National Upper-air Station Performance Scores

Objective

To evaluate NWS upper-air station performance nationwide to help improve data availability, quantity, and quality. Scores are also used to help determine the winner of the National Isaac Cline Award for Upper-air Observations.

Method

The following equation is used to rank station performance, which includes appropriate weighting factors:

Score = A/2 + B + C + D/2 - E/5 - F/5   where,

A = Percentage of monthly soundings arriving at NCEP within 3 hours after balloon release (by 14:00 or 02:00 UTC). This is based on NCEP and FMH#3 requirements. To score in this category, all coded messages (with or without data) must be received. This percentage is divided by 2.

B = Percentage of monthly soundings achieving the minimum 400 hPa pressure level requirement or higher.

C = Percentage of monthly soundings achieving 50 hPa or higher.

D = Percentage of monthly soundings achieving 20 hPa or higher. This percentage is divided by 2.

E = Percentage of monthly temperature levels between surface & 400 hPa rejected by NCEP.  This percentage is divided by 5.

F = Percentage of monthly wind levels between 400 and 100 hPa rejected by NCEP. This percentage is divided by 5.

NOTE: Starting with the August, 1999, data, element "A" above now includes soundings with AND without data.  Prior to this change, points were only given in this element if the coded messages contained data. Messages without data (i.e., no sounding taken) were not included in this element. This change will result in slightly higher average scores.

Elements B through F are compiled 6 hours or more after balloon release and before NCEP data deletions are applied to the soundings.  The maximum score a station can achieve with this equation is 300.  Histograms are available that show station performance for some of the above elements

Data Sources

Data used for generating the scores come from data quality reports provided by NCEP each month. 

Evaluation

It is important to note that a station's score does not solely reflect station staff performance. Factors such as equipment and communication failures, maintenance personnel performance, and support from NWS Regional office and Headquarters management, must also be taken into consideration when evaluating station scores.   Furthermore, many times a low score is the result of a system failure (e.g., lightning strike) beyond the control of station staff.  Thus, station scores reflect the performance of the entire upper-air program.  Upper-air station managers should use the scores as only one of several tools for assessing how well their station is performing.

A station's average score for the year plays a role in determining the winner of the National Isaac Cline Award for Upper-air Observations given each year, but it's only given a 40% weighting factor.  Scores are not used as the only indicator for determining this award.

***IMPORTANT***

Stations must not under inflate balloons in an attempt to reach higher sounding termination heights and a higher monthly score.  Likewise, over inflation of the balloon must be avoided as this wastes gas and can lower balloon burst heights

Stations must inflate balloons so that the average (surface to flight termination) ascension rate falls between  275 and 350 meters/minute for each sounding (References: FMH#3 and WSOH#10).  Balloon ascension rates from each sounding are evaluated when determining the winner of the Isaac Cline Award.  Observations are checked to see if the balloon ascended between 275 and 350 meters/minute.  Routine under inflation and over inflation of the balloon is unacceptable.   

NEW: Stations should review balloon ascension rate graphics based on the National Climatic Data Center (NCDC) archive and adjust the balloon gas amounts accordingly.  NWS stations should have no more than 5 % of their monthly flights with ascent rates below 275 meters/minute or above 350 meters/minute. 

NWS upper-air station scores for the past 3 months and the 12 month running average

300  =  Perfect Score.   Click here for trends in the National average and median score.

NOTE:  

The office at Cold Bay, AK,  (CDB) was damaged during a storm and no observations were taken in January.  This caused their score for that month to be very low and will impact the 12 month average.

Because of budget cuts, the upper-air station at Desert Rock, NV, ("DRA") does not operate on weekends and scores will be low.

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