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Question: It seems like the last 4 weeks have been some of the wettest I can recall. Every few days I seem to be emptying my rain gauge of water ranging from 1 - 3". Have we broken any records? And also where are we on track for the year? — Mike Carroll

Answer: Records for certain time spans are a bit of a moving target of course. It has been a wet pattern, though, anyway you look at it. If we take Nov 15th as an end point, for example, the previous month brought 5.4 inches of rain at RDU, which ranks as the 13th wettest period for that 4 weeks in 129 years of data and represents 169% of normal.

There have been a few daily rainfall records set or tied in the past 6 weeks or so as well, including 2.07 inches on Oct 2 (old record 2.01 from 1969), 1.23 inches on Oct 3 (ties with 1988) and 1.52 inches on Nov 2 (old mark was 1.37 from 1979).

As for the longer term, if we look at the year 2015 to date, we've had 48.3 inches, which is 9.69 inches above normal and ranks 16th wettest in 129 years. If we instead use a rolling full year period, we find the past 365 days has brought 56.23 inches, 13.0 above normal and 11th wettest for that period.

You can find graphs of rainfall versus normal over several time periods for RDU here on our site at www.wral.com/weather/page/1934052/.
Nov. 22, 2015 | Tags: cool sites, normals, past weather, rain, records/extremes, wral.com

Question: My tender annual plants are still growing. Is it unusual that it's almost mid-November and we haven't yet had a light frost? — Matt

Answer: You don't mention where you live, but we had already had a couple of frost/freeze events by mid-November this year, although as is often the case due to variations in local topography, winds, buildings, vegetation and cloud cover, they weren't absolutely uniform across the region. For the Raleigh-Durham airport, the average first freeze is around the end of October to early November, with substantial year-to-year variability. The earliest first occurrence of a freezing air temperature there was October 3rd in 1974, while the latest first freeze was November 28, 2009.
Nov. 21, 2015 | Tags: cold, dew/frost, normals, records/extremes

Question: During this time of the year we have temperatures from the 70s to 30s with danger of frost some days / morning and not on others. Where would someone find a frost warning at? I like to put the plants outside as much as I can but don’t want to leave them out if there is a danger of frost. — Ricky Ezell

Answer: It gets a little tricky in that sense this time of year, because once we've had a night or two with frost and frezzing temperatures, the natural growing season is considered to be over, and frost/freeze warnings will no longer be issued until we've passed roughly the average last freeze date of the spring. You can check for frost/freeze warnings on our main weather page or on our WRAL Weather App, where "alerts" will be highlighted. However, since warnings may no longer be issued, you're probably better off simply keeping the plants in unless the forecast low temperature for your area is around 40 degrees or higher (since frost on surfaces can occur on nights with air temperatures that remain in the mid or even upper 30s).
Nov. 20, 2015 | Tags: cold, dew/frost, preparedness, wral.com

Question: Is it true that we will have a strong El Nino this winter, and that it will bring mostly rain? — Jeffrey Langley

Answer: Forecasts do continue to call for the current "strong" to "very strong" El Nino persisting into the mid-winter or so, before weakening to a neutral state again by late spring or early summer 2016.

In general, the average effect of El Nino for central and eastern North Carolina in the winter is to tilt the odds somewhat in favor of cooler than normal temperatures and greater than normal precipitation. The level of correlation associated with those impacts is only moderate, so it's worth noting that in any given El Nino year, the results can vary a good bit. It's also worth noting that because of all the other smaller scale influences that determine the character of wintry precipitation, the correlation between El Nino and snowfall, for example, is very low so that the presence of El Nino doesn't offer much predictive power when it comes to snow.

We took a look a while back at the three seasons in the past that featured strong or very strong El Nino patterns, and found the following averages for rainfall, snow and mean temperature at RDU, for the period December through March. Rainfall was 20.1" (compared to an average for the period, for all years since 1887, of 13.96"), while snowfall averaged 7.9" (long-term average 7.1") and mean temperature 45.0 (versus a long-term 44.5).

It's interesting to note that the temperature in these episodes averages near to a little above the long-term value, while El Nino in general tilts us toward cooler-than-normal levels. This may be because some of the strongest episodes have a tendency to cause such an enhancement in the number and intensity of southern jet stream disturbances crossing the southeastern U.S. that a number of them may sweep unseasonably warm air into the state at a level that doesn't happen as much with weaker episodes. The strongest El Nino on record, from 1997-98, resulted in a heavy 23.4 inches of rain and a temperature notably above normal at 45.4 degrees, with only 2.4 inches of snow. Of course, all these numbers should be viewed with the caveat that three strong events makes for a very small historical sample. The bottom line is, while one of the previous strongest El Ninos did result in a lot of rain and not much snow, there's enough variability even among the few most intense past El Nino events that we can't make a very confident call on whether this one will result in a lot of snow or very little.
Nov. 19, 2015 | Tags: el nino/la nina, past weather, rain, snow

Question: Will Clayton be getting any snow this year? Has there ever been a white Christmas? — Emma P.

Answer: We have no way to be certain whether or how much snow Clayton will receive for the upcoming winter, but it's reasonable to expect that there would be at least a couple of events, given what should be an active storm track pattern across the southeastern U.S. due to a strong El Nino.

As for past "White Christmas" events, there have been a very few. In a statewide database of winter storms that reaches back to 1959 and defines White Christmas as any measurable snow that occurs anytime on December 24, 25 and/or 26, most of the events were mixes of snow, sleet and ice with most of the snow confined to the mountains. However, a more widespread snow occurred on 25-26 December in 2010, with roughly the western half of the state seeing measurable snow on Christmas Day (in the range of 4-12 inches for about the western third of the state) and much of central and eastern NC (including Clayton) adding between 5 and 13 inches on 26 Dec, with the highest amounts in the general vicinity of Rocky Mount, Wilson and Tarboro. You can check out the winter storm summaries for the dates surrounding Christmas at www.nc-climate.ncsu.edu/white-christmas.php, and there is also a link there to the broader winter storm database for anytime of the year and one that checks observed snow for a large selection of individual cities in our state. For the Clayton Water Treatment Plant station, for example, the database shows .2" in 1966, .3" in 1998 and 1.5" in 2010, which seems low compared to maps indicating the Clayton area should have had around 8-10 inches in that 2010 storm.

Historical records for some other individual sites also show .4" of combined snow and sleet in Raleigh on Christmas Day 1947, and .5" in southwest Raleigh (but nothing at RDU) on Christmas Day in 1966.
Nov. 18, 2015 | Tags: cool sites, el nino/la nina, snow

Question: I had lived in the Triangle Area for over 30 years, then moved to Arkansas and have been here for 4 years now. I just wanted you to know that I miss seeing and hearing you on the weather very much! — Valerie

Answer: Thanks for the kind sentiments, and the years as a loyal viewer! Although it may not have a lot of relevance to your local situation there, do take note that if you'd like to check back in on your old stomping grounds from time to time, our newscasts are streamed live here on the web site and on our mobile news app, and you can also watch the most recent newscast when we aren't on the air, in addition to recently updated short video forecasts, all from links at www.wral.com/video/.
Nov. 17, 2015 | Tags: wral.com

Question: Why is it that when we have a rain event it can last over several days but when we have a snowstorm it falls only for 1 day at the most? — Richard

Answer: We do have some occasions withe measurable snow extending over more than a day or so, with records for the Raleigh area showing 17 cases in which snow has fallen on 3 consecutive days. However, we've had rain for as many as 12 straight days on rare occasion, and your point is well taken. The principle reason for the relative rarity of extended periods of snowfall is that our combination of latitude and geography requires a few fairly specific combinations of moisture, temperature and vertical motion fields to produce snow here. While precipitation in the form of rain can be produced by a wide range of such combinations that aren't all that rare or sensitive to small changes, we don't have have a very large change in temperature, humidity at certain levels of the atmosphere, or dynamic forcing for lift to cause snow to either cease altogether or to change to a different precipitation type (be it sleet, freezing rain or, more commonly, rain). This dependence on a pretty narrow range of ideal conditions is likely the main reason for shorter durations of snow than rain.
Nov. 16, 2015 | Tags: general meteorology, rain, snow

Question: Where is the best spot for a home weather station? On the roof of the house like WRAL or somewhere else? Currently mine is in the back yard but there are many trees and other houses around that block the wind so the wind is inaccurate but the temperature is usually right on. — Dennis Cossa

Answer: Ideal siting locations for measuring surface weather conditions are on a fairly level, open piece of grass-covered land, with trees and buildings a good distance away so as to minimize their impact on the flow of winds, on temperatures that might be affected by solar heating of walls and exhaust from HVAC equipment, and on the ability of the rain gauge to accurately measure precipitation. This kind of representative siting is often achieved at airport locations, and at carefully selected and maintained climate monitoring stations. For home weather stations, stations at schools and businesses (including our campus in southwest Raleigh), there are often practical considerations that force some compromises. In your case, unless the trees you mention are rather short or quite distant from your home, you may find that they still impact winds even if the station was placed on your roof. If you did place it there, you'd want the anemometer to be a good ten or twelve feet above the highest point of the roof to best measure the ambient wind with reduced influence from the roof itself. At "official" weather stations, the standard temperature and humidity measurements are taken about 4-6 feet above the ground, while the wind is measure at about 30 feet above ground level. Again, this is often impractical in home applications.
Nov. 15, 2015 | Tags: instruments, winds

Question: Can you explain the three lights in the sky last Saturday night that circled over and over again and converged each time in the center? Could this be something in the atmosphere? Several of us in my neighborhood saw this. — Nancy

Answer: Searchlights came to mind as a possible explanation, and some photos you sent later seem to confirm that - we don't know who or where exactly, but would guess some event or business promotion was going on that involved a set of three lights swiveling around and projecting light onto the base of the clouds that were present that evening. By that late in the day, the lower atmosphere had dried out quite a lot compared to earlier in the wake of a cold front, so visibility was good and there was little in the way of haze, fog or mist, and under those conditions you typically wouldn't see obvious "beams" from the lights, similar to the way it would appear if someone down the hall in your home was shining a flashlight at the ceiling. Typically, you would see the light on the ceiling, but little if anything in the way of a beam so long as the house was free of any smoke or steam. In this case, you saw the spots on the cloud "ceiling," which varied between about 3,000 and 8,000 feet above the ground late Saturday evening.
Nov. 14, 2015 | Tags: atmospheric optics, past weather

Question: Is there a way I can look up the daily rainfall for Tulsa, OK as far back as 1978. I lived near Tulsa for over 20 years and remember a 10" rainfall one Memorial day weekend. I believe it was 1979 or 1980. This question is important and not a trivia question. I looked at some data on the National Weather Service site and found the monthly rainfall for the time period, but not the daily rainfall. — Reginald Tharrington

Answer: We looked at a couple of sources of data on rainfall for the Tulsa area, and found a NWS climate summary page for Tulsa, based on a long-running cooperative observing site there, that showed that on the Saturday and Sunday of Memorial Day in 1984, over 9 inches of rain was recorded. This is likely the weekend you're thinking of. At that reporting site, 2.4 inches was recorded on Saturday the 26th, and 6.95 inches on the 27th, for a total of 9.35 inches. This was found in the table at www.srh.noaa.gov/tsa/?n=climo_tulcli55. We also checked archived data for Tulsa airport (KTUL) available through our "Almanac" link at the Weather Underground site. (The archives default to RDU, but you can change the location to retrieve data from other places). At that location, .16" of rain was recorded on the 26th and 8.97 inches on the 27th, for a total of 9.13 inches.
Nov. 13, 2015 | Tags: past weather, rain, wral.com

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