Preliminary Storm Outlook

By: sullivanweather , 8:25 PM GMT on November 26, 2007

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Short-term Update

Montague, NY Radar


Lake-effect snow will pick up over the next few hours as flow becomes better aligned and colder air advects into the region behind departing shortwave. Accumulations of 1-3 inches are possible tonight with isolated 4 inch amounts.

As this shortwave moves into northern New England a few brief, but intense, snow showers will coat the ground.

Otherwise expect partly cloudy skies and breezy conditions during the overnight for the remainder of the Northeast.

Potential exists for a Winter Storm late this weekend into early next week. Peliminary synposis is below.


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Current watches, warnings and advisories.


Eastern US current watches/warnings


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Regional Forecast

Storm system currently affecting the Northeast this Monday with rain and when moisture makes its way into northern Maine tonight, snow. Low clears the region on Tuesday with lake-effect snow and blustery conditions in its wake. High pressure moves over the region on Wednesday with mostly clear skies and near normal temperatures. Low approaches on both Thursday and Saturday, bringing rain and snow showers and leaving behind progressively colder air and lake snows. By the end of the weekend into early next week and potentially larger system will make its way towards the Northeast which could result in a significant snowfall for some in this very active pattern.

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Rain currently engulfs most of New York and Pennsylvania late this Monday afternoon with a stripe of rain also across central New England. Expect precipitation to gradualy overspread the entire area this evening as low pressure moves through the Ohio Valley and into the Northeast. Precipitation will be steady and fall moderately to heavy at times. As precipitation reaches northern Maine vertical profiles would suggest that the predominate precipitation type will be in the form of snow. Up to a half foot of snow could fall over extreme northern Maine during the overnight period. Further south along the coastal plain of New Jersey, southeastern New York and southern New England a line of low-topped convection could form in a slightly unstable airmass in the warm sector along the cold front as it moves through. This line could have some gusty winds and torrential downpours associated with it and will make for very difficult travel as there could be rapid ponding of water and reduced visibilities. Overall three quarters of an inch to an inch and a half of rainfall should occur for the length of this storm. Isolated amounts of 2 inches or more is also possible. This will lead to some flashier creeks and streams possibly coming out of their banks and sharp within bank rises on area main stem rivers. As low moves into New England rain could change over to snow showers across western New York acorss the northerntier of New York into the Adirondakcs. Temperatures will be mild this evening to the south of the warm front over the coastal plain. Expect 50's here with temperatures dropping into the 40s after the frontal passage around midnight. Over the interior temperatures will be in the 40's before the low/front moves through and fall back to the 30's after it's passage. Further north over northern New York and central to northern New England, excluding northern Maine, temperatures will be in the upper 30's during the evening, falling back to then low 30's after the passage of the low. Over northern Maine temperatures will be in the low 30's socked in with frozen precipitation.

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Low pressure moves through New England and off into the Canadian Maritimes on Tuesday morning with steady precipitation tapers quickly after its passage. Over northern Maine an additional 2-4 inches could fall during the morning hours with up to half an inch of rain towards the south over the rest of northern and eastern New England. Behind the departing storm gusty northwest winds will usher in a cooler, but not terribly cold, airmass. Lake-effect snows will begin during the morning hours over the eastern lakes with several inches of accumulation downwind, especially over the higher terrain with boundary layer temps only marginal for accumulating snows in valley locations. Away from the lakes skies over the rest of New York and Pennsylvania to the coastal plain skies will be partly cloudy with a few stray rain or snow showers. Temperatures will likely remain steady during the morning then slowly fall by mid-afternoon after peak heating.

A short wave disturbance dropping down the backside of the trough that will be carved out over the Northeast could provide a brief enhancment of lake-effect snows during Tuesday evening. Multi-bands will likely be disrupted with the passage of this disturbance and could form a line of snow squalls that will push off the lakes and drop into New York State. Flow will likely re-align after the passage of this shortwave bringing another round of multi-band lake effect. In total, an additional 2-4 inches of snow could fall downwind of Lake Ontario, with up to an inch or two of snow with the passage of potential snow squalls. Down wind of Lake Erie amounts will be similar, but with more isolated occurances of 2-4 inch amounts. Otherwise expect clearing skies with gradually diminishing winds over the Northeast, aside from northern New England where clouds and snow showers will hang tough due to cyclonic flow, upslope and passage of shortwave and associated PVA. Lows will likely fall to near freezing along the coastal plain with 20's over the interior. Only higher elevations of the Adirondacks, Green and White mountains could see lows fall into the teens. Wind chills will also be quite chilly during the evening hours before winds diminish.

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High pressure will build into the Northeast on Wednesday shutting down the lake-effect. Skies will be mostly clear for the majority of the day. Towards evening some high clouds will begin to filter into western and northern New York State as the next system approaches from the west. Temperatures will be near to slightly above normal across the southern half of the region, near to slightly below normal acorss the northern half. This translates to upper 20's to low 30's over northern New England. Mid to upper 30's over northern New York into central New England. Low 40's over central New York and northern Pennsylvania and upper 40's to low 50's across southern Pennsylvania to the coastal plain and southern New England.

Fast moving low pressure coming out of the Plains will make it to the Great Lakes Wednesday night spreading clouds into the region with some snow showers developing after midnight across western New York and Pennsylvania, with rain showers towards the Pittsburgh area of southwestern Pennsylvania. With clouds moving in overnight lows will likely be up to 5 degrees or so above normal.


Low pressure moves north of the area on Thursday across southern Ontario into southern Quebec. A cold/occluded front will be dragged through the Northeast with scattered rain and snow showers. Elevation will likely dictate who sees what, with most places across the northern half and above 1000' seeing more snow. Less than 1000' elevation and towards the south, more liquid. Lake-effect snows will likely commence immediately following the passage of this front, along with steady or slowly falling temperatures under strong cold air advection. Moderate accumulations downwind of the eastern Great Lakes appear likely with west-northwest flow being able to tap moisture from upstream lakes. High temperatures will once again be near normal levels for this time of year, despite their early occurance. Winds will become quite brisk after the passage of this front as well.

Lake-effect continues into Thursday night downwind of the Great Lakes with snow showers over central and northern New England due to passage of the trough. Several more inches of snow accumulations should occur in lake-effect areas and the mountainous terrain of northern New England. Winds will remain quite gusty over New England but begin to diminish over the southern third of the region. Overnight lows will likely fall back below normal.

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High pressure moves to the south of the region on Friday. Lake-effect will lessen some, but not totally taper and snow showers will persist throughout the day immediately downwind of the lakes. Elsewhere clearing skies over northern New England and partly cloudy to mostly clear skies throughout the rest of the Northeast will lead to a nice, albeit, chilly day. High temperatures will average 3-7 degrees below normal on Friday with a brisk wind over northern New England.

A clipper system quickly moves back into the Northeast for Friday night and Saturday. Disrupted flow just ahead of the low will likely cut-off lake-effect, but scattered snow showers associated with the clipper system itself will develop during the overnight and the day on Saturday. Greatest concentration of these snow showers will be across the north, with southern areas mainly seeing an increase in cloud cover and perhaps a stray snow shower. Temperatures will continue to average around 5 degrees below normal. After system passes lake-effect will commence once again during Saturday afternoon.

High pressure quickly builds in behind clipper system, likely limiting lake-effect accumulations to just a couple of inches. Skies will clear and winds will calm. With very chilly airmass overhead, Saturday night will likely be the coldest night thus far this season. I wouldn't rule out the possibility of below zero temperatures in the colder mountain valleys of the Northeast Kingdom. Elsewhere acorss northern New York and New England temperatures are likely to fall into the single digits with low teens over most of the interior. Even along the coast and urban areas, temperatures could drop to near 20°F with even colder wind chills during the evening hours.

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Active pattern will continue into the second half of the weekend into early next week. Energy dropping down into the western US to the Four Corners region will cross the southern Rockys and spawn low pressure in the southern Plains. With high pressure anchored over the Ohio Valley and Great Lakes and a fast jet stream developing over the center of the country, precipitation will break out over the southern Plains and Mid-Mississippi Valley spreading quickly eastward.

A number of different scenarios could play out from this juncture, depending on how much energy comes out of the southwest. In any event, favorable high position over southern Canada nosing down the eastside of the Appalachians should make for a wintry precipitation event once this moisture reaches the Northeast late Sunday into Monday. Peliminary estimates from models show a solid half to three quarters of an inch of liquid equivilent precipitation across the southern half of the Northeast with lesser amounts towards the north. Of course, with this event being a week away much can change. A stronger high pressure could keep the system further south, with lighter precipitation amounts. A stronger low and weaker high could allow the system to take a further west track bringing a snow to mix/rain event, with significant snows falling further north and in Canada.


Peliminary forecast for Sunday-Monday storm

Sunday precip type map


Sunday night - Monday precip type map


Based on model trends I believe a common set-up to this system will evolve. An area low pressure will ride into the Ohio Valley from the Mid-Mississippi Valley where it will weaken and transfer its energy to a developing low pressure area off the Delmarva. The primary low will weaken as it moves into western Pennsylvania as the secondary low strengthens and moves up the coast, just offshore.

Given this scenario, this is how I believe the snowfall totals would pan out

peliminary snow totals dec 2-3 storm

A stripe of moderate snow should fall from northeast Missouri to southern Michigan and northern Ohio. Another area of moderate to heavy snow should fall from north-central Pennsylvania northeastward to Maine. Enhanced totals downwind of the Great Lakes is due to lake-effect snow and only partly associated with the low pressure system itself.

Please note: This is a peliminary forecast based on knowledge of past events. Basically a climatology forecast. Individual storm characteristics will likely not be known until later this week.


Behind this storm the arctic gates open allowing some moderated arctic air to move into the Northeast with 850mb temps falling to -15°C and 500mb thicknesses falling below 520dm and a potentially extended lake-effect event.


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Radar: Northeast Region

NE radar

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Local SST's

Northeast SST's


Current SST's off the Northeast Coast.

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Great Lakes SST's 9-29

Great Lakes SST's as of 11/23/2007.

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Fillipini's Pond conditions (Lake across street)

11/6: 42°F
11/9: 37°F
11/11: 33°F - 1st morning with grease ice on lake.
11/17: 33°F
11/22: 34°F
11/24: 32°F - patchy ice on lake this morning
11/25: 32°F - lake iced over completely, melting along the shores during the afternoon.

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November Daily Weather Statistics

Date___________Hi/Lo____Precip___Sun___Snow

November 1st - 53°F/38°F....0.00"....40%
November 2nd - 52°F/30°F....0.00"....90%
November 3rd - 51°F/35°F....0.00"....30%
November 4th - 48°F/36°F....0.00"....15%
November 5th - 52°F/28°F....0.23"....60%
November 6th - 45°F/36°F....0.26"....40% Trace
November 7th - 37°F/27°F....Trace....40% Trace
November 8th - 37°F/19°F....0.00"....60%
November 9th - 38°F/27°F....0.21"....0% 1.5"
November 10th - 37°F/26°F....0.26"....20% 3.1"
November 11th - 42°F/20°F....0.00"....95%
November 12th - 39°F/24°F....0.12"....0%
November 13th - 54°F/29°F....0.31"....80%
November 14th - 48°F/27°F....0.39"....5%
November 15th - 52°F/35°F....1.53"....0% Trace
November 16th - 37°F/27°F....0.02"....40% 0.1"
November 17th - 36°F/26°F....0.00"....20%
November 18th - 35°F/28°F....0.02"....0% 0.2"
November 19th - 33°F/28°F....0.18"....0% 2.6"
November 20th - 37°F/31°F....0.31"....0% Trace
November 21st - 48°F/37°F....0.02"....0%
November 22nd - 63°F/29°F....0.04"....30%
November 23rd - 31°F/18°F....Trace....75% Trace
November 24th - 32°F/15°F....0.00"....60%
November 25th - 44°F/18°F....0.08"....95% 0.2"
November 26th - 50°F/30°F....1.01"....0% 0.1"
Nevember 27th - 52°F/29°F....0.04"....70% Trace



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13. sullivanweather
5:35 PM GMT on November 28, 2007
Hey everyone.

I'll have an update in the evening, most likely to move the snow line north by 100 miles or so and add in more ice for the Northeast.

GFS has shown some consistancy in its previous 5 runs now, which, along with the ECMWF and Canadian models, brings this low into the Great Lakes. These models phase the jet over the western US digging out a pretty deep trough and amplifying the ridge over the Southeast.

Thus far the NAM seems to be the only model not on board with this scenario.


At 84 hours the GFS has a baggy low pressure complex already out in the Plains, one over Iowa another along the front range in Colorado. It also has an amplifying ridge over the Southeast in response to devleoping low pressure in the Plains.

The NAM, on the other hand, has a much flatter ridge over the Southeast. Most likely due to the fact that it still has the jets seperate, with southern stream energy moving out of the southern Rockys into the southern Plains and northern stream energy still over the Pacific Northwest Coast.

The NAM would have a much less aggressive push of warm air into the Eastern US than the GFS or any of the other models, for that matter. It is an outlier, but worth noting, because the models ALWAYS have trouble when it comes to where and when to phase the jets.

Will likely have a better idea of what's going on this evening, hance the update will come then.
Member Since: March 8, 2007 Posts: 273 Comments: 12612
12. dean2007
11:18 PM GMT on November 27, 2007
Hey sullivanweather, I have just updated my blog and my thoughts on this weekend storm are on there with maps. Check it out and see what you think.
11. sullivanweather
11:08 PM GMT on November 27, 2007
MS paint and a blank map.
Member Since: March 8, 2007 Posts: 273 Comments: 12612
10. MrSea
11:04 PM GMT on November 27, 2007
how do you make those maps?
9. PalmyraPunishment
9:04 PM GMT on November 27, 2007
Hey Sullivan,

How about you stop being so realistic and start wishcasting like the rest of us, heh? lol

Member Since: January 31, 2007 Posts: 9 Comments: 2250
8. sullivanweather
8:55 PM GMT on November 27, 2007
About an hour or so....

Trying to find the right colours was the hard part ;0)
Member Since: March 8, 2007 Posts: 273 Comments: 12612
7. eaglesrock
8:49 PM GMT on November 27, 2007
I really like this forecast. How long did it take you to make the maps?
6. sullivanweather
8:19 PM GMT on November 27, 2007
MrSea,

It all depends on how much energy comes out of the southwest. If a bigger than expected chunk of energy comes out of the southwest it will spawn a stronger cyclone over the middle of the nation that would have no trouble at all driving up into the Great Lakes. I'm thinking that not all the energy comes out in one big chunk, they hardly ever do. Usually it's more of a piecemeal release of energy from deeply dug upper lows out of the southwest which leads to less ridge amplification upstream over the southeast.



Member Since: March 8, 2007 Posts: 273 Comments: 12612
5. MrSea
8:08 PM GMT on November 27, 2007
I think the 12z is wrong, I think the cold air is too dense for the storm to cut through. I think a more southerly track with the storm redeveloping out over the ocean is more likely. However, my forecast is biased because I am just a kid who wants snow here on Long Island!!
4. sullivanweather
7:35 PM GMT on November 27, 2007
Hey WSB,

I noticed that the 12z model run of the GFS started to come more in line with the ECMWF and Canadian models of 00z. Right now that means a stronger primary low driving up into Michigan and secondary development closer to Long Island at the triple point.

I still think that this storm won't be as strong as advertised in the 12z model runs. Usually the GFS will start to swing wildly from one solution to the other when the storm is in the 96-132hr period before settling on a solution somewhere in between. Which I think should be the primary heading into northern Ohio with secondary development just off the Delmarva.

Member Since: March 8, 2007 Posts: 273 Comments: 12612
3. Winterstormsblog
3:15 PM GMT on November 27, 2007
GREAT POST TODAY!!

on top of that i am in your HEAVY SNOW area, lol!!!

will be stopping by whenever u update again.

-WSB
Member Since: October 5, 2007 Posts: 86 Comments: 5650
2. Bonedog
11:35 AM GMT on November 27, 2007
Thanks for the update sullivan. Great work and very informative
Member Since: July 14, 2005 Posts: 14 Comments: 7418
1. NumberWise
12:03 AM GMT on November 27, 2007
As usual, interesting, informative, and useful information. Thanks for the updates.
Member Since: October 22, 2005 Posts: 0 Comments: 1774

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Thomas is an avid weather enthusiast, landscaper and organic gardener. This blog is dedicated to Northeast and tropical weather forecasting. Enjoy!

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