Ceaseless Wind

Computer Model Temperature Projections

Another round of excessive heat is forecast to develop over the Ozarks beginning on Sunday and lasting through at least the first few days of next week.

You can watch my twice daily briefings on the weather patterns which will affect the Ozarks on this web site.  Follow the “Weather Info” then “Wx Review” menu items above.

A ridge of high pressure in the upper atmosphere is responsible for most heat waves.  This develops rather naturally over the central U.S. during the summer months as the land mass heats quickly in the strong summer sun.  This feature promotes sinking air which not only restricts the hot, humid and unstable air from rising, in actually helps to build the heat as sinking air compresses and heats up.

A few things can disrupt heat waves. One, if a small disturbance(s) can find its way into the ridge, then thunderstorms can pop up which can lessen the effects of the heat for some.  Also, if the dew points are low for the season the heat index value won’t be as high, thereby lessening the effects of prolonged heat.

Case in point: On Monday, we had a high of 100 and the dew points were very high for the season, running in the middle and upper seventies.  This was a pretty dangerous condition for the Ozarks.  The Heat Index (HI)  was exceeding 110 degrees on this day.  On Tuesday, the dew points dropped into the sixties over much of the area so with about the same actual temperatures, the HI’s wereonly  between 100 and 105.  On Wednesday we split the difference a bit, settling somewhere in the middle.

This next heat wave may be mitigated a bit by afternoon storms on any day next week.  Still, afternoon temperature have the potential to rise into the upper nineties on any of the days.

Surface Temperatures/Radar at 1:15 pm

Thanks to very persistent clouds in the wake of morning rain and storms, our temperatures have remained quite cool this afternoon.

Readings are only in the seventies over much of the Ozarks.  Meanwhile, areas south of the rain and cooler front are in the one-hundred’s again.  Also, where the sun has come out in upstate Missouri, temperatures are recovering to near ninety. (which was my forecast for today, it won’t work out form much of the area but in this case I’m happy!)

Notice that in Iowa, the temperature do cool and dew points drop.  This are is behind a second cool front dropping southward.  The upshot of all of this is that we will be more comfortable over the next few days!

500 mb Flow 7am Thursday

The pattern of weather we are in features a dome of hot air which has advanced over the Ozarks and much of the central U.S. for the first part of this week. 

An Excessive Heat Warning is in effect through Wednesday early evening through all of the Missouri portion of our viewing area as is in effect also for Thursday for extreme southern Missouri.

This pattern will be broken down by a wrinkle in the jet stream flow diving southeast out of Canada through the Great Lake states by later in the week.  Interestingly, this feature will be responsible for steering tropical storm “Colin” eastward toward open ocean (or at least holding the system over the western Atlantic for a while).

This jet stream change will allow a front to ease into the Ozarks Thursday afternoon.  This will have the effect of bringing temperatures down closer to normal values of around ninety during the afternoon through about half of the Ozarks Thursday and all of the area on Friday.

Computer Projections for Temperature

But the heat will build back ino the central and eastern U.S. beginning on Saturday.  Widespread one hundred degree values will likely be seen on Monday and Tuesday from Missouri and Arkansas eastward to the Atlantic coast.

Heat Advisories and Warnings

We officially hit 100 yesterday!  This is the first one hundred since August 16th of 2007 which was the end of a stretch of five 100 plus days in that month.  Our low this morning in Springfield only dropped to 76 degrees!  Many areas only fell into the upper seventies overnight!

100 degree heat can be expected again today.  The heat index will rise into the 105-110 range once again during the afternoon.  A heat advisory is in affect for all of the area and excessive heat warnings have been hoisted by the National Weather Service for the counties shaded in purple on the map including the Joplin and West Plains areas.

The heat will be broken back down to near normal levels for August by a front which will slip through early on Thursday.  This front will generate some rain and storms as well.

Heat Index at 3 pm

Heat index values have stayed consistently above 105 this afternoon over nearly all of the Ozarks.  This is the hottest airmass of the year so far and all signs are that this level of heat and humidity will continue on Tuesday and Wednesday.

The forecast is for actual temperatures to be in the upper nineties to near one hundred for the next two days.  Please remember to check on those who may not have air conditioning, the elderly or the very young and watch your exertion level, you’re limits are different in this heat than a normal summer day!

Heat advisories continue through Thursday.  A cool front will break up this heat beginning on Thursday.

Visible Satellite

Projection for TD#4

Tropical depression number four was just announced this morning which would be named storm number three for the season if it continues to develop.  “Colin” is the next name on the list!

This area of development is forming close to the InterTropicalConvergenceZone (ITCZ) which is statistically the area which produces more tropical storms as we head into August.  Last year at about this time, I blogged about this although the wind shear of last year’s La Nina pattern prevented many of these systems from holding together as they crossed the Atlantic.

This developing storm does have some issues with both shear and dry air aloft, both tropical storm killers.  Despite this setback, the overall path of this “disturbed” weather area does take it into the western Atlantic by the weekend.  Too early to know whether the U.S. will be affected.  More on this developing storm as the week progresses.