Allegheny, and
Westmoreland Counties. Given the long overland trajectory from
the lake, it would seem substantial accumulations would be
unlikely, however the persistence in this band in guidance
coupled with an impressive instability profile have resulted in
PoPs being increased along this corridor with general snow
expectations kicked up about an inch from previous forecasts.
This includes the Pittsburgh area.

Given the first dominant banding position, while upslope snows
should be fairly minimized tonight into Wednesday for most of
the ridge locations, this many not end up being the case for the
ridges in Westmoreland County. Here again, the evolution of this
band will need to be evaluated, as any persistence of it
combined with upslope flow will necessitate an upgrade of the
current advisory to a warning.

The second band is the shore-parallel band that is currently
extending down the eastern shore of Lake Michigan that models
across suggest will traverse all the way into central Ohio and
WV as the Arctic front surges southeast by tonight. While the
consensus suggests this band will lie just to the south of our
CWA, it seemed worth mentioning here as it may play a role in
the forecast depending upon low-level wind evolution.

While flow starts to turn more southwesterly by Wednesday
afternoon, lake effect bands will quickly transition to the
northeast and out of the area. However, as warm advection begins
in earnest ahead of the next system dropping toward the area for
Wednesday night, isentropic ascent in the 290-300K layer and
strong southwesterly moisture transport will rapidly increase a
field of snowfall from west to east across the area. This will
be in advance of a surface low that the model consensus tracks
southeastward from the western Great Lakes toward the PA/WV
border during Wednesday night. Some disagreement exists on the
strength of the system, with the NAM persisting a closed low-
level center and thus stronger deformation than the
GFS/EC/Canadian, however indications are that at least modest
deformation/frontogenetical light will follow the isentropic
ascent such that a maximized swath of QPF will be likely from
northern Ohio through western PA toward the Alleghenies. Lifting
and moisture profiles suggest a much deeper moist layer and a
far higher dendritic growth region. Thus, snow-to-liquid ratios
will not be as impressive as earlier in the week, however a
gradation from 15 to 10 from N to S is suggested, and as such a
swath of winter weather advisories may be necessary as this
system dives southeastward. These will need to be covered in
future forecast updates, however, as ongoing headlines preclude
issuing them at the moment for the sake of clarity. Fries

[KPITSnow]

33 minutes ago, RitualOfTheTrout said:

Great discussion by NWS:

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Surface low pressure is currently departing the northeastern
reaches of the area. Cold advection has already started quickly
with its passage. Thus, most all areas have seen their highs
for the day with a slowly falling temperature trend this
morning, folloed by a remarkably quicker decline this afternoon
as a secondary frontal boundary surges through the area.

Large scale deformation around the surface low tracking through
is spreading snow across areas north of its track this morning
largely in line with previous expectations, even if the snow got
started a bit later than previously projected. Temperatures in
the deformation zone quickly fall toward and below freezing with
precipitation onset, and given weak snow-to-liquid ratios
through the start of the snowfall that have always been
expected, snow accumulations from the system itself this morning
should largely be relegated to areas north of Pittsburgh.

Things rapidly change as the Arctic boundary pushes into the
area as the last vestiges of deformational ascent depart to the
east. Rapid cold advection will work to quickly destabilize the
column and saturate the dendritic growth zone. This is
evidenced by the linear band of snow activity pushing southeast
of the Michigan/Ohio border, and it will continue southeastward
through our area today. As it passes, a burst of snow in a more
unstable dendritic growth regime will be likely and rapidly
cooling temperatures along the much stronger wind gusts will
follow in its wake. This boundary would seem likely to drop up
to an inch in just about every location in the lower elevations
it passes, but the calculus looks to change dramatically as it
intercepts the terrain.

As boundary layer moisture gets progressively sandwiched into
the terrain with the incoming boundary, rapid cooling aloft and
upslope WNW flow will mean a drastically increasing snowfall
intensity late this morning. A period of heavy upslope snow
showers is likely as the -18C isotherm falls toward the
ridgetops and wind gusts increase toward 40 mph. It is possible
that local blizzard conditions will result, particularly in
Garrett/Preston/Tucker Counties, however the duration of heavy
snowfall should only continue through the afternoon as once the
immediate post-frontal instability effects are exhausted, flow
looks to be too westerly for a decent moisture feed toward the
terrain. Thus, the winter weather advisory has been maintained,
even with high snow rates expected through the daytime today, as
they should fall off tonight. Fries

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
Right as the moisture into the ridges starts to become
exhausted, yet another mid-level short wave tracks southward
across Lake Erie, which will turn our eyes farther north for the
overnight hours. An increase in inversion heights and
reorientation of the flow over basically all of the Great Lakes
starts to occur tonight. A multi-lake fetch from Lake Huron over
eastern Lake Erie is probably the moist poignant feature to
follow. In this area, with inversion heights running up over 11
kft and lake-induced troughing downstream from the lake
increasing boundary layer friction effects, a single dominant
band is suggested by both large scale and meso-models that
tracks into the northern CWA overnight into Wednesday morning.
The models are showing good consistency with this feature, and
previous discussions and headlines have captured the threat
quite realistically with the meteorology being rehashed ad
nauseum. Timing on tongiht`s runs is similar, and thus tonight
still looks like the highest accumulation period for
Venango/Forest/northern Clarion.

Elsewhere tonight, again two other bands seem to be showing up
in large scale model guidances with remarkable persistence such
that incorporating them into the forecast became a bit more
necessary. The first and probably most impactful of these is a
Superior-northern Michigan-western Erie band with a trajectory
over northern Ohio toward Columbiana, Beaver, Allegheny, and
Westmoreland Counties. Given the long overland trajectory from
the lake, it would seem substantial accumulations would be
unlikely, however the persistence in this band in guidance
coupled with an impressive instability profile have resulted in
PoPs being increased along this corridor with general snow
expectations kicked up about an inch from previous forecasts.
This includes the Pittsburgh area.

Given the first dominant banding position, while upslope snows
should be fairly minimized tonight into Wednesday for most of
the ridge locations, this many not end up being the case for the
ridges in Westmoreland County. Here again, the evolution of this
band will need to be evaluated, as any persistence of it
combined with upslope flow will necessitate an upgrade of the
current advisory to a warning.

The second band is the shore-parallel band that is currently
extending down the eastern shore of Lake Michigan that models
across suggest will traverse all the way into central Ohio and
WV as the Arctic front surges southeast by tonight. While the
consensus suggests this band will lie just to the south of our
CWA, it seemed worth mentioning here as it may play a role in
the forecast depending upon low-level wind evolution.

While flow starts to turn more southwesterly by Wednesday
afternoon, lake effect bands will quickly transition to the
northeast and out of the area. However, as warm advection begins
in earnest ahead of the next system dropping toward the area for
Wednesday night, isentropic ascent in the 290-300K layer and
strong southwesterly moisture transport will rapidly increase a
field of snowfall from west to east across the area. This will
be in advance of a surface low that the model consensus tracks
southeastward from the western Great Lakes toward the PA/WV
border during Wednesday night. Some disagreement exists on the
strength of the system, with the NAM persisting a closed low-
level center and thus stronger deformation than the
GFS/EC/Canadian, however indications are that at least modest
deformation/frontogenetical light will follow the isentropic
ascent such that a maximized swath of QPF will be likely from
northern Ohio through western PA toward the Alleghenies. Lifting
and moisture profiles suggest a much deeper moist layer and a
far higher dendritic growth region. Thus, snow-to-liquid ratios
will not be as impressive as earlier in the week, however a
gradation from 15 to 10 from N to S is suggested, and as such a
swath of winter weather advisories may be necessary as this
system dives southeastward. These will need to be covered in
future forecast updates, however, as ongoing headlines preclude
issuing them at the moment for the sake of clarity. Fries

Great discussion! It seems that puts out detailed, in depth discussions all the time.

[dj3]

Tomorrow night looks promising. A nice cold event, hopefully it ends up over-performing. I’d love to have something to track around the holiday so hopefully the long range look trends a bit colder as the signal for precip seems stronger during the period. 

[Rd9108]

NAM sucks this one is dying. 

[blackngoldrules]

NAM sucks this one is dying. 

What else is new. Lol

Sent from my SM-G920P using Tapatalk

[Rd9108]

Just now, blackngoldrules said:

What else is new. Lol

Sent from my SM-G920P using Tapatalk
 

Now that I think about it it's not as bad as I thought. It all depends on the ratios. I doubt they will be 10 to 1

[Longdong]

8 minutes ago, Rd9108 said:

Now that I think about it it's not as bad as I thought. It all depends on the ratios. I doubt they will be 10 to 1

What’s it saying?

[KPITSnow]

7 minutes ago, Rd9108 said:

Now that I think about it it's not as bad as I thought. It all depends on the ratios. I doubt they will be 10 to 1

 

As usual, we are fringed. Best qpf is north. 80 north could get 3 to 5 inches while we are closer to 1-2 unfortunately. 

[MikeB_01]

1 minute ago, Rd9108 said:

Now that I think about it it's not as bad as I thought. It all depends on the ratios. I doubt they will be 10 to 1

Honestly, I think this run should be rejected in a sense.  Not that it was a bad run, the L is a little stronger, the precip just wasn't there. The important thing is that we still have the same general idea from the system. Keep it where it is and we can nowcast. Hopefully over producing. 

SREF is showing 2-3 and so is the GEFS. Hoping for 4 

[Mailman]

[Rd9108]

RGEM looks great

[KPITSnow]

4 minutes ago, Rd9108 said:

RGEM looks great

Images?

[Mailman]

18z GFS looks better than the RGEM (although I guess that depends on where you are).

GFS:

RGEM:

[jwilson]

On the fringes to the North and East.  Not really expecting much from this thing.  In a season without the southern jet, I probably should get used to this.

[RitualOfTheTrout]

Anyone been under that persistent band cutting through Allegheny county? When I left work there was about a 1.5 - 2 inches on the ground. By the time I got home saying I have a dusting would be generous. It's literally about 10 miles south of me, hoping it pivots to the north for a bit.

 

As for tomorrow, I think 2-4 looks good right now. Don't like seeing that cutoff in extreme SW corner of PA.

[north pgh]

2 hours ago, RitualOfTheTrout said:

Anyone been under that persistent band cutting through Allegheny county? When I left work there was about a 1.5 - 2 inches on the ground. By the time I got home saying I have a dusting would be generous. It's literally about 10 miles south of me, hoping it pivots to the north for a bit.

 

 

As for tomorrow, I think 2-4 looks good right now. Don't like seeing that cutoff in extreme SW corner of PA.

I was under one of those bands and picked up a solid inch between 4 and 6. Roads weren't too bad but traffic was horrible. 

[ChalkHillSnowNut]

I’ll tell you what I was just out shoveling our 1” of snow-lol and it’s freaking COOOLD!!...wish we could hang on to the cold for Christmas but that weekend leading up looks like rain/snow mix....

[blackngoldrules]

47 minutes ago, ChalkHillSnowNut said:

I’ll tell you what I was just out shoveling our 1” of snow-lol and it’s freaking COOOLD!!...wish we could hang on to the cold for Christmas but that weekend leading up looks like rain/snow mix....

I was just outside shoveling our dusting of snow, and agree that it's freaking COOOLD!!!!!

[CoraopolisWx]

3 hours ago, RitualOfTheTrout said:

Anyone been under that persistent band cutting through Allegheny county? When I left work there was about a 1.5 - 2 inches on the ground. By the time I got home saying I have a dusting would be generous. It's literally about 10 miles south of me, hoping it pivots to the north for a bit.

 

 

As for tomorrow, I think 2-4 looks good right now. Don't like seeing that cutoff in extreme SW corner of PA.

Checking out the traffic cams this afternoon, I noticed the 28 corridor was almost bare in many spots.

I thought at first the images were from yesterday, but it was actually real time.

There must've been a pocket of dry air in that area, causing the low amounts.