Heat Wave for the Coming Week.

The map on the right covers what is normally our wettest time of the year across the state and it is quite obvious that most of the state has received far less than our normal Spring Rains would produce. In fact, according to the OK Climatological Survey, this is the third driest such period on record for the state. Yesterday, I covered the effect of the rain footprint from the recent rains and their impact on temperatures. As you can see from the map on the right, only portions of N OK are anywhere close to normal rainfall over the last 60 days so even those areas that are reasonably wet will be quickly drying out unless we get additional rainfall soon.

That is not likely, in fact our rain chances are pretty much in the slim to none category throughout the coming week. So, the cooling effect of the evapotranspiration will be reduced rather quickly as the combination of evaporation and the removal of moisture by the green vegetation will quickly deplete the available soil moisture. As the soils dry out, the vegetation becomes stressed and then goes dormant which leads to hotter temperatures which leads to more evaporation which leads to…..well you get the idea, it can be a vicious feedback cycle.

Anyway you look at it, we are in for an extended period of much above normal temperatures, or what we call a heat wave. In fact, after topping out in the mid-upper 90s today, it looks very likely that many locations will see their first triple digit temperatures on Sunday. That is several days ahead of our first triple digit day of 2011 in case you were wondering.

Although a weak boundary may provide a brief wind shift Monday into Tuesday, it looks like it will have little effect on temperatures and provide no opportunity for rain. Thus, we are expecting temperatures at or above 100 pretty much all week long.

Our winds will be rather brisk today with southerly winds of 10-20 mph, a more S to SW wind on Sunday at 10-15, and generally very light winds after that. That could also create some air quality issues during the coming week in addition to the light winds not providing much ventilation and therefore little relief from the heat.

Fortunately, dew point temperatures are expected to stay generally in the low-mid 60s for the most part which means minimum relative humidity values will be dropping to near the 30% range during the heat of the day. That, in turn, helps to keep the heat index from being more than a few degrees above the actual air temperature. Hot and humid, sure, but not nearly as bad as when the dew point is at 70 or above which does happen from time to time.

Is there any relief in sight? Perhaps by this coming weekend we will see a change in the pattern, but right now the guidance is very inconsistent so until we see better continuity will go with persistence and keep it hot.

In the meantime, stay tuned and check back for updates.

Dick Faurot