Weekend Threat 12/14-12/15

[dbc]

What is this fetish with a 50/50 low as if it's impossible to get a big snowstorm without one?

 

The positioning of the arctic jet is doing all the dirty work here. Would it be nice to have something to lock in that high better? Yes, but then you start to walk the fine line of suppression.

It was my understanding anyway that the Euro and for that matter the GFS both did show a 50/50 low at 12z but I did not have the ability to view it for myself. Is that an incorrect assertion?

[jm1220]

What is this fetish with a 50/50 low as if it's impossible to get a big snowstorm without one?

 

The positioning of the arctic jet is doing all the dirty work here. Would it be nice to have something to lock in that high better? Yes, but then you start to walk the fine line of suppression.

Not saying it's impossible, but for at least areas near the city you want some kind of blocking in place before becoming confident of a significant snow event. But I agree, it's not do-or-die.

[bluewave]

That really strong LLJ just to our east makes me wonder if 850-800 mb temps bump above

freezing and coastal sections have sleet issues.

 

[NEG NAO]

That really strong LLJ just to our east makes me wonder if 850-800 mb temps bump above

freezing and coastal sections have sleet issues?

 

ecmwfUS_850_spd_120.gif

all depends on the positioning of different players on the field - the problem the models have been having the last 2 waves is timing - so have to wait a couple days to get any idea on timing and where each player is going to be and if they are in favorable positions to hold the cold enough 850's in place ....indicies are not favorable except for the EPO

[SnoSki14]

In these setups, we've always seemed to get colder as we get closer to the event because the models underestimate the intensity and extent of the cold air pressing down with those highs to our north. I expect the models to trend gradually further to the south and east and get colder for us if the depiction of the location/intensity of the PV is correct and the strength and extension of the highs to our north. 

 

The snow cover will add to the low level cold air at least. 

[bluewave]

all depends on the positioning of different players on the field - the problem the models have been having the last 2 waves is timing - so have to wait a couple days to get any idea on timing and where each player is going to be and if they are in favorable positions to hold the cold enough 850's in place ....indicies are not favorable except for the EPO

 

The low level cold air looks good due to the big Arctic high out ahead of the storm. Someone could also see freezing rain

if the 800-950 WAA is strong enough with a shallow cold layer just above the ground. The system looks like it will be juicy

since we are getting southern stream energy involved.

[NEG NAO]

The low level cold air looks good due to the big Arctic high out ahead of the storm. Someone could also see freezing rain

if the 800-950 WAA is strong enough with a shallow cold layer just above the ground. The system looks like it will be juicy

since we are getting southern stream energy involved.

the arctic high needs to stay north or northwest of us - what is going to hold it in place and prevent it from sliding off the northeast coast and turning the winds too much off the warmer water ? expecially considerering the combination low to the south and high OFF the coast east southeast winds turn the snow/ice to rain along the coast - inland is a different story...

[PB GFI]

That really strong LLJ just to our east makes me wonder if 850-800 mb temps bump above

freezing and coastal sections have sleet issues.

ecmwfUS_850_spd_120.gif

I thnk the 850 s hav to on the coast based on this run , But that surface is cold and has trended our way

I would like to kill the 1st max in the OH valley and die somehow keep our winds NE but 5 days out I'm

Just looking for trends for the best possible placement of any new arriving air mass thru the NE

[jm1220]

the arctic high needs to stay north or northwest of us - what is going to hold it in place and prevent it from sliding off the northeast coast and turning the winds too much off the warmer water ? expecially considerering the combination low to the south and high OFF the coast east southeast winds turn the snow/ice to rain along the coast - inland is a different story...

If there's a strong progressive pattern over SE Canada, nothing stops the high from sliding east, and we get bombarded by east winds. That's another strike against the possibility of any significant snow/wintry weather near the coast.

[Storm At Sea]

That's not really true about the indices...especially in a pattern where the EPO is negative (significantly so), the rapid rate of change of the NAO and PNA are pretty indicative of a major East Coast precip event. If the NAO was sitting pretty in the negative phase, we'd probably be watching a storm whiffing out to sea.

 

 

all depends on the positioning of different players on the field - the problem the models have been having the last 2 waves is timing - so have to wait a couple days to get any idea on timing and where each player is going to be and if they are in favorable positions to hold the cold enough 850's in place ....indicies are not favorable except for the EPO

[Storm At Sea]

Read Kocin chapter about coastal fronts and frontogenesis.

 

If there's a strong progressive pattern over SE Canada, nothing stops the high from sliding east, and we get bombarded by east winds. That's another strike against the possibility of any significant snow/wintry weather near the coast.

[Weathergun]

The low level cold air looks good due to the big Arctic high out ahead of the storm. Someone could also see freezing rain

if the 800-950 WAA is strong enough with a shallow cold layer just above the ground. The system looks like it will be juicy

since we are getting southern stream energy involved.

 

The mid-level warm air advection is often underestimated as well.

[PB GFI]

That's not really true about the indices...especially in a pattern where the EPO is negative (significantly so), the rapid rate of change of the NAO and PNA are pretty indicative of a major East Coast precip event. If the NAO was sitting pretty in the negative phase, we'd probably be watching a storm whiffing out to sea.

I agree. Just in this case when u have a flexing SE ridge sometimes u can get those huge cut offs

But ur right don't need it , in this case the PV keeps sliding fresh air masses into

New England. So I'm hoping we can get this seeded just in time

[bluewave]

The mid-level warm air advection is often underestimated as well.

 

The evolution looks a little like Valentine's Day 2007 mess that also had the primary track to our west

while low level cold air held on and the secondary hugged the coast.

 

http://www.meteo.psu.edu/ewall/NARR/2007/us0214.php

[Superstorm93]

Can't help but say that this time period has my full attention. The 12z ECMWF looks beautiful with Northern NJ seeing 12"+ from a classic Miller B

 

The fact that this is in the medium range only makes things more interesting. The ensembles will be out soon, and I'd hazard a guess they show a somewhat similar solution since they have been excited about this one for a while now. Control run had this system along the coast since about D10

 

[PB GFI]

Lastly before my wife kills me , if the Euro is right. The 2 to 3 we got today is followed by the rest of the week cold , a day 5 threat ,

day 8 threat at the BM and cold 9 and 10

For Dec that's an impressive week , u usually dont see it that often

[NEG NAO]

The evolution looks a little like Valentine's Day 2007 mess that also had the primary track to our west

while low level cold air held on and the secondary hugged the coast.

 

http://www.meteo.psu.edu/ewall/NARR/2007/us0214.php

will be interesting see if that is one of the analog storms - that was one nasty sleetfest

 

http://www.raymondcmartinjr.com/weather/2007/14-Feb-07.html

[SnowGoose69]

What is this fetish with a 50/50 low as if it's impossible to get a big snowstorm without one?

 

The positioning of the arctic jet is doing all the dirty work here. Would it be nice to have something to lock in that high better? Yes, but then you start to walk the fine line of suppression.

 

The biggest problem with this event if it happens without the 50/50 low is its a much faster event, chances are another 6-8 hour deal...today's event too is probably longer with a bit more blocking but then again not too much...as another person posted, if we had a raging -NAO right now we may very well have just been cold and dry.

[Superstorm93]

12z ECMWF Ensembles have the low over ACY instead of offshore. Bit west of the operational 

[Superstorm93]

Portion of our system will be over CA/MX in 48 hours or so (better sampling) 

 

 

 

[Austinwx]

The top CIPS analog @ 120 hours is 1/08/1994...woowee

 

http://www.eas.slu.edu/CIPS/ANALOG/stats.php?reg=EC&model=GFS212&fhr=F120&flg=

[Allsnow]

That's some really cold air on the ensembles, before the storm

[NEG NAO]

The biggest problem with this event if it happens without the 50/50 low is its a much faster event, chances are another 6-8 hour deal...today's event too is probably longer with a bit more blocking but then again not too much...as another person posted, if we had a raging -NAO right now we may very well have just been cold and dry.

who said the NAO has to be raging  ? Chances of that right now aren't good NAO hasn't approached -2 or greater in almost 2 months

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

[Superstorm93]

The top CIPS analog @ 120 hours is 1/08/1994...woowee

 

http://www.eas.slu.edu/CIPS/ANALOG/stats.php?reg=EC&model=GFS212&fhr=F120&flg=

 

 

 

.  Ice accretion from freezing rain exceeded 1 inch across much of central New Jersey, making this the worst ice storm in modern times across this part of the state.  Further north, snow and ice accumulations ranged from 2 to 8 inches.  In southern New Jersey, warm air at low levels prevented much more than trace amounts of ice and snow from falling.

[NEG NAO]

The top CIPS analog @ 120 hours is 1/08/1994...woowee

 

http://www.eas.slu.edu/CIPS/ANALOG/stats.php?reg=EC&model=GFS212&fhr=F120&flg=

that was a nightmare storm especially in areas that had black ice - driving was impossible - hope that doesn't verify

 

http://www.raymondcmartinjr.com/weather/1994/07-Jan-94.html

[Superstorm93]

...wait...who kidnapped the mets at Upton and wrote this? 

 

 

 

 

 

THEN ATTENTION TURNS TOWARD THE GULF STATES AS LOW PRESSURE
ASSOCIATED WITH SOUTHERN STREAM TROUGH MOVES NORTHEAST. PARENT LOW
REMAINS WELL TO THE WEST SATURDAY AND SATURDAY NIGHT AS COASTAL LOW
DEVELOPS NEAR THE CAROLINAS AND MOVES OFF THE MID ATLANTIC
COAST...LIKELY PASSING JUST INSIDE OF THE 40/70 BENCHMARK EARLY
SUNDAY.

THIS COASTAL LOW DEEPENS LATE THIS WEEKEND AND EARLY NEXT WEEK AS IT
TRACKS ACROSS THE CANADIAN MARITIMES. HIGH PRESSURE BUILDS TUESDAY.

AS FOR SENSIBLE WEATHER...DRY CONDITIONS EXPECTED THURSDAY THROUGH
FRIDAY. A FEW FLURRIES ARE POSSIBLE AS THE ATMOSPHERE MOISTENS
FRIDAY NIGHT...WITH THE PASSAGE OF THE FRONT.

AS FOR SATURDAY/SATURDAY NIGHT...MODELS HAVE TRENDED COLDER THIS RUN.

WITH VERY COLD AIR IS IN PLACE...SNOW WILL BEGIN SOMETIME SATURDAY
MORNING ALL LOCATIONS. WARM AIR ADVECTION WILL BE UNDERWAY...AND A
GRADUAL WARMUP IS EXPECTED TO OCCUR. EXACT DETAILS/TIMING STILL IN
QUESTION...BUT AT THIS TIME WOULD EXPECT SNOW SATURDAY GRADUALLY
CHANGING TO RAIN NEAR THE IMMEDIATE COAST...WITH PREDOMINATELY SNOW
ELSEWHERE.

SNOW ACCUMULATIONS ARE LIKELY...WITH TIME TO FINE TUNE DETAILS AS WE
GET CLOSER TO THE EVENT.

[SnowGoose69]

I took a closer look at the Euro to see if maybe its reason for being more south was that it was holding the energy over the SW too long but it does not, at 84 hours it more or less agrees with the GFS with placement over OK/TX...evolution thereafter is different, DT says he thinks the Euro is wrong due to the lack of the -NAO but an interesting note is the NAM at 84 hours is not more noably amped or north than the GFS...thi is a great comparison to use to sometimes tell when the GFS may be too far north or south with an event, you should see the NAM be decently NW of it at 84 hours, if you do not it likely means the GFS is too far north though not always...with today's event when the NAM was markedly more inland at 84 hours than the GFS it led me to believe we had a good chance of seeing snow.

[IntenseBlizzard2014]

 

 

Oh boy. I heard stories about this. I really don't want power outages this weekend.

[Allsnow]

Light snow moves in around mid morning on Saturday. 18z gfs

[NEG NAO]

...wait...who kidnapped the mets at Upton and wrote this? 

 

ScreenHunter_57 Dec. 10 16.22.png

JB maybe - but that forecast makes alot of sense at this point ........