7/16 - 11am - Heat Building Back In

Ridge over Central US on Wednesday

It's been cooler and quiet over the past couple of days in Louisville with temperatures around and just below 90. That's going to change fast though as a hot and dry upper-level ridge begins to build into the eastern half of the nation next week. Today and tomorrow don't look particularly bad with temperatures in the low 90's and a slight chance of some afternoon pop-up thunderstorms

Thursday Eve. temperatures (GFS)

By Monday we'll be talking temperatures in the mid 90's and not a chance of rain in sight. The warming temperatures aloft with this ridge will limit instability for thunderstorm development significantly. Surface features like fronts will also be very hard to come by once this thing moves over us, so there won't be a trigger for storms either. What this means is that while the heat is building in we won't have any relief via the normal summertime afternoon storms that form. The compounding of the heat and dry air over the course of next week could send our temperatures to the 100 degree mark for the first time this season. Humidity-wise next week won't be as bad as it was earlier this week with dew points exceeding 80 degrees, but dew points in the mid 70's, still very humid, are possible especially on Tuesday and Wednesday. Below is some raw data from the GFS MOS output, which is basically a combination of numerical and statistical weather models. This output usually runs a  degree or two on the warm side this time of year, but I've highlighted the warmest temperatures of the week in red and highest dew points in green:

GFSX MOS (MEX)
 KSDF   GFSX MOS GUIDANCE   7/16/2011  0000 UTC                       
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|
 SAT  16| SUN 17| MON 18| TUE 19| WED 20| THU 21| FRI 22|
 X/N  89| 73  93| 75  95| 78  96| 79  98| 78  99| 78  97|
 TMP  85| 75  88| 77  90| 80  91| 81  92| 80  93| 80  91|
 DPT  69| 70  69| 72  70| 75  74| 75  72| 72  71| 71  70| 
 CLD  PC| PC  PC| CL  PC| PC  PC| PC  PC| PC  PC| PC  PC| 
 WND   6|  6   7|  6   9|  9   9|  9   8|  7   8|  7   8|
 P12  24| 13  14|  7   9| 19  40| 27  20| 12  25| 14  19|
 P24    |     19|      9|     40|     40|     25|     34|
 Q12   0|  0   0|  0   0|  0   1|  0   0|  0   0|  0    |
 Q24    |      0|      0|      1|      1|      0|       |
 T12  26|  8  32| 10  24| 37  49| 49  39| 29  28| 21  36|
 T24    | 30    | 40    | 50    | 71    | 49    | 44    |

Looks pretty hot doesn't it? A span of three or more 90 degree plus days is usually considered a heat wave, so I think we'll meet and exceed that definition easily. Next week will be a good time to take it easy and drink lots of fluids when working or playing outside. Here comes the heat!