Well, the next 7 days look like a rollercoaster with some warmer temps the next couple of days, then a major winter storm that looks mostly wet for our area Thursday/Friday, possibly ending icy/snowy, followed by very cold temps for the weekend, possibly followed by a more wintry storm next Monday. The Thursday/Friday event will be a huge snowstorm (a foot or more) for much of the Plains, Midwest/Great Lakes and then the northern tier from Cleveland to central/northern New England and possibly much further south (all the way down to I-84 on a couple of models) with a foot or more of snow on Thursday/Friday.
With regard to the main point of this thread, however, most of the models are showing heavy rain (1-2") for the Philly-NJ-NYC area, Thursday into Friday, which could lead to urban flooding due to rain + melting snow (although probably 1/2" to 1" of rain would be largely absorbed in the snowpack, especially near the coast where 12"+ of snow fell,, but more than 1" of rain would likely lead to a lot more melting/runoff), but then enough cold air coming in on Friday morning to give the northern parts of our area some freezing rain (and maybe a bit of sleet and then snow), with the freezing rain scenario being especially concerning, with maybe 0.1-0.2" of freezing rain along and N of 78.
However, two models, the UK (which has been horrible this winter) and the GFS, which has done pretty well this winter (except for Saturday), are showing a much colder solution with this “southwest flow event” (from a low approaching from the Midwest), bringing heavy rain, then a potentially serious ice storm (1/2" or more of ice accretion) as far south as 276/195 late Thursday into Friday, followed by a few inches of sleet and then snow after that – but until there is support from other models, these should be considered as outliers, like when both of these models were showing only snow for the coast 3-4 days before Saturday’s storm. In this case, though, the GFS has been rock solid on this solution for several runs and this setup is very different, as it's not a coastal low, where the GFS has a known SE track bias, plus the cold front approaching from Canada is a very strong one, so it's possible the cold air push into our area is being undermodeled by the other models, especially as they have been trending a bit colder since yesterday. So, while the GFS (and UK) is an outlier, it can't be ignored, at this time, and the evolution of this system needs to be watched very closely. Stay tuned on this one, as the models are so far apart from each other now that confidence is very low. See the NWS discussion below.
All models agree that in the wake of this storm, it gets very cold this weekend with temps possibly dipping into the single digits for many on Saturday and Sunday mornings with very cold wind chills, plus if there is any freezing rain on Friday, the ice could stick around for awhile with the very cold temps. Also, as mentioned above we have another opportunity for a winter storm to affect our area on Monday. While this one is further out, it actually has better model support for at least a moderate snowstorm for most of the area. Not worth saying much more on that one yet, as it's too far out for more than a heads up.
https://www.weather.gov/phi/
https://www.americanwx.com/bb/topic...event-some-snow-possible-far-interior/page/7/
Area Forecast Discussion
National Weather Service Mount Holly NJ
624 AM EST Tue Feb 1 2022
LONG TERM /THURSDAY THROUGH MONDAY/...
For Thursday and Friday...A strong cold front to our northwest
will gradually move into the region during this time as a wave
of low pressure tracks along it. Ahead of the front, a much
milder air mass will move in as heights continue to rise and
surface winds remain southerly. Areas mainly along and
south/east of I-95 will climb into the 50s on Thursday. Gradual
rain development from northwest to southeast is expected as the
front slowly approaches, although much of the day may remain dry
south and east of I-95. We then watch the evolution of the
front as this will be critical to the arrival time of the cold
air. Model agreement is not great regarding the evolution of
this system, with the GFS charging the strong cold front faster
southeastward which results in a much colder solution and
therefore a significant snow and ice event for at least the
northern half of the region. However, other guidance remains
warmer with mainly rain with the exception for the very far
north as the low tracks just north of us. This would bring
another round of temperatures in the upper 40s and 50s on
Friday. The GFS has been consistent the past several runs in a
farther southward push of the front/cold air. The last few runs
of the ECMWF (including the new 00z run) has been shifting ever
so slightly southward though as well, so even though the GFS
seems to be a cold outlier it cannot be completely ruled out.
With a very strong arctic high to the north of this frontal
system and at least some lingering snowpack over parts of our
region, the setup is ripe for models to display some warm bias.
For now, we continued to indicate a changeover to a wintry mix
for at least parts of our northern and western zones.
Temperatures should start to fall during Friday afternoon as
strong cold air advection surges southeastward.
For Friday night...We see the departure of the frontal system.
As the cold front moves away, arctic air will rush into the
region. The mild conditions of Thursday and Friday will be
replaced by readings in the teens and 20s. The overall evolution
of the system will determine how precipitation ends. It is
typically a challenge to get a rain to ice to snow event to
occur as the precipitation is usually tapering off or ending
before the colder air arrives. However, if the colder model
solutions are right the rain/ice/snow line will collapse towards
the coast late in the event. The further north you go, the
better the chances for a lengthier period of frozen
precipitation near the end of the system. Either way, with the
temperatures likely to be crashing, the setup looks quite
favorable for a rapid freeze-up Friday night, so we will be
keeping an eye on this.
With regard to the main point of this thread, however, most of the models are showing heavy rain (1-2") for the Philly-NJ-NYC area, Thursday into Friday, which could lead to urban flooding due to rain + melting snow (although probably 1/2" to 1" of rain would be largely absorbed in the snowpack, especially near the coast where 12"+ of snow fell,, but more than 1" of rain would likely lead to a lot more melting/runoff), but then enough cold air coming in on Friday morning to give the northern parts of our area some freezing rain (and maybe a bit of sleet and then snow), with the freezing rain scenario being especially concerning, with maybe 0.1-0.2" of freezing rain along and N of 78.
However, two models, the UK (which has been horrible this winter) and the GFS, which has done pretty well this winter (except for Saturday), are showing a much colder solution with this “southwest flow event” (from a low approaching from the Midwest), bringing heavy rain, then a potentially serious ice storm (1/2" or more of ice accretion) as far south as 276/195 late Thursday into Friday, followed by a few inches of sleet and then snow after that – but until there is support from other models, these should be considered as outliers, like when both of these models were showing only snow for the coast 3-4 days before Saturday’s storm. In this case, though, the GFS has been rock solid on this solution for several runs and this setup is very different, as it's not a coastal low, where the GFS has a known SE track bias, plus the cold front approaching from Canada is a very strong one, so it's possible the cold air push into our area is being undermodeled by the other models, especially as they have been trending a bit colder since yesterday. So, while the GFS (and UK) is an outlier, it can't be ignored, at this time, and the evolution of this system needs to be watched very closely. Stay tuned on this one, as the models are so far apart from each other now that confidence is very low. See the NWS discussion below.
All models agree that in the wake of this storm, it gets very cold this weekend with temps possibly dipping into the single digits for many on Saturday and Sunday mornings with very cold wind chills, plus if there is any freezing rain on Friday, the ice could stick around for awhile with the very cold temps. Also, as mentioned above we have another opportunity for a winter storm to affect our area on Monday. While this one is further out, it actually has better model support for at least a moderate snowstorm for most of the area. Not worth saying much more on that one yet, as it's too far out for more than a heads up.
https://www.weather.gov/phi/
https://www.americanwx.com/bb/topic...event-some-snow-possible-far-interior/page/7/
Area Forecast Discussion
National Weather Service Mount Holly NJ
624 AM EST Tue Feb 1 2022
LONG TERM /THURSDAY THROUGH MONDAY/...
For Thursday and Friday...A strong cold front to our northwest
will gradually move into the region during this time as a wave
of low pressure tracks along it. Ahead of the front, a much
milder air mass will move in as heights continue to rise and
surface winds remain southerly. Areas mainly along and
south/east of I-95 will climb into the 50s on Thursday. Gradual
rain development from northwest to southeast is expected as the
front slowly approaches, although much of the day may remain dry
south and east of I-95. We then watch the evolution of the
front as this will be critical to the arrival time of the cold
air. Model agreement is not great regarding the evolution of
this system, with the GFS charging the strong cold front faster
southeastward which results in a much colder solution and
therefore a significant snow and ice event for at least the
northern half of the region. However, other guidance remains
warmer with mainly rain with the exception for the very far
north as the low tracks just north of us. This would bring
another round of temperatures in the upper 40s and 50s on
Friday. The GFS has been consistent the past several runs in a
farther southward push of the front/cold air. The last few runs
of the ECMWF (including the new 00z run) has been shifting ever
so slightly southward though as well, so even though the GFS
seems to be a cold outlier it cannot be completely ruled out.
With a very strong arctic high to the north of this frontal
system and at least some lingering snowpack over parts of our
region, the setup is ripe for models to display some warm bias.
For now, we continued to indicate a changeover to a wintry mix
for at least parts of our northern and western zones.
Temperatures should start to fall during Friday afternoon as
strong cold air advection surges southeastward.
For Friday night...We see the departure of the frontal system.
As the cold front moves away, arctic air will rush into the
region. The mild conditions of Thursday and Friday will be
replaced by readings in the teens and 20s. The overall evolution
of the system will determine how precipitation ends. It is
typically a challenge to get a rain to ice to snow event to
occur as the precipitation is usually tapering off or ending
before the colder air arrives. However, if the colder model
solutions are right the rain/ice/snow line will collapse towards
the coast late in the event. The further north you go, the
better the chances for a lengthier period of frozen
precipitation near the end of the system. Either way, with the
temperatures likely to be crashing, the setup looks quite
favorable for a rapid freeze-up Friday night, so we will be
keeping an eye on this.
