Mar 1 & 2

3-1

Woke up to a half inch of light snow this morning.  A little surprised at the timing, but otherwise expected it.

The below scenario has substantially evolved since the 25th and I haven't had time to update.
Instead of one storm, we've had three.  This morning an upper level disturbance moved through, a little further north than expected, bringing snow all the way to CT.

Its going to be followed by a more organized low pressure system which now is forecast to bomb off the NJ coast, especially as it moves by SE Mass.   Using the NAM for sanity sake.

This is unfortunate as I'm leading a church retreat on Saturday that we've been preparing for since last June.  The R/S line for this is going to be fun to watch.  Long Island and Central NJ seem to be the battle area.  Also fun to watch are the various snow maps.  GFS sniffed this out first, followed by the NAM and Euro. 

Euro

GFS

NAM

To be honest, the GFS seems overdone.  I think 4-7" is more likely than 10", but the way this has been developing/trending, maybe we see a foot. 



2-26
From the 3-1 thread at wxdisco, I thought I was opening, but Shaulov beat me

Sometimes size doesn't matter.
Upper level disturbance coming through on the first, separate from the system hitting the NE on the 28th and from the following coastal or cutter on the 2nd.  
500mb and 700mb show the upward motion.


700 RH is moist

Results in this surface

And this snow

   




2-25
Another forecasting nightmare.  I blog to show and remember how difficult it is to predict the weather.
Saturday's storm has looked to be a rainstorm for most of the area as a low cuts through the lakes.  However, this isn't set in stone.  And the models at 5 days out are all over the place. The two models that are the most different are....the GFS and European.  So lets look at he 500mb maps and see why.

Both start off fairly similar on thursday. System over Canada, ULL entering WA/OR




In less than a day the differences begin. The GFS unwinds the energy in the PACNW and sends it into a ULL coming down from Canada.  The Euro holds the energy back (a known bias), but more importantly, doesn't send the ULL down into the CONUS, but keeps moving it east in Canada.


The GFS has the pacnw energy start to build a ridge which influences the ULL in Canada, which it has held back, causing the ULL to dig down a little as the energies interact.  The Euro keeps them separate.

Then you end up with a strong storm on the GFS, but just strung out energy on the Euro.


Resulting in this surface map.  GFS with low going toward lakes.  Euro with some weak energy seen over GA/SC on the 500mb map triggers a weak low off the coast grazing the mid atlantic


Other model solutions - UKMET looks to completely ignore all of this.

CMC hits us with a southern system

And JMA and WPC have what is probably the right scenario - its whats happened all season. A low to the lakes, but a second low forming.  This solution puts us into that snow/sleet/ice type of storm we've had all year.  If the secondary is stronger, its colder.  If its weaker, then we are more likely to get rain until you get north of MA.

Feb 28th.

2-28  Only a dusting from this. 

2-25
First, lets look at Thursdays event. Its a shortwave coming down from Canada over the lakes.  Should hit overnight and believe it or not, may be ALL snow.  First all snow event for us.  Now it depends on the track of course.  GFS and Euro are similar, so I'll show the GFS. Note on the GFS how that LP comes up from the south and meets up with our event.  That phase was forecast by the Euro days ago, but right over us resulting in a huge blizzard.

 NAM is a little further north which is typical.  But as I type the new run is coming in.

We should be in for a 1-3 or 2-4" event over NNJ, NY, CT, RI.  If it trends further south, perhaps even Philly sees some snow.

2-18 Hudson Valley, CT, MA, RI special

Results

2-18  1-3" in Albany area including Litchfield.  2-4 rest of N CT and RI.  3-5" in MA
Radar image shows basically what happened. Precip split N and S of us.  We did get some showery type of snow later and some sleet mixed in over night.

2-17
Been watching the 2/18 and 2/10 period for a week now.  Two systems, both weak and not much to be excited about.  The first will come through tonite.  For areas north of the Merritt I think should remain mostly snow and 2-4".  From I 80 south, ice/rain.  In between 1-3" snow with some mix. 

The 12z model runs were fairly diverse with the ICON having 1" and the RGEM having 6".

Icon

 

RGEM

Euro is right in the middle.  GFS is lighter and warmer.

Euro

GFS

Should note the GFS map may include sleet and ice, so it really should look like the Pivotal map

NWS has a winter weather advisory out for the northern suburbs.

After the heavier stuff falls overnight, Monday should be dreary with either some light snow, freezing mist or rain.   Nothing to accumulate unless you're further east in RI/MA

The 18z Nam threw out some pretty impressive precip for some reason.  Could be that it sees the -8c line as collapsing in some heavier precip and during the upward motion at 10,000 feet.

That resulted in this snow map, which is less likely, but still possible.  This type of snow would required a winter storm warning.  18z GFS came in a bit heavier too, though more along the CT/MA line

So look for 1-2" in NNJ, LI, CT coast.  2-4" from the Merritt to I84 (with some potential for 6") and 3-5" for 84 to the MA/VT/NH line (with some potential for 8")

Winter wakes up

1-24  Results

We had 2-4" generally in the I84 corridor with 4-5" to the north.  DXR reported .35" of ice. Meriden Airport  reported .57" of ice.  I'd go with .45" for here. Other reports from Upton are here

Started as snow Sat evening, transitioned briefly to sleet, so that we didn't even hear it.  Then around 3am we lost power.  Came back around 4:30.  Then went off again around daybreak.  Generator went on around 8am.  Power came back around 11:30am and went off from 2:30pm Sunday until 5pm Monday.

Temps plummeted to -1 Monday morning and the generator ran longer hours than usual. Winds gusted to 40mph.  Newtown had 25% of customers without power at the peak.

The low pressure actually passed just south of LI, which was only forecast by a few models, NAM3k, WRFARW2 and ICON.  NAM 3k came closest to idea of ice. 

1-19 - Well its here.  NAM abandoned the idea of a southern low, now all models agree.
NWS was a little slow recognizing this but has since lessesed the expected amounts.  These snow amounts are only possible if we get a good front thump of snow sometime between 10pm and 2am (adjust to 8pm and midnight for NJ, etc).  I'm uncomfortable giving up on the idea of ice in the I84 corridor and north.  But snow looks right. Its not all that cold out at 6:30 pm.  32°

1-18  late afternoon

Despite many attempts to draw a snow map, I've given up.  The system coming across the country now has little opportunity to shift. The questions are does it head through the Cumberland gap and out the Delmarva/ACY area, ala the NAM, or does it go through PA/NJ over NYC and inside ACK?

Whichever, we will get some heavy snow to start.  Typically these events stay snow longer than forecast, and the ground temp stays cold longer. Moisture streams in faster than the rise in temps.   Then the NAM has us in CT going to sleet.  GFS/Euro/CMC/UKMet have us turning to rain.

Winter Storm warnings have gone up for most of the area. The NWS office in Upton has the following outlooks

 I think it may be overdone, but only by an inch.  I like this map too.

 Euro is my second favorite, GFS third

12z Euro

12z GFS

Freezing rain remains a threat.  Pay attention to this line as it can cause some serious trouble.  NWS says its more likely sleet than freezing rain though.

1-16 evening

We did see shifts today in the 12z runs and the NAM is starting to come into range and looks to be colder than the GFS.  Actually, the hr 84 of the nam had the temp here at 19 while the GFS was 35.  😲
I can't figure out why the GFS isn't shifting further SE, which is concerning me.   The pieces of the storm are the main storm(A). Energy from the north (B) and energy from the west (C).

 

Parts B&C act to steer the storm.  Should they remain separate from A, as depicted on the NAM run below, then the storm should exit south of the area and bring more in the way of frozen precip.

If either part ends up in the back side of the trough, that may cause the trough to tilt negative and the storm comes up to our west or over us. GFS was advertising this yesterday, but no longer does.  The problem is that it didn't correct enough.

WXDisco comment on this


1-16  Tomorrow is the day to really start taking model runs seriously.  Yesterday morning started out with a shift NW of the GFS, Euro, Navy and GEM.  Then in the afternoon, the UKMET, usually the furthest west, jumped to an off shore solution.  Slowly the GFS and Euro have followed with the shift evident in the images below.   The energy for this storm is hitting the coast on the 17th.  Currently there is no data other than from satellite so models have less to go on.  This is why through the day Thursday and into Friday, there could be some major changes.

Wednesday morning Euro snowfall forecast

Tuesday afternoon Euro snowfall forecast

0z Wednesday Euro ensemble members

12z Tuesday Euro ens members

The GFS snowfall GIF shows the retreat NW yesterday then a jump to the coast today.

The Experimental GFS Replacement FV3 also shows the advancing southeast of the snow line

GEM shifted SE too

Timing and track are not the only open questions.  We have to contend with two different scenarios with type of storm as well.  GFS is more strung out like a frontal passage.  Two lows develop and as the trough approaches, they ride up in front of it.  The other low is by the yellow convection

While the GEM, Euro, JMA, UKMET all have a single low.

CMC single low as example

The timing portion is do they ride up before, after or during the cold front passage. The track depends where the trough is - the track is pretty certain to be between midway to the 40/70 benchmark and Albany.  Closer the benchmark means all snow, Albany means snow to rain.  In between may result in snow-ice-rain-ice-snow.  We're only talking 200 miles difference here 4 days out.


1-13  Winter woke up today in the Mid Atlantic with 2-6" of snow reported in the VA/DC/MD area.  But as alluded to in the last post, a more meaningful storm is brewing for MLK weekend.

This will grab attention!

0z Canadian

6z FV3

18z FV3

18z GFS

Well you laugh and say, thats the GFS or FV3 - what about the Euro

 

We're a week out or so.  Don't be surprised to see this move out of our area the next two days.  But if that happens, check back in on day 3 or 4.   

Details as to what causes this storm when I have time to look at it more, along with a what can go wrong analysis.  Sadly with work and a wake tomorrow, Tuesday might be the earliest I can spend some time.

ZZZZZZ......old man winter sleeping

1/10  Well this post shouldn't take long.  Next chance at meaningful snow is around the 20th.  Being 10 days out, I'm not biting.  The snow this weekend should stay south, more impactful around DC/Delmarva.

Out of boredom, some stats from my area.

Counting today's snow showers, we've now had 6 days in which it snowed in December and January, surpassing the # of days it snowed in November finally.

Using OXC (Oxford/Waterbury Airport) as my official weather info climate site I've found the following interesting.

• we haven't had a low temperature that was below normal since December 19th.  
• since December 1st, we've had 8 nights with below normal low temps, all before December 19th and were mostly in the 12/4 to 12/12 date range
• December was 2.9° above normal with 7.24" of rain and 0.5" of snow.  Normal precip is 3.65"
• November was also wet with 7.28" of rain.  Normal is 4.26".  Also had 8" of snow
• Since December 14th, there have been 3 days averaging below normal temps, and those were -2
• January is running +8.5 temperature wise and on par for precip
• Our average temperature (high+low)/2 is 34.2 which is higher than our average high.
• OXC coldest days are 1/14 to 1/27 where highs are 33 and lows are 13.

There's been a lot of chatter about a sudden stratospheric warming (SSW) that took place in the beginning of the month.  These typically shake up the troposphere eventually and are thought to bring colder temperatures.  There is a shot at that on the Euro weeklies, but it doesn't stick around.  Not what is usually expected from an SSW event.

-----------------------------------------------------------------------------------------------------------------------------

Looking at December stats from DXR.  High temp of 62, low of 13.  Average departure 1.8 (likely +2 after today).  Precip was 124% of normal. 0.6" of snow.

Looking at other Decembers with under an inch of snow: 2011, 2014 and 2015.  Throwing out 2015 since it was 12 degrees above normal and dry.

Dec 2011 - High temp of 60, low of 13 (very similar).  Average departure +4.8 (a little warmer, but yet a torch).  Precip 126% (very close) and snow a trace.

Dec 2014 - High temp 61, low 13 (very similar).  Average departure +2.8 (closer than 2011).  Precip 110% (pretty close) and snow .4"

So what happened in Jan-Mar of 2012?  Stayed warm the entire winter.  January +4.8; Feb +4.1 and Mar +8.  11" of snow between those three months.  

And Jan-Mar of 2015?  Brutally cold - seriously bad.   January 3.6 degrees below normal with 16" of snow; Feb was nearly 16 degrees below normal with 26" of snow and Mar was 7.6 below normal with 14" of snow. 

Even after the torch of Dec 15, we came back with 26" of snow in Jan-Mar. 

Point is that, well, anything can happen.