|Aviation Weather Forecast at Manassas, Virginia|
Station: KHEF North: 38.72 West: -77.52 Timezone: Eastern Standard Time UTC: -5 Model: National Blend of Models - Aviation Format
The Raw Data used in this forecast was obtained from the National Weather Service's National Blend of Models and is not subject to copyright protection. The contents, including graphics and display format, are under copyright by Air Sports Net.
Launch Code Frequently Asked Questions
Q) Can you add another city to the list of available cities in the Launch Code program?.
A) The list of cities shown is the cities in which the National Weather Service has forecast for. We believe that this list is the most current available but from time to time we do omit a city without knowing. You can check our list against the NWS list by visiting this page and comparing it to our list of cities. If you find a city not listed on our site, please contact us and we will add the forecast to our database.
Q) The Launch Code time is 3 hour time blocks. What is the forecast for other times than the ones shown?
A) The National Weather Service only provides the data in 3 hour blocks. You can estimate what the forecast might be at a particular time by using the times before and after the time you want. The temperature and wind speed graphs utilizes such an estimate by connecting the data with a straight line.
Q) How accurate is the forecast?
A) You local accuracy may vary from week to week and season to season. We have found that the forecast are generally accurate and often very close. We do get the occasional email that complains about the accuracy but 99% of all emails concerning accuracy have spoken highly of the quality of the forecast. Just remember that there are no guarantees of accuracy or suitability for a particular purpose. The National Weather Service has performed accuracy test on their forecast data. The results of these tests can be found at http://www.nws.noaa.gov/mdl/synop/smbpublications.php
Q) Does the time correspond to the middle of the box or to either the left or right side of the column?
A) The times shown going across the page is representative of the middle of the column that it is in.
Q) Are the altitudes MSL or AGL?
A) Altitudes are based upon Above Ground Level (AGL) for the height of cloud base.
Q) Does the cloudbase / ceiling range show the forecasted top and bottom of the clouds?
A) No. The cloudbase / ceiling is the elevation range of the bottom of the cloud. There is no reference given to the top of the cloud.
Q) What is an Azimuth?
A) See this page for help with understanding azimiths
Q) I have noticed that the date on the raw data screen and National Weather Service web page is different than the date shown on the Launch Code forecast page. Why?
A) At first glance it may look like the dates generated by the Launch Code program are different. Actually there is no difference in the time the weather events occur. The data from the National Weather Service and the raw data screen is based upon Universal Time Code or UTC. UTC is the time in London England. If the date of the UTC is for 0100 on July 4th or 1:00 am July 4th then this would equate to 9:00 PM on July 3rd for the east coast of the USA (DST). Why? Just as there is a difference in New York time and California time, there is a difference in UTC time and your local time. The Launch Code program automatically converts the UTC time to the local time of the forecast city.
Q) Why are the humidity, dew point, and the temperature dew point spread important.
A) See this page for help with understanding humidity, dew point, and spread and how it interacts with flying.
Q) Why can't I see the entire forecast on my computer screen without having to scroll to the right?
A) If you can't see the entire forecast without scrolling left and right, you can change your screen resolution. For Windows users, simply right click anywhere on an empty space on your desktop, select properties, select settings, then select your screen resolution by sliding the screen resolution bar to the right. This page is best viewed with a 1280 x 1024 or larger screen resolution. For more information on changing your screen resolution visit this Microsoft Windows page
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