About the MEX Text Product

The extended-range GFS-Based MOS (MEX) guidance is generated from the 0000 and 1200 UTC cycles of NCEP's Global Forecast System (GFS) Model. This guidance is valid for stations in the United States, Puerto Rico, and the U.S. Virgin Islands. Station lists and histories can be found at MOS Station Archive Page. Forecast elements are valid from 24 to 192 hours in advance.

Detailed Documentation can be found in the following documents (pdf):

The MEX Message

Sample Message
 IAD   GFSX MOS GUIDANCE   3/05/2013  0000 UTC
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192
 TUE  05| WED 06| THU 07| FRI 08| SAT 09| SUN 10| MON 11| TUE 12 CLIMO
 X/N  47| 34  42| 32  44| 29  45| 32  50| 33  57| 38  58| 40  54 29 53
 TMP  42| 36  39| 34  39| 32  41| 34  44| 37  50| 42  52| 43  47
 DPT  23| 26  28| 24  29| 24  25| 25  29| 30  34| 34  38| 34  28
 CLD  OV| OV  OV| OV  PC| CL  PC| CL  CL| PC  OV| OV  OV| OV  PC
 WND   5| 18  20| 20  16| 13  22| 14   8|  5   8|  5  10| 18  14
 P12  36| 99  93| 36   5|  0   7|  5   5|  7  17| 30  35| 31  24 24 24
 P24    |    100|     36|      7|      6|     19|     53|     46    34
 Q12   0|  5   5|  0   0|  0   0|  0   0|  0   0|  1    |
 Q24    |      5|      0|      0|      0|      0|       |
 T12   1|  1   7|  2   1|  0   1|  1   1|  1   2|  1   5|  4   6
 T24    |  1    |  9    |  2    |  1    |  1    |  2    |  6
 PZP  13| 27   4| 13   9|  6   6| 17  13|  6   5|  4   4|  4   5
 PSN  25|  4  28| 16  45| 64  52| 32  24| 16   2|  3   4|  4  21
 PRS  28| 47  29| 45  26| 16  15| 18   8|  3   4|  4   3|  9  14
 TYP  RS|  Z  RS| RS   S|  S   S|  S  RS|  R   R|  R   R|  R   R
 SNW    |      4|      0|      0|      0|      0|       |
  • FHR = Forecast hour, i.e. how many hours from the model run time
  • X/N = daytime max/nightime min temperatures
  • TMP = temperature valid at that hour
  • DPT = dewpoint valid at that hour
  • CLD = mean total sky cover over the 12-hr period ending at that time
  • WND = maximum sustained surface wind (WND) during a 12-h period
  • P12 = 12-hr probability of precipitation (PoP) ending at that time
  • P24 = 24-hr PoP ending at that time
  • Q12 = 12-hr quantitative precipitation forecast (QPF) ending at that time
  • Q24 = 24-hr QPF ending at that time
  • T12 = 12-hr probability of thunderstorm ending at that time
  • T24 = 24-hr probability of thunderstorm for the 1200-1200 UTC time period ending at that time
  • PZP = conditional probability of freezing pcp occurring for the 12-hr period ending at that time
  • PSN = conditional probability of snow occurring for the 12-hr period ending at that time
  • PRS = conditional probability of rain/snow mix occurring for the 12-hr period ending at that time
  • TYP = conditional precipitation type for the 12-hr period ending at that time
  • SNW = snow fall categorical forecasts during a 24-h period ending at the indicated time.
     
  • CLIMO = Go here for more information on climatology

 

Definitions of Categorical Elements

MEX QPF Categories
0 no precipitation
1 0.01 to 0.09 inches
2 0.10 to 0.24 inches
3 0.25 to 0.49 inches
4 0.50 to 0.99 inches
5 1.00 to 1.99 inches
6 2.00 inches or greater


MEX Snow Fall Amount Categories
0 no snow or a trace expected
1 > a trace to < 2 inches
2 2 to < 4 inches
4 4 to < 6 inches
6 6 to < 8 inches
8 >= 8 inches
MEX Cloud (CLD) Categories
CL mostly clear                  
PC partly cloudy
OV mostly cloudy


MEX Precipitation Type (TYP) Categories
S pure snow or snow grains
Z freezing rain/drizzle, ice pellets, or
anything mixed with freezing precip
RS rain/drizzle and snow mixed
R pure rain/drizzle

Canadian Min/Max Temperature Guidance

In addition to the standard MEX output, additional guidance for Maximum and Minimum Temperatures is also available for select Canadian stations. This is currently only available as an all-stations text product (not included in GRIB and BUFR downloadable data). 

Canadian Min/Max Temperature

Sample Message

 GFSX-BASED STATISTICAL MAX/MIN GUIDANCE 10/26/15  0000 UTC
       MON 26| TUE 27| WED 28| THU 29| FRI 30| SAT 31| SUN 01| MON 02
 CWRT      47| 30  44| 29  49| 37  50| 35  50| 42  55| 45  49| 27  38
 CWRY      56| 33  42| 23  53| 36  58| 31  57| 38  58| 41  55| 30  41
 CWSS      45| 23  51| 26  50| 43  62| 40  52| 27  44| 24  45| 26  46
 CWST      41| 29  46| 26  46| 43  56| 38  46| 28  40| 26  41| 29  43
 CWVN      49| 32  44| 19  45| 23  53| 27  50| 25  56| 36  58| 28  44
 CWVU      47| 38  48| 42  51| 49  60| 50  52| 43  45| 39  44| 43  47
 CWWB      51| 43  51| 49  59| 48  50| 42  50| 40  51| 43  52| 44  55
 CWWF      51| 34  45| 26  40| 20  43| 27  41| 28  49| 38  59| 34  43
 CWWZ      52| 44  55| 49  59| 48  51| 43  51| 42  51| 43  54| 45  55
 CWYY      57| 39  58| 40  50| 44  55| 43  54| 47  60| 46  56| 40  50
 CWZA      59| 49  62| 48  54| 47  56| 48  53| 48  57| 45  54| 42  51
 CXDI      51| 36  55| 47  63| 46  49| 36  50| 33  51| 40  54| 41  58

MOS