Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 10:08 PM GMT on December 31, 2011
The first major lake effect/upslope snow event will be occurring in the next few days. Since I have been tracking the weather, this is one of the latest first lake effect snow outbreaks I have witnessed. None the less, it will only feel like January conditions for a few days before milder air moves into the region towards the end of the week as H85s rise above 0C up to the Canadian border.
Thoughts on January 1-3 Lake Effect Snow Outbreak and Arctic Blast
A strong cold front is advancing towards the Northeast on Sunday associated with light rain showers. QPF generally will remain less than .2in for most areas. Behind the front is a surge of arctic air as H85s rapidly drop below 0C changing any residual rain along the front to snow particularly for western New England. A 1040mb anticyclone across the Northwest territories along with an amplified western +PNA ridge is allowing for a cross polar flow directly across the contiguous United States. Given the close proximity between the high and low pressure, a tight isobaric flow will give way to strong winds at the surface. Directly behind the front, winds will shift to the west-southwest gusting to nearly 45mph for most locations. Across western New York state, particularly along the Adirondacks and the Chautauqua Ridge, winds could exceed 60mph briefly Sunday night. As 850mb thermals drop to nearly -10C by Sunday night, the 260 degree flow will slowly organize lake effect snow bands off of Erie and Ontario. Temperature differentials well over the 8-13C threshold, will allow defined bands to begin to develop until a highly unstable setup as elevated CAPE values approach several hundred joules.
Bands initially will favor northern locations particularly in New York state with a band Sunday night situated from Erie, PA to Jamestown, NY to Buffalo, NY. This band will slowly drift south overnight as the flow shifts more westerly. Another band in this time frame will stretch from Rochester along the lake shore to Oswego and possibly up as far north as Watertown, NY. Snow accumulations for both of the bands will be in the 4-8in range. These bands will be migratory and will preclude higher accumulations especially in the Buffalo metro. The southern portion of the metro will be prone to the higher accumulations up to 8in. Weak snow showers will begin to form along upslope locations in Pennsylvania and Maryland, but accumulations will be less than 1in through most of Sunday night.
By Monday morning the flow will shift more westerly to around 280 degrees. This will allow bands to shift southward into northern Pennsylvania with heavy snow from Erie, Crawford, McKean, and Warren counties. Ratios will begin to increase to near 25:1 as H85s drop to nearly -20C and a favorable dendritic growth area occurs according to recent SkewT charts. Given the fluffy snow, accumulations will approach 12in by Tuesday across northern Pennsylvania and the Chautauqua Ridge region in southern New York. The band off of Erie will situate a bit more due west stretching from Oswego through the Tug Hill. Given the great amount of instability and relatively low shear values under adequate moisture aloft, snow rates will increase to nearly 3in/hr. Total snowfall is likely around 2ft for areas in the Tug Hill plateau given the additional orographic lift.
Monday afternoon will continue to see a veering in the winds with an increase in shear as the flow turns due northwest around 310-320 degrees. This will decrease the intensity in singular bands allowing for a multi-band and cellular flow. Accumulation rates will decline in the typical snow belts, but increase across the upslope regions in the Laurel Highlands and western Maryland. Past analogs indicate a high likelihood of a Huron-Erie streamer funneling through the Laurel Highlands across parts of southern Cambria county where accumulations will max to nearly a foot of snow by Tuesday night. The lower valleys are more likely to see accumulations on the order of 2-5in. Elsewhere across Pennsylvania, widespread snow showers are likely. The northwest flow with sustained winds at nearly 20-30mph will allow for a near ideal fetch off the lakes with snow showers east of the mountains. As the flow continues to shift more northerly, snow showers from the Delaware and Chesapeake Bays are likely across coastal regions. No accumulation is likely.
Monday night will feature a waning in diurnal activity, but several streamers are likely to form. Across New York state, additional moisture from the finger lakes is likely with a north-northwest flow with amounts across this region at nearly 3-8in. Several streamers are possible over western Pennsylvania near Pittsburgh and across central Pennsylvania. Amounts will be light, but a 2-3in amount cannot be ruled out. Farther east streamers will be more isolated, but the potential will exist for a quick 1-2in of snow.
By Tuesday the low pressure across Canada will pull to the east and this will allow the moisture to reach the upslope regions across New Hampshire and particularly Vermont. Amounts look less than originally expected only reach 6-12in for the higher elevations. The snow maps below, produced yesterday, are likely a bit too high in accumulation for this area. Snow showers and multi bands will continue off Erie and Ontario along with some Georgian Bay and Huron enhancement. Once again diurnal snow showers are possible across the entire Northeast, but little to no accumulation is likely. H85s will drop to -20C and thicknesses will approach sub 510dm 1000-500mb. The core of the coldest air will be over the region. Winds continuously sustained at 20-30mph will allow for dangerous wind chills approaching advisory criteria for northern locations. Highs will struggle to reach 30F as far south as northern Virginia. High pressure moves in towards the region by Tuesday night cutting off the snow machine and allowing for the coldest night of the season with negative values likely for northern New England.
The heaviest snow amounts will be over the Tug Hill plateau and Chautauqua Ridge region in New York State with amounts upwards of 2ft. Accumulations across the Laurel Highlands and northern Pennsylvania will be closer to a foot. Towards the Vermont upslope region and across the Finger Lakes advisory criteria amounts are likely. Outside these areas accumulations will be more localized. I will have periodic updates throughout the next 72 hours on the development of the lake effect snow bands. Stay tuned!
(Courtesy of NOAA)
(Courtesy of NOAA)
... Crawford County...
canadohta lake 11.2 959 am 1/02
Conneautville 6sw 8.0 1001 am 1/02
Meadville 5w 4.0 1018 am 1/02
Linesville 3.6 1006 am 1/02
Meadville 3.2 1011 am 1/02
... Erie County...
Colt station 5.0 1001 am 1/02
Franklin ctr 4.6 1003 am 1/02
3 NNW Colt station 4.0 1020 am 1/02
northeast 6sw 4.0 1012 am 1/02
Waterford 3.0 1021 am 1/02
Millcreek TWP 2.4 805 am 1/02
2 WSW Erie Airport 2.0 1010 am 1/02
Fairview 1.8 1009 am 1/02
Amity TWP 1.5 804 am 1/02
Erie Airport 1.4 1024 am 1/02
1. High winds sustained at 20-30mph with gusts upwards of 55mph above 1500ft. Whiteout conditions with visibility less than .25mi in squalls.
2. Dangerous wind chills for northern areas approaching -20F at times.
3. Heavy snow amounts in favored snow belts with accumulations up to 2ft.
4. Widespread snow showers and squalls will bring wintry feel to the entire Northeast.
5. Temperatures will struggle to reach 32F as far south as Virginia for Monday and Tuesday.
***Both snow maps show the same event for lake effect and upslope snows over the January 1-3 period. Given the isolated nature of snow squalls, amounts will vary of small distances. Areas outside the 1-3in range have the threat of C-3in given any rogue snow showers or squalls. The area of higher accumulations over northern New England is associated with the upslope effect from the Green and White mountains. Accumulations will approach 1-2ft above 3000ft in parts of northern Vermont particularily towards ski resorts such as Stowe.
Current Great Lakes Water Temperatures...
(Courtesy of NOAA)
Current Lake Erie Wind Direction and Speed...
(Courtesy of NOAA)
Current Lake Erie Water Temperature...
(Courtesy of NOAA)
"Selected City Accumulations"
Erie- 10-15in with higher amounts southeast of the city (12-24in)
Meadville, PA- 10-15in of snow
Bradford, PA- 8-14in of snow
Butler, PA- 3-5in of snow
Pittsburgh, PA- 1-4in of snow
Latrobe, PA- 2-5in of snow
Indiana, PA- 3-6in of snow
Johnstown, PA- 9-15in of snow
Somerset, PA- 4-8in of snow
Altoona, PA- 2-4in of snow
Du Bois/Clearfield, PA- 3-6in of snow with locally higher amounts
Philipsburg, PA- 3-5in of snow
State College, PA- 1-4in of snow
Lock Haven, PA- 1-3in of snow
Williamsport, PA- Locally 1-3in of snow
Mt. Pocono, PA- 1-4in of snow
Selinsgrove, PA- Locally 1-3in of snow
Harrisburg, PA- C-2in of snow
Hagerstown, MD- Locally C-2in of snow
Cumberland, MD- 1-3in of snow
Frostburg, MD- 4-8in of snow
McHenry, MD- 6-12in of snow
Oakland, MD- 7-14in of snow
Snowshoe, WV- 12in+ of snow
Buffalo, NY- 3-7in of snow. Higher amounts in southern metro region
Watertown, NY- 4-8in of snow
Syracuse, NY- 4-8in of snow
Albany, NY- Locally 1-2in of snow
Ithaca, NY- 2-4in of snow
Binghamton, NY- 1-3in of snow
Saranac Lake, NY- 3-5in of snow
Utica, NY- 5-10in of snow
Burlington, VT- 1-2in of snow. Higher amounts to east approaching 12in
North Conway, NH- 3-5in of snow
"Subject to Change"
Current Northeast Snow Depth and Northeast Wind chills...
(Courtesy of Wunderground)
We are still a bit out of range for the high resolution guidance to depict the positioning of the mesoscale bands, but the 4km WRF is beginning to get into range for the first half of the event with the flow more westerly. It indicates two larger bands generally across New York state Sunday night with one off Erie stretching into the Chautauqua Ridge region well into the Finger Lakes. The strong gradient will favor an excellent fetch far inland. Amounts will be highest across the Jamestown region. This band may initially form farther north into the Buffalo metro region, but latest guidance argues that amounts will stay at low end advisory for the metro area with a generally unfavorable flow. It is likely the band will not be overly intense given the strong gradient. A more distinct band is likely off Ontario into Watertown, NY and dropping south into Oswego and the Tug Hill Plateau. WRF QPF is generally around .6-.8in for most areas. Given 25:1 ratios, amounts up to 2ft are certainly possible. Keep in mind the resolution is not high enough on most models to accurately depict mesoscale QPF totals. As the flow turns more northwesterly, a classic orographic/upslope effect lift for snowfall will occur with more widespread snow shower activity. GFS 0.01in QPF drops well east to even the I-95 corridor as the arctic front passes through Monday night and may be accompanied by a few squalls and/or snow showers. Indices generally do not favor a windex event though given unfavorable timing and several other unfavorable indices. The typical upslope areas are given about .4in QPF by most higher resolution guidance and should translate to about 6-12in of snow. As we get closer to the event, the HRRR and other HIRES guidance should be able to help us pinpoint any surprise streamers that may form. The 4km WRF also indicates the impressive fetch may streamer the initial Erie streamer into the Mohawk Valley region towards Albany, NY, but given some directional shear aloft, it is likely less than 1in accumulation will be reported towards downtown. Few model discrepancies exist other than timing issues as the arctic front approaches and the transition from west to north-northwest winds occurs. The ECMWF is a bit faster and certainly limits snowfall especially across the Buffalo metro.
After the Storm
Global models are in fairly good agreement in the 6-10 day range. Increasing upper level heights over the eastern United States will allow warm Pacific air to once again flood the region by next weekend. The period will generally be dry with temperatures around 10F above normal. The 1000-500mb 540dm thickness will be as far north as northern New England so any precipitation in this time frame will generally be rain for the entire Northeast. The warmest air though will stay to the west over the central Plains, which will feature temperatures nearly 15-20F above normal continuing the snow drought over the Great Lakes and Midwest. Teleconnections remain in support of this mild period with a -PNA and continuing +NAO. At this point the Arctic Oscillation shows no sign of heading negative keeping the cold air locked up across the arctic and on the other side of the globe. The polar jet is very progressive with little buckling this year in comparison to the last few winters.
Guidance begins to diverge past the day 10 frame. Towards January 10, the GFS shows signs of an eastern based -NAO forming along with a positive PNA. The east can do fairly well in +PNA regimes (example: winter of 93-94). The cold blast for the first week in January is fueled directly by a positive PNA cycle. The MJO shows weak forcing in this period and perhaps in a more favorable phase. The stratospheric warming event that was forecast for early January still has yet to occur and looks to be continuously delayed. The CME (coronal mass ejection) forecast by astrometeorologists is helping to keep the stratosphere very cold and definitely not helping the eastern blocking situation. Generally weak solar periods are more favorable for upstream blocking. The GFS is indicating the pattern will be a bit more favorable by January 10 under a sharp gradient flow. A gradient flow indicates a strong thermal boundary will setup somewhere across the Northeast. South of the boundary will feature well above normal temperatures, while north of the boundary will feature seasonable chill. Forecasting the position of the thermal boundary is nearly impossible at this point. But areas north of the boundary may see an increased chance for wintry precipitation. The ECWMF is certainly more progressive towards this period with the ECMWF weeklies just dreadful for the next 30 days. On a more encouraging note, the ECMWF ensembles tend to favor a more GFS-type gradient flow by January 10.
Coastal chances will remain minimal, although current wavelengths are being watched around the January 8-10th period for possible eastern cyclogenesis. Stay tuned for this date. Snow chances will definitely be more likely than back in December, but the pattern still remains relatively poor. It is likely temperatures will be above normal for most locations for the month of January with below normal snowfall, but I doubt it will be nearly as poor as November and December.
Please post storm reports in this blog from across the Northeast during the winter storm and please post location of observation in each report...
This blog is in progress. Check back soon...
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Lower Susquehanna Valley Doppler...
(Courtesy of WGAL)
"10mi northeast of Harrisburg 2011-2012 winter statistics"
Current Snow Cover- 0.0in
Monthly Total (October)- 5.5in
Monthly Total (November)- 0.0in
Monthly Total (December)- 0.4in
Seasonal Total- 5.9in
Winter Weather Advisories- 1
Winter Storm Warnings- 1
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 0
Winter Storm Watches- 1
Lowest High Temperature- 29F
Lowest Low Temperature- 10F
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Snow Storms Stats)
Historic October Nor'easter - October 29 - 5.5in of wet snow
322 Lake Effect Snow Band - December 17 - 0.3in of wet snow
Weak Clipper - December 29 - 0.1in of snow
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