JetStream Acronyms: U's

U/S Unserviceable
UAB Until advised by ...
UCP Unit Control Position
UDDF Up and down drafts
UFN Until further notice
UIR Upper flight information region
UKMET United Kingdom METeorological Agency
ULJ Upper Level Jet
UN Unable
UNA Unable
UNAVBL Unavailable
UNEC Unnecessary
UNKN Unknown
UNL Unlimited
UNREL Unreliable
UNRELBL Unreliable
UNRSTD Unrestricted
UNSATFY Unsatisfactory
UNSBL Unseasonable
UNSTBL Unstable
UNSTDY Unsteady
UNSTL Unsettle
UNSTLD Unsettled
UNUSBL Unusable
UPDFTS Updrafts
UPR Upper
UPSLP Upslope
UPSTRM Upstream
URG Urgent
USACE U.S. Army Corps of Engineers
USBL Usable
USBR U.S. Bureau of Reclamation
USFS U.S. Forest Service
USGS U.S. Geological Survey
UT Utah
UTC Coordinated Universal Time
UV Ultraviolet
UVM Upward Vertical Motion.
UVV Upward Vertical Velocity
UVVS Upward vertical velocities
UWNDS Upper winds