Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 8:13 PM GMT on December 30, 2009
"Afternoon Thoughts" (Updated 12/30)
Good afternoon!!! Usually being New Year's Day only a short few days away I would give one of those annoying and cliched "New Year, New You" type feel good about yourself paragraphs. But this year I decided to stay away and talk about forecasting. Quite a bit of confusion has occurred surrounding this New Year's Day storm system. Being a multi-wave event, details are highly questionable even 24hrs from the first impacts. Much of this week and past week at that, many speculated on possible analogs for this coming storm system. Even the HPC mentioned January of 1996 as a possible similar synoptic setup. Eventually GFS ensembles and MREF trends indicates several embedded vortices of energy located in the H5 flow causing some discrepancies between guidance trends. Then finally yesterday I found my own analog for the second wave of this event (coastal low wave) and noted January 14-15, 2008 being a close relative. This now appears to be exact, although a warm air advection wave Wednesday night and the first half of Thursday will cause some light snow. So after nearly a week of speculation, the final scenario looks evident excluding a few minute details. A 'forecast' so to speak encompasses quite a bit more than just model guidance. The most accurate forecasts encompass two important qualities... 1) The ability to correlate past events 2) The ability to analyze trends and biases in previous forecasts. Of course one could argue some other important qualities, but in general those two in combination make for the most accurate forecasts. The first ability is often abused in a mismanner... Typically people evolve analogs for storm systems based on the synoptic setup, but they use the exact forecast from the analog and use it for the current event. An analog is a basis for general storm track for the most part and also helps in indentifying mesoscale features. The best aspect of forecasting is being able to encompass all of these variables to make a prediction. Simplistically, it is the 'scientific method.' Essentially meteorologists use observations and gather data to make a hypothesis, which is proven true or false. As in a detailed hypothesis, there will always be one aspect proven false. Every forecast is false in some aspect, for if it was accurate one could able to say you will see 3in of snow instead of the generic forecast of 2-4in of snow. Forecasting the weather involves practice and a boatload of trial and error, but typically results can be rewarding. The general public whom tune in for the 6pm news for the most part are not able to identify the difficulty in making the forecast. Several accurate forecasts in a string can be destroyed by one critical error the next day. Also the forecaster has a responsibility, one may recognize and acknowledge the error and taken knowledge from the 'why' but they also must see to the accurate side of the forecast. So for those going into the New Year looking to make weather forecasts remember three essential factors and/or abilities; recall, analyze, and acknowledge.
"Current Surface Plot"
(Courtesy of HPC)
(Courtesy of Wunderground)
(Courtesy of NOAA)
"Forecast Discussion"(Pennsylvania, Maryland, Delaware)(Updated 12/30)
(Courtesy of Penn State Meteo.)
"Current Water Vapor Loop"
(Courtesy of Penn State Meteo.)
"7-Day Zonal Forecast Outlooks"(Pennsylvania, Maryland, and Delaware)(Updated 12/30)
Snow Map- December 31...
*Locally higher amounts are definitely possible. It would definitely not surprise me if the 2-4in amounts are a bit more widespread.
"Current River Ice Reports and Ski Conditions" (Updated 12/30)
Approaching the coldest month of the winter, January, we generally see an increase in ice located on local waterways. The first river ice report of the year was received a few days ago for central Pennsylvania along the main stem of the Susquehanna with small frazzle planes being reported in the shallow waters towards areas just north of Sunbury, but for the most part most of the channel remains open. Further northward across Pennsylvania, recent cold temperatures have allowed for ice development on local streams and creeks, but across southern areas towards Maryland and Delaware this remains to be seen. Many small farm ponds are now also ice covered from about the Mason-Dixon Line on northward but for the most part ice remains too thin courtesy of the recent thaw in the December 25-27 time frame. But an arctic blast is approaching the region towards January 1, which will allow for dramatically colder temperatures bringing an increase in ice on local waterways even southward into Maryland and Delaware. By the end of the cold spell it is likely many main stem rivers also see ice development. For now though it is advised to stay away from ice even on smaller farm ponds. Towards Lake Erie, for the most part the lake remains ice free. Although towards the more shallow lake bed near Cleveland at the southwest corner, ice buildup has begun especially along the shoreline. Expect this to increase by mid January. For now the ice build-up will generally not affect lake effect snow patterns. Ski conditions remain excellent over the region especially towards the Laurel Highlands and northeastern Poconos. Recent lake effect snow has allowed for 4-9in of snow across ski resorts such as Hidden Valley Four Seasons and Blue Knob. Also towards Blue Mountain Ski Area recent snow showers have added about 1in or so. Many ski resorts across the Laurel Highlands are 100% in trail openings with even the natural snow trails being opened. Towards the southern half of the state from South Mountain east towards the mountains of York County, snow is generally machine packed, but fresh snow is likely Wednesday evening through Thursday morning with light lake effect snow possible also towards the end of the week. A major lake effect event is likely towards the end of the week adding up to a foot of snow or more for elevations above 1600ft in the snowbelts. In general the next two weeks look to be excellent for skiing across the northern Middle Atlantic. Towards Maryland, Garret County ski resorts will also likely pick up a total of 6-9in by the end of the week with light snow likely Wednesday night and lake affect towards the end of the week.
-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 12/30)
Impressive setup is poised towards the lake effect snow belts towards the end of the week and weekend. The synoptic setup allows for a wave of low pressure to form towards Thursday, but with weak and slow southern stream interaction, phasing will occur to late for the northern Middle Atlantic. Towards New England cyclogenesis will occur as the low moves northeast. But as it counteracts with the dropping south Polar Vortex and impressive upstream blocking, it will retrograde slightly to south and west in the Gulf of Maine eventually becoming cutoff from the general mean flow. As the low pressure begins to fall below 975mb, the cyclonic regime will be quite impressive with even a bit of relative humidity towards 700mb aloft. This will set the stage for an extended northwest flow, which may produce very heavy snow totals along with having a large extension towards some bands east of the mountains. Towards Saturday will be the initial start of the pure lake effect snow event. Low resolution GFS QPF is towards 1.25in for Erie and nearly .5in towards Bradford with .1in or so even as far southeast as Harrisburg. GFS QPF has the tendency to not be able to forecast high enough numbers for lake effect, so this is already impressive. With generally directionally shear, this will allow for a multi-band event during the night with the loss of diurnal heating along with a cellular and embedded band event during the day with more orographic lift type snow. Initially Saturday the trajectory will be around 305degrees, which is favorable for a majority of Pennsylvania including the Laurel Highlands. Starting Sunday the flow shifts a bit more northerly towards 320degrees. The questionable factor in this event remains how much is the northerly component, for now it looks northwest enough to effect Pennsylvania. Sunday appears to be the most widespread lake effect day with bands stretching east of the mountains courtesy of enhanced moisture aloft and instability. H7 plumes indicate RH values over 40% impressively for some areas, indicative of quite a bit of moisture aloft. Saturday and Sunday will have the most westerly component favoring orographic lift towards the Laurel Highlands. Snow accumulations are likely 4-8in across the Laurels. Towards the northwestern mountains snow accumulations will be over a foot for favorable snow belts. I will have more details on banding locations with a snow map coming out Friday. Towards northeastern Pennsylvania being this is a north-northwest event, lake effect will cause 2-4in towards Wayne, Susquehanna, and Bradford Counties with 1-3in towards the Poconos. The rest of Pennsylvania stands the opportunity for C-1in throughout the multi-day event. GFS and ECWMF plumes indicate lake effect lasting through midweek as the cutoff low maintains the cyclonic flow and gradually lifts northeast and weakens. Snow growth looks excellent with Omega approaching values such as -10 for Bradford and Erie with excellent dendritic growth as H85s drop below -10C with a favorable saturated column around -12C. Another limiting factor in this event will be the lack of band with unidirectional shear towards the end of the week preventing mesoscale banding. The event generally looks to have light to moderate orographic lift snow shields over the region. All in all an extended lake effect snow event is likely after New Years.
*Note the higher end of totals are confined to higher elevations with lower values for valley locations. For instance 2-4in designates 4in above 1700ft and 2in below 1500ft. Also this is over an extended period therefore for instance the 1-3in zone will accumulate 1in over time persay through several coatings and such. Also the southern extension of 1-3in will generally just have coatings with isolated 1inch several day storm total. Also many areas may not even see more than a few flurries in the 1-3in extension.
"Current Lake Erie Wind Direction and Speed"
(Courtesy of NOAA)
"Current Lake Erie Water Temperature"
(Courtesy of NOAA)
"Long Term Outlook" (Updated 12/30)
Looking towards the longer range side of the forecast allows for the highly advertised Arctic blast to approach the region. Current AO values are approaching -6, which have only occurred about five times since records have been kept for the Arctic Oscillation. Several similarities are evident with the brutally cold airmasses of the winter of 1976-1977; although I doubt anything too that record extent will approach the region. The beginning of the air mass will approach towards January 2, as a closed low near the Gulf of Maine becomes cutoff from the flow maintaining a steady northwest cyclonic flow across the region up through the Great Lakes. Impressive snow cover across the Great Lakes will allow this arctic air mass to maintain much of its intensity as it moves south and east. Recent 12/30/09 0UTC GFS and ECMWF runs indicate the coldest weather to occur in the 6-10 time frame with H85 height anomalies around -3SD. This cold will also penetrate the Southeast as a cold front moves through areas such as the Panhandle of Florida. Several GFS runs indicate record low temperatures and freezes possible towards Florida. A few individual GFS ensemble runs indicate storm formation towards the time frame of January 5-7, but at this point operational guidance proves otherwise and with a retrograding 50/50 low and west based negative NAO along with the PV sliding south through the Hudson Bay, suppression is highly possible in this time frame. The general theme of the long range is cold and dry, but maybe it is a good thing the GFS and ECMWF do not show east coast storm threats as long range storms never pan out. None the less lake effect snow and clippers may be prevalent in this range, which will allow for some interesting forecasting. So in general very cold temperatures with generally dry conditions are likely from the 4th of January to about the 10th of January.
"Current NAO and PNA Predictions"
(Courtesy of NOAA)
"Anchorage, Alaska Tower Cam"
*Note I am only posting this towercam until snow starts falling over the northern Middle Atlantic, lol. For now we can all be jealous of the Alaskan snow.
"Monthly Outlook" (January)
In general I am extremely pleased with my December Outlook. While forecasting for long term, it is important not to focus on the minute details, but look at the general idea and/or perspective. The temperature anomaly outlook for the month came in a shy warm with forecasts for (+.5)-(-.5). In general across the northern Middle Atlantic, temperature anomalies for the month were around (-.5)-(-1.0). Now diving in a bit deeper, the general temperature trends were forecast near accurately. The increasing warmth around Christmas went ideally with the forecast of warmer anomalies towards the end of the month courtesy of some weak undefined southeast ridging. In actual verification a La Nina like pattern for a few days allowing for a large Great Lakes storm complex with temperature anomalies over the east near +5.0 for the time period. Also what seems to be accurate is the idea of a cold regime towards the beginning of January and in near verification it appears an arctic blast is headed across the northern two thirds of the United States. In general the temperature forecast was relatively accurate with a slight warm bias for the overall anomaly. Precipitation for December was again a shy warm with snowfall across the entire Northern Middle Atlantic averaging well above normal. But once again diving deeper into the forecast, the forecast for first accumulating snow on December 5 went perfectly with a general 1-5in over the northern Middle Atlantic. Also my best forecast here on Wunderground occurred this month with the advertisement of the December 19 KU storm nearly 10-12 days in advance. But my forecast for normal snowfall and above normal snowfall over the northwest fell a tad too dry. Once again I am pleased for December. Now we look towards January...
Temperature- January will be an interesting month. Teleconnections point to in general a well below normal month. Interestingly enough the Arctic Oscillation Index is towards record values of below -5 and -6. In fact the CPC had to enlarge their AO index chart to include values as low as -6. An interesting of note was also accompanied by similar values and that would be 1976-1977, which was one of the coldest winters on record for a majority of the northern United States. Also the NAO is diving through negative values and as this closed low becomes cutoff towards the Gulf of Maine up through Nova Scotia and Newfoundland towards January 1, this will reestablish a more favorable 50/50 low position allowing with retrograding the negative NAO towards more west-based. This all may allow for a favorable storm track most of this month along with steep troughing over the east coast. Looking though at long range H85 temperature anomalies they are showing above normal temperatures towards Canada. This may have implications farther down the road for a temporary relief from the cold. Currently it appears my forecast will generally appeal to an arctic blast towards the first two weeks of January with perhaps a few record numbers being broken especially across the lower Middle Atlantic where ECMWF and GFS numbers indicate H85 anomalies near -3SD. Towards the last two weeks of the month may be a more thaw-like pattern as the cold air retrogrades back across the arctic before another 'step down' pattern towards February. Keep in mind considering January climatology even occasion warm patterns favor snow. Overall anomalies for the month I am going pretty cold with (-1.5)-(-2.5) for the entire Northern Middle Atlantic.
Precipitation- Forecasts for monthly precipitation are generally the most difficult as one large storm system can throw a monkey wrench into the forecast. This was evident back in December where the historical Middle Atlantic snowstorm caused many areas in Virginia and parts of Maryland to receive nearly their average seasonal snow total in one event. But considering an Arctic blast poised to enter the region along with a cutoff low allowing for a cyclonic flow for nearly a week, it is a likely call for above normal snowfall for northern and western areas especially towards the snowbelts. This also includes western Maryland too from Frostburg on westward. Being an arctic air mass, dew points are usually dry and storm systems are typically suppressed, but considering the El Nino climatology and brief warmer temperatures towards the end of the month normal to above normal snowfall is likely for a majority of the northern Middle Atlantic. I do not have any storm dates currently other than lake effect from January 1-6.
"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- 0.00in
Monthly Total- 2.1in
Seasonal Total- 18.1in
October Total- 0.0in
November Total- Trace
December Total- 16.0in
January Total- 2.1in
Winter Weather Advisories- 5
Winter Storm Warnings- 1
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 1
Winter Storm Watches- 1
Lowest High Temperature- 22.9F
Lowest Low Temperature- 13.7F
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
Update 4:30pm 29 December 2009...
Good afternoon!!! In a few days I will be approaching my third year on Wunderground. When I approached this site in December of 2007, I expected creating a blog only forecasting basically my opinions for the Harrisburg geographic region. To some it may be a surprise, my age 17, or perhaps not in some regard. I kept my age hidden in part because of the dangers of the internet, but also the reaction. How in the world would adults respect a teenager forecasting the weather and telling them information? Knowing the acceptance level across the meteorological community for teenagers being regarded as weather weenies, I was apprehensive and kept this minuscule fact hidden. Upon the creation of my blog, I was going to go above and beyond a mediocre performance.
My passion for weather is correlated back to a very young age and my interest consumes not just the actual tangible thunderstorm presence, but for the "physics" behind the mechanics of the atmosphere. I built a foundation in general with the presence of books, in my meteorological library. But as I advanced in books from "The Weather Channel Basic Comprehension Weather Book" I moved into meteorological textbooks. This correlated with my current curriculum in high school of college level honors Calculus and Physics allowed me to bridge the transition from pure weather enthusiasts and weenie to actually understanding the process of let’s say "the reason driving a car on a clear night will allow for violent temperature fluctuations driving over hills and into valleys." Having pursued personal interviews with meteorologists, taking online courses, visiting different meteorological communities, and using the resources of the 21st century; I grew as a young adult. The sails of my ship were visible at a young age, which is for the definite pursuance of meteorology and this goal has not left the tip of my eyes ever since.
Information in my actual physical blog and comments has always been and will always be of my own. While I learn from others, as asking a question is key for education, I believe in credit given where it is due. Being apprehensive about being accepted on here was critical and has always been. Understanding perfectly, I can see adults being unable to accept me for being anything but a weather weenie. While yes I love the idea of monstrosity of a blizzard affecting my region; I also enjoy the physics behind the due process of the low pressure bombogenesis. All I am asking is really for no changes on the blog as really nothing is changing other than this announcement. I have been on this blog for three years and I have gained a solid reputation and a plethora of experience. Yes I love vegetable gardening, photography, PennDOT jokes, etc... I am what you would call perhaps unusual for one's age, hahaha. But my peers, family, associates, community, have continued to always encourage my passion for the science of meteorology. There is a cliche saying "you learn something new every day," this is true more than ever in the process of education. It is a constant transition and/or push or pull between educating others with adults teaching students, and students teaching adults.
In general I ask this, approach this with an open mind and not with a biased opinion and conclusion. Wunderground remains a mature and respecting community, so expect nothing to change here. While I may come off a bit conceded or mellow dramatic, this is all to prove my point that my blog is all collaboration of my knowledge and not that of others in some twisted form of plagiarism. One can consume as much education as the next if you put your mind to it. So go about this in strife as we have been the last three years here on Wunderground. Thank you to all in support of my blog over the years.
Here is to another few years!!!
***Update as of 1/7 6:30pm...
A highly advertised clipper is poised to move through the northern Middle Atlantic including the Ohio Valley spreading light snow in its wake. While it does not appear many high totals will occur in the accumulation department, several mesoscale features may allow for some higher snow totals closer to the moderate range. As of 6:15pm, NEXRAD radar indicated a comma head type precipitation shield with the front wave moving into western Pennsylvania with visibilities from observations around 1mi. Towards northern Michigan a deformation axis of snow was added in a well mixed moist column with snow ratios upwards of 20:1 or slightly higher. The 500hPa low will continue to transfer energy towards the coast as it progresses along the Mason-Dixon line. The center is very evident on radar as coincided with the dry slot across the Northern West Virginia. Temperatures aloft in the H85 layer will range around (-10)-(-14)C, with cloud temperatures well below -10C corresponding to excellent ice crystal growth with the dendritic growth layer around -10C. A well saturated column will support also the ice crystal growth. This combined with some PVA support and favorable Omega growth will favor high snow ratios despite the moistured starved clipper originating out of Alberta, Canada. Snow ratios near 15:1 south of the Mason-Dixon line and 20:1 will be common, even being highly advertised on GFS/NAM Bufkit prognostics. Throughout the night the front band will progress eastward across the Laurel Highlands where orographic enhanced precipitation courtesy of additional lift provided by upsloping will help to produce locally higher totals. Downsloping to the east despite surface dewpoint temperatures around -20F, will cause a general weakening of dbz on radar. But mesoscale models indicate the transfer or energy will occur a bit closer to the coast, but not too amplified with the positively tilted trough. A weak inverted trough situation will likely setup towards daybreak over the Delmarva and eastern Pennsylvania albeit light. GFS and ECMWF profiles indicate QPF ranging from .4in over KJST to about .2in near KPHL with .1-.15 over central Pennsylvania. NAM and local high resolutions WRFs indicate lesser amounts with a dry slot indication towards southern Pennsylvania paricularily from KAOO to KMDT, which may or may not verify. In any case snow totals will be light but a few favored upslope regions may receive moderate totals. Clippers typically cause a few surprises and disappointments so expect that to occur as usual. Also just to note the local NEXRAD NWS radars are having several issues this evening so hopefully the turn on clear mode tonight. My largest concern is the potential for dry slotting in Pennsylvania courtesy of the energy transfer to the coast, but we shall see. I have final note as I have mentioned before there are several techniques that need to be used against public NWS forecsts and especially local weatherman such as high temperatures on snow days always verifying colder than forecast as the wetbulb temperature is usually around the high. Anyways here is another, if you have not noticed precipitation events always start and end about 2-3hrs earlier than forecasts, especially end times. So I expect the main accumulating snow to be towards the eastern zones by rush hour with leftover snow showers elsewhere. The following are my forecasts snow totals in a zone forecast for the clipper. Snow belts will pick up to 6-12in of additional lake effect snow on Friday into Saturday...
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
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