Tuesday, June 23, 2020

Saharan dust getting closer to the United States

By now you have probably heard talk about a cloud of dust moving across the Atlantic Ocean that originated from the Saharan Desert in Africa.  The large area of dust is just about to reach the Gulf of Mexico.

(Click image to see larger version)
This is a visible satellite loop over the last 6-hours this morning, ending at 10:50am EDT.  If you look towards the Caribbean you can see the brown colored cloud.  That's the dust!  Look at how far it stretches from nearly the Gulf of Mexico all the way off the screen.  Thousands and thousands of miles.

The dust will help inhibit tropical storm development over the Gulf of Mexico.

NASA computer models project some of the dust could make it to the Midwest as we get towards the end of the week and in to the weekend.  That could make for some very pretty sunrises and sunsets.

For more on the dust layer and tracking it by satellite, check out this page from the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin.

Thursday, June 18, 2020

Parts of Indiana register in Drought Monitor

The latest Drought Monitor classifies 70.5% of Indiana as D0 (Abnormally Dry).
(Click image to see a larger version.)
A lack of rain since June 5 is starting to show when looking at lawns around central Indiana.  What was once green grass is now turning brown.  Look under the grass and you can see soil drying out.

This ties for the driest June 5 through June 18 since 1871 in Indianapolis - tying 2012 - with only a trace of rain recorded.

Amazingly, Indianapolis has lost 31% of its annual precipitation surplus in 14 days.  Indy was well ahead of normal as of June 4.  The city was 5.70" above normal.  Today, June 18, the surplus has dropped to 3.89".

A 2-computer model average suggests 1.19" of rain falling through the next seven days.  That equates to 117% the normal for the period.

A couple things to keep in mind:
  1. We are currently losing approximately 0.25" of water from the ground daily from evaporation.  So to keep "even", we need 1" of rain every 4 days.
  2. "Dry breads dry."  When dry conditions begin to set in, it is hard to break.  Often times in this situation computer models will start putting in precipitation 5-7 days out, but as we get closer to those days the models back off on the precipitation.  That is the case with with the above numbers.  The computer models start to introduce rainfall starting Tuesday, 5 days out.
What does this all mean?  If you want to have green grass, or revive your brown, it is time to start watering.  I wouldn't count on Mother Nature to do it for you anytime soon.

Tuesday, June 16, 2020

Lack of rainfall in the Midwest

Taking a closer look at regional precipitation data.  It is easy to see the have's and have not's, as well as the path Cristobal took through Arkansas, Missouri, Iowa, and Wisconsin.

The map shows the percentage of the normal accumulated precipitation from June 5-15.  Parts of Indiana and Illinois are running 5%-10% the normal rainfall according to data from Midwestern Regional Climate Center.  Some locations are even 0%.  Example: Indianapolis has only had a trace of precipitation for the period.

Are you noticing things turning brown in your neck of the woods?

Driest on record and not much relief in sight

If you look around central Indiana you'll notice lawns starting to turn brown.  That is because we have fallen in to a dry stretch as suggested last week.

Indianapolis has only measured a trace of precipitation since June 5.  This makes this the driest June 5 through June 16 since 2012.  This also ties for the record driest June 5-16 on record.  Records in Indianapolis started in 1871.

This has also putting a hit on the annual precipitation surplus.  Last week we were nearing 5" above normal.  Through the end of today - we are not expecting any precipitation today - the surplus has dropped to 4.17"

Those looking for help from Mother Nature won't find any.  Long range computer models suggest 0.49" of rain in Indianapolis over the next seven days.  That is only 49% the normal rainfall.  Combine that with the area losing about 0.25" of moisture from the ground due to evaporation, expect lawns to quickly turn brown.

If you haven't already, it is time to pull out sprinklers.

Saturday, June 13, 2020

Refreshing air set to arrive later today

Humidity will begin to quickly drop once a backdoor cold front slides through central Indiana.

Dew point temperatures were in the middle 50°s Saturday morning.  They are forecast to drop in to the 40°s by late afternoon and evening.

Interesting to note that the HRRR (computer model) takes the dew point down to 31° in Indianapolis tonight. That would shatter the record low dew point for the date since 1942; 36° in 2012.

The record low dew point for the month of June is 24°. Two dates dropped that low. June 2, 1994 and June 22, 1974.

Thursday, June 11, 2020

This year's precipitation surplus likely to fall this week

Indianapolis is running a 4.84" precipitation surplus this year (through the end of today).

I'm not seeing much in the way of rain coming to central Indiana over the next week.  In fact, if you enjoy sunshine and low humidity you are going to like the weather through the weekend and next week.

A 2-computer model average for the next 7 days is only 0.005" in Indianapolis.  That is 0.96" below normal for the time period.

It is looking like a dry stretch is upon us and the next week could put a dent in the surplus.

What are conditions like where you live?

Wednesday, June 10, 2020

Severe thunderstorms possible Wednesday afternoon

It is a warm and humid morning around central Indiana.  The temperature only dropped to 79° overnight and dew point temperatures (measure of moisture in the atmosphere) remain in the 70°s.

As temperatures increase today instability in the atmosphere will increase, especially at the surface, in eastern Indiana and Ohio.

This is computer model projection of instability at 3pm EDT.

A cold front will begin to sweep through the Hoosier state during the early afternoon.  Behind the front, much drier air will begin arriving.  However, the front will provide lift at the surface, which in turn will aid in thunderstorm development.

A few thunderstorms have already developed in southwest Indiana.  Storms will continue to "pop" over the next couple hours in central Indiana. The storms will eventually evolve in to a line of thunderstorms while moving very quickly to the north/northeast towards the Indiana/Ohio state line.

Computer models suggest the line of thunderstorms reach the Indiana/Ohio state line between around 4pm EDT.

I think the highest threat for severe weather resides in Ohio and southeast Michigan. However, strong to severe thunderstorm are possible in the eastern third of Indiana.

The main threat from thunderstorms, especially once they develop in to a line, is damaging wind.  A few storms may be possible of producing hail and a few tornadoes cannot be ruled out, especially in northeast Indiana, Ohio, and southeast Michigan.

Tuesday, June 2, 2020

Increasing humidity taking heat index to highest levels of 2020

Say goodbye to low humidity. Southerly to southwesterly winds will help draw up low level moisture in the Hoosier state over the next 36 hours.

Dew point temperatures will climb through the 50°s today. It turns "muggly" Wednesday as dew points climb to around 70° - creating a heat index (the feel like temperature) in to the 90°s for the first time this year.