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About the Quantitative Precipitation Forecasts



About 24 Hour QPF      About 6 Hourly QPF


 24 Hour QPF Issuance Times

Product Time
94q (preliminary Day 1) 0615Z & 1815Z
94q (final Day 1) 1015Z & 2215Z
98q (preliminary Day 2) 0700Z & 1900Z
98q (final Day 2) 1015Z & 2215Z
99q 1015Z & 2215Z
95e (Day 1-5 total) 1730Z
QPFPFD (prelim. Day 1) 0700Z  & 1900Z
QPFPFD (prelim. Day 2) 0745Z & 1945Z
QPFPFD (with Days 1-3) 1100Z & 2300Z


About The 24 Hour QPF Products

Isohyets of expected areal average rainfall of .01 inch, .25 inch, .50 inch, 1 inch, 1.50 inch and greater (in inch increments) are drawn for the 24 hour forecast period ending at 1200Z on both days 1, 2, and 3. The daily QPF package begins on the midnight shift with the 0000Z model run.  A preliminary Day 1 forecast (94Q) is issued by 06Z and the Final Day 1 (94Q) is issued by 10Z and is valid at 1200Z the following morning. The Day 2 QPF (98Q) is issued by 1000Z. The Day 2 forecast (98Q) is updated on the day shift and is issued by 1800Z. 

An electronically generated bulletin, which describes the location of the forecast isohyets using latitude and longitude points, is transmitted at the end of the qpf discussion for the Day 1 through Day 3 finals. 

Example: 
 0.25 350731 349761 349789 347803 340819 327837 310854 297864 284874
 0.50 404072 395071 390076 387081 389084 395085 402082 404076 404072

The first field is the value of the contour (in this case...0.25" or 0.50"). The following fields are the latitude/longitude pairs for the contour. The first three digits of the pair are the degrees of latitude (in tenths of degrees North latitude). The last three digits of the pair are the degrees of longitude (in tenths of degrees West longitude). If the fourth digit is less than 5, a leading "1" is added to indicate longitudes greater than or equal to 100° W. From the above message...the following table gives the decoded lat/long pairs 


Value: 0.25" Value: 0.50"
35.0N, 73.1W 40.4N, 107.2W
34.9N, 76.1W 39.5N, 107.1W
34.9N, 78.9W 39.0N, 107.6W
34.7N, 80.3W 38.7N, 108.1W
34.0N, 81.9W 38.9N, 108.4W
32.7N, 83.7W 39.5N, 108.5W
31.0N, 85.4W 40.2N, 108.2W
29.7N, 86.4W 40.4N, 107.6W
28.4N, 87.4W 40.4N, 107.2W


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Page last modified: Thursday, 01-Mar-2007 18:43:03 UTC