US Weather Commentary Location: New York Author: Weather 2000, Inc. Date: Monday, December 10, 2007 This will be a new ongoing feature to keep tabs on cumulative weather for key hubs during the month so we don't lose sight of where we're coming from, when we look ahead to where we are going. December Running Log * Chicago: 0°F on 12/05; 18% HDD surplus * Cincinnati: 1"+ of snow; 17% HDD surplus * Boston: Every Day Below Normal; 42% HDD surplus * New York: Every Day Below Normal; 39% HDD surplus * Washington D.C.: 2"+ of snow; 21% HDD surplus * Dallas: 4 Days > 70°F; 8°F Above Normal * Houston: 7 CDD's * Atlanta: 42% Below Normal Rainfall for 2007; 17% HDD deficit. * Seattle: 4 Times Normal Rainfall Sit-Down Q & A with Chief Meteorologist Michael Schlacter: Q: If you had to pick just 1 word to describe the 2007-2008 U.S. Winter Season, what would it be? A: Volatile. Q: And if you were able to pick a phrase? A: Enhanced North-South temperature gradient. Q: When anomalous warmth in the (southern) U.S. has people's attention, they shouldn't overlook anomalous cold elsewhere in......? A: ......(southern) Canada. Q: Before the 2007 Summer you were asked to pick the geographic epicenter (or bullseye) of CDD Anomalies, and you selected Cincinnati (which incredibly went on to tally its most CDD's on record). Where did you pick the geographic epicenter of HDD anomalies this Winter? A: Minneapolis. Over the course of the Winter this could swing as far East as Burlington VT/Syracuse NY for periods, or as far West as Billings MT, but for the entire Season the Upper-Mid-West should be the common-denominator. Q: What do you think will be the most SURPRISING Winter Season outcome compared to prevailing or consensus thought? A: People of course assume there will be some cold & snow in the North and warmth in the South, but they may be surprised at the end of the Season as to how much cold actually was achieved across the North-Central regions of the Nation. December-March HDD Totals potentially falling between the 2002-2003 and 1995-1996 Winters is something to be reckoned with. Q: What do you think will be the most CONCERNING aspect of this Winter Season? A: Severe Southeastern Drought carried over from the Summer probably won't get much relief this Winter, leading to a potentially extreme drought situation by the time the 2008 heat Season is about to start. Tangentially, dry ground is a good thermodynamic radiator so when the South does receive occasional cold waves, the freeze consequences could be that much more intense for Agricultural/Citrus entities. Q: What do you think will be the most FRUSTRATING aspect of this Winter Season? A: Computer Models fluctuations and commercial services' increasing reliance on them. For example, yesterday's model output called for Chicago reaching a Low Temperature of 12°F this morning and it wound up falling to 0°F. Earlier this week forecasts were being released showing that Philadelphia would surge into the 55°F-61°F range for this coming Monday-Wednesday, which has now been revised down to a 44°F-48°F range. If models can be off by so many degrees for 6-7 Day forecasts, let alone 1 Day forecasts, 8-14 Day output is going to give folks even more headaches. Q: So why the over-reliance on models? A: It's convenient, it's quick, and it provides pretty pictures. Most commercial services are mass-disseminating forecasts to hundreds of recipients and don't have the time to go over each city with a fine-tooth comb. Sitting down with pencil & paper to calculate the fluid-dynamics of short-waves boundaries, the thermodynamics of snow-pack surface fluxes, etc., is critically important, but also takes a lot time and physics analysis. Q: What do you think will be the most CONFUSING aspect of this Winter Season? A: For a typical location, a standard "Cold" Winter might have 60 Below Normal Days for every 40 Above Normal Days. In very variable Winters that ratio may flatten to 55/45. So people might get confused how a forecast for a cold Month {Season} could also contain numerous mild Days {Weeks}. Q: What advice do you have for people tracking cumulative weather, especially in the North? A: Don't miss the Forest for the Trees. Under cold regimes, a sort of 'Conservation of Degree Days' applies. If you see that an approaching week might be trending 25 HDD's milder than you originally thought, there is a good chance it's because the previous or following week is coming in with an extra 25 HDD's than predicted. Same goes for a Half-Month interval (think January 2005), or entire Months (think January to February 2007). Q: Contrasted to the past 1-2 Winters, where will some of the largest contrasts be found? A: There's recently been a general void of Cold Air Masses for the U.S. from mid-December to mid-January, so any waves of Polar Air in the North (or indications of such) will be noticeable with regards to year-on-year HDD tallies. Unfortunately for climate science, there has been a rush to simply lump the 3 most recent ENSO Events together, without taking into account intensity or other Tele-Connections. This infamously happened in Autumn 2002, which led to calls for a Warm Winter in the Northeast (which ended up be quite cold), and is happening again with an artificially large warm signal for Northern States this January. Conversely, the U.S. had a frigid February last year, so even a cold February 2008 is likely to pale in comparison. Q: Your Unsung Weather Variable? A: Snow. The albedo, conductive and radiative properties of snowfall/snow-pack are an enormously powerful 1st-order term in thermodynamics. It is often undervalued and misrepresented in modeling. For the Northern-Half of the Nation: Where snowfall/snow-pack is present (or nearby), temperatures will routinely come in colder than expected on the chilly days and no warm-up as much on the milder days; Where snowfall/snow-pack is absent (or nearby), cold days will routinely come in warmer than expected on the mild days and not chill off a much on the cooler days.