Tuesday, July 17, 2018

Brief "cool-downs" expected over the next several days

A couple of frontal passages today and in the coming days have allowed our forecast to have a little bit more variability than a typical summertime pattern. Overall, while temperatures look to stay in the 90s throughout the foreseeable future, we will have periods of both slightly above and slightly below average temperatures, and also reduced humidity, which should really lift our spirits!

GEFS temperature forecast through the beginning of August. *MODEL DATA - SUBJECT TO CHANGE* (WeatherBell)

Even if you look at the next couple weeks, you can see this small roller coaster type feature of some above average temps and some below average temps. It will be nice to have this variability in the coming weeks.


We're still highlighting above average warmth today though as temperatures are expected to reach the mid 90s by this afternoon with dewpoints in the very muggy mid 70s. With temps and dewpoints so high, portions of the Mid-South are currently under a Heat Advisory as heat index values will top off between 105 and 110 this afternoon.

Counties highlighted in orange are under a Heat Advisory until 8 PM this evening. 
The good news is that a "cold" front is expected to pass through the area today. While this won't knock down our temps a whole lot, we will feel some relief in the coming days, particularly a reduction in the dewpoint. 

Current surface analysis shows a surface low pressure system located near the Missouri Bootheel with a frontal boundary draped across Arkansas and northern Tennessee. (NOAA/WPC)
I don't know about you , but I am really looking forward to the somewhat drier airmass!

This front could initiate some shower and thunderstorm activity into this afternoon. Like most summertime thunderstorms, coverage will likely begin to decrease after sunset.  Overnight temps will fall back into the mid 70s.

HRRR model loop shows scattered thunderstorms developing in the afternoon hours and continuing into the early evening.  (WeatherBell)

Wednesday & Thursday

Into tomorrow, we will begin to feel this somewhat cooler and drier weather pattern. An upper-level trough will continue to dig into our area over the next few days. What does this mean for us? Well, it will help to keep our winds out of the north, bringing cooler and drier air into the Mid-South. 

300mb analysis shows a trough digging into the eastern half of the U.S. through the middle and second half of the week. (Pivotal Weather)

Looking at temperatures just above the surface across the U.S., the western half of the U.S. is experiencing some pretty warm temperatures. Luckily for us, our winds will stay out of the north, northeast over the next few days, ushering in the cooler and drier air.

850mb (5000 feet) temperatures and winds show cooler air being brought into the Mid-South, keeping the much warmer temperatures to our west. (Pivotal Weather)

Overall, temps look to hang around near 90 over the next couple days with dewpoints backing off into the upper 60s. These lower dewpoints will keep the extreme mugginess away. However, with the upper levels of the atmosphere exhibiting northwest wind (what we call "northwest flow"), storm complexes moving out of the Plains could affect the Mid-South. This possibility means we'll keep shower and thunderstorm chances in the forecast Wednesday, and a lower chance Thursday.


Good things can only last so long as warmer and muggy air attempts to make a comeback on Friday. 

The predominately northerly winds discussed above will begin to shift to more westerly, allowing all those hot temperatures from the western U.S. to slowly migrate over to our area.

850mb (5000 feet) temperature and winds show westerly winds by Friday afternoon across the Mid-South, allowing warmer temperature to push eastward. (Pivotal Weather)
Highs on Friday will reach back into the mid 90s with dewpoints creeping back into the humid 70s. As for rain chances, we will have to keep an eye on another front that poses to sweep through the Mid-South late Friday into Saturday. Depending the timing of this front, we could see some shower and thunderstorm activity later in the day.

Surface analysis for early Saturday morning shows a closed low pressure located in Michigan with a cold front sweeping across the Ohio River Valley into portions of the Mid-South. (NOAA/WPC)

Weekend and beyond

Our muggy and hot weather pattern will begin to move out following the frontal passage. Temps look to stay in the mid 90s on Saturday before backing off into the low 90s on Sunday.

GFS shows a chance of thunderstorms moving through late Friday into early Saturday, with rain chances clearing through the weekend. (Tropical Tidbits)

Luckily, rain chances will be minimal through the weekend. So if you have any outdoor weekend plans, it looks like you picked a fantastic weekend to have them!

Caroline MacDonald
MWN Meteorologist Intern

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Thursday, July 12, 2018

Extreme heat & high pressure continue to dominate the Mid-South

It's summer. It's hot. We know it's coming every year, but somehow it always feels worse when it does arrive. The big weather maker to highlight for the next week is in fact the heat. Heat index values are expected to climb well over 100 degrees for the rest of the week and even into the beginning of next week. For the past couple of days, several of our counties have been included in a Heat Advisory for these dangerous heat indices. A Heat Advisory is issued when heat index values are expect to rise above 105 degrees. While the current Heat Advisory will expire this evening, given the forecast, it will be back before long!

Late afternoon warning map shows the Heat Advisory in orange. A Special Weather Statement, also highlighting heat potential, is shown in tan and also includes the Heat Advisory counties.

As we head into the weekend, be sure to remember some heat safety tips. I would also suggest finding a pool to cool off in!

Tomorrow and this weekend

Hot, muggy, afternoon showers. With any summertime pattern, like we are in right now, those three phrases are the ones to live by. Expect temps to stay a few degrees above average the next few days with dew points hanging in the 70s. This will provide that sticky feeling we all love during the summertime.

I'm sure many are wondering about our precipitation chances. Well, it looks like our afternoon pop-up showers and thunderstorms will hold on for now. Scattered showers and thunderstorms will likely develop each afternoon with coverage decreasing once the sun sets. This translates to a 20 to 30% chance each day. Whether you have plans to head to Levitt Shell or the Memphis Botanic Gardens for concerts or have other outdoor plans this weekend, things will likely stay muggy, but any afternoon showers should be on the downward slope by evening. 

Saturday and Sunday look to have the same old song and dance on the surface, but not necessarily in the middle and upper atmosphere. While temps will stay in the mid 90s during the daytime and "cool" into the upper 70s at night, the high pressure system that has been dominating our weather pattern will begin to lose strength. 

GFS shows a ridge pattern initially that begins to lose strength into Sunday. By Monday and next week, a mid-level trough begins to take its place. (Pivotal Weather)
With any meteorological phenomena, it usually takes some time for things that start aloft to reach the surface. So while the ridge appears like it will break down aloft, it will take some time for the extreme heat to go away. 

Beginning of next week

While we may not begin to feel the implications of the ridge weakening and the trough taking over, we will notice some increased thunderstorm coverage for the first half of the week. Temps will stay mild, muggy, and in the mid 90s Monday and Tuesday with overnight temps coasting in the upper 70s, proving little nighttime relief.

As for our rain chances, each day will likely have a few more showers and thunderstorms than we have seen in recent times. Typically in this pattern, they fizzle out after sunset, so that is good to keep in mind when making evening plans. 

GFS loop from Saturday evening through Tuesday evening shows scattered showers each day. (TropicalTidbits)

Second half of next week

With the mid-level trough digging into the eastern half of the U.S for the second portion of the week, expect things to finally cool off just a tiny bit compared to the above average temperatures and extreme heat we've been having recently. 

The Climate Prediction Center releases daily graphics highlighting the 6 to 10 day temperature and precipitation outlooks for the U.S. They currently span from next Wednesday through the following Sunday. On average over the period, temps will likely stay right around average here in Memphis with precipitation being a little higher than average for summertime. I don't know about you, but I could use some more showers and a little less heat. Stay cool until then!

The Climate Prediction Center's 6 to 10 day outlook shows a near normal temperature outlook over the Mid-South. (NOAA/CPC)

The Climate Prediction Center's 6 to 10 day outlook shows a slightly above average (33%) precipitation outlook over the Mid-South. (NOAA/CPC)

Caroline MacDonald
MWN Meteorologist Intern

Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder