ImpactWeather StormWatch Manager Fred Schmude guest-posts today with a parched outlook for those of us who don’t mind a hot summer but don’t care for a brown one, either.
Since February 1st, the Houston area – not to mention a grand swath of the south-central U.S. – has experienced one of the driest periods in recorded history and it looks like any change in the weather pattern will be slow to occur over the next month or two as strong upper-level high pressure remains over the area. The record dry spell is mainly being contributed to by a strong La Niña event (cold Pacific water) during the past winter into the spring. Even though La Niña is quickly dissipating, the residual effects of that weather pattern combined with very dry soil are enhancing the record-setting dry conditions over much of Texas. Dry soil tends to heat up faster due to evaporation (and lower specific heat values) resulting in hotter ground, hotter weather and higher pressure well above the surface. Higher pressure aloft also creates sinking air which limits cloud cover and blocks rain-producing weather systems from moving into the region. Additionally, the sinking air of a high pressure system further exacerbates the situation, as sinking air heats up as it sinks and compresses.
The big question now is when will we see a break in the pattern? New long-range data indicates very little change in the weather pattern over the next week or two. Daytime temperatures in the Houston area will likely average in the upper 90s to low 100s this week into the weekend. There are signs that the upper high may break down a little as we move into the fourth week of June which may provide the focus for a better chance of rain. Confidence this far out is still on the low side, but at least there’s a glimmer of some hope by the end of the month.
In the extended forecast, analog data from the past indicates we are mimicking very closely the years of 1971 and 2008. During those years we saw drier than normal weather in July followed by a wetter than normal August, and this is the preferred direction we are following now based on current trends. As a result, we may see a little more rain in July but for the most part rainfall amounts are forecast to remain below normal. Not until August that we’re forecasting to see an abrupt change in the weather pattern which could result in frequent periods of locally heavy rainfall. Let’s just hope that doesn’t come in the form of a tropical cyclone!
[Note: portions of Mr. Schmude’s forecast also appear today in EricBerger’s SciGuy blog at chron.com, the online version of The Houston Chronicle.]