MWN Blog: Upper level pattern favors fall-like temperatures as we head deeper in to May

Today and Wednesday

Thanks to a slow-moving cold front, we had a cloudy start to the day with a few isolated showers this morning. Thankfully as the cold front finally sags south and out of our region, clouds will begin to clear and leave us with partly sunny skies by late afternoon. Highs will warm up into the mid-70s today but behind the cold front, winds will shift to out of the north-northwest up to 15 mph. We will continue to stay dry overnight with lows falling into the low 50s.

Weather Prediction Center's surface analysis from 7:00am this morning showing a sluggish cold front moving through the metro area. (WPC)

[Editor's Note: Allison is about to go all weather-nerdy on you. Know that long-wave and short-wave troughs are basically fronts at the upper levels of the atmosphere. A long-wave trough is like the dominant Auntee and the short-waves are her ne'er-do-well little nephews. The Auntee is best represented on a weather map by a valley in the pressure pattern that encompasses a large region. Misbehaving nephew short-waves run circles around the Auntee and serve to reinforce her general exasperation.]

Cool and windy conditions continue as a long-wave upper level trough fully situates over the eastern United States Wednesday. A quick-moving short-wave trough will move through the Ohio Valley strengthening the long-wave trough, pulling a much cooler air mass into the southeast. Thankfully, the short-wave will not bring any shower activity to the region on Wednesday. Overall, Hump Day looks very pleasant! We will have a mix of sun and clouds throughout the day. Afternoon highs will be well below the nearly 80-degree average high temperature for this time of year with temperatures topping out in the upper 60s!

Tuesday morning NAM3 model pressure values at about 18,000', valid from noon on Tuesday through Thursday evening. This shows a short-wave trough moving through the Ohio Valley on Wednesday that strengthens the long-wave trough over the eastern U.S. as well as a second shortwave trough forming Thursday. (PivotalWeather.com)

Thursday - Friday

By Thursday, a weak high pressure system will build over the region as the upstream ridge in the western United States moves eastward. This will allow for much of Thursday to be dry with mostly sunny skies and afternoon highs reaching into the low 70s. This will be short-lived as another short-wave trough and associated cold front at the surface moves through the southeast Thursday evening into Friday afternoon. Winds will become more southerly Thursday afternoon allowing for clouds to build back quickly throughout the evening. Showers and a few thunderstorms return to the metro area by Thursday night, continuing for much of the night and into Friday morning with lows falling into the mid 50s. Given the lack of unstable air and fairly cool temperatures, severe weather is not expected.

Tuesday morning GFS model precipitation and surface pressure valid for Wednesday at midnight through Friday at 7:00pm. This shows another short-wave trough and associated cold front moving through, bringing showers and much cooler air to the southeast. (PivotalWeather.com)

By Friday afternoon, rain chances will diminish as winds become more northerly and possibly quite gusty. Friday will be on the chilly side, with highs only reaching up into the mid-60s. When it is all said and done, rain totals for this event will likely be between a quarter and three-quarters of an inch.

Tuesday morning GFS model showing the total accumulated rainfall through midnight Friday. (PivotalWeather.com)

Friday night, northerly winds will continue at 10-15 mph pulling in a much cooler air mass to the southeast U.S. This will keep temperatures unseasonably cool with Saturday morning lows falling into the low 40s, threatening the current record low of 44 set nearly a century ago! The average low temperature for this time of year is 59; that's just shy of what Friday's high temperatures will be!

Tuesday morning GFS model surface temperatures valid for midnight Wednesday through Saturday morning. This show the progression of temperatures and the well below average lows for Friday night into Saturday morning. (PivotalWeather.com)

Saturday - Tuesday

A much calmer pattern will be present Saturday through Monday. Saturday will be nearly a perfect day with tons of sunshine and blue sky! Cool temperatures stick around with afternoon highs only warming into the mid-60s and overnight lows falling into the mid-40s once again. Sunday will be a bit warmer with high temperatures reaching back into the low 70s and lows falling near 50. Thankfully sunshine sticks around for Sunday and Monday with a few clouds building back across the region into Monday afternoon. Cool highs continue to start off the work week with highs near 70 (though "cool" is really "ideal" given we're heading into mid May!). Tuesday will bring another isolated chance for a few showers as mostly cloudy skies return to region!

Allison Paige
MWN Meteorologist Intern

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