Tuesday, July 19, 2016

Break in the Heat In Sight?

I want to preface this by saying this is a preliminary look at some of the data.  I'm off work today and have not been able to dig deeper into this, but will later today or Wednesday.  Because of that, this will be a brief post.  The European model indicates the big ridge of high pressure sitting on top of the middle section of the country will retrograde to the west allowing a trough to develop.  A northwesterly flow aloft would drive a front towards Arkansas and make the atmosphere a bit more conducive to thunderstorm chances. 

While the heat and humidity will be bad over the next several days, this is extremely typical for mid to late July in our part of the world.  We have also seen and experienced much worse.  It's also very important to remember, it's still dangerous and deadly.  From 2000 to 2015, heat killed more than lightning, floods, and tornadoes across the country.


The European model today shows the ridge right on top of us with the jet stream well to the north.  This cuts off our rain chances and we cook!

In 7-10 days, the high moves west allowing a trough to develop.  This would bring relief.

Remember, heat kills.  Please take breaks, stay hydrated, and check on those who are sensitive to this heat.


Friday, July 15, 2016

Possible Dent In That 100 Degree Forecast

In the post below, I talked about one of the variables in making a forecast for the 1st 100 degree temperatures of the summer, recent rainfall.

The suns energy will go into evaporation before it can efficiently be used to heat the surface.  Once the soil moisture is basically gone, we can bake with actual air temperatures of 100 degrees or higher.

As I also mentioned, this should NOT be our focus when forecasting next week.  The "heat index" is the real story and that should exceed 100 degrees and possibly reach 110 degrees.  The heat advisory criteria is 105 degrees for at least 1 hour.  I have a strong feeling heat advisories will be issued.

This is a particularly dangerous time of the year, especially for young guys.  Football practice will be starting soon and heat exhaustion and heat stroke are real threats.  PLEASE AVOID THE HEAT OF THE DAY AND STAY VERY HYDRATED!

By the way, the storm complex Thursday produced a wind gust to 68 mph at the Little Rock airport which is the strongest in July weather history.  Also, that's the 5th strongest of all-time for that location.  Very amazing stuff.

48 hour rainfall ending Friday morning at 7:40.  Notice the heaviest of the rainfall has been over northern and western Arkansas with lesser amounts south and east.

Courtesy of Weatherbell.com.  21 day rainfall with the heaviest amounts over the north and west with lesser amounts east and southwest.

Courtesy of EuroWx.com.  Forecast highs from the Euro on Monday the 18th.  Notice highs in the mid and upper 90s across areas that have seen the least amount of rainfall as this new ridge of high pressure builds into the central United States.  I have a feeling these actual air temperatures might be overdone a bit.  We'll see.

Euro forecast highs Tuesday should the coolest across the north with plenty of heat across the south.

The same carries into Wednesday with near 100 degree temperatures across the southwest.  That's one of the areas which has received the least amount of rainfall.

Thursday highs from the Euro.

Friday highs show near 100 degrees east (where least amount of soil moisture exists) and far southwest.   Remember, these are just computer model forecasts.

Saturday the 23rd has highs near 100 across the southeast half of the state with cooler readings north.


IN SUMMARY... A LARGE RIDGE OF HIGH PRESSURE WILL BUILD INTO THE CENTRAL UNITED STATES NEXT WEEK.  IT'S NOT A GOOD IDEA TO FOCUS ON WHETHER OR NOT WE HIT 100 DEGREES BECAUSE THE HEAT INDEX WILL TOP 105-110.  HEAT ADVISORIES WILL LIKELY BE ISSUED.

THE FIRST ACTUAL 100 DEGREE TEMPERATURES COULD BE SEEN, ESPECIALLY LATE NEXT WEEK IF WE DON'T RECEIVE MORE RAINFALL.  BY THAT TIME, THE GROUND COULD DRY OUT ENOUGH FOR THAT TO HAPPEN ESPECIALLY OVER AREAS WHERE THE LEAST HAS FALLEN OVER THE PAST FEW WEEKS.  NEVERTHELESS, STAY SAFE AND HYDRATED!

Wednesday, July 13, 2016

Summer To Sizzle ArkanSauna Style

Climatologically, we are going into the hottest time of the year and we can see it clearly with many of the long range models.  The only question is, how hot?

To answer that, we need to know where the ridge of high pressure will set up, the potential for any short term rainfall, and who has recently received significant amounts of rainfall over the past few weeks.  With all that said, it is my belief at this time, the southeastern half of the state will begin to sizzle next week with high temperatures very close to 100 degrees, BUT that's NOT what our focus should be!!!!  The combination of heat and humidity will make the heat index soar into the 100-110 degree range and heat advisories may be needed.

Most of the following maps are from Eurowx.com and Weatherbell.com

Total 5 day rainfall amounts will be heaviest across northern Arkansas closer to a frontal boundary.  The best chance for storms will arrive Thursday into Friday and some could be strong and maybe even severe across the north.  During the summertime, rainfall is from convection (thunderstorms) which means some receive much more than others depending on where these storms develop and track.  Most of the activity will be centered across the north, but some could go a bit further south.
Total 14 day rainfall amounts gives us guidance into the future.   The ground has plenty of water in it across northwest Arkansas with lesser amounts across the southeast half.  The suns energy goes into evaporation rather than completely heating the surface.  Once the ground dries out, actual air temperatures soar!  However, the heat index will go above 100 degrees and that's what we really need to pay attention to.  This map is courtesy of weatherbell.com  
In the upper levels, a ridge of high pressure sets up over the central United States next week.  This will be a pressure cooker for many with highs near 100 and heat index values around 100-110 degrees.

ALL OF THE FOLLOWING MAPS ARE FROM EUROWX.COM.
Monday high temperatures according to the Euro.  Notice the heat really builds (mid 90s) across the southeastern half of the state.

The heat expands a bit on Wednesday the 20th with highs near 100 across much of Arkansas except the NW.

By Thursday, the 21st, the heat continues in the same areas.  Northwest Arkansas is cooler due to the rainfall over the past few weeks AND the higher elevations.

By Friday, the heat continues with highs near 100 for much of the state
This is valid on Monday the 18th.  Ignore the time stamp in the upper left.  That's UTC or Zulu time.  Any area in purple is the heat index above 100 degrees.  The next shade of purple is 105.  Once again, notice the core of the high heat will be over much of Arkansas except the higher elevations of northwest and west central AR.

Tuesday, heat index values soar to 100 with 105 or greater northeast.

Wednesday the 20th, it's the same song and dance.
 

By Thursday, it's getting very old.
And by Friday, it's more of the same.
IN SUMMARY, IT'S GOING TO GET HOT AND HUMID AGAIN NEXT WEEK WITH HEAT ADVISORIES POSSIBLE.  THIS IS VERY TYPICAL THIS TIME OF YEAR AS WE ENTER THE CLIMOTOLOGICALLY HOTTEST PERIOD.  IN OTHER WORDS, WE HAVE SEEN WORSE!  AS FAR AS THE FOLLOWING WEEK AND ENDING JULY, THE HEAT RULES AND TEMPERATURES SHOULD STAY ABOVE AVERAGE.  SO WHAT'S AVERAGE?  HIGHS IN THE MID 90S AND LOWS IN THE MID 70S.  

TIME TO DRINK WATER, FIND SOME SHADE, AND TAKE A DIP IN THE POOL.  STAY SAFE!!!!!!