February 5th beefed up swfe thread-let's get some December 2007 juju,

[free_man]

Even they flip to plain rain?

The 12z ECMWF continues to show a significant snow to sleet/ice event for interior SNE and over to rain along the coastal areas.Though even northern coastal areas around Boston and north shore could see a prolonged period of sleet and/or FZRA. It looks to be mostly snow in central and northern New England.

[N. OF PIKE]

Boston is not far from staying all snow and with thumpidity dumpidty maybe will.

Model trends from now thru sunday pm are key.

[ctsnowstorm628]

I think everyone on the board would take the 12z Euro and run. even the south coast would see ~2-4" before pinging. Many see 6-12"...thats what GOM interaction will do.

[ctsnowstorm628]

This really reminds me of 12/15. Remember modeling had an amped solution, then backed off, giving SNE 12+", then came right back amped. Don't hop on to any one run and just think SWFE climo.

[weathafella]

Even they flip to plain rain?

If they do, most of the qpf is done.

[dryslot]

6-10" is pretty common for these types, 07/08 had many up here and all fell in that range mainly

[N. OF PIKE]

Even they flip to plain rain?

They were always part of the flip crowd, bos is on the water. (But i think u knew that)

[wxeyeNH]

I always wonder what qualifies as "coast" when we are discussing rain/snow lines and storm track.  This term "coast" as well as "eastern Massachusetts" seem to mean different things to different people.  Perhaps that is because each storm is different and in some set ups coast in 5 miles from the ocean and in others "coast" is 30 miles from the ocean.  What are we thinking defines coast for this Wednesday event?  Thanks

Coast can mean different things to different people.  Either way it makes no difference when we are looking at a storm next Wednesday. Way too far out and all that can inferred at this time is the further inland and north you are the better.  Once a storm starts getting into the 48 to 60 hour time frame you can start tightening up forecasting changeover lines but for right now I think all you can say is there is good agreement on a winter event mid next week.

[ORH_wxman]

Even they flip to plain rain?

 

 

Yeah very late in the storm. N&W of 128 never sniffs freezing though.

 

 

These details are fairly irrelevant though on a120 hour prog. I'll leave them mostly to the Feb 5th general storm threat thread.

[CardinalWinds]

It almost all has to do with the upper levels.  Surface pressure decreases over a point when the mass of air on top of that point decreases.  Rising air motions cause a decrease in the mass of a column of air and therefore decrease the surface pressure.  So then you have to look for mechanisms that cause rising air motions.  The most obvious one is upper level divergence, when the upper level flow lines spread out or when the magnitude chances, e.g., jet streaks.  The other mechanism is positive vorticity advection.  When vorticity increases over a region, the upward vertical motion increases (explained by vorticity equation and other mathematical formulas etc).  By looking at the 500mb and 300mb charts around day 5, it looks like there isn't much upper level divergence or PVA along the east coast.  It's better to our west, which is why surface pressures are lower there.  As you mentioned before, the natural baroclinic environment along the east coast as well as frictional effects with mountain ranges promotes a minor surface pressure decrease along or just offshore.  But unless upper level support is favorable to enhance surface deepening (and also favorable for the filling of the primary - upper level convergence in the vicinity of the primary etc), transfer and deepening of any 2ndary low will be slow and weak.

 

Thanks, eduggs. This is surely common knowledge for most on here, but for the relatively ignorant weenie like myself, it was a nice succinct explanation.

[dryslot]

May be time to pin this thread as well, If we could get one of our mods to do it, Thanks

[CoastalWx]

To me, when we refer to the "coast"..it has differences based on latitude. Usually it means BOS, the cstl towns of the north shore and then SW down I-95 into RI. That's the general overview I think. Even though a place like Andover MA is on the coastal plain....it doesn't mean they get grouped into the whole "coast" talk because the climate there is not the same as areas to their east along the shore. This whole assumption usually arises from cstl front positions, hence why a town 5 miles inland from the beaches of Essex county might be snow, while a town 30 miles inland over Bristol country might be rain. Coastal fronts tend to hug the coast more along Essex county due to a few different features...one of them geography.

[SnowGoose69]

Don't know how SNE did in this one...the 500mb setup over the CONUS though looks close....biggest difference is the event this week has a much better positioned high and shows more chance for a transfer...

 

http://www.meteo.psu.edu/~fxg1/NARR/1993/us0216.php

[ORH_wxman]

Don't know how SNE did in this one...the 500mb setup over the CONUS though looks close....biggest difference is the event this week has a much better positioned high and shows more chance for a transfer...

 

http://www.meteo.psu.edu/~fxg1/NARR/1993/us0216.php

 

 

I posted that last night as a similar system.

 

That one gave ORH about 5 inches and BOS 2 inches before a flip. There was some significant sleet and freezing rain in the interior in that one. I think the snow potential in this one may be a bit higher...but we are still a really long ways out.

 

 

We've been tracking this one for so long that its hard to remember that it is 120 hours out.

[HoarfrostHubb]

I am a bit confused by part of the 1:20 AFD from BOX... how is this an anomalous event?

NEVERTHELESS...FOCUSING ON THE PATH AND EVOLUTION OF THE H85 LOW
WHICH HAS EXHIBITED A MORE CONSISTENT TRACK RECORD WITHIN FORECAST
SOLUTIONS /ACROSS THE NORTHERN OHIO VALLEY INTO THE EASTERN GREAT
LAKES REGION AND INTO NEW ENGLAND/. SUCH A TRACK WOULD DRAW WARMER
AIR FURTHER BACK ALOFT ACROSS THE INTERIOR NORTHEASTERN CONUS. WITH
A COLD AIR DAMMING SITUATION APPARENT AS COLD HIGH PRESSURE REMAINS
SITUATED NORTH AND EAST OF THE LOW...PRECIP-TYPES ARE EXPECTED TO BE
COMPLICATED DURING ONSET OF THE STORM AND WARMER-AIR BUILDING ALOFT
ALONG THE INITIAL WARM FRONT. ANTICIPATING A SNOWY START CHANGING
OVER TO A WINTRY MIX FOLLOWED BY RAIN FOR MOST LOCATIONS EXCEPT FOR
THE INTERIOR NORTH AND WEST. AN ANOMALOUS STORM /AS IT IS APPEARING/
DRAWING UP SUBSTANTIAL MOISTURE FROM THE DEEP-SOUTH MAY ALSO
RESULT IN AREAS OF HEAVY RAIN /MAINLY SOUTH AND EAST AS IT
APPEARS/. HEADLINES MAY BE NEEDED. ACTIVITY CONCLUDES IN WAKE OF A
COLD FRONT LATE WEDNESDAY INTO WEDNESDAY NIGHT.

[eduggs]

I am a bit confused by part of the 1:20 AFD from BOX... how is this an anomalous event?

 

Statistically anomalous... as in PWATs several standard deviations above normal for this time of year.  Which is another way of saying a high QPF event.  They don't necessarily mean that this is going to be an unusual or historic storm... just a moisture laden one.

[CoastalWx]

It's definitely not anomalous in terms of having these types of lows. Maybe they mean above avg PWATs or something.

[ORH_wxman]

The EC ensemble mean is a bit more robust with the high pressure to the north, so its a little bit colder than the OP run...but again, 120 hours...still a lot of noise going on.

[OceanStWx]

I am a bit confused by part of the 1:20 AFD from BOX... how is this an anomalous event?

NEVERTHELESS...FOCUSING ON THE PATH AND EVOLUTION OF THE H85 LOW

WHICH HAS EXHIBITED A MORE CONSISTENT TRACK RECORD WITHIN FORECAST

SOLUTIONS /ACROSS THE NORTHERN OHIO VALLEY INTO THE EASTERN GREAT

LAKES REGION AND INTO NEW ENGLAND/. SUCH A TRACK WOULD DRAW WARMER

AIR FURTHER BACK ALOFT ACROSS THE INTERIOR NORTHEASTERN CONUS. WITH

A COLD AIR DAMMING SITUATION APPARENT AS COLD HIGH PRESSURE REMAINS

SITUATED NORTH AND EAST OF THE LOW...PRECIP-TYPES ARE EXPECTED TO BE

COMPLICATED DURING ONSET OF THE STORM AND WARMER-AIR BUILDING ALOFT

ALONG THE INITIAL WARM FRONT. ANTICIPATING A SNOWY START CHANGING

OVER TO A WINTRY MIX FOLLOWED BY RAIN FOR MOST LOCATIONS EXCEPT FOR

THE INTERIOR NORTH AND WEST. AN ANOMALOUS STORM /AS IT IS APPEARING/

DRAWING UP SUBSTANTIAL MOISTURE FROM THE DEEP-SOUTH MAY ALSO

RESULT IN AREAS OF HEAVY RAIN /MAINLY SOUTH AND EAST AS IT

APPEARS/. HEADLINES MAY BE NEEDED. ACTIVITY CONCLUDES IN WAKE OF A

COLD FRONT LATE WEDNESDAY INTO WEDNESDAY NIGHT.

 

Anomalous moisture.

 

[Ginx snewx]

Chris on my phone what are -sds 850s?

[OceanStWx]

Chris on my phone what are -sds 850s?

 

+2 to 3 V anomaly (southerly). Not much in the way of easterly anomalies, which is probably to be expected with a SWFish event.

[CoastalWx]

I like that high pressure and the fact thicknesses stop rising abruptly as the secondary takes over. That's a fairly cold look overall.

[HoarfrostHubb]

Statistically anomalous... as in PWATs several standard deviations above normal for this time of year. Which is another way of saying a high QPF event. They don't necessarily mean that this is going to be an unusual or historic storm... just a moisture laden one.

I see. Makes sense

[HoarfrostHubb]

Any similarities to 2/24/10?

[powderfreak]

Wow I just saw the 12z ECMWF... lock that one up, lol.  That's a nice hit.

 

BTV already going with 80% chances for snow...

 

Tuesday Night Snow. Low around 17. Calm wind becoming east 5 to 7 mph after midnight. Chance of precipitation is 80%.

 

Wednesday Snow. High near 25. East wind 6 to 8 mph. Chance of precipitation is 80%.

[ORH_wxman]

Any similarities to 2/24/10?

 

No that was totally different. A big firehose from the SE due to an amplifying trough just to our west. You might almost call that a Southeast Flow Event.

[H2Otown_WX]

Any similarities to 2/24/10?

Wasn't that more of a rain/snow scenario? Not really any transitional mixed precip.

[powderfreak]

No that was totally different. A big firehose from the SE due to an amplifying trough just to our west. You might almost call that a Southeast Flow Event.

 

I really loved that event for the rarity of it.  That was bizarre and dumped 12-24" on a straight SE moisture feed.

[CardinalWinds]

Wow I just saw the 12z ECMWF... lock that one up, lol.  That's a nice hit.

 

BTV already going with 80% chances for snow...

 

Tuesday Night Snow. Low around 17. Calm wind becoming east 5 to 7 mph after midnight. Chance of precipitation is 80%.

 

Wednesday Snow. High near 25. East wind 6 to 8 mph. Chance of precipitation is 80%.

 

Yeah, BTV lovin' this one. I'd feel better if it wasn't still so far out, though:

 

A LOW PRESSURE SYSTEM WHICH ORIGINATES IN THE GULF COAST AREA ON TUESDAY WILL TRACK NORTHEASTWARD THROUGH THE OHIO RIVER VALLEY TUESDAY NIGHT. DURING THE DAY WEDNESDAY THE MOISTURE LADEN LOW TRACKS SOUTHEAST OF OUR CWA...INSIDE THE BENCHMARK. THIS LOW TRACK WILL PROVIDE THE NORTH COUNTRY WITH AN ALL SNOW EVENT. DEEP MOISTURE ASSOCIATED WITH THIS SYSTEM...AND PWATS WELL ABOVE NORMAL...QPF ACROSS THE AREA WILL BE IN THE HALF INCH TO THREE QUARTERS OF AN INCH RANGE. THIS IS ALL DEPENDENT ON THE TRACK OF THE LOW...WHICH IS STILL IN THE DAY 5 TIMEFRAME...BUT FEEL LIKE MODELS HAVE SHOWN VERY GOOD MODEL-TO-MODEL AND RUN-TO-RUN CONSISTENCY AT THIS POINT. ONLY FLY IN THE OINTMENT AT THIS POINT IS THE 12Z GFS SHOWING A SLIGHTLY MORE NORTHERN TRACK THAN PREVIOUS RUNS. RAISED POPS FROM 06-18Z WED INTO THE CATEGORICAL RANGE. AT THIS POINT THINK THAT MOST OF THE AREA WILL HAVE AROUND 6-12 INCHES OF SNOW...WITH BULK OF THE SNOW FALLING TUESDAY NIGHT INTO WEDNESDAY MORNING.

[powderfreak]

Yeah, BTV lovin' this one. I'd feel better if it wasn't still so far out, though:

 

I'd feel better if it wasn't winter 2013-2014, haha.  It is funny how skeptical people have become up here in this area now... literally won't believe it may snow until it actually happens.  Everyone I talked to today was like, we'll believe it after its on the ground, haha.