Update #3: Final Snow Map, Ice Accretion, Flash Freeze

Hey I was just reading forecast discos from Mt. Holly/Binghampton, and they said that the GFS is over-amplifying the system, while the EURO seems to be a little too cold. They are going with a "middle of the road approach, which follows the NAM". Interesting.

"A FRONTAL BOUNDARY WILL BE STALLED FROM WEST TO EAST ACROSS THE
REGION AS LOW PRESSURE RIDES ALONG THE BOUNDARY. PLENTY OF MOISTURE
AND UPPER LEVEL WARM AIR WILL CONTINUE TO BE DRAWN NORTH AND RUNG
OUT ALONG THE FRONTAL BOUNDARY. THIS MAY LEAD TO
POTENTIALLY MODERATE TO HEAVY PERIODS OF PRECIPITATION MONDAY
MORNING. THE RAIN/ WINTRY MIX LINE WILL SLOWLY MOVE NORTH FROM THE
NORTHERN SUBURBS OF PHILADELPHIA TOWARD THE LEHIGH VALLEY AND
CENTRAL NJ FROM 12-15Z. A SECONDARY LOW MAY FORM OFFSHORE AS WELL
DURING THE MORNING WHICH COULD ALLOW COLD AIR TO ADVECT IN AT THE
SURFACE DURING THE LATE MORNING AND AFTERNOON, NON-DIURNAL
TEMPERATURE TREND. MAV AND MET BOTH APPEAR TO WARM MONDAY AFTERNOON
BUT THE ECMWF TWO METER TEMPERATURES LOOK TO COLD. THE CAA WOULD
STOP THE NORTHWARD ADVANCE OF THE CHANGEOVER TO RAIN BY MID MORNING. A WARM
NOSE MAY MAKE ALL THE WAY INTO THE POCONOS AROUND SUNRISE MONDAY IF
THE 00Z GFS SOUNDING IS TO VERIFY, SO HAVE ADDED SLEET INTO THE
EQUATION HERE. THE PRECIPITATION TYPE FORECAST IS MAINLY DERIVED
FROM THE 00Z NAM. THE 00Z GFS LOOKED TO HAVE TO INTENSE OF A LOW
PRESSURE SYSTEM WHICH IN TURN ALLOWS FOR MORE WARM AIR ADVECTION.
THE ECMWF IS STILL ON THE COOLER END OF THE SPECTRUM WITH THE NAM IN
BETWEEN THESE SOLUTIONS. THE SREF AND WPC QPF FORECAST WAS USED AS
WELL WITH GOOD MODEL AGREEMENT ON QPF IN THIS PERIOD. THIS RESULTS
IN ADDITIONAL SNOW AND ICE ACCUMULATIONS FOR NORTHERN PARTS OF THE
CWA IN THIS PERIOD. ALSO, SOUNDINGS INDICATE THE POTENTIAL FOR SOME
30 MPH NORTHWEST WIND GUSTS MONDAY EVENING AS WELL."

jmanley32 wrote:Accuwx is calling for .3 ice accretion for my area, what is the criteria for a ice storm warning my bad I thought it was 0.25 or above, are u starting to believe this will not be a issue or is it pretty much a nowcast?  I want to let my friends and family what to expect for the morning commute, but from I have read and your great analysis Frank seems like a big ?

we will have several inches of snow otg when it changes to sleet and then fzr for a very brief period before going to plain rain. the snow will minimize the fzr threat as it will absorb most of it. any treated roadway should not be a problem with temp around 32* and occurring during daylight. some one on here mentioned and I agree wide spread fzr happens rarely around here. actually i'm glad its turning to rain as I loathe fzr. still wishing it some how stays all snow but looks unlikely

If someone has the H-D 12z EURO snow, could you please post? I'm curious. Thanks!!!

Here's the low-res one based on 10:1:

http://images1.earthsat.com/misc/mod-images/ECM/OP/12/snosums/0024/ECM_12_opUS_SF_0036.png

temps really soaring today most in the 30's now and not likely to drop until precip stars falling late tonight. I knew we were in trouble when temps in cpk rose from 20 to 24* between midnight and 5am.

rb924119 wrote:If someone has the H-D 12z EURO snow, could you please post? I'm curious. Thanks!!!

Here's the low-res one based on 10:1:

http://images1.earthsat.com/misc/mod-images/ECM/OP/12/snosums/0024/ECM_12_opUS_SF_0036.png

I can't believe euro is still showing 8 to 12 " of snow for nyc metro.

It's pretty amazing at how different the global models still are with this: The GFS tracks the surface low straight east down I-80. I'd swear it's catching a ride with somebody. The EURO takes it and follows the PA/MD border to a "T", and the CMC is somewhere in between lmao

algae888 wrote:

rb924119 wrote:If someone has the H-D 12z EURO snow, could you please post? I'm curious. Thanks!!!

Here's the low-res one based on 10:1:

http://images1.earthsat.com/misc/mod-images/ECM/OP/12/snosums/0024/ECM_12_opUS_SF_0036.png

I can't believe euro is still showing 8 to 12 " of snow for nyc metro.

This may include sleet, as well. I don't honestly know, Al.

NWS still has me under a winter storm warning with 4-8" of snow and .25 of ice. Head spinning like the exorcist (again)

The differences all exist in exactly when the primary low begins transferring its energy to the coast, as well as how developed the mid-levels are able to get. The GFS retains the primary circulation the longest, while the EURO begins to break it down six or eight hours sooner. The CMC follows the EURO fairly closely with regards to its handling of the transfer, but still allows the warm nose in a little more than the EURO (I think) because it has a slightly stronger H850 circulation, which would support that fact that although it follows the EURO closely, the difference at H850 is enough to allow a tick north of the surface low via synoptic-scale dynamics (hence, middle-ground between EURO/GFS). The GFS, however, is entirely alone, because it actually develops the system so much so that H7 remains closed off and continues to deepen as it crosses our area. Take your pick.

rb924119 wrote:The differences all exist in exactly when the primary low begins transferring its energy to the coast, as well as how developed the mid-levels are able to get. The GFS retains the primary circulation the longest, while the EURO begins to break it down six or eight hours sooner. The CMC follows the EURO fairly closely with regards to its handling of the transfer, but still allows the warm nose in a little more than the EURO (I think) because it has a slightly stronger H850 hPa circulation, which would support that fact that although it follows the EURO closely, the difference at H850 is enough to allow a tick north of the surface low via synoptic-scale dynamics (hence, middle-ground between EURO/GFS). The GFS, however, is entirely alone, because it actually develops the system so much so that H7 remains closed off and continues to deepen as it crosses our area. Take your pick.

I didn't think models would have such a hard time with this storm. its basically just waa. cant believe such differences with storm on our door step. I love tracking weather and love the different outcomes each model has but also would like to lock in to a solution 24 hours out.

Al wxbell shows less than 6 inches of snow, just north of us starts to climb quick 8-10+. If NWS is going ith NAM then a big ice accretion is possible, and roads may not be such a problem as trees and wires, we will see, its down to nowcast IMO. The models were agreeing now it seems they are further apart than 48 hrs ago, annoying lol, WSW are probably up still due to the uncertainty and the possibility of increased ice potential, if those go down then i see WWA or nothing, if stay or even go up WSW will stay. Euro looked colder, but snow map shows that it in fact is pretty warm in NYC. No idea how much is snow, sleet of frz though.

Taffy wrote:NWS still has me under a winter storm warning with 4-8" of snow and .25 of ice.  Head spinning like the exorcist (again)

Taffy....i am still under the same warning and my head is spinning too lol

algae888 wrote:

rb924119 wrote:The differences all exist in exactly when the primary low begins transferring its energy to the coast, as well as how developed the mid-levels are able to get. The GFS retains the primary circulation the longest, while the EURO begins to break it down six or eight hours sooner. The CMC follows the EURO fairly closely with regards to its handling of the transfer, but still allows the warm nose in a little more than the EURO (I think) because it has a slightly stronger H850 hPa circulation, which would support that fact that although it follows the EURO closely, the difference at H850 is enough to allow a tick north of the surface low via synoptic-scale dynamics (hence, middle-ground between EURO/GFS). The GFS, however, is entirely alone, because it actually develops the system so much so that H7 remains closed off and continues to deepen as it crosses our area. Take your pick.

I didn't think models would have such a hard time with this storm. its basically just waa. cant believe such differences with storm on our door step. I love tracking weather and love the different outcomes each model has but also would like to lock in to a solution 24 hours out.

I think I can say within the 99.9% confidence level, that every other member of this board agrees, and might possibly die from excitement if models locked in within 24 hours of events this season ahahahahaha That's how it goes, though. Hey, 1) if was easy, everyone would do it; and 2) that's why we enjoy it and how we get better. Can't ever learn if you're never wrong.

jmanley32 wrote:Al wxbell shows less than 6 inches of snow, just north of us starts to climb quick 8-10+.  If NWS is going ith NAM then a big ice accretion is possible, and roads may not be such a problem as trees and wires, we will see, its down to nowcast IMO.  The models were agreeing now it seems they are further apart than 48 hrs ago, annoying lol, WSW are probably up still due to the uncertainty and the possibility of increased ice potential, if those go down then i see WWA or nothing, if stay or even go up WSW will stay.  Euro looked colder, but snow map shows that it in fact is pretty warm in NYC.  No idea how much is snow, sleet of frz though.

Jman, could you post? Thanks!!

I posted my final call snow map in the snow maps thread.

12z Euro

jmanley32 wrote:12z Euro

I'll take that and run lol.

Taffy wrote:NWS still has me under a winter storm warning with 4-8" of snow and .25 of ice.  Head spinning like the exorcist (again)

Euro has me at 6-10, anyway to tell how much of that is ice if any rb? wxbell does not have breakdown map for Euro.

With ratios that's like a 14-16" snow for anybody north of I-80 essentially.

snow247 wrote:

jmanley32 wrote:12z Euro

I'll take that and run lol.

Yeah who wouldn't, but I have no faith right now in Euro after the last storm debacle.

Deleted text

Deleted this-repeat post.

CPcantmeasuresnow wrote:

rb924119 wrote:With ratios that's like a 14-16" snow for anybody north of I-81 essentially.

RB, I81 runs north to south, so I'm not sure what you mean here, you can only be east or west of I81.

My fault. My fat-ass fingers hit "1" instead of "0" lmao thanks for catching that, CP!!

jmanley32 wrote:Euro has me at 6-10, anyway to tell how much of that is ice if any rb?  wxbell does not have breakdown map for Euro.

The easiest way would be to look at the soundings and then go frame by frame. As soon as you see the warm nose crest 0*C that would be a transition to sleet. Once the warm nose fills a good portion of the column, say between 925 and 800 (or 700) hPa, that would be freezing rain, as long as the surface is below 0*C. I don't have access to EURO soundings, unfortunately. Not yet at least. I have to wait for AccuWeather's site to update, which won't be until like 4pm -_-

I have to admit after the last Euro run I'm now intrigued to see the uNAMed model at 3pm.
Of course they were the deadly duo during the storm of the century last week, so it's probably best to avoid that combination today.

However where there is a storm and a cold High, there is always hope.