Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 2:03 AM GMT on February 14, 2010
A northern stream shortwave will rotate through the 500mb charts in the form of an enhanced clipper in the Monday-Tuesday time frame, which will redevelop near the coastal front enhancing moisture/precipitation from West Virginia to Maine. A moderate snow axis is likely to develop slightly north of the track. Sunshine prevails much of the rest of the week before wavelengths favor another increasing chance of cyclogenesis in the 7-8 day time frame towards next Sunday.
"Afternoon Thoughts" (Updated 2/13)
Navigating through south-central Pennsylvania is a daunting task and one that takes you through perhaps a northern New England winter instead of the Middle Atlantic. Drifting snow is more of the common place instead of a brown horizon line along the southern edge of the Appalachians. Perhaps it is more reminiscent of a Norman Rockwell winter scene than typical winters. With children sledding down hills at every corner and snow mounds continue to grow, it appears finally our wishes of a snowy winter have laid their mark here in the Middle Atlantic. Considering snow depths near 40in on the north side of the Blue Mountain here in Harrisburg, it is likely that will not melt for a few more weeks as the region remains under the threat for more snowfall and colder temperatures. I suppose this is what it is likely every winter for those along the Great Lakes where powdery snow drifts from day to day higher and higher and some roads just never seem to see asphalt for days on end. Driving around the mountain valleys north of Harrisburg reminds me of a trip up towards Potter and Tioga Counties of Pennsylvania where deep snow cover was persistent especially on the north side of mountains where there is little sunshine. My statistics already have this month being the snowiest ever on record for Harrisburg surpassing January of 1996, but KMDT is a few inches behind which will likely occur Monday night. This will likely make February 2010 the snowiest month ever on record in the Harrisburg area with records dating back to 1888. The snowier than normal winter was an obvious call back in the fall as a record low negative AO below -4 in correlation with a moderate to strong El Nino is a recipe for a wintry forecast for the eastern seaboard. As for what this all equates for in summer is still up in the air for now and pure speculation, but something to monitor. For those interested in a climatology perspective on snowy winters and the preceding summer, take an interesting read in "The Pennsylvania Weather Book" by Ben Gelber. Anyways for those of us in the Northern Middle Atlantic enjoy this unusual amount of snow and ignore those New Englanders who are finally getting a taste of what it is like here in the Middle Atlantic, hahaha. Have a wonderful day!!!
"Current Surface Plot"
(Courtesy of HPC)
(Courtesy of Wunderground)
(Courtesy of NOAA)
"Forecast Discussion"(Pennsylvania, Maryland, Delaware)(Updated 2/14)
(Courtesy of Penn State Meteo.)
"Current Water Vapor Loop"
(Courtesy of Penn State Meteo.)
"7-Day Zonal Forecast Outlooks"(Pennsylvania, Maryland, and Delaware)(Updated 2/14)
"Current River Ice Reports and Ski Conditions" (Updated 2/13)
Excellent ski conditions are occurring statewide in Pennsylvania favoring areas south of interstate 80. In fact many would argue these are the best conditions since January of 1996. Heavy snow has wreaked havoc for transportation and travel concerns, but it has certainly helped the skiing industry especially with the renewed interest in winter sports courtesy of the Winter Olympics 2010. The Laurel Highlands have been basking in plentiful snowfall with Seven Springs reporting now over 140in of natural snowfall for the 2009-2010 winter season with over 55in of natural snow in the past seven days. Several natural snow trails have recently been opened. Blue Knob Ski Area is also nosing over the century mark for seasonal snowfall coming in a hair lower at just over 90in of snow. Four Seasons Hidden Valley in the Laurel Highlands is also reporting excellent conditions with over 50in of natural snow in the past seven days. With below normal temperatures under a northwest cyclonic flow, conditions could not get any better with little snow melt courtesy of dense cloud cover from upsloping over the Laurel Highlands. Although partially frozen Lake Erie is limiting lake effect snow down to nuisance amounts with orographic lift aiding in an additional 3-5in of snow across the Laurel Highlands Saturday night. As subsidence inversion levels lower, the light snow shower activity will begin to subside towards Sunday morning with clearing skies for the entire state of Pennsylvania. Across the south-central Mountains skiing conditions are the best in over a decade at least with Ski Whitetail picking up nearly 50in of natural snow at the summit this month. Ski Roundtop and Ski Liberty have also picked up nearly 40in of natural snow with all resorts at 100% operating conditions. No new snowfall is expected through Monday morning. Across the Poconos and north central mountains conditions have been excellent, but fresh natural snow has not been as heavy as the southern half of the state. Ski Sawmill recently picked up 10in of snow from the past storm with areas towards Blue Mountain Ski Area up through the Poconos receiving around a foot of snow or so with a bit more in some areas towards 2ft. So generally for now the best conditions appear to be at Ski Whitetail and Seven Springs down through Wisp, Maryland near Deep Creek where snowfall for the season is well over 100in. Snow chances remain optimum for the week ahead with a synoptic moderate snow accumulation likely for the entire region especially north of the Mason-Dixon line. Also a bit of lake effect snow is likely throughout the week as multiple embedded vortices move through the northeast allowing for light 1-3in snows possible several times this week for the Laurel Highlands. Finally towards the weekend another synoptic precipitation event is aimed at the region, but confidence remains low at this point.
Widespread frazil ice pans remain across local main stem rivers in the northern Middle Atlantic with recent surveys suggesting widespread coverage of moving ice pans across the Susquehanna River Basin. Also the Delaware River is reporting several areas of widespread ice coverage and this may increase in the coming days as the region remains under the gun for more snowfall. Local ponds and lakes have widespread ice coverage but thicknesses vary across the region depending on depth and other factors. Best advice to those ice fishing and ice skating is to check with local authorities for safe ice thickness levels on local ponds. With below normal temperatures expected in the next seven days, ice thicknesses will likely be on the increase with a statewide snow cover.
-Link to official reports page from NWS... Link.
-Link to local ski resort snow conditions... Link.
"Current Northeast Snow Depth and Northeast Wind chills"
(Courtesy of Wunderground)
"Lake Effect Snow Conditions" (Updated 2/13)
With the entire northern Middle Atlantic encased in a rare region wide snowpack; many of the lake effect snow belts will be satisfied in a dwindling threat of lake effect for the upcoming last few weeks of winter. A majority of the southeast bank of Lake Erie is ice covered with SSTs generally below 31F for those with open channels. A bit more open water remains on the north end of the lake along with widespread open channels for Lake Huron. This Huron-Erie connections favors lake effect snow for the Laurel Highlands, but nothing overly significant. A 315degree northwest flow will allow for a bit of light snow courtesy of orographic lift along the leeward sides of the Laurel Highlands ridge tops. Light snow shower visibility around MVRF to IFR will favor visibilities generally at 1mi or above therefore limiting accumulations to western facing slopes above 1900ft with accumulations in that region generally 3-5in for Saturday night. Lowering subsidence inversion heights will allow for clearing skies towards Sunday with no additional snow accumulation. Little to no accumulation is likely Saturday night for the northwest snow belts. High pressure and weak ridging aloft will allow for a dominate westerly flow with sunshine through Monday before clouds increase with a threat of synoptic snow. Towards Tuesday a cyclonic flow regime will induce across the entire northern Middle Atlantic. But with limited moisture from the Great Lakes, lake effect snow accumulations will be kept in check for the Tuesday-Thursday time frame not exceeding advisory levels during any point. Omega values remain low throughout the week along with a slightly displaced dendritic growth layer keeping ratios around 15:1. GFS/NAM QPF means suggest around .3-.4in for the snow belts by the week's end from lake effect snow and upslope enhanced. Accumulations will favor towards the Laurel Highlands into western Maryland in Garret County towards Frostburg, MD under a 300degree flow. Up to 8in of total snowfall is likely towards Mt. Davis and Laurel Summit in Somerset County, Pennsylvania above 2850ft. Valley snow accumulations through the week in the Laurels will generally be less than 4in. Downsloping winds will limit the snow shower extent quickly eliminating snow bands east of the Altoona-State College-Lock Haven line. Snow accumulation across northwestern Pennsylvania will be totaled around 2-4in by the week’s end favoring Clearfield County. Little to no pure lake effect snow is likely for northeastern Pennsylvania which such a westerly flow, but a deformation band from the coastal low will allow for some synoptical precipitation. Weak ridging aloft and high pressure move across the region towards the week’s end allowing for region wide sunshine through Saturday with below normal temperatures.
"Current Lake Erie Wind Direction and Speed"
(Courtesy of NOAA)
"Current Lake Erie Water Temperature"
(Courtesy of NOAA)
"Long Term Outlook" (Updated 2/13)
With the GFS operation and ensembles continuing to indicate a solid phase 8 MJO, it appears troughing will dominate the eastern seaboard. Coupled with an anomalous negative AO below -4, which continues the record stretch, the active southern stream courtesy of the moderate El Nino will allow for an above normal chance of another significant coastal storm along the eastern seaboard. Wavelengths and global ensembles continue to indicate a threat in the day 7-8 time frame around the 21st of February. 2/13 12utc ECMWF run indicates a low pressure undergoing cyclogenesis near the Delmarva with a surface pressure well below 990mb. With prognostics coinciding the negative NAO regime and positive PNA regime it is likely for a coastal influence. While the ECMWF highlights this as a significant threat, the GFS maintains a conservative approach with a more meridian jet stream flow with a flat west to east traversing shortwave. In any case I am highlighting the period from the 20th-22nd of February as a potential significant east coast storm threat date. Again being 7-8 days away I will highlight very few details, but I will mention cyclogenesis towards the eastern seaboard has an above normal potential. Looking at the general winter theme it would suggest the Middle Atlantic features the brunt of this system, but in this time frame the 50/50 low, while still quite favorable, is it a bit weaker and therefore will probably allow the low pressure to spread the wealth a bit more, but that is considering the low pressure even forms. Looking towards the last two weeks of the month, it appears colder than normal temperatures will dominate the weather for much of the weather east of the Mississippi with normal to above normal precipitation. The GFS tries to introduce Pacific modified air towards the end of the month, but I believe it is a bit too quick in doing so. In any case stay tuned throughout the week on the threat towards next weekend!
"Current NAO and PNA Predictions"
(Courtesy of NOAA)
"Anchorage, Alaska Tower Cam"
*Note I am only posting this tower cam until snow starts falling over the northern Middle Atlantic, lol. For now we can all be jealous of the Alaskan snow.
"Monthly Outlook" (March)
February sure has been a memorable month for those with concerns across the viewing region. In fact century old records have been broken for many large cities and towns across the northern Middle Atlantic with even snowfall being recorded on the ground in at least 49 states during the February 12-13 period, which many climatologists are hard pressed to find any other date with such widespread snow cover. The NCDC reports nearly 68% of the nation snow covered as of February 13th with an eight inch average depth. With temperature anomalies also well below -2SD for much of the United States, this has certainly been a February of wintry notation. While the month is generally about 1/2 over and an end to the meteorological winter is quickly approaching, more wintry precipitation will likely continue for the eastern seaboard. For more details for the last two weeks of the month consult the long term disco above. As for a February forecast, due to time constraints unfortunately I was unable to post one. But on second glance of my winter forecast, it clearly advertised February being a very snowy and cold month in fact the snowiest of the winter. Despite what the final two weeks of the month show, these statistics have already been verified. Soon or perhaps now many will be basking in the threat of spring-like weather which is not too far off. It is evident based on teleconnections the worst is over as far as arctic air and climatology means. For those interested in my winter outlook verification blog, it will be issued upon the first week of March as the meteorological winter comes to a close. Now as we look towards March teleconnections diverge... Global models including the GFS/ECMWF begin to lose direct correspondence in forecast similarities after the 10 day time frame. ECMWF weeklies continue to advertise anomalous blocking as we continue in this record -4 AO with troughing over the east coast. But the GFS highlights a zonal flow with Pacific air flooding the nation with cold air bottling up towards Canada. What is interesting this year has been the lack of arctic. Due to the polar vortex being displaced a bit too far north, we have been close to record cold air, but it is just a bit too far displaced. In any case this looks to continue. As common with El Ninos, an active southern stream will continue. But current Nino 3.4 region SSTs indicate a general cooling regime with weakening into low end moderate stage. MJO on the other hand using GEFS supports more of an ECMWF solution. Using a few analogs up my sleeve, climatology, and teleconnections I support a mean forecast of the following for the month of March...
Temperature- I look entitled to enter a pretty typical temperature anomaly forecast for the month averaging from (-0.5)-(+0.5) F across the entire northern Middle Atlantic. This being said I favor guidance for a cooler pattern for the first week or two of the month with temperatures around -5F averages each day; nothing overly cold. Then I believe the pattern radically swings around midmonth or potentially earlier to a much warmer flow as we pardon goodbye to a historic winter. In fact the pattern change is critical for timing as it appears once we swing the pendulum warmer; it is not going to come back. Previous patterns this winter even back into the fall of 2009 favor about 30 day patterns so the timing on this troughing over the east is coming to an end soon. I would not be surprised if the month rounds things on the warmer side of the forecast more so than verifying colder than normal.
Precipitation- Considering climatology of moderate El Ninos on the weakening trend and the considerably active southern stream, I am inclined to lean towards the wetter side of guidance favoring above normal precipitation for the month across the entire northern Middle Atlantic. As for snowfall which is really what most people are concerned with, I will go with normal snowfall for most regions with the higher threat of snow being during the first week of the month before the large pattern change.
"Temperature and Precipitation Outlooks from Climate Prediction Center for next 30 days"
(Courtesy of NOAA)
-Winter Outlook 2009-2010... Link.
"Here northeast of Harrisburg 2009-2010 winter statistics"
Current Snow Cover- 5in
Monthly Total- 45.75in
Seasonal Total- 63.80in
October Total- 0.0in
November Total- Trace
December Total- 16.0in
January Total- 2.1in
February Total- 45.75in
Winter Weather Advisories- 6
Winter Storm Warnings- 3
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 2
Winter Storm Watches- 3
Lowest High Temperature- 18.8F
Lowest Low Temperature- 9.3F
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Winter Storms Stats)
Dec 5 - 1.5in - First accumulating snow of season
Dec 8-9 - 2.5in - Snow changed to plain rain
Dec 13 - .1in - Freezing rain
Dec 19 - 9.0in - Heavy snow, higher amounts to south
Dec 31 - 3.0in - 2.5hr warm air advection event
Dec 31 #2 - .2in - Freezing rain/sleet later in day
Jan 8 - 1.5in - Light snow associated with clipper
Feb 2 - 3.75in - Weak coastal storm
Feb 5-7 - 19.0in - 10th largest snowstorm on record
Feb 9-10 - 20.5in - Blizzard conditions/snow depth up to 36in
Feb 15-16 - 1.25in - Light snow from clipper
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