Mount Pocono, PA Weather Observations and Forecast Verifications

Mount Pocono, PA Daily Weather Statistics

Below are links for monthly data (location information). Daily stats are for the 24 hour period beginning & ending midnight mean solar time. Min & Max are minimum and maximum temperatures (°F), Pcp is precipitation amount (inches), and Snow is accumulation of frozen precipitation except hail from thunderstorms (inches). Blank precipitation amounts mean 0, T a trace, and M missing data. Please see explanations below.

Below is data using an octal scale I devised - now discontinued, but perhaps interesting for those curious.

Bill Woodworth kindly took the readings for September 8-16 of 2000 and George Buynak for the November 11 minimum, such that the data for that year is complete.

Below are tables of monthly temperature averages and precipitation/snow totals. Trace amounts are counted as 0 for this.

Standard: 1999 2000 2001 2002 2003 2004 2005 2006 2007

Octal: 1999 2000 2001 2002 2003 2004 2005 2006 2007

Temperature

Temperature readings are obtained with a Hobo Temp H8 logger and a Taylor mercury max/min thermometer - both elevated 7 feet above ground and shielded from direct and most diffuse solar radiation. These are occasionally compared with readings from electronic devices at various locations, and the effects of diffuse solar radiation were tested similarly and are minimal. If unrepresentative for this elevation of the Mount Pocono area, the readings are probably a ° or 2 too low during a sunny summer day (abundant vegetation & shade in the nearby area) and likewise too high during night (radiation from house, trees, and the nearby slope perhaps countering cooling). There is such a phenomenon as the slope-side warm belt, which Professor Donald Portman of University of Michigan mentioned to me - the slope being warmer during relatively calm & clear nights than an adjacent valley and plateau, where cool air tends to settle. Dr. Portman feels the nocturnal low-level jet stream may contribute, but he seems to want to blame it for everything

I noticed many more odd than even numbers reported (143-95) when I counted 20 July 1999 - probably because of the larger space between even markings on the scale. After being aware of that, any bias for odd or even numbers is unlikely. I began using readings primarily from the Hobo Temp instrument early 2002. Data for the summer of 2000 probably has a low bias for maximum temperature - it was cool, but I also placed the thermometer in a particularly shaded area.

Precipitation

These readings are obtained 2 ways - using a calibrated plastic rain gauge & sometimes comparing with or collecting rainfall on a surface approximately horizontal using a coffee can of nearly 4 inches diameter.

The gauge is from Productive Alternatives, purchased from Robert E. White Instruments. Drops sticking on the sides of the funnel is a bit of a problem, and I measured the inner tube as 1.257 inches at its bottom & 1.263 inches at its top, such that the offset for selected amounts to 1 inch is : 1 inch, +.0037 ; .75 inches, +.0019 ; .5 inches, +.0006 (i.e., almost 0 for amounts near .5 inch or less). The first .01 inch appears rather accurate, which is a nice quality for a calibrated gauge (the scale on my thermometer requires a slight adjustment also). I am satisfied with its performance.

Using the can, contents are spilled in another rain gauge with a much smaller diameter. From these, a ratio is determined, and an adjustment for consideration of the amounts I cannot remove from the sides of the large can (which is typically much less than .01 inches). This method is probably more accurate than generally thought if the observer is attentive. Several problems with an automated gauge are avoided, and the approximate 25:1 or 16:1 ratio (depending which gauge I pour into) makes good precision possible. I particularly try noticing when .01 inch amounts occur (when possible) and estimate accumulation of trace amounts. These amounts cause problems for any gauge because of initial drops sticking to/wetting the sides of a container and evaporation (thus, I think significantly more .01 & .02 inch amounts and fewer traces occur than are commonly reported.) Actually, the main problem here is when very strong winds can blow even rain at a great enough angle that it is partially obstructed. Comparisons of the 2 methods side-by-side almost always agree within 0-2%.

For snowfall, I try collecting in the plastic cylinder and/or can, which is often effective, though sometimes not during strong winds. For those situations, the most seemingly representative snow:water ratio is determined (collecting snow disturbing it as little as possible, then melting it in a closed container) and then used with the best estimated total snow amount fallen.

Snow

Snow measurement causes a great amount of discussion and argument. The most relevant quantity may be the liquid water equivalent of accumulated snow, because it determines the weight of snow which must be dealt with. For reporting a daily snow amount though, I primarily consider the most representative maximum accumulation during periods of snow activity. I.e., I am not trying to determine the average amount of snow which fell over the local area, but the most representative (i.e., quasi-average) maximum accumulation on surfaces where it accumulates well. If possible, I use the natural ground condition. E.g., if a snow or ice cover is prevalent, I measure directly on that (packing down the snow in an area if necessary). Otherwise I try to use accumulation on grass - though if there is clearly no melting a flat wooden surface or even the top of a parked car (if calm) will provide a more accurate measurement. A snowboard can be misleading though because situations occur with temperatures around freezing for which the snow accumulates well on that but not on the ground. When winds blow snow around, accumulation will generally be less because of compaction and because some enters ground waters (this can be quite significant here). Yet once it leaves a roof, it doesn't go back either. As snow occurs during a large storm (especially if temperatures are near or greater than freezing), it compacts and can melt. ¼ inch per hour of snow may be required for maintaining snow depth during such a situation. For these types of situations, I try to measure at the time of maximum accumulation. I don't brush areas at specific intervals such as 1, 3 or 6 hours, measure new accumulations for each period, and add them. This can create a number much larger than what a person will be seeing around the locale. Why not brush away every 10 minutes then? Where do you draw the proverbial line? I begin determining a new daily snow amount with new accumulations at midnight though, which essentially is brushing away every 24 hours.

Example of periods of snow activity : Suppose 3 separate snow squalls during a day deposit .5, 1.0, and .9 inches, after which sunshine primarily melts each. These would clearly be 3 periods of activity, thus a daily accumulation of 2.4 inches; though I suppose a good argument can be made that 1.0 or perhaps 1.4 inches was the maximum accumulation at any time during the day.

Mean Solar Time uses the local meridian as reference - mean time the sun passes it being noon. Because the latitude of my location is 75.347 °W, it differs very little from Eastern Standard Time (EST), which uses 75 °W as reference. 15° of longitude corresponds with 1 hour of time, so midnight Mean Solar Time = 12:01:23 AM EST. Data prior to 10 August 2000 is for midnight-midnight EST. Note that using this, observations remain consistent across time zones.

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