MONTHLY WEATHER DATA AND OBS - WESTMONT 1.1W PA DECEMBER 2008 OBSERVER NATE MULLINS Special Observations: F=fog, T=thunder, H=hail, S=sleet, G=glaze, DW=damaging winds Observation time for this station is midnight. Temperature, °F Precipitation, In. Liquid Solid 7am 24-hour At Rain Snow/ Snow Date Max Min Obs Equiv Ice Depth Special Obs. 1 33 26 .05 0.2 1 G 2 27 21 T 0.1 1 3 38 20 1 4 37 23 .16 T T 5 23 14 .02 0.4 T 6 24 13 .05 1.1 T 7 16 9 .05 1.1 2 8 24 10 2 9 49 21 2 10 49 22 .51 1 F 11 32 29 .82 0.3 T F,G 12 29 19 .40 3.0 2 13 24 16 .02 0.5 3 14 37 19 3 15 50 28 .32 2 F 16 28 24 .25 1.5 1 S,G 17 35 28 .72 0.2 1 F,G 18 34 27 T T 1 S 19 42 32 2.09 T F 20 32 23 .03 T 0 G 21 26 8 .08 0.4 T S,G 22 8 -1 .07 0.6 1 23 22 6 T T 1 24 50 21 2.31 0.2 1 F,G 25 29 19 0 26 36 19 .73 0 F 27 64 32 0 28 60 32 .07 0 DW 29 38 26 0 30 35 27 0 31 41 14 .05 0.8 1 DW AVG/SUM 34.6 20.2 8.80 10.4 0.9 <--Mean EXT 64 -1 2.31 3.0 3 Date 27 22 24 12 14* *=Also occurred on earlier dates Miscellaneous Stats Mean Monthly Temperature: 27.4 F Year precipitation to date: 59.94" (final total for 2008) Season snowfall to date: 29.0" Number of days with: Fog 7 Sleet 3 Glaze 7 Damaging Winds 2 DETAILED OBSERVATION NOTES 1: Few overnight light showers with icy glaze on all surfaces & light SW winds. Mostly cloudy with occasional snow showers, very light accumulations. 2: Breezy overnight with light snow showers, little to no accumulation. Mostly overcast with little temperature variation, cold 3: Clear, sunny, light WSW winds 4: Warming overnight with a cold light rain developing. Overcast with light rain changing to light snow, negligible accumulations, breezy, overcast. COLD - LIGHT SNOWS 5: Mostly overcast and cold with occasional light snow or snow showers 6: Overcast and cold with light winds and fine light snow through the PM hours, just over 1 inch of accumulation 7: Overnight light snow (another 1" accumulation). Variable clouds, blustery & cold with a high of only 16 F and alternating sun and snow showers. Little additional accumulation. NW winds gusting 25-30 mph. Clear skies by mid evening. 8: Some weak sun early then heavy overcast and cold with light W winds. 9: Partly to mostly cloudy skies with increasing SW winds through the day and temperatures rising to 49 F by late evening and a heavy overcast developing. RAIN/ICE THEN SNOW/COLDER 10: Rain began around 2am and continued steadily through the day tapering to drizzle by late afternoon and dense fog developing .51" rain fell. Temperatures were mild early and dropped to near freezing by late evening. 11: Light rain showers overnight and through the AM hours with temperatures near freezing and some light icing. Rain became moderate after sunset and mixed with then changed to snow by late evening. About 0.3" snow and 0.82" melted precipitation. 12: Overnight snow (2" by 7am). Fine light snow through much of the day with temperatures falling and gusty NW winds. Another 1 inch of snow fell for a total of 3 inches today 13: Light snow showers overnight another 0.5 inches. Became mostly sunny but remained cold. Much lighter winds. 14: Mostly sunny with AM haze and light S winds developing. Became variably cloudy by late afternoon & evening. RAIN/SNOW/ICE 15: Warming overnight and becoming overcast. Periods of light to moderate rain developed with occasionally gusty S winds that eroded a thermal inversion and brought the temperature up to 50 F by mid afternoon. Patchy dense fog developed. 16: Overnight light snow. Overcast with snow/precipitation line just to our S much of the day finally inching north and bringing a brief period of moderate snow before mixing with and changing to freezing rain and sleet. 0.25" precipitation and 1.5" snow. 17: Overnight and AM freezing rain was moderate to heavy at times with nearly a quarter- inch of ice/glaze on everything and some limbs down due to the weight of the ice. Dense fog with temperatures rising above freezing by late morning and gusty winds 18: A brief period of sleet around dawn (trace). Overcast with near calm winds. COLD HEAVY RAIN - FLOODING 19: Rain developed shortly pre-dawn and quickly became moderate to heavy and steady with temperatures steady in the mid 30s. Heavy rain abruptly tapered to showers by 2pm. SW winds shifting to W & gusting 25+ mph. 2.09" of rain fell today most of it in a 7-hour period causing much flooding in the area. Many Basements, fields and roads were flooded with some roads closed and mud/rock slides reported from the heavy rain. 20: Overnight drizzle and falling temperatures. Overcast with increasing NW winds VERY COLD - LIGHT SNOW/ICE 21: Overnight light snow mixed with some sleet and freezing rain/glaze. Much less snow and ice than expected only 0.4" of snow and 0.08" of precipitation. Skies ended up becoming mostly sunny by mid-afternoon with W winds gusting 25-30 mph. Temperatures fell to a chilly 8 F by evening with wind chills well below zero. 22: Very cold overnight with a low of -1 F and very fine/light snow of about 0.5 inches. Strong W winds gusting to 40 mph creating wind chills below -30 F. Some flurries on and off through the day. Despite some PM sun a high of only 8 F with brutal wind chills all day long. Frigid! 23: Overcast and cold with light W winds. Few spits of freezing rain late MORE HEAVY RAIN - ICE - FLOODING 24: Warming overnight with moderate to heavy rain developing and creating a dangerous icy glaze on all surfaces of 1/8" to 1/4". Precipitation slowly became all rain and was relatively steady and heavy at times. Another big thermal inversion with temperatures 10-15 F higher at higher elevations. Temperatures finally shot up to 50 F around 8:30pm with very strong W winds developing and gusting to 45 mph and rain ending by 9:30pm. Another 2.31" fell today causing more flooding although this rain was not quite as intense as last Friday's rain and was more spread out through the day so the flooding was not quite as severe. 25: Winds dimished overnight and became near calm during the morning. Mostly cloudy and cold but dry. 26: Mostly cloudy early becoming mostly sunny by late morning. Clouds moved in quickly around 3pm with moderate rain by 4:30pm. A brief break then more rain from 7-10pm moderate to heavy then drizzle and fog afterwards. Another .73" rain fell today. MILD 27: Temperatures rising through the overnight and morning hours becoming very mild this afternoon with temperatures reaching 62 F and gusty SSW winds. Partly to mostly sunny skies. WINDY 28: Fair and very mild early then became very windy around 9am with a period of showers 9:30-11am dropping .07" rain and rapidly falling temperatures. Skies became mostly sunny in the afternoon with winds diminishing by evening. 29: Mostly sunny with more seasonable temperatures and light W winds. Winds became very strong and gusty again after sunset but skies remained clear. Gusts 40+ mph again. 30: Gusty winds overnight and continued breezy through the day. Fair skies through most of the day. Calmer winds by evening. 31: Very strong NW winds developed overnight with a snow squall at 6:30am dropping about 3/4" of snow in 20 minutes. Flurries and light snow showers with blustery conditions and gusty winds through the day but snow did not accumulate much, just blew around. MONTHLY SUMMARY 2008 ended on an exceptionally wet note, and, despite some rather chilly temperatures at various times throughout December, there was a mysterious absence of snowfall, which struggled to reach the 10-inch mark. 2008 had a rare combination of a White Thanksgiving (and almost a white Halloween) yet a brown and soggy Christmas. Precipitation was abundant, almost all of it falling from the 10th-26th, and totaled a whopping 8.80 inches, which is almost certainly a record for December and probably for any winter month. There were two 2-inch events 5 days apart, which is also rare for this time of year. The first one (19th) almost all fell in 7 hours and caused much flooding in the area. The second one on Christmas Eve brought a dangerous coat of ice and even more rain than on the 19th, but fortunately was more spread out through the day and caused less flooding (though a good bit of flooding still occurred). Temperatures were up and down like a yo-yo, and varied quite a bit from day to day and even within individual days, and also varied quite a bit across town with many inversions where the airport or higher elevations such as Richland would be 10 to 15 degrees warmer than here in Westmont. These inversions led to many "overrunning" situations" that would explain why there was so much mixed precipitation and so little snowfall. Overall, temperatures were near normal, with a mild monthly max of 64 and a chilly low of -1 F. These temperatures were set only 5 days apart. The month and year ended on a chilly note with temperatures in the 10s on New Year's Eve and below zero wind chills. December was also a very windy month, with many days of strong winds gusting over 40 mph that accompanied the passage of frontal systems, of which there were plenty this month.