Feb 24th threat part deux

[eduggs]

I thought they used the current cycle? That's why they dont' come out until the Nam run is done

From http://www.spc.noaa.gov/exper/sref/index_old.html

 

The SPC Short-Range Ensemble Forecast (SREF) is constructed by post-processing all 21 members of the NCEP SREF plus the 3-hour time lagged, operational WRF-NAM (for a total of 22 members) each 6 hours (03, 09, 15, and 21 UTC). Output is available at 3h intervals through 87 hours. The SPC ensemble post-processing focuses on diagnostics relevant to the prediction of SPC mission-critical high-impact, mesoscale weather including: thunderstorms and severe thunderstorms, large scale critical fire weather conditions, and mesoscale areas of hazardous winter weather. Presentation of the SREF output via this WEB portal is similar to its presentation at the SPC within the N-AWIPS operational display system. All SREF information presented herein is for guidance purposes only and remains under development. This ensemble guidance should not be mistaken for or used in lieu of operational SPC products and forecasts.

 

That sounds to me like it uses the previous NAM cycle.  But it also sounds like the rest of the members are independent of the NAM.  But I'm not certain there isn't some other indirect connection like boundary conditions or initialization etc

[OceanStWx]

I couldn't draw this up any better for here vs NE CT. lol

 

We toss?

 

At least the focus was always on the upper levels up this way, and we haven't lost that yet.

[OceanStWx]

From http://www.spc.noaa.gov/exper/sref/index_old.html

 

The SPC Short-Range Ensemble Forecast (SREF) is constructed by post-processing all 21 members of the NCEP SREF plus the 3-hour time lagged, operational WRF-NAM (for a total of 22 members) each 6 hours (03, 09, 15, and 21 UTC). Output is available at 3h intervals through 87 hours. The SPC ensemble post-processing focuses on diagnostics relevant to the prediction of SPC mission-critical high-impact, mesoscale weather including: thunderstorms and severe thunderstorms, large scale critical fire weather conditions, and mesoscale areas of hazardous winter weather. Presentation of the SREF output via this WEB portal is similar to its presentation at the SPC within the N-AWIPS operational display system. All SREF information presented herein is for guidance purposes only and remains under development. This ensemble guidance should not be mistaken for or used in lieu of operational SPC products and forecasts.

 

That sounds to me like it uses the previous NAM cycle.  But it also sounds like the rest of the members are independent of the NAM.  But I'm not certain there isn't some other indirect connection like boundary conditions or initialization etc

 

The SREF members are all WRF based with different cores for model physics (ARW, NMM, etc).

[dendrite]

From http://www.spc.noaa.gov/exper/sref/index_old.html'>http://www.spc.noaa.gov/exper/sref/index_old.html

 

The SPC Short-Range Ensemble Forecast (SREF) is constructed by post-processing all 21 members of the NCEP SREF plus the 3-hour time lagged, operational WRF-NAM (for a total of 22 members) each 6 hours (03, 09, 15, and 21 UTC). Output is available at 3h intervals through 87 hours. The SPC ensemble post-processing focuses on diagnostics relevant to the prediction of SPC mission-critical high-impact, mesoscale weather including: thunderstorms and severe thunderstorms, large scale critical fire weather conditions, and mesoscale areas of hazardous winter weather. Presentation of the SREF output via this WEB portal is similar to its presentation at the SPC within the N-AWIPS operational display system. All SREF information presented herein is for guidance purposes only and remains under development. This ensemble guidance should not be mistaken for or used in lieu of operational SPC products and forecasts.

 

That sounds to me like it uses the previous NAM cycle.  But it also sounds like the rest of the members are independent of the NAM.  But I'm not certain there isn't some other indirect connection like boundary conditions or initialization etc

That's old.

http://www.nws.noaa.gov/os/notification/tin12-30sref.htm

[ORH_wxman]

 

This whole thing has been bizarre from day 1. I'm sure something ridiculous will happen.

 

Getting that vort trackign south of us will always keep us on edge for something pretty good. The vort track really hasn't changed much in all of this, but how quickly it interacts with the initial sfc low and associated ML center is what has been the difference between big solutions and uglier ones.

As soon as the vort tracks underneath us and that additional energy from the lakes is sort of drawn into it...its going to want to "pull" back on the sfc low and try to generate precip over us. Its a hard forecast.

The one good thing I feel about back here is that seemingly no matter how this evolves, it ends up giving warning snow here one way or the other. Obviously that isn't the case everywhere though.

[eduggs]

Sweetness.  Looks like I get my coating on the GFS in Rensselaer Co.  Gotta stay ahead of Newark and Central Park in seasonal snowfall.  Don't wanna come in last this year.

[Tropopause_Fold]

I couldn't draw this up any better for here vs NE CT. lol

Haha. Oh how we pray.

[dendrite]

Haha. Oh how we pray.

Minutes and minutes of drizzle.

[eduggs]

The SREF members are all WRF based with different cores for model physics (ARW, NMM, etc).

Then that makes a lot of sense based on run to run observations.  Thanks!

[powderfreak]

Almost half of the members try to get 1" liquid here from the inverted middle finger. I hate relying on that, but the EC has the signal too so hopefully it's legit. Rates won't be too heavy, but it's wintry appealing!

 

A lot of the meso-scale models go nuts with that inverted trough across VT/NH/S.ME later in the event.  The old school ETA hits SNE on Saturday night and Sunday morning with precip before shutting off, while persistent light snows continue into Monday morning in NNE. 

 

Southern/Central NH gets the best snow between coastal and inverted trough...

 

[dendrite]

A lot of the meso-scale models go nuts with that inverted trough across VT/NH/S.ME later in the event.  The old school ETA hits SNE on Saturday night and Sunday morning with precip before shutting off, while persistent light snows continue into Monday morning in NNE. 

 

Southern/Central NH gets the best snow between coastal and inverted trough...

 

http://www.americanwx.com/bb/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=91115'>Untitled.png

That's not the ETA anymore...that's the NMM control of the SREFs. ETA is 6ft underground now.

[Clinch Leatherwood]

It's not just the Euro. It seems almost EVERY model has continually shifted weaker and further SE... feasibly still with room to do so a bit more.

But the euro has been dead consistent in shifting this away for a day or so. Others have still hinted at this being something better. Likely it's not, maybe it gets its act together in time for the cp, but the trend post blizzard has been for later bloomers.

Haven't posted a ton because this one didnt seem that much different than the last two. Ncep guidance goes ape, euro gradually backs away saying not much to see here. Ncep guidance finally caves.

Thought s and se areas would be in the game but we will see

[powderfreak]

I'd take that GFS run, haha.  This inverted trough thing is always a sketchy proposition but its looking decent on some of these models.  If we can get a half inch of QPF up into north/central VT that'll be a win.

[powderfreak]

That's not the ETA anymore...that's the NMM control of the SREFs. ETA is 6ft underground now.

 

Ahhhh I was wondering why its titled NMM but the page says ETA.  I figured it was still getting run in someone's basement or something, haha.

 

Actually looks remarkably like the GFS in its evolution.

[eduggs]

  

Getting that vort trackign south of us will always keep us on edge for something pretty good. The vort track really hasn't changed much in all of this, but how quickly it interacts with the initial sfc low and associated ML center is what has been the difference between big solutions and uglier ones.

As soon as the vort tracks underneath us and that additional energy from the lakes is sort of drawn into it...its going to want to "pull" back on the sfc low and try to generate precip over us. Its a hard forecast.

The one good thing I feel about back here is that seemingly no matter how this evolves, it ends up giving warning snow here one way or the other. Obviously that isn't the case everywhere though.

I like Orh for thump snow not nickle dime, upper level, inverted trof BS.  You know local snow climo much better obviously, but this doesn't seem to be the sort of setup where Orh really cashes in.  Elevation will always help, but now QPF is in question.  I think warning criteria is looking much less certain now.

[Arnold214]

GFS snow through 18z monday FWIW.

[Baroclinic Zone]

thanks mike.

[Tropopause_Fold]

GFS snow through 18z monday FWIW.

Funny that even with a different evolution it still gives that banana shape across SNE.

[eduggs]

Hanging your hat on a long duration inverted trof is asking for disappointment IMO.  This feature could disappear tomorrow just like the coastal did today.  Even if heavier bands do develop, there's no telling exactly where and for how long.  Flakes should be in the air on Sunday, but I think it would be wise to stay very conservative with potential accumulations at this point.

[powderfreak]

GFS snow through 18z monday FWIW.

 

I'd take 8" in a heartbeat... no way, though, haha.  I hate relying on an inverted trough.  I still like 2-4" or 3-5" up here.

 

And you must've altered that to bring the 3" line north of Tolland County, right?  And bring ORH into the 8" line?  lol

[CoastalWx]

The wobbling east of the ULL over the GL and the Vortmax hanging back definitely is the issue. Although, it seems like today the srn s/w has gone se. Perhaps the GL upper level low that helped cause the issue can actually help.

[dendrite]

Hanging your hat on a long duration inverted trof is asking for disappointment IMO.  This feature could disappear tomorrow just like the coastal did today.  Even if heavier bands do develop, there's no telling exactly where and for how long.  Flakes should be in the air on Sunday, but I think it would be wise to stay very conservative with potential accumulations at this point.

Synoptically it makes sense. An inv trough doesn't have to mean a localized weenie NORLUN band.

[subdude]

GFS snow through 18z monday FWIW.

Myself and hubbdave look to be in the zone from that GFS map. 

[jsw]

Synoptically it makes sense. An inv trough doesn't have to mean a localized weenie NORLUN band.

 

Hazardous Weather Outlook only here thus far. NWS says may upgrade to Storm Warning when more confidence. 

 

 

A LOW PRESSURE SYSTEM MOVING FROM THE DELMARVA REGION LATESATURDAY AFTERNOON TO SOUTH AND EAST OF CAPE COD ON SUNDAY...MAYBRING A MODERATE TO PERHAPS HEAVY SNOWFALL TO THE AREA. IFCONFIDENCE INCREASES SUCH THAT SNOWFALL FORECASTS BECOME MORECERTAIN...THEN A WINTER WEATHER ADVISORY OR WINTER STORM WARNINGWOULD BE ISSUED.

 

Just curious, anyone else in the Bratt/Keene area?

[#NoPoles]

Synoptically it makes sense. An inv trough doesn't have to mean a localized weenie NORLUN band.

sorry to ask an IMBY question...but i'm in concord, nh for work...right off exit 13...how does this storm look for this area...6-8?

[eduggs]

Synoptically it makes sense. An inv trough doesn't have to mean a localized weenie NORLUN band.

A slight change in the evolution of the height contours between 850mb and 500mb and a lot of that QPF disappears.  Or it shifts someplace else.  The lift is relatively weak throughout the period.  I don't believe the setup is conducive to a widespread high QPF event.  I am more confident about the track of the coastal low now, but Sunday- Monday is still pretty far out for any confidence.

[HIPPYVALLEY]

GFS snow through 18z monday FWIW.

 

A little underwhelming after the earlier forecasts but still not a disaster.  That map still indicates a nice little event N of RT 2.

[HIPPYVALLEY]

Hazardous Weather Outlook only here thus far. NWS says may upgrade to Storm Warning when more confidence. 

 

 

A LOW PRESSURE SYSTEM MOVING FROM THE DELMARVA REGION LATESATURDAY AFTERNOON TO SOUTH AND EAST OF CAPE COD ON SUNDAY...MAYBRING A MODERATE TO PERHAPS HEAVY SNOWFALL TO THE AREA. IFCONFIDENCE INCREASES SUCH THAT SNOWFALL FORECASTS BECOME MORECERTAIN...THEN A WINTER WEATHER ADVISORY OR WINTER STORM WARNINGWOULD BE ISSUED.

 

Just curious, anyone else in the Bratt/Keene area?

 

We are thin on posters from your area meaning almost none. I would love if a few more joined b/c I'm always curious what's going on just N of here.  

The higher terrain around Bratt/Keene will do ok.  (Snow shoening up Monad on monday might be nice.)

[moneypitmike]

What a hoot of a GFS run.  My left nut I don' get the 6-8 on the BOX map.

[eduggs]

It looks like the RGEM has a little more impact from the coastal low... probably rain with snow for the hills.  Beyond that it's difficult to guess, but it probably swings the ULL through in a similar fashion to the GFS.  I still think this would be more of a localized snowfall than widespread heavy snow.