Sunday, November 20, 2016

Storms lining up over the Pacific Ocean

Weather systems are lining up over the Pacific Ocean that have the potential of impacting central Indiana through the Thanksgiving holiday weekend.

As of Sunday night, there are three that I am tracking three on satellite imagery.
  1. This one will bring rain to Indiana as early as Tuesday night and continue through Wednesday.
  2. Computer models are still working the calculations on this one.  Saturday the data suggested the upper-level energy could pass through the Midwest as a clipper – bringing rain and then cold air to Indiana, changing some of the rain over to snow – for Black Friday.  Sunday’s run of computer models suggest an area of low pressure in the Rocky Mountains and it will move east through the central United States.  In this scenario, rain for Black Friday would be the primary issue as temperatures look to stay warm enough to keep everything in liquid form.  However, on the tail end of the rain, there could be wintry mix.
  3. Long range computer data brings this system in to the Midwest late next weekend/early the following week.
Looking waaaay out, computer models are indicating a strong signal for a larger storm to impact the United States November 28 through December 1.

To trace the origin of this storm, you have to look off the northern Siberian coast over the East Siberian Sea.  So far north, it is more difficult to get satellite imagery.

As with most long-range forecasts, we will continue to monitor trends and see if whether or not some of these storms – especially #3 and #4 – happen or not.

TRADITIONAL TURKEY TEMPERATURE

Over the last 40 years, the average high temperature in Indianapolis for Thanksgiving is 47°.  Coincidentally, we are currently forecasting 48° as the high temperature Thursday.

Through Saturday, November 19, this November ranks the 9th warmest in the previous 145 years of records.  As we go through the remainder of the week, temperatures are forecast to be near normal if not slightly below.

Sunday, November 13, 2016

From near record highs to to winter in hours; BIG changes coming this week!

Sunday night we are watching a weather system over the Gulf of Alaska.  This system will have big impacts on the weather in central Indiana.  We'll go from mild, and even near record breaking warmth, to December-like temperatures in the matter of hours.  All over the upcoming week.

An area of low pressure is spinning and will send pieces of upper-level energy through the United States.
Satellite imagery Sunday night. (click image to see larger version)
The low will send pieces of upper-level energy to the lower 48.  The below animation is a computer model projection of the upper-levels of the atmosphere Tuesday through Friday afternoon.  The areas of yellow and red indicate enhanced areas of spin/energy.

Computer model projection of upper-level energy Tuesday through Friday. (click image to see larger version)
A "dip" in the white lines indicate a trough of low pressure moving onshore by Wednesday.  An area of low pressure will eventually develop in the lower, mid and upper-levels of the atmosphere.  At the end of the animation, an upper-level low is over Minnesota.

A cold front will develop and extend from the surface low, moving through the Midwest Thursday and Friday.  A line of showers and thunderstorms may develop and move through Indiana Friday PM.

Ahead of the front, winds will increase out of the south and southwest.  Early indications point to temperatures climbing in to the lower 70°s in central Indiana prior to rain developing.  This would allow temperatures to approach record levels.  The record high temperature for Friday, November 18 is 73° set in 1941.
Computer model projection of temperatures Friday through Sunday. (click image to see larger version)
After the front passes sometime Friday/early Saturday, temperatures will start to fall.  At this early view, high temperatures Saturday will occur early Saturday morning.

From the above animation, you can see cooler air filtering in throughout the day Saturday and Sunday.  It is still early, but it appears temperatures may struggle to get out of the 30°s Sunday afternoon.

There are a lot of details to be ironed out over the coming days.  Will there be rain Saturday?  Could upper-levels be cold enough to support a few snow showers (over northern Indiana)?  If the wind moves from a direction that could produce lake effect snow showers?

One of the BIG details to work out is whether or not the cold air will move south as aggressively as computer models suggest.  As has been the case over the previous two months, computer models hint at shots of cold coming to Indiana only to back off on the strength of the cold air.  Stay Tuned!

(click image to see larger version)


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