Our two-week dry spell is about to come to an end, but it's going out cookin'! Temperatures in the Cascades have been outrageously warm the last couple of days:

Some Cascade foothill locations were even warmer. Horse Creek, at elevation 3402 ft east of Salem, hit 70-degrees Tuesday while a bit farther south, east of Albany, Yellowstone Mtn at 3080 ft hit 73-degrees!

When it's warmer in the mountains than it is in the valleys, this is called a temperature inversion, because the temperature profile of the atmosphere is the opposite, or inverse, of how it normally gets colder as you ascend.

The graph below is called a sounding. It's made from data collected from the weather balloon that is released twice a day from Salem (and about 70 other locations in the continental U.S.).

The solid red line is the temperature trace, the dotted red line is the dewpoint temperature trace. The closer the two lines are to each other, the higher the humidity. Notice how the temperature increases as you go up in altitude: the solid red line moves from left to right more than it goes up, indicating a strong inversion. Also notice where the dotted line suddenly moves far away from the solid line: that's the top of the fog layer.

Below is a table of the same data presented in the graph above. You can check temperatures here against the graph.

  RAOB:  00110807.UPA  //  72694 - KSLE - SALEM/McNARY, OR   at 00Z 08 Nov 2007
 
       Data Type: CODED     Integrated data levels: 128
 
       Lat: 44°55'00" N     Lon: 123°00'00" W     Elev: 61 meters
 
       ________________________________________________________________________________
 
              Height   Pres     T     Td   RH   DD/FF    CAT   LLWS   Icing - Type
       Level (ft-MSL)  (mb)    (F)   (F)  (%) (deg/kts) (FAA)         (AF @ 75% RH)
       ________________________________________________________________________________
                          
                                            
          41    8000  761.8                    275/13                                  
          40    7398  779.0   46.0   17.2  31                                          
          39    7053  789.0   46.8   30.6  53                                          
          38    7000  790.5                    275/11                                  
          37    6643  801.0   48.2   30.2  49            MDT                           
          36    6272  812.0   48.9   36.3  62                                          
          35    6105  817.0   49.3   33.1  53                                          
          34    6005  820.0   49.6   35.2  57                                          
          33    6000  820.1                    310/8                                   
          32    5905  823.0   50.4   25.2  37            LGT                           
          31    5806  826.0   51.1   20.5  30                                          
          30    5314  841.0   51.8   30.2  43                                          
          29    5022  850.0   52.9   33.1  47  280/8                                   
          28    4509  866.0   54.7   38.5  54                                          
          27    4414  869.0   55.4   26.6  33                                          
          26    4256  874.0   56.5   16.9  21                                          
          25    4098  879.0   57.2   17.6  21                                          
          24    4000  882.1                    280/5                                   
          23    3848  887.0   57.2   23.0  26            MDT                           
          22    3631  894.0   56.8   17.2  21                                          
          21    3354  903.0   56.1   27.3  33                                          
          20    3110  911.0   56.5   33.1  41                                          
          19    3000  914.6                     60/5                                   
          18    2718  924.0   57.2   33.8  41                                          
          17    2688  925.0   57.2   33.8  41   35/5                                   
          16    2598  928.0   57.2   39.2  51            LGT                           
          15    2538  930.0   57.2   35.6  44                                          
          14    2479  932.0   56.8   38.8  51                                          
          13    2272  939.0   56.8   38.8  51                                          
          12    2243  940.0   56.8   35.2  44                                          
          11    2000  948.3                     35/8                                   
          10    1951  950.0   55.8   39.6  54            MDT                           
           9    1777  956.0   55.8   37.8  51                                          
           8    1690  959.0   55.8   41.4  58                                          
           7    1461  967.0   52.2   43.2  71                                          
           6    1264  974.0   45.7   43.0  90                                          
           5    1153  978.0   44.2   41.4  90                                          
           4    1000  983.5                    120/1                                   
           3     551 1000.0   46.8   41.0  80  360/2                                   
           2     227 1012.0   48.6   39.6  71                                          
           1     200 1013.0   48.9   45.9  89  340/3                                   

I hope you've enjoyed the warm dry weather, it comes to an end late Thursday night. After which we'll be finding snow in the mountains, not 60° temperatures.

Matt Zaffino
KGW Chief Meteorologist
mzaffino@kgw.com