No Relief Yet

Tuesday, July 19th 2011, 5:03 am
By: News On 6

The forecast continues to be dominated by the strong mid level ridge of high pressure anchored over the central part of the nation.  The forecast issues involve if or when this ridge will give us a break. 

The 12z EURO run is now keeping the center of the high over the state through early next week while the operational GFS continues to suggest the mid level ridge will be a hair to our west by Monday and Tuesday.  Both sets of ensembles continue to move the ridge to the west of the state by early next week, but the smoothing of the ensembles after hours 144 leave little confidence.  Bottom line:  until we see something in the day 4 to 6 day periods suggesting the ridge will actually move to our west or weaken, we can't get too excited or worked up about any major changes in the forecast.  Persistence will be the rule.  This means what happened yesterday will more than likely happen today since the features the caused yesterdays outcome will be nearly the same as today.  

Before we get into early next week, we'll see the ridge sliding slightly eastward or southeast by Thursday and Friday.  This should create a southwest flow on the back side of the ridge and may actually bring slightly drier air to the state.  This means by tomorrow into Thursday and Friday our daytimes highs may be scooting upward a few degrees, possibly near record high territory in some locations, while the overnight and morning lows may also move into the lower or mid 80s in the Tulsa metro with some upper 70s and lower 80s in other settings. 

 The metro areas typically are slower to cool down due to the enhanced concrete and the lack of green vegetation.  This effect, commonly called the Heat Island effect can be very pronounced in periods of extreme weather during morning hours.  During very cold winter periods, outlying areas may be 10 to 14 degrees cooler compared to the Tulsa metro.  During summer months, the Tulsa metro may be anywhere from 5 to 7 degrees warmer compared to the rural areas during the morning hours.  A very rudimental explanation of this effect means the incoming solar radiation is absorbed by the concrete and is slow to radiate back to the atmosphere during the evening and overnight hours.  Some research has suggested metro areas may be able to slightly offset this effect by planting areas of green vegetation where possible, including vacant lots, corners, medians, and even rooftops.  The vast amounts of concrete and the impact on the ambient temperature won't change drastically, but some minor variation in temperature and transpiration could have a positive feedback on the area. 

 Back to the current heat wave.  A tropical system in the Gulf, while being potentially a bad thing for a highly populated coastal region, would be a good thing for a drought stricken state.  Fortunately for some, and unfortunately for others, we have no such system in the works at this time.  A system did form recently but has no role in our weather as the 2nd named storm of the Atlantic basin is now moving northeast away from the western Florida coastline.  Tropical storm Bret will have no major impact on mainland US interests, but some high swells along the east coast may occur today.

Tropical storm Dora, a Pacific basin system, is located 300 miles south of Puerto Angel, Mexico, and is moving west at 16 mph.  This storm may become a hurricane soon, but will have no direct impact on our weather.