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The most direct way to find your question is to search for the name you used when you submitted it (first name, last name or both). If you did not include a name, then you can search using keywords from your question. Of course, since many weather-related terms are common to a lot of the questions we receive, this may turn up a number of others in addition to your own.

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Answer: In somewhat oversimplified terms, winds in a tornado blow in a more or less circular fashion around a vortex that extends from the base of a cumulonimbus cloud to the ground. The strongest winds tend to be tightly concentrated close to the tornado, and can be extremely strong in the most violent tornadoes, topping 200 miles per hour in storms rating EF-5 on the Enhanced Fujita scale.

Straight-line winds, also known as downbursts or microbursts, occur when air that rapidly descends from a thunderstorm reaches the ground and spreads out at high speed near the surface. These winds may fan out radially in all directions, or may be channeled toward a given direction depending on the motion of the parent storm, local topography and other factors. Most downburst winds have speeds well below 100 miles per hour, but on very rare occasions have been known to reach 150 miles per hour or more.
Oct. 15, 2010 | Tags: severe weather, thunderstorms, tornadoes, winds

Answer: Generically, a cyclone is any closed atmospheric circulation that rotates in the same sense as the earth does around the nearest pole, so counterclockwise for the northern hemisphere. That being the case, there are tropical and non-tropical cyclones. The same meteorological phenomenon that is called a hurricane in the Atlantic and eastern Pacific is called a typhoon in the northwestern Pacific and a cyclone (sometimes Severe Tropical Cyclone) in the southwestern Pacific and Indian Oceans.

Regarding intensity, the northwest Pacific typhoons have resulted in some of the lowest central pressures on record, but measurements of top wind speeds are less conclusive in terms of any one basin routinely having the "worst" storms. The highest surface wind measured in any such storm thus far was a 253 mph gust in Tropical Cyclone Olivia, a Category 4 storm that cross Barrow Island off the northwest coast of Australia on April 10, 1996. This measurement also rates as the strongest surface wind of any kind on record globally.
Sep. 29, 2010 | Tags: hurricanes, records/extremes, winds

Answer: "Always" is a little too strong a word, but in general you're correct. Tropical cyclones in the Atlantic are typically steered along toward the west or west-northwest while they are at low latitudes on the south side of a semi-permanent high pressure ridge. This ridge often terminates or weakens over the western Atlantic and if so the storm may slow and turn more northward up the west side of the ridge. Occasionally the ridge will extend into the U.S. or connect with another high over the mainland, in which case the storm may be trapped at lower latitudes and continue into the Caribbean or southeastern U.S.

When storms do "recurve" and begin to move north, they usually start to encounter steering flow associated with the mid-latitude westerlies (the jet stream and it's surroundings) which carry our typical weather disturbances such as upper-level troughs and frontal systems across the U.S from west to east. As tropical cyclones move north of about 25-35 degrees latitude, they become more and more likely to be influenced by the much stronger flow associated with this belt of westerlies, which accelerates the storm toward the east or, in cases involving a trough in the westerlies approaching the storm, toward the northeast.
Sep. 25, 2010 | Tags: hurricanes, winds

Answer: If you are referring to what level winds are ideally referenced when listing a hurricane's intensity, that reference is to a one-minute average wind speed at 10 meters (about 33 feet) above the surface. The wind at the ground itself drops to zero, of course, and there is a roughly logarithmic and then linear profile of increasing wind from the ground interface upward. At the height of a typical adult, say 5-6 feet, the wind would on average be about 40-60% percent of the value at 10 meters, although there can be great variation in this percentage depending on the characteristics of the surface and any nearby obstacles, not to mention short-term variation in the wind speed associated with turbulent gusts and lulls.

You may have been referring to what altitudes hurricane hunter aircraft use to estimate winds in active storms. For weak systems just forming, they often fly at around 500-1000 feet, and estimate surface winds using visual cues based on appearance of the sea surface in addition to using instruments such as a stepped-frequency microwave radiometer. In more fully developed hurricanes, aircraft penetrate the storms most frequently at altitudes of about 2500, 5000 or 10,000 feet (and only the latter height for category three storms and stronger). Surface wind speeds on these flights are usually measured using dropsondes and by measuring the maximum wind speed encountered at flight level and then applying a reduction factor to obtain a corresponding surface (10-meter) wind. For winds measured at 10,000 feet, the surface wind is estimated to be about 90 percent of that value.

The National Hurricane Center assigns a maximum sustained wind value to the storm based on its best estimate from a combination of multiple techniques from the reconnaissance aircraft, satellite measurements and any surface instruments in the vicinity of the storm.
Sep. 21, 2010 | Tags: hurricanes, winds

Answer: Based on wind measurements at the Raleigh-Durham airport, the average wind speed for the year as a whole is 6.8 mph, with a prevailing direction from the southwest, or 240 degrees. The monthly mean wind speed ranges from a low of 5.7 mph in October to a high of 8.2 in March, and the prevailing direction is southwest in every month except for September and October, when it nearly reverses to become northeasterly (040 degrees in September and 030 degrees in October).
Sep. 3, 2010 | Tags: normals, winds

Answer: You've observed a common feature of the lower atmosphere that occurs most noticeably on nights that are mainly clear, so that radiative cooling of the surface (and resulting conductive cooling of air near the ground) causes development of a surface-based temperature inversion.

During the daytime, surface heating leads to convective mixing of the lower atmosphere that transfers wind energy (momentum) to the surface. This mixing increases the average speed of winds near the ground and reduces the average wind speed a few hundred to a few thousand feet up. In essence, the mixing spreads the effect of friction upward from ground level into the atmosphere.

When an inversion forms, a process called "decoupling" may ensue, in which turbulent mixing ceases, the density of air near the ground increases, surface winds become light or calm, and the momentum that was previously transferred to the surface is channeled into increasing winds near the top of the inversion layer. To some extent, at the top of that layer friction has been "turned off" and so the wind at, say, 1000 feet, is able to speed up. This increase in wind typically occurs in a "sheet" covering a large area, although in certain situations there can also be a geographically confined area that is faster than others (a low level jet). Since air at higher elevations was already moving largely in the absence of friction, those speeds don't change much at first.

The result is typically a build-up of wind a few hundred to a few thousand feet up that peaks by an hour or two after midnight. Beyond that, the shear between the peak of the wind and lower speed at higher elevations may lead to some turbulence and mixing that increases winds at higher altitu8ded and decreases the speed at the peak of the profile. Even later, of course, the sun rises, the ground heats up, the inversion is eventually erased, and the profile of wind returns to its daytime configuration. Of course, all of this is subject to great variation depending on the weather pattern in place.

While not perfect, computer model projections of wind profiles often do a reasonable job of forecasting the structure of this phenomenon. You can step through such profiles (forecast soundings) of temperature, dew point and wind direction/speed at a number of web sites, one example being http://ready.arl.noaa.gov/READYcmet.php, and another http://www-frd.fsl.noaa.gov/mab/soundings/java/.
Jul. 30, 2010 | Tags: cool sites, general meteorology, winds

Answer: We can't be absolutely certain, but there are a couple of scenarios that come to mind. First, you may have experienced a brief "dust devil," or "whirlwind." These vortices often occur on otherwise quiet days, usually when the sun is shining brightly, the ground is dry and temperatures are rising quickly. Strong heating of the ground leads to updrafts, and if one happens to capture a swirl of wind, vertical stretching and horizontal contraction of that rotating column of air can intensify it enough to pick up dust, sand, leaves and other debris, perhaps in your case even a beach umbrella!

It is also possible your experience was related to the formation and passage of a sea breeze front across your location. Some nearby stations reported a sharp wind shift from N/NE to E/SE between mid-morning and early afternoon. Wind speeds at that time rose from around 5-8 mph up to around 12-15, with some gusts near 20 mph. If the strengthened winds were channeled through the local dune system in just the right way, you might have encountered a brief stronger gust via that mechanism that could have caused the disruption you observed.
Jul. 16, 2010 | Tags: past weather, winds

Answer: It can sometimes be a little tricky to separate cloud propagation (apparent motion due to development and dissipation) from the motion of cloud elements due to the wind. However, as long as you can see individual elements of cloud that can be followed along without much change, they can serve as good markers of wind speed, since small cloud elements do move along at about the speed of the wind at their altitude. This is true for any elevation above the ground, but requires that you make a good estimate of the height of the clouds above the ground. This can be done to a rough degree with some knowledge of the appearance of clouds typical of different altitudes (cirrus versus altocumulus versus stratocumulus, etc), but for more precision requires measurement with a ceilometer or ceiling balloon, for example. You can find measured cloud heights in METAR observations from most airports, and forecast cloud heights in Terminal Aerodrome Forecasts issued by the National Weather Service and Military forecasters. For access to both, see the "METARs" and "TAFs" tabs at aviationweather.gov/adds/metars/. Finally, if you have a good idea of the height of a cloud layer and can follow some of its cloud elements from a point directly overhead (point A) until they reach a location 45 degrees above the horizon (point B), dividing the cloud height by the time it takes to move from A to B will give you a rough wind speed at the height of the clouds.
Jun. 30, 2010 | Tags: clouds, cool sites, winds

Answer: Wind direction and speed can be quite variable day to day of course, but for just about all of central and eastern NC the prevailing wind direction is southwesterly for much of the year, including August in the counties you're asking about. The average speed for that month is about 6 mph. Although they don't cover Sampson and Duplin county stations specifically, you can find some regional wind climate data at a couple of sites online. See www.ncdc.noaa.gov/oa/documentlibrary/wind/wind1996.pdf for a national wind climatology. You can also access "wind roses" showing a more detailed monthly distribution of wind directions and speeds for several cities in our state at ftp://ftp.wcc.nrcs.usda.gov/downloads/climate/windrose/north_carolina/.
Jun. 23, 2010 | Tags: cool sites, normals, winds

Answer: We had an upper level low to our southeast and a surface low off the southeast coast as well at that time. A check of cloud observations and radiosonde wind profiles showed that around the time of your sighting there were scattered clouds at about 6-800 feet above the ground and 11,00 feet, and a broken layer around 20,000 feet up. Winds at those levels were generally from the east at all levels, about 15-20 knots at 6-800 feet, 25 knots at 11,000 and 20 knots at 20,000 feet. These speeds are not especially high, but you probably were struck by the apparent speed of the lowest clouds. Even at only 15-20 knots, they would have appeared to noticeably speed along relative to the moon due to their very low altitude.
Jun. 5, 2010 | Tags: clouds, winds