Cracking the 7-Day

Six days away from wedding-palooza and we are getting more details on the forecast for Labor Day. Over the last few days, numerical data has flipped-flopped almost hourly with giving us showers or not. One thing that remained constant was temperature, which looks to be somewhere in the low to mid-70's. Tuesday morning's run gives us a high temperature of 76 degrees.

The general weather pattern for Monday evening (5 P.M.) shows a weak trough off the Oregon/California coast. A general westerly flow is evident here. That would promote average or slightly below average temperatures. Notice the wind barbs are generally flowing in a northwesterly pattern. That tells me some cooler, Canadian air is heading our direction in the upper atmosphere. Winds closer to the surface tell a slightly different story.

Our 850mb chart (5,000 feet) is giving us a northerly wind at 5 P.M. on Monday. This is good news because a northerly wind usually means dry air is moving over us. Air that has spent more time over land is drier and warmer than air coming off the ocean. We would normally avoid seeing morning fog with this type of setup, the same would be true if we had an easterly wind.

Below is MOS (model output statistics) and it is just another numerical forecast.

 KPDX   GFSX MOS GUIDANCE   8/28/2012  0000 UTC                       
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192      
 TUE  28| WED 29| THU 30| FRI 31| SAT 01| SUN 02| MON 03| TUE 04 CLIMO
 X/N  76| 55  72| 54  75| 54  71| 51  72| 52  76| 53  76| 55  78 53 78
 TMP  75| 57  71| 55  73| 55  70| 53  72| 54  75| 54  75| 56  77      
 DPT  49| 50  49| 51  48| 50  47| 47  45| 48  45| 48  47| 50  50      
 CLD  PC| PC  PC| CL  CL| CL  CL| CL  CL| CL  CL| CL  CL| CL  CL      
 WND   7|  7   6|  5   8|  8  10| 10   6|  6   7|  7   8|  7   8      
 P12   9| 17  10|  2   9| 12  11|  7  12|  6   7|  5   9|  8  12 18 17
 P24    |     20|     12|     12|     12|      7|      9|     12    25
 Q12   0|  0   0|  0   0|  0   0|  0   0|  0   0|  0    |             
 Q24    |      0|      0|      0|      0|      0|       |             
 T12   1|  0   6|999   0|  2   1|  1   1|  1   2|  2   4|  2   1      
 T24    |  1    |999    |  2    |  1    |  1    |  4    |  4          

Highlighted is the pertinent information. MOS gives us a temperature (TMP) of 75, which corresponds with what I was thinking as well. CLD stands for Cloud and CL is not "cloudy" but "clear". It's tough to tell what a calculator thinks is "clear" or "partly cloudy" but generally there would be a good amount of sunshine expected. The numerical output is producing a very similar forecast to mine. At least partly cloudy and temperatures in the mid-70's. The days leading up to Labor Day are giving us dry, bright weather, so hopefully the trend holds on one extra day! The forecast has been improving!