MONTHLY WEATHER DATA AND OBS - WESTMONT 1.1W PA DECEMBER 2009 OBSERVERS NATE AND STEVE MULLINS Special Observations: F=fog, T=thunder, H=hail, S=sleet, G=glaze, DW=damaging winds Observation time for this station is midnight (EST). Temperature, °F Precipitation, In. Liquid Solid 7am 24-hour At Rain Snow/ Snow Date Max Min Obs Equiv Ice Depth Special Obs. 1 43 26 30 2 48 25 43 .30 F 3 50 27 27 .36 4 34 27 27 5 29 21 24 .27 2.8 F 6 25 15 19 T T 3 7 31 18 30 T T 2 8 32 24 24 .57 3.5 2 S 9 48 24 28 1.55 2.0 5 S,G,T,DW 10 28 8 8 .09 2.0 3 11 24 7 19 4 12 32 18 27 4 13 42 27 37 .59 0.1 4 F,G 14 45 36 37 2 15 47 24 24 .05 T 1 S 16 24 16 18 .01 0.5 1 17 24 16 20 1 18 31 19 23 .07 0.6 1 19 23 18 18 .83 10.5 4 20 23 14 21 .03 0.3 10 21 26 21 24 .05 0.9 9 22 25 23 23 .01 0.1 9 F 23 25 11 13 9 24 32 2 23 8 25 37 22 37 .36 0.5 8 F,S,G 26 38 25 25 .25 7 F 27 41 24 31 T T 6 F 28 31 17 19 .22 5.0 7 29 19 11 11 .01 0.2 8 30 25 5 21 8 31 33 20 32 .33 2.6 9 F,S AVG/SUM 32.7 19.1 24.6 5.95 31.6 4.4 (mean depth) EXT 50 2 - 1.55 10.5 10 Date 3 24 - 9 19 20 *=Also occurred on earlier dates Miscellaneous Stats Mean Monthly Temperature: 25.9 F (-3.9 F) Year precipitation to date: 45.04" (-2.65") - final total for 2009 Season snowfall to date: 33.1" Number of days with: Fog 8 Sleet 5 Glaze 3 Thunder 1 Damaging Winds 1 DETAILED OBSERVATION NOTES 1: Mostly sunny & breezy with W winds gusting 20-30 mph RAIN SHOWERS 2: Overcast with heavy frost on elevated surfaces early this morning. Temperatures warmed to 48 this afternoon with intermittent rain beginning at 3pm. SE winds increased and gusted 30-40 mph. 3: A period of heavy rain and strong winds around 2:30 am .31" rain fell in a short time. Strong winds continued overnight and shifted from S to W. Mild early with falling temperatures. Some drizzle/light rain this afternoon with winds finally diminishing. Some scattered tree damage and power outages were reported from the high winds in the area today. 4: Overcast with occasional breaks of sun and light W breezes, temperatures steady near freezing SNOW 5: Light steady snow through the morning with low clouds and fog. Snow became lighter and more intermittent in the afternoon, ended during the evening with NE/N breezes. 2.8" total snow. 6: Chilly this morning 15 F with mostly cloudy skies & snow flurries. Mostly cloudy AM, partly cloudy PM, light W winds with occasional 20 mph gusts. Calm and overcast after sunset. 7: Overcast with near calm winds and occasional snow flurries through the day (trace). Became breezy during the evening with W winds 10-20 mph, gusting 25-30. BIG ICE STORM - STRONG WINDS - SNOW SHOWERS - COLD 8: Mostly cloudy with clouds darkening and thickening during the late afternoon. Very light W winds. Snow began ~ 7pm and quickly became moderate to heavy by 8pm. 3" of snow fell by 11pm before mixing with then changing to sleet. Winds shifted to SE and became gusty at times. 9: Windy with heavy sleet and freezing rain overnight. Precipitation ended abruptly at daybreak. 2.03" of precipitation fell in only 12 hours from 7pm-7am. 5.5" of snow/sleet and ice. Low overcast early AM with temperatures rising above freezing, creating a big slushy mess. Became partly cloudy by 10am and mild high 50 F then the cold front plowed through mid-afternoon with a brief strong thunderstorm at 2pm - lots of thunder, rain mixed with sleet, very high winds and rapidly falling temperatures. Very windy during the afternoon and evening with W winds 30-40 mph and gusts over 50. A wind gust of 56 was measured at the airport. Trees were reported down throughout the area. Some snow flurries this evening, continued very windy. 10: Howling winds and light snow showers overnight. 0.4" of fluffy snow by 7am. Light snow and snow showers with falling temperatures and continued very windy with gusts from the W over 40 mph at times. A period of moderate to heavy snow from about 3-5pm. 2" total snowfall with a lot of blowing snow. Became partly cloudy after sunset with snow ending but continued very windy with the low dropping to 8 by midnight and wind chills well below zero. 11: Howling winds continued overnight with temperatures steady around 7-8 F and fair skies. Mostly sunny during the day with relentless strong winds; very blustery and cold. 12: Sunny and continued windy early, finally diminishing through the day. Not as cold or blustery as the previous two days. Became variably to mostly cloudy during the evening. RAIN AND ICE 13: Steady rain began this morning, freezing on everything through mid-day before temperatures finally rose above freezing. About 1/8" or so of ice accumulation, .59" of precip. Patchy dense fog. This morning it was 10 degrees warmer at the airport (2283 ft) than downtown (1273 ft) 35 vs 25. It was a mess in the valleys, but higher elevations had plain rain. 14: Overcast with virtually calm winds all day, and somewhat mild. 15: Mild overnight, then temperatures dropping throughout the day and becoming windy with intermittent light rain, drizzle, some brief showers of ice pellets (sleet) and snow flurries by late evening. Temperatures dropped to 24 F by midnight. 16: Overnight light snow, ending by 0900 with clearing skies. Sunny, cold & breezy with WNW wind gusting to 30 mph at times. Fair skies during the evening and continued chilly/blustery. 17: Variable clouds overnight w/ breezy NW winds. HEAVY SNOW 18: Overcast and cold with a brief period of partly cloudy skies at midday then becoming completely overcast again. Light fine snow began around 9pm and continued through midnight (0.6"). 19: Light to moderate steady snow overnight. 4" new snow since 9pm last night by 7am. Light E to NE winds with steady temperatures around 20 F and snow continuing. 6.5" new snow by noon. Light to occasionally moderate snow through the PM hours. 10.5" of new snowfall by @ midnight with ~ 9 inches on the ground. This is the 2nd heaviest snow day since we moved in 2004. 20: Light snow ended early overnight (another 0.3") with skies becoming partly cloudy by mid- morning. Storm total snowfall 11.4", ~ 9" on the ground. Variably to mostly cloudy during the day with snow flurries resuming late this evening around 11pm. 21: Flurries and light snow showers overnight (0.7"). Occasional flurries or light snow showers during the day, only 0.2" additional accumulation. Breezy at times, temps in the low-mid 20s. 22: Overcast with a brief period of very fine light snow at mid-afternoon, only 0.1" accumulation. Temperatures steady around 24 all day, light WNW winds with occasional 15-20 mph gusts. 23: Temperatures dropped overnight to 11 F, skies became partly cloudy. Fair/sunny skies through the afternoon, remained cold w/ light WNW breezes. 24: Cold low 2 F early this morning then sunny and a bit milder with calm to light E/variable wind. 100% sun today though high clouds gradually increased in coverage after sunset. WHITE - ICY - WET - WINDY CHRISTMAS 25: Cloudy overnight with sleet/freezing rain mix beginning ~ 7am. Sleet, freezing rain and snow mix continued through the morning with gusty SE winds. A period of plain rain late aftenoon as temperatures rose above freezing. 0.5" of sleet/ice, 1/8" glaze and 0.36" melted precip. 26: Light rain & drizzle continued overnight with temperatures steady around 36/37. Patchy fog. Drizzle ending early PM 0.25" more precip today. Winds near calm & variable. 27: Cloudy early, then clearing to mostly sunny w/ near calm winds. Became cloudy again by mid- evening with snow and gusty winds commencing at 11:55 pm. SNOW 28: Windy overnight with light to occasionally moderate snow showers and falling temperatures. 2" by 8am with snow tapering off. Brief peaks of sun, then snow resumed this afternoon and continued through evening another 3" fell by midnight with howling W winds gusting to 40 mph. Total snow today 5.0". Lots of blowing & drifting snow. 29: Light snow showers ended overnight another 0.2" for a storm total of 5.2". Snow was light & fluffy only .23" melted precip and measuring the total snow depth was very difficult due to blowing & drifting. Partly to mostly sunny, cold, windy, blustery. 30: Cold low 5F this morning, partly sunny early then mostly cloudy, light SSW winds. MORE SNOW 31: Snow developed overnight, 2.6" accumulation by 8am with snow tapering off and changing to light freezing drizzle. Overcast with patchy dense fog at times by ~ 4 pm and drizzle, then later mixing with light sleet and snow. 32 F by midnight. MONTHLY SUMMARY For the 3rd consecutive year, December brought a parade of winter storms, ice, snow, cold & wind. While not as wet as the previous two Decembers, it was still the wettest month of 2009, and also a lot more snow fell, 31.6", beating out Dec. 2005's mark of 31.4". Many winter storms affected the area. The first one occurred on the 5th with light snows, heavier snows to the east. A wild weather system slammed the area on the 9th, dumping over 2 inches of precipitation and 5.5" of snow and ice in only 12 hours from 7pm on the 8th to 7am on the 9th. Then came howling winds, a rare thunderstorm with sleet, and more snow showers on the 10th. Another rain/ice storm passed through on the 13th. The season's heaviest snow of 11.4" fell on the 18th-20th, 10.5" of that on the 19th from a Nor' Easter that brought record or near-record snows south & east of the area over parts of WV, VA, MD, DE, southeastern PA, NJ, NY and southern New England. Another ice storm moved through on Christmas Day, the 25th; a lake-effect snow event brought 5.2" on the 28th-29th, and another system brought snow, sleet and rain to the area on New Year's Eve. Needless to say, it was a very active weather month. After a near-record warm November, temperatures returned to below normal in December. Unlike many other months in 2009, where below normal temperatures owed almost entirely to below normal max temperatures, both the min and max average temperatures this month were nearly 4 degrees below the 1973-2009 normals. There were some mild to moderate Arctic outbreaks, with a handful of days (4) in the single figures, the low reaching 2 F on Christmas Eve, but nothing extreme in either direction. Temperatures were on the cold side all month, and coupled with some very windy days, December felt, at most times, like a typical Johnstown area winter month. With December's below- average temperatures, the year 2009 finished with temperatures over 2 degrees below normal, a big contrast from the past several years.