Cooler Weather Ahead!

The jet stream will change over the next few days to a more "amplified" (more north-south motion over a greater distance) flow over the U.S later this week. This means cool fronts will actually move through our region. One is due late Wednesday and a reinforcement of cooler air moves through Friday.

This means a return to the below normal temperatures we experienced early in the week of July 6th: lows in the lower sixties (or upper fifties?) and highs in the eighties. Don't forget the lower humidity too!

SUNDAY EVENING AND OVERNIGHT UPDATE

Wind are flowing from all kinds of different directions across Missouri and surrounding states which clearly shows that we have a couple boundaries around. There is a weak stationary front from Rolla to Kansas City that is currently causing a few light showers to develop along. There is another boundary across southwest Missouri. Notice the winds are coming from the southwest across Oklahoma and from the northeast from Chanute to West Plains. It is where the air converges that you have a boundary, hence lift. As the low level jet kicks in tonight we'll have to watch for further shower and storm development along those boundaries. The most unstable air is located in and around the southernmost boundary. Severe storms can't be ruled out, though we are no longer under a slight risk for them.

HEAT & PERIODS OF SHOWERS AND STORMS

The northwest flow aloft has been a blessing in ways because it has allowed disturbances to move in which has kept temperatures down. The unsettled pattern is expected to continue through Monday. Where the sun shines the most, temperatures will easily soar into the middle and upper 90s. That kind of heat combined with the humidity in place will make it feel like it's in the lower 100's. We'll remain on the periphery of the heat wave the rest of this weekend! The hottest air is set to move in early in the week before a front moves through on Wednesday and cools us down. Storms that pop up have the potential to become severe, especially tomorrow afternoon across the northeastern half of the Ozarks. Wind gusts up to 60 mph and quarter size hail are the main threats. It appears that the Ozarks will stand a better chance of nocturnal rather than diurnal convection both tonight and tomorrow night due to the low level jet kicking in. The low level jet helps to transport warm and moist air northward and creates an unstable atmosphere at night.

Weekend and Beyond

The heat and humidity have both been buildly slowly this week with the offical high finally cracking ninety today. While it might get a bit hotter Friday, the temperature climvb is expected to be cut off by the development of clouds, showers and storms starting Friday and lasting through Sunday.

The heat which may require advisories will start Monday and last through Wednesday. Expect some middle nineties on these days and heat index values to common;y rise above 100.

El Nino Pattern Established

The start of El Nino, a pattern of ocean temperatures in the central Pacific Ocean which affects global weather patterns, has been observed and is officially forecast to be with us through winter 2009-2010.

During an El Nino cycle, large areas of the central and eastern equatorial Pacific Ocean experience warmer than normal sea surface temperatures. This produces a flip-flop of normally observed weather on both ends of this region with coastal areas of western South America, normally stable and dry, subjected to more rain and storms while places like Indonesia and Australia, normally wet, seeing a much drier pattern of weather.

Read more about this and other weather information at:

Ceaseless Wind

The Heat Will Build Back

The main questions this week are: how hot and whether storms will pop up? The heat will build in slowly this week so that nineties will be common beginning on Thursday. The flow of air aloft is still out of the northwest which is slowing the heat down a bit and may also produce a very isolated shower or storm any day this week.

By Friday, a front drops into northern Missouri, close enough to organize storms perhaps a bit better. Over the weekend, a "backdoor" cool front (from the northeast) will be in Missouri as well. All of this means scattered storms are possible and high temperatures may stay more reasonable through this period.

THIS WEEK

High pressure builds across northwest Missouri on Monday, causing the winds to flow from the northeast. This flow is a dry one and typically results in cooler than normal readings. Temperatures will once again be below normal with highs in the lower to middle 80s. The unseasonably cool conditions won't last beyond Tuesday due to a ridge of high pressure building eastward with time.

Northwest flow sets up aloft, which is the same flow we experienced during the heat wave. If you recall, we saw brief relief from the heat due to disturbances riding up and over the ridge and across the Ozarks. We could see that same situation set up at times this week. The days in which I'm seeing a disturbance tracking close or across the Ozarks is on Wednesday and Saturday. There is not a big signal for rain this week and is only subtle at this point. Timing and location is still a big question mark. The ridge is forecast to also build eastward with time and cause temperatures to heat up once again. We'll be back in the 90s on Wednesday and staying that way through the weekend.