Thursday, February 28, 2013

Unsettled Pattern Through Weekend

Yesterday's storm brought over an inch of rain to most of Southern New England along with wind gusts in excess of 50 mph.  There was also snow in the highest elevations of Massachusetts and New Hampshire.  Here is a list of storm reports from the NWS.  Due to an upstream block in the atmosphere the system is taking its time to exit the Northeast but its not strong.

NWS Northeast Radar
At the surface we see several low pressure centers
SPC Surface Analysis 5 am EST
We see low pressure north of Lake Ontario and along the Maine coast.  There is a another low pressure center developing near Maryland, which is picked up on the HPC surface analysis
HPC Surface Analysis 530 am EST
This system has been largely driven by the upper level energy and that continues this morning.  Here is the 500 mb chart from 1 AM
06 NAM 500 mb vort valid 1 AM (image NCEP)
As this spins toward the coast more weak low pressure centers should form and these will have the potential to drop some locally heavy rain.  It will be rain as its not all that cold this morning
5 AM Temperature Analysis (image weatherbell)
By afternoon we are jumping into the mid to upper 40's
10z RAP 2 m T 2 PM EST (image weatherbell)
Short range guidance is indicating a band of rain for most of Southeast New England around 1 or 2 PM today.  Moving on to tonight the same threat will exist BUT temperatures will fall to around freezing.  This will potentially allow for snow.  Accumulations are likely light but a quick inch or two is not out of the question for CT/RI/SE MA.  Here are the temperatures for 4 am Friday Morning
06z NAM Hires 2 m T 4 am (image weatherbell)
Basically you can take this forecast and repeat Friday, Saturday, Sunday, and Monday.  Precipitation at night is more likely to fall as snow.  Daytime temperatures look to be in the upper 30's/low 40's.  The reason is a slow moving upper level low.  These are difficult to forecast so I will be paying attention to the short range models in case there are any surprises.  Here is the 500 mb on Sunday Afternoon
06z NAM 500 mb vorticitiy (image weatherbell)
If you scroll back up you can see the closed low over New England has not moved much.  In late April or May its these type of systems that can sit and we don't see the sun for days (think May 05, 06).  Actually most of you probably won't remember that unless you are a weather weenie like me.  None the less here is the 5 day precipitation totals
HPC 5 day precipitation totals
It doesn't look impressive, but that max off the Cape is worth watching.  Finally there is a rumor about a storm next week.  I'm not on board for a storm but its going to be close.  Have a good day.

Wednesday, February 27, 2013

Slop North of the MA Pike, Rain South

From what my eyes can see it has not snowed even a trace overnight in Northbridge and we have plain rain. That ok with me, you do not have to shovel rain.  Other areas well north and west will be doing the backbreaking work.

Current Conditions
NE radar 0538 am
Surface Temperatures
4 am temperatures (image weatherbell)
Areas along the coast from NH down to CT were just too warm to support any snow.  Its not all that cold at the 925 mb level above the surface either
SPC mesoanalysis 925 mb
A secondary low pressure has formed and is ushering warm marine air off the Atlantic.  Here is what the surface looks like
530 am Surface Analysis
High pressure to the north is not strong enough to lock cold in as its almost March, we need some serious Arctic air for a snowstorm.  Instead the higher elevations will see a solid snowfall.  Here is the NAM hires snowfall totals
00z NAM hires snowfall through 7 pm (image weatherbell)
What I find interesting is the how detailed this high resolution model is.  It is showing snow in all the higher elevations (Worcester Hills, Adirondacks, Berkshires, etc) and rain in the valley's along the rivers (Blackstone, Connecticut, Hudson etc).    The rain will clear by 7 PM tonight.  Here is the precipitation expected between now and tonight
10z RAP total precip through 11 PM (image weatherbell)
The average temperatures during the period
10z RAP average temperature next 18 hours
This makes it clear why its wet and not white.  Thursday will be unsettled with mainly overcast skies with scattered showers.  Temperatures will be in the mid 40's.  Overnight Thursday into Friday is interesting.  Just like Sunday an upper level feature will slowly move east towards New England.  
06 NAM 500 mb vort valid Friday 7 am
Where will this set up?  It looks like SE MA may be the sweet spot where several inches may accumulate.  After this clears Friday the weekend through Monday looks good.  The storm I saw for this weekend has backed off because the pattern is not breaking as the model anticipated- the cold air will eject all the way to the Gulf Coast.  When cold Arctic air moves over the warm moist Gulf in March big things happen.  Next chance for a storm is about 6-7 days.  Plenty of time to watch.

Tuesday, February 26, 2013

Mainly Rain for SNE

Snow will fall tomorrow night into the morning before changing over to plain rain.  A surge of warm marine air will work into New England overwhelming the cold at mid levels.  The Berkshires, extreme Northern Worcester County, and NH, VT, and ME will do well with this storm.

Snow breaks out West of 495 in MA and North of 95 in RI/CT between 1-4 AM.  It will accumulate in these areas until 7-8 AM before daylight and warm air take over South of the MA Pike.  Here is the latest NAM with snow totals by 10 AM Wed
06z NAM 33 hour snow totals (image weatherbell)
I expect Northern Worcester County to do better than this model is advertising but the rest looks good.    The NAM and EURO agree in principle.  Here is the storm total by Thursday Morning
06 NAM 60 hr forecast
Total precipitation 
HPC 3 day precip totals
Finally there is some hint that another low pressure system tries to form Thursday Afternoon/night.  It may be like Sunday afternoon or something heavier in SNE.  I'm still watching that.  Average confidence in the forecast overall.  

Enjoy today, highs in upper 30's/low 40's with a mix of sun and clouds.

Monday, February 25, 2013

Winter Storm Begins Wednesday

A major winter storm in the Southern Plains will push towards the Great Lakes (just like last week) and greet New England with a wintry slop on Wednesday.  Before then we will see a mix of sun and clouds on Tuesday with highs in the low 40's in Southern New England and mid to upper 30's in Central and Northern New England.  Now onto the storm

Current Observations
Quite a few watches and warnings across the United States
NWS Hazards Map
There are winter storm watches and warnings, Blizzard warnings, Tornado Watches, Ice Storm Warnings among others.  The primary systems driving these are shown on the surface chart
HPC surface chart 4 PM
A surface low pressure in Oklahoma is producing the major snow from the Texas Panhandle through NW Oklahoma, Kansas, Missouri, and Illinois.  As the storm occludes to the Northeast a new low pressure center will gradually develop and grab Gulf Moisture and head along the Mid Atlantic coast and eventually New England. 

By tomorrow evening the storm will be taking shape
HPC Tuesday 7 PM forecast
A good slug of snow will work in overnight for areas west of 95 and north of the Pike.  Southern Worcester County is tricky- the Valley will likely be too warm to support accumulations past 9 AM on Wednesday.  The Western part of the county should do well.  The higher elevations are going to do very well.  My snowfall accumulations for Wednesday look like this
Wednesday-Thursday snow forecast
This is going to be a heavy thump Wednesday morning before switching to rain.  On the backside of the storm there will be a few flakes.  The morning commute looks to be snowy if one is heading to Worcester.  If you are heading to Boston or Providence things will improve as you get closer.  Rain will be heavy at times on Wednesday.  Here is the expected precipitation
HPC 3 day rainfall totals
This will make drains clog with runoff from the rain and leftover snow from the morning.  Everything will be a pure winter slop.  Even the snow should be heavy as temperatures will be marginal for snowfall on Wednesday.  I will update in the morning.

Sunday, February 24, 2013

Short Range Forecast, Long Range Discussion

Looking back on this storm I made several mistakes.  First of all I am jumping on the long range a bit too quickly.  To be fair there was considerable agreement 3-4 days out, then it backed away as it became apparent the main storm would be weaker.  I also knew Central New England was going to get pounded but compromised with 6-10.  Many locations are already exceeding that with additional snow to come.
NWS Gray radar return 1254 PM
Here in Southern New England rain is changing to snow
NWS Boston radar return 1257 PM
The bright colors in SE MA is a good approximation as to where the rain/snow line is.  Here is the surface analysis 
HPC 10 am Surface Analysis
Notice the primary low south of the Cape.  That system was largely responsible for the snow/rain yesterday.  Today we seeing an interaction between an Upper level system with a weak surface low (remnants of the Plains snowstorm earlier in the week) and the coastal storm.  
NOAA GOES_E Water Vapor 1245 PM
Cyclonic (counter clockwise) flow around both is leading to a convergence zone in Maine/NH as well as SE MA.  Temperatures are crashing, so most places will go to all snow for the rest of the day.  Winds have shifted in Eastern MA
12 Noon 2 m Temps (image weatherbell)
Notice winds are off the land, not water.  North wind is the snow wind
10 m winds
As I type snow is building back west of Worcester.  The latest RAP model (very short range) is has this for additional snow accumulations 
17z RAP total snowfall through 1 am (image weatherbell)
So all in all we didn't get the coastal storm that was originally anticipated, but we will end up with a small-moderate event.

Storm clears overnight and Monday will be nice. High pressure takes control and most of the region is in the mid to upper 30's.  CT looks to approach 40.
NAM Hires 2 m T 1 PM Monday (image weatherbell)
Another nice day under the influence of high pressure.  Similar to Monday in all regards.

Ah yes.  Here is what I am seeing- a strong winter storm will impact the Southern Plains beginning today (Sunday).  It will track to the NE towards the Great Lakes.  It will run into a block, slow its momentum and develop a new low pressure center off the Mid Atlantic coast by Wednesday morning.  A powerful high pressure area will begin to develop in Canada- looking at possibly a 1050 high!  This is very complex; in fact I don't have many details for you as of this morning.  The models will struggle and so will forecasters.   My take is that the EURO will have the best forecast so I will likely lean heavily on that model and its output.

So that puts snow down Wednesday Morning before a switch to rain, then back to snow.  My best advice is  look out for snow/rain/wind  for the second half of the week.  Plenty of time to fine tune the details but my sense is something big is lurking.  I won't post until tomorrow afternoon as I have a post to do for Tornado Titans.  Look for the weekly snowfall outlook on that site! 

Saturday, February 23, 2013

Winter Storm Watches Downgraded to Winter Weather Advisory

The storm that looked so promising (for snow lovers) early in the week has largely trended warmer and weaker.  I'm not a fan of changing a forecast because A) it means I was wrong and B) no one likes a flip flopper.  None the less when there is no support left for a 48 hour forecast I must blow it up and start over.
NWS Boston watches/warnings
The National Weather Service has downgraded its Winter Storm Watches to a Winter Storm Advisory.  The NWS likes this for snowfall totals

NWS Storm Forecast
Often times a more southerly storm track will lead to a colder solutions.  High pressure is not found in the ideal location; its too far east
HPC surface analysis (NOAA)
The high is over Hudson Bay and another high in Quebec near the Gulf of St. Lawrence.  That is not allowing for a true northerly flow.  Current Temps
2 m Temps Analysis 9 AM (image weatherbell)
As the weak low pressure lifts north it will warm the upper levels too.  It should be mostly wet from Springfield to Worcester to Boston overnight.  If any heavier bands of precipitation develop and make it onshore they could create enough cold air to push the rain/snow line back.  There is a lot of moisture to work with
East Coast Radar 
The precipitation will not begin until later this afternoon.  The majority of the snowfall will be Sunday.  It will not be from the storm but rather an interaction between low pressure in the Great Lakes and the departing storm.  The Southern Maine/NH seacoast/Northeastern MA may actually do quite well Sunday/Sunday night.  York, ME and surrounding area's may get over a foot!
12z NAM 1000-500 thickness, mslp. precip valid Sunday 7 PM
See how the low is departing? Check out the 500 mb level
12z NAM 500 mb vorticity valid Sunday 7 PM
A band of heavy snowfall will form along this boundary.  Exactly where this sets up will be a challenge and I can see a scenario in which Portland, ME receives 4 inches while Scarborough, ME gets a foot.  There will be large differences within a small area.  Here is what the NAM hires is printing out (I've heard the NAM compared to a closer by some meteorologists which is a great analogy.  Inside 24 hours the model is money)  
12z NAM hires total snowfall (image weatherbell)
The EURO control is in with the same type of idea for Sunday into Sunday night but has a bit more snow into Massachusetts.  So here is my updated snowfall map

Finally stay tuned! There is more active weather expected next week.  I will update this weekends storm as needed and will post on next week tomorrow morning.

Friday, February 22, 2013

Winter Storm Watches Posted

A winter storm watch was issued by the National Weather Service in Taunton for Hampden, Hampshire, Franklin, Worcester, Middlesex, and Essex county from Saturday Afternoon-Sunday Afternoon.
NWS Boston Advisories 
All systems are go for a moderate to major storm.  Again we will not see the Blizzard of 2013 again but this time around Southern New England is in for heavy wet snow which will take down trees and power lines.  First lets talk about today's weather.

Current Conditions
HPC surface analysis 529 AM EST
High pressure still in control in Ontario, a major snowstorm is cutting towards the Great Lakes and also occluding, and a front/low pressure loaded with precipitation is working through the Southeast.

HPC 24 hour precip totals
The transfer from the upper level low to the coast will begin tomorrow morning but before that we will have a calm relatively mild Friday.
06 NAM 2 m T Friday 4 PM EST (image weatherbell)
Most will rise into the upper 30's and some lucky ones will get into the low 40's.  

Storm Update
Rumor has it that the TV stations are all over the place with snowfall totals (I honestly do not look until the evening news, missed it last night).  That makes sense as the rain/snow line is a nightmare to forecast.  Also some models are indicating more precipitation than others.  I am splitting the difference in essence and going with the HPC QPF
3 day precip totals HPC thru Monday 7 am
This puts most of Southeastern New England greater than 1 inch of liquid precip.  My take is that some models (including EURO OP) are overwarming the surface.  At the 850 mb level it will be cold enough to support all snow from the CT/RI/MA border on north.  There is no classic high pressure to the north (like we saw in the blizzard) but these systems can create there own cold air when the precipitation is heavy.  

The snow/rain begins to fly around 4 or 5 tomorrow afternoon.  It will last into Sunday afternoon but the heaviest will be overnight Saturday into Sunday morning.  Snowfall totals...
My forecast
You can probably chop some of the 4-8 off Northern Maine- the 12+ is going to be tricky.  I will refine tomorrow morning.  I think Boston comes in over 6 inches, but under the 9.4 needed to set the February record.  Lets also keep in mind yesterday's North American Meso Model runs at 12/00z- they advertised much more snow with a stronger system.  


Thursday, February 21, 2013

Short Term Forecast/Weekend Update

For the third straight weekend there is a Nor'easter for meteorologists and weather enthusiasts to track (early heads up-something wild next weekend is lurking to make it 4/4).  For the first time this year a rain/snow line will try to work north and west.  I think it will struggle to get past 495 or north of the Pike but those areas will see a brief mix with rain or sleet.

Short Term Forecast
After a cold start temperatures will only rebound into the upper 20's/low 30's
NWS Tauton 7 am low temps
As I mentioned yesterday high pressure over Central Canada moved to its east so we will be under the influence of more direct Northwesterly winds
HPC Surface 0530 am EST
I've drawn the path of a major, potentially record breaking snowstorm in the plains and the wind flow around the high.  First of all the wind flow around the high will support temperatures like this
08z RAP 2m Temp valid 4 PM EST (image weatherbell)
Overnight lows will drop into the lower 20's/upper teens.  By Friday the track of the Central storm (aka "Q") will lift some warmer air into New England.
06 NAM 1000-500 thick, mslp, precip Fri 1 PM EST (image weatherbell)
We will not be getting "Q" but the ultimate track of "Q" will play a role in the track of our storm.  Here is what should happen at the 500 mb level

Tonight 7 PM
00z GFS 24 hr 500 mb vort
Tomorrow 7 PM
00z GFS 48 hr 500 mb vort
Saturday 7 PM
00z GFS 72 hr 500 mb vort
Sunday 7 AM
00z GFS 84 hr 500 mb vort
So what will happen at the surface is the low will work its way into the Wisconsin/UP of Michigan and weaken.  Meanwhile energy will round the base of the trough through Texas and develop a new surface low in the Southeast which will move off the east coast and head up the coast.
00z GFS 850 T,, mslp, precip Sunday 4 am
The question is will the High pressure up by Hudson Bay be strong enough to keep most areas cold.  Given that the NAO is negative I tend to think the storm will not be able to come to far north as shown by the EURO ensemble control (I cannot show that even though I pay money to look at it).  HPC has the storm over the Cape by Sunday morning
HPC Sunday morning forecast
Here is what I am expecting (updated a tad)
General expectations (2)
No amounts yet, you'll have them tomorrow.  That blue and pink may feature plain rain for a time as the center makes its closest pass and wraps warm air in.  The Atlantic Ocean, though warmer than average, is still cold. If need be there will be an afternoon update, if not see you tomorrow morning!

Biggest Snow Storm Of The Season Heads To Impact Region Tonight

The National Weather Service (NWS) in Norton, MA has issued a * Winter Storm Warning * from 7 PM tonight until 10 AM Wednesday.  A widesprea...