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Epic winter signal continues to beam, part IV


Baroclinic Zone

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Even with a track that far N...BOS is hanging onto all snow through 54h....thats basically like 90% of the qpf before pellets.

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I just saw that. The column dries out pretty good right after 18z. I'm questionable on that 850 track as the issue arises well to the west. It actually has a pretty big difference in sensible wx during late aftn and early evening. You lose the easterly flow in the lower 8000ft or so, which ends the more prolonged lighter snows.

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This message sent on behalf of the MPTN Department of Public Safety

STATUS OF THE STATE EMERGENCY OPERATIONS CENTER - MONITORING

Good Morning,

LONG DURATION DOUBLE BARREL WINTER STORM EXPECTED TUESDAY MORNING THROUGH WEDNESDAY NIGHT…

SIGNIFICANT RISK OF ROOF & DECK COLLAPSE IS POSSIBLE…

This morning's runs of the GFS and NAM models are forecasting a long duration winter storm Tuesday morning through Wednesday evening. The GFS and NAM models are forecasting a double barrel system (somewhat similar to the last storm). The weight of this new snow, sleet and rain added to the tremendous weight of the existing snow load on many flat or shallow sloped roofs and decks may pose a significant risk for roof and building collapses during the storm.

The following forecast is based on a blend of the GFS and NAM models:

Tuesday: Light snow developing around daybreak and becoming steadier during the day. Some sleet and freezing rain may mix into the state by Tuesday afternoon with 2 - 4 inches of snow expected by the afternoon rush hour. Highs in the 20's. Some icing on power lines and trees is possible in Southern and Central CT. A minor impact is expected for the Tuesday morning rush hour with just some light snow. The impact is gradually expected to increase to moderate by the Tuesday afternoon rush hour.

Tuesday Night: Drizzle overnight with an additional inch of snow, sleet and freezing rain possible. Lows in the 20's. A minor impact on overnight travel is expected.

Wednesday: Snow, Sleet and Freezing rain becoming moderate to heavy around daybreak and continuing into the late afternoon. The mixed precipitation is expected to change back to snow before ending by Wednesday at midnight. Highs in the upper 20's to low 30's. A considerable risk of roof and deck collapses is forecast during the day on Wednesday and continuing into early Thursday as the snow, sleet and rain add more weight to roofs and decks. Considerable icing may also occur causing significant power outages. The outlook for both Wednesday rush hours is for a moderate impact on travel with mixed precipitation melting on most treated and heavily traveled highways, but sticking to the less traveled and treated secondary roads.

Storm total snowfall is forecast to range from 3 - 5 inches along the coast up to 14 inches in Northern CT. Approximately 1 inch of sleet and 1/2 - 3/4 inch of icing is also expected during the storm. Forecast confidence is good at this time. However the rain/snow line is going to be fairly narrow (only 150 miles between all rain and all snow) across Southern New England during the storm. If the track of the storm moves 50 miles north or south then we can expect the snowfall amounts and icing to shift north or south with the storm track.

The Department of Emergency Management and Homeland Security will continue to monitor this approaching storm and will issue another update at 2:00 PM.

This is an excellent Text forecast. The local tv stations could learn a thing or two and follow this format for their websites instead of the crap they all have and video forecasts that never seem to be updated.

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the GFS thermal proflies make complete sense.. in fact it looks cold based on where the low pressure is.. how often are we that cold with a low in Northern Indiana.. the only thing that is odd about GFS is the storm track.. From NE arkansas at 36hr goes NE to Northern Indiana then due East pretty much to Northern PA by 54.. weird

Well the track is def going to turn pretty sharply E at some point as the shortwave gets put into the meat grinder of confluence over S Quebec and New England...its just a matter of how soon it starts to get crushed to the E which will make the difference on how far north the sleet line gets.

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what i dont understand is why does it seem like the cold stays on longer the further east you go such as my area vs Kevin or Hartford,Ct?

Best cold air drainage is coming right down the coastal plain of Maine. The warm punch meets slightly more resistance the further east it goes. Its still mostly a latitude event, but further E might do slightly better than a place west at the same exact latitude in this setup.

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12z NAM and GFS both come in warmer than 06z. Not surprising given the on/off hour runs the past day. This run looks more like 00z GFS.

At 57 hours the 12z NAM is colder than the 0z NAM (just about or just after the height of part 2) around Boston, Easton, northern RI and northern CT. It's been the pattern all year that the off hour runs over correct and the main runs pull back. The GFS - not really worried about it. Not sure anyone would use it for temp profiles if this were a normal year over the NAM.

I think when we see the slight bump east in surface track of the developing low the rest of the models will jump in too. Towards SW MO and NE OK it's colder again this run early on (NAM 24hrs)...the GFS/24hrs is colder at the same time along the TX border. It's just not picking up possibly on the shift east further north. With this track...NNE then a hard right even 20 miles early on will make a big(ger) difference up here.

I like that both models shifted the cold air east/southeast to some degree very early.

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At 57 hours the 12z NAM is colder than the 0z NAM (just about or just after the height of part 2) around Boston, Easton, northern RI and northern CT. It's been the pattern all year that the off hour runs over correct and the main runs pull back. The GFS - not really worried about it. Not sure anyone would use it for temp profiles if this were a normal year over the NAM.

Should have specified, I meant in the mid-levels. Around 750mb 12z NAM is warmer, but you're right--a bit colder at the surface. Basically just leads to a larger swath of sleet/zr.

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Should have specified, I meant in the mid-levels. Around 750mb 12z NAM is warmer, but you're right--a bit colder at the surface. Basically just leads to a larger swath of sleet/zr.

I should have specified too I'm just looking at straight 1000-700 for now. It's so far out and performance has been so poor on all models (oddly aside of the RUC inside of 12-15 hours) on temp profiles I'm not sure speaking specifically makes sense. I like the wedge o' atmosphere approach for right now. But as you and Ryan have noted there are red flags in the layers too.

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At 57 hours the 12z NAM is colder than the 0z NAM (just about or just after the height of part 2) around Boston, Easton, northern RI and northern CT. It's been the pattern all year that the off hour runs over correct and the main runs pull back. The GFS - not really worried about it. Not sure anyone would use it for temp profiles if this were a normal year over the NAM.

I think when we see the slight bump east in surface track of the developing low the rest of the models will jump in too. Towards SW MO and NE OK it's colder again this run early on (NAM 24hrs)...the GFS/24hrs is colder at the same time along the TX border. It's just not picking up possibly on the shift east further north. With this track...NNE then a hard right even 20 miles early on will make a big(ger) difference up here.

I like that both models shifted the cold air east/southeast to some degree very early.

I think folks aren't focusing enough on the big picture >overall both models were postive if you want more snow and less ice

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