MONTHLY SUMMARY: DECEMBER 1997 UPDATED: 1/19/98 --------------------------------------------------------------------------- Another new member for December! Our second observer from Herndon is Russ Topping. We'll assign him the station id, HRN. Ran a metar check on those and nothing came-up. Our other long-time observer from Herndon is Bob Beall. Bob Woodson of Raleigh makes a nice contribution this month, especially to those of us who visit cyberspace every day. He has identified an Internet site which shows daily snow depths across the US and includes coop and airport obs. The site address is: http://nic.fb4.noaa.gov:80/products/season_update/snow_map/ Thanks Bob! Instrument calibration time! John Bullock just acquired a new Taylor Maximum/Minimum thermometer that I assume is the standard "greenhouse" type mercurial thermometer. These are VERY accurate and I've used two calibrated together which have remained identical in readout over 20 years. They have become the standard to which I have calibrated all my temperature sensors over the years, particularly the electronic instruments. Through time and a variety of circumstances, however, these instruments can loose their accuracy. For instance, the Taylor mercurial thermometer's U-tube can shift or the left and ride side scales behind either side of the tube can move. Since they can be adjusted by untightening a main screw, they should be kept in mind as well when calibrating. The scales on both sides behind the U-tube should give the exact same reading. Correct calibration is easily achieved by using one instrument as a standard for your other sensors. If you can not trust the accuracy of your temp readout, look for a source that provides information on how to calibrate temp, for instance using the ice water method. Don't try to set temp using info from a local ASOS station or by telephone using the newspaper's or phone company's sensors. Distance from your station and conditions under which those sensors are mounted can create a huge difference from the weather at your site, if only a few blocks away!! Instrument cleaning and calibration is a MUST activity several times a year for most of us. If, on the other hand, you're like many and calibrate only once a year, then the week before New Year's Day is an excellent time. Any ideas on calibration, then send them along. Please note several changes in the email address list below! ----------------------------------------------------------------------------- NOTES FROM "AROUND THE LEAGUE"- Arlington - December was fairly typical, according to NWS WBC. Temps were slightly above normal with two days even reaching the 60s. A nor-easter snowstorm on the 28th narrowly missed Washington but clobbered the mountains with one to one-and-one-half feet of snow. Although the northern and western burbs received an inch or two of snow, the city and areas south and east received mainly rain. The month was fairly dry with just about 50% of the normal rainfall. Boston - According to Tom, December was fairly comfortable, except at the very end. Bridgewater - Our first measurable snow of this winter season occurred on the 9th. It really wasn't much of a storm. We only got .8 inch. Our first really significant snow occurred on the 27th followed by another one on 29th. These two storms produced 9 inches. These storms were rather interesting. It is quite unusal for two completely separate snowstorms to occur with only a day between. Also, many places in the deep south got snow while areas far to the north got only rain or mixed precipitation. Precipitation for the year was about normal. We received 20.8 inches of snow which was about 3 inches below normal. The average temperature for 1997 was a little above normal. Only 12 thunderstorms recorded this year. In 1996, 38 such storms were noted. What a contrast! Centreville - Paul imagines those who awoke on January 1st, 1998 thinking their headaches were due totally to the night before!!! On New Year's Day the barometer was 30.59" at 9 AM EST!!! December 1997's average high temp was 1.9 degrees above normal while the average low temp was 6.8 degrees above normal. The month ended was 4.3 degrees above normal. Falls Church - At his site, Lowell noted a December that was warmer and drier that average. The mean temp was 1.78 degrees above normal while precip was 1.66 inches below normal and the least since 1988. The lowest temp of the month, 22 degrees, was a record for the highest December minimum in the last 18 years. A barometer of 29.20" was the fourth lowest ever recorded for December since records began here in 1960. The record low December barometer was 28.98" in 1968. Falls Church - Erica Page noted that December '97 was a dry one with precip some 2 inches below average for both rain and snow. Her station's average high was 3.6 degrees above average and the average low was 2.2 degrees above average. Hampton - Dave Kessel noted variable weather conditions for December. The month started on a mild note but cold, stormy weather ended the month as a trough strengthened over the Eastern US. Rainfall total in 1997 was ten (10.00) inches below normal! The year would have been much drier had not Tropical Storm Danny provided much needed rains in July. The most noteworthy event of the year was the golfball to baseball size hail which fell on May 1st. Mechanicsville - Glenn noted on the 9th that precip began with large snow flakes that, after a brief time, changed to rain. On the 22nd, rain began as sleet, but quicly changed to rain. On the 27th, snow moved into the area. Newport News - Gary notes that December, all-in-all, was very average. For the year, he only had 57 days below the 32 degree mark. That beat the old record of 63 set in 1985. Norfolk - The monthly average temp was 1.0 degrees below normal while the monthly rainfall was 0.58 inches below normal. Portsmouth - With regard to temps, an average December here with a 0.0 degree departure. The month was drier than normal with only 75% of average 2.97". The first half of the month was well-below normal temperature-wise while the second half was above normal for the most part. On the 27th, low pressure pulled out of the south producing an onshore flow that circulated sufficient warmth to protect us from snow until the associated trough moved through when we then picked-up a trace of snow during a 4 hour light snowfall on the evening of the 27th. The large snowstorm for western Virginia on the 29th moved right over this area circulating warmer onshore southeast winds at the surface and aloft and giving us only 0.28" of rain. Far more had been anticipated. As the low moved over the area, the sea level pressure bottomed at 29.290". Cold air moving south on New Year's Eve triggered a five minute snowshower. We had an unusually high number of frosty mornings (and one late evening) this month, with a total of 11 days experiencing the crystals. Richmond - NWS AKQ noted: The monthly average temp was 0.2 degrees below normal while the monthly rainfall was 0.90 inches below normal. Roanoke - No white Christmas here, says Wendell. On two days snowfall was recorded; on the 27th, 2 inches fell and on the 29th, 6.8 inches was recorded. Some snow was still left on north facing slopes as of 1/4/98. Average temps were only 0.1 degree below normal while precip was 0.41" below normal. Stafford - Danny says that some type of precip was recorded on 8 or the last 10 days in the month. The year ended with an excess of 0.36" precip when compared with the norm. Woodstock - Temperatures were slightly above average while precip was below average. Asheville - The monthly average temp was 2.6 degrees below normal while the monthly rainfall was 0.54 inches below normal. Brevard - The average temperature for December was 37.4 deg. F, the second coldest since 1990, the coldest being 1995 when the mean fell to 33.6 deg.F. Moisture-wise, December was a little above average, the 4.38 inches recorded was exceeded three times since 1990, in 1991, 1992, and 1996. Charlotte - The monthly average temp was 0.4 degrees above while the monthly rainfall was 0.60 inches above normal. Greensboro - No record high or low temps. 5.2" of snow fell on the 29th, the highest snowfall Dec total since 1973. The monthly average temp was 1.6 degrees below normal while the monthly rainfall was 1.19 inches below normal. Henderson - Temps here were above normal while rainfall was below normal. Yearly rainfall for the year was above normal. (report from George Stevenson, Jr.) Raleigh - Bob reports snowfalls on 4 days which resulted in a "grand total" of 0.50" Temps for December were 1.6 degrees below normal while precip was 0.32" below normal. Raleigh - NWS noted: The monthly average temp was 1.7 degrees below normal while the monthly rainfall was 0.49 inches below normal. No temp high/low records for the month. Rockwell - The month overall was cloudy and damp and cooler than normal with the mean temp 3.2 degrees below normal. Monthly precip, adds Tom, was 0.23" below normal although the yearly precip ended-up 7.61" ABOVE normal. Roxboro - December ended with average max temps above normal and average min temps slightly below normal. Rainfall was only about half of normal. Frozen precip was noted on several days. (report form Merriell Jay) Wilmington - After a warmer than average January '97, the remainder of the year saw each month cooler than average! The average temp for the month was 47.3 degrees which was 1.2 below normal. No temp/precip records were tied or broken. The month of Dec '97 saw an excess of rain, some 1.2 inches above the normal. A rather cloudy month here with only 51% of possible sunshine. Columbia - The monthly average temp was 1.4 degrees below normal while the monthly rainfall was 0.80 inches above normal. Greenville-Spartanburg - The monthly average temp was 1.4 degrees below normal while the monthly rainfall was 0.11 inches above normal. Ruby - December was a cool and damp month but did not have too much real freezing weather. (from Franklin) Tri-cities - The monthly average temp was 1.6 degrees below normal while the monthly rainfall was 1.22 inches below normal. ----------------------------------------------------------------------------- UPDATED MEMBERS' E-MAIL ADDRESSES: (posted by permission) BRE Bob Keehn Bob_Keehn@citcom.net BRI Clayton Towers Ctowers@rica.net POR Bill Trotter wtrotter@whro.org RAL Bob Woodson woods@pipeline.com CEN Paul Bassett III pbassett@digizen.net WSH David Yowell deyowell@mnsinc.com FCH Erica Page erica@erols.com RMD Roy Britt rbritt@erols.com NEW Joyce Winfree joywood@shentel.net FRB Ken McKneely mckneelys@email.msn.com STF Danny Jessee tornado@tidalwave.net BOS Thomas Hensley thomas@summit.net RWL Tom Myers tmyers@salisbury.net WOO Lauck Walton jwalton@shentel.net -----------------------------------------------------------------------------