Spring has been a wild ride…of course… that is typical for St. Louis…at times cold, at times hot…very hot…hitting 88 for a day in April…temperatures could not make up their mind.. As expected, April was a rock and roll thunderstorm month…the main features… large and damaging hail and a rather large number of small (EF2 or less) tornadoes…some of the largest hail we have seen in years and a large number of tornadoes…and of course the big EF3 on the 16th of the month…and yes it has been wet.
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The keys to the Summer season...a neutral ocean temperature pattern in the Pacific… La Nina continues to fade…though it is a slow process and still may play a very small part in Summer weather patterns…one thing is for sure El Nino is not a factor for the Summer and into this Fall…but may be a watcher going through the Winter season.
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Most think the Summer Forecast is easy and you are right compared to the other seasons…but not so fast my friend…this Summer looks interesting…and not a slam dunk…that is because there will be part of the nation…in fact a large part, that will have a beast of Summer…others will not…that is tough contrast.
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So this Summer season...ocean temps are all showing their hands...one feature I'm also interested in...is warmer than average ocean temps along the East Coast and the Gulf of Mexico...a factor especially in the hurricane forecast...Also the warmer Pacific temperatures will be a major factor for the Pacific season. I will cover that at the end of this forecast.
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Summer officially begins…June 20th at 9:42 PM. and in turn our days will start to slowly get shorter…very slowly.
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There are about 20 factors that I look at and study when putting these long range forecasts together… And in my book they all have some heavy weight in the final forecast...and this is just not a quick look...this is a process that goes on every day(yes even in retirement)...I don't miss the T.V. side at all...but weather is my life… I love it..
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On to the factors that are in play… Here's a short list...can't give all my trade secrets away.
The analogs...looking back at past weather and then moving forward to compare what's going on in our atmosphere now… The analogs may be the most important thing in my long range forecast…focusing on 2001, 2006, 2012 and 2018
.The solar cycle… we are now in a strong solar cycle…there were signs is fading getting out of the strong stage of the cycle but that downward trend is very, very slow…with a major uptick in solar activity over the last few months…but the maximum sunspot activity should start to fade on the way to the solar min part of the sun's cycle.
World wide volcanoes… Not just the activity but the locations...critical in a long range forecast...action has slowed slightly…only slightly.
The ocean patterns...just not the Pacific but all around the world.
Over the last 2 decades there appears to be more and more of a correlation between the solar cycle and an El Nino or La Nina. What does all this mean for us…it means we sit back and watch the development… never lump these things into a generic pattern…there are no two solar cycles and no two El Nino or La Nina that are exactly the same… I never try to lump possible weather into one pile…just can't do that…you should not do that either
There are a number of other features that I look at when it comes to the atmosphere and the oceans...without getting into too much detail...here are some of the items...the most important first...then, in my mind the least important for this Summer season.
The most important:
The MJO... While the MJO is a lesser-known phenomenon, it can have dramatic impacts in the mid-latitudes. Several times a year the MJO is a strong contributor to various extreme events in the United States.
The eastern pacific oscillation (EPO)
The Arctic oscillation (AO)
The shift to all La Nina.
A warm (PDO) pacific decadal oscillation…maybe more of a feature for Winter than Summer…but it is in place.
A positive (AMO) Atlantic multidecadal oscillation.
The jet stream settles into its typical quiet Summer flow...along the U.S. Canadian border.
These are many of the factors that come into play and must be looked at all the time for these seasonal forecasts… So let's get to the details… The Summer season in STL.
JUNE:
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June Facts:
June 1st…sunrise: 5:38…sunset: 8:20
June 30th...sunrise: 5:40…sunset: 8:29
Average high and low: 85.9/67.2…Records: 108(2012)/43(1969)
Average rainfall: 4.49"
Average snowfall: 0.0"
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June Dates:
The Full Moon…June 11–the strawberry moon
Father's Day…June 15
Summer Begins…June 20
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The major factors:
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*** Temperatures will be bouncing around once again…much like the Spring season…Summer gets stronger but does not lock in.
*** We will be on the edge of a hot and dry pattern over the southwest and Texas…this area will be important to watch as we go through the Summer season.
*** June will see more wild swings from pleasant to just plain hot…it's the building heat from the southwest that will bring our strong heat and the northwest flow will try to keep things in check…the Yo-Yo weather is alive and well…no clear pattern.
*** Temperatures…we will have some very hot runs of weather but that will get slapped back by runs of pleasant temperatures…so when we add up the numbers…temperatures will average out near to slightly above average.
*** The spells of heat will be a warning shot…Make sure the A.C. units are in tip top shape.
*** June is also a month when thunderstorms typically really rock and roll...typically is the key word...in my book it is the wettest month of the year...mainly due to thunderstorms
*** June storms will be active...but nothing crazy active…even with temperature flips…let's think 3 to 4 strong to severe weather events.
*** All-day rains never happen in June.
*** I think rainfall for the month will be near average…but since Spring was so wet…drought is not coming into the picture this June.
*** Flooding in June will stay in check...however when the thunderstorms roll in…each will create a flash flooding set up…small streams and creeks… up and down very quickly…we have had some great examples of this during the Spring.
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Things to look for in June:
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***watch for birds carrying food to their young.
***check evergreens for bagworms
***the cattail blooms are covered with pollen
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JULY:
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July Facts:
July 1st…sunrise: 5:40…sunset: 8:29
July 31st...sunrise: 6:02…sunset: 8:13
Average high and low: 89.6/71.1…Records: 115(1954)/51(19601972)
Average rainfall: 3.93"
Average snowfall: 0.0"
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July Dates:
The Full Moon…July 10–the Buck moon
Independence Day…July 4
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The major factors:
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*** Typically a hot and humid month...we all know that...hard core Summer in STL...and this July will live up to the billing ... .Signs this could be a classic July beast.
*** It will be a battle between intense surges from the southwest…a hot…at times very hot and bone dry flow and the Summer break from the northwest flow.
*** The key…the southwest flow…this allows our temperatures to sky rocket…and even though July records are intense…this bone dry flow could bring a high record or two.
*** The northwest flow will knock back the heat…but it is a Summer northwest flow…and these surges from the northwest will be limited…a break from time to time.
*** The hot and dry times will have a great effect on the overall temperatures for the month…and I don't think the northwest flow will do a big job in neutralizing that heat…so temperatures will be above average for this July…in fact thinking temps may be way, way above average
*** This should be the hottest month of Summer
*** With the bone dry southwest flow…humidity levels will not be extreme…not our typical Summer wet washcloth feel. And that is the key to my rainfall outlook.
*** With the swings in temperature you might think the month would be really active…not going down that road because there will be limited moisture coming up from the Gulf of Mexico.
*** Yes, there will be some thunderstorms…frequency will be near average…but that is rather low.
*** In turn…thinking that July rainfall and storms will be near average. The drought word is in play even after the wet Spring…the main reason…the dry southwest flow will quickly dry out the soil…and stress plants…farmers and gardeners be alert…but not thinking extreme
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Things to look for in July:
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***the song bird songs have now subsided...the birds are busy raising their young
***long-tailed weasels breed through August
***watch for hummingbirds bringing their young to feeders.
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AUGUST:
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August Facts:
August 1st…sunrise: 6:33…sunset: 7:54
August 31st...sunrise: 6:48…sunset: 7:23
Average high and low: 88.3/69.3…Records: 110(1934)/47(1986)
Average rainfall: 3.50"
Average snowfall: 0.0"
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August Dates::
The Full Moon…August 9–the sturgeon moon
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The major factors:
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*** There will be plenty of hot weather for this month of August…not as intense as July but pretty intense.
*** The hot and bone dry southwest flow will be the main feature…a few days of the northwest flow…but the southwest flow is the winner.
*** The dry heat will allow nightime temperatures to relax…not like the heat and humidity that keeps nighttime temps up. So that is a good thing.
*** Records are a real tough thing to hit in the Summertime...because the records are very intense...but this hot and dry southwest flow could snap 2 maybe 3 record high temps…that's a day to day forecast.
*** Temperatures when we add up all the numbers will be above average.
*** Rainfall...August is typically a very dry month...and the dry idea will stay with us…the same reason…the hot and dry southwest flow.
*** The storm track remains active…but should stay well to our north…and the northwest flow will be weak at best…so rain and thunderstorms will be limited.
*** So drought is a big concern…so we turn attention to the hurricane season(see that forecast below). Sometimes a Gulf storm could be a drought buster…and I'm thinking this August we could get one of those systems that will really help with rainfall totals…that would be toward the end of the month of August.
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Things to look for in August:
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***look for large flocks of purple martins gathering for fall migration…also hummingbirds start to head south too.
***late summer molt produces drab colors in robins and other birds...they are not sick
***wild cherries and wild grapes begin to ripen
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TROPICAL-HURRICANE IDEAS:
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In the Summer forecast, I also like to look at the Hurricane season in the Atlantic and Gulf of Mexico…the key this season…at least one of the keys will be a weak La Nina to neutral ocean pattern in the Pacific.
So thinking this will be a season with above average storms…but nowhere near the heavy duty season of last year.
Let's review…
El Nino conditions typically knock down the number of storms. El Nino creates more shear…tropical storms and hurricanes don't like that…no El Nino this season.
La Nina creates more hurricanes due to weaker vertical wind shear and trade winds and less atmospheric stability. In the Pacific…fewer hurricanes due to stronger vertical wind shear.
Other things: Solar cycles and volcanism play a role in the activity level of hurricanes as they influence the atmospheric and oceanic temperature profiles…and as we all know, the sun is cooking right now.
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So thinking this hurricane season will rock but not as rock and roll as last year…all areas in the Atlantic Basin will be in play with the peak area being the Caribbean, Florida and over the entire Gulf of Mexico. Very concerned about the state of Florida.
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Enjoy the Summer season...we all know Summer will fly by...before we know it summer vacations are over, the pools close and it is back to school...STL has a lot to offer...get out there and enjoy...but be safe and smart.
My Fall forecast will be out in late August…
Dave Murray
