NASA's Weather Criteria
		Clouds: (types known to contain hazardous electric fields) Do not launch if any part of the planned flight path is through a layer of clouds any part of which is within 5 nautical miles is 4,500 feet thick or greater and the temperature of any part of the layer is between 32 degrees F. and -4 degrees F. Launch may occur if the cloud layer is a cirrus-like cloud that has never been associated with convective clouds, is located entirely at temperatures of 5 degrees F. or colder, and shows no evidence of containing water droplets. Cirrus clouds are the most common of the High Cloud (5000-13000m) group. They are composed entirely of ice and consist of long, thin, wispy streamers. They are commonly known as "mare's tails" because of their appearance. Cirrus clouds are usually white and predict fair weather. Image & caption courtesy of Windows to the Universe Photographed by Ronald L. Holle Click for full size version (89K GIF) Do not launch through cumulus type clouds with tops higher than the 41 degree F. temperature level. Launch may occur through clouds as cold as 23 degrees F. if the cloud is not producing precipitation, and all field mills within 5 nautical miles of the flight path and at least one field mill within 2 nautical miles of the cloud center read between -100 volts per meter and +500 volts per meter. Cumulus clouds belong to the Clouds with Vertical Growth group. They are puffy white or light gray clouds that look like floating cotton balls. Cumulus clouds have sharp outlines and a flat base. Cumulus clouds generally have a base height of 1000m and a width of 1km. Cumulus clouds can be associated with good or bad weather. Image & caption courtesy of Windows to the Universe Photo by Angie J Venturato Click for full size version (52K JPG) Do not launch through or within 5 nautical miles of the nearest edge of cumulus type clouds with tops higher than the 14 degree F level through or within 10 nautical miles of the nearest edge of cumulus clouds with tops higher than the -4 degrees F. level. Do not launch if the flight path is through any non-transparent clouds that extend to altitudes at or above the 32 degrees F. level which are associated with disturbed weather producing moderate or greater precipitation, or melting precipitation, within five nautical miles of the flight path. Do not launch through an attached anvil cloud. If lightning occurs in the anvil or the associated main cloud, do not launch within 10 nautical miles for the first 30 minutes after lightning is observed, or within 5 nautical miles from 30 minutes to 3 hours after lightning is observed. Do not launch if the flight path will carry the vehicle: through non-transparent parts of a detached anvil for the first three hours after the anvil detaches from the parent cloud, or the first four hours after the last lightning occurs in the detached anvil. within 10 nautical miles of non-transparent parts of a detached anvil for the first thirty minutes after the time of the last lightning in the parent or anvil cloud before detachment, or the detached anvil after its detachment. within 5 nautical miles of non-transparent parts of a detached anvil for the first three hours after the time of the last lightning in the parent or anvil cloud before detachment, or the detached anvil after detachment, unless there is a field mill within 5 nautical miles of the detached anvil reading less than 1,000 volts per meter for the last 15 minutes and a maximum radar returns from any part of the detached anvil within 5 nautical miles of the flight path have been less than 10 dbz (light rain) for 15 minutes. Do not launch if the flight path will carry the vehicle through a thunderstorm or cumulonimbus debris cloud which is not transparent and less than three hours old. Launch may not occur within five nautical miles of these debris clouds unless: for 15 minutes preceding launch there is at least one working field mill within five nautical miles of the debris cloud all electric field mill readings are between -1 kilovolt and + 1 kilovolt per meter within five nautical miles of the flight path no precipitation has been detected in the debris cloud (less than 10 dbz by radar) within 5 nautical miles of the flight path. Do not launch if the flight path will carry the vehicle through any cumulus cloud that has developed from a smoke plume while the cloud is attached to the plume, or for the first 60 minutes after the cumulus cloud detaches from the smoke plume. Supporting Table: KSC Seasonal Altitudes of Temperature Levels in thousands of feet January July Temp (F) Low (Kft) Avg (Kft) High (Kft) Temp (F) Low (Kft) Avg (Kft) High (Kft) -4 21 24 26 -4 23 27 29 14 13 18 21 14 18 21 23 23 9 15 18 23 16 18 20 32 sfc 12 16 32 13 15 18 41 sfc 9 14 41 10 12 15 Range Safety Cloud Ceiling and Visibility constraints: Direct visual observation of the Shuttle is required through 8,000 feet. This requirement may be satisfied using optical tracking sites or a forward observer For cloud ceilings of any thickness between 6, 000 feet and 8,000 feet the following conditions must be met for launch to occur: the vehicle integrity can be observed without interruption through 6,000 feet. all required Range Safety instrumentation is functioning properly the U.S. Air Force 45th Space Wing Commander approves the decision to proceed For cloud ceilings between 4,000 feet and 6,000 feet the following conditions must be met for launch to proceed: the thickness of the clouds must be less than 500 feet the vehicle integrity can be monitored by the Eastern Range airborne and/or the ground forward observers through 8,000 feet all required Range Safety instrumentation is functioning properly the U.S. Air Force 45th Space Wing Commander approves the decision to proceed A "Good Sense Rule" is in effect for launch which states: "Even when constraints are not violated, if any other hazardous conditions exist, the launch weather officer will report the threat to the launch director. The launch director may hold at any time based on the instability of the weather."

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