Monday is what we call a "transition day" in weather speak, also known as an upside-down day. This generally refers to a day marked by strong cold air advection, where you hit the high temperature in the morning and then temps progressively plummet. We were in the mid-50s early this morning, and by midnight, we will likely be in the mid-30s. 

This is notable because if you simply check a phone app and see that today's high is 54, it doesn't alert you to the fact that, well, that temperature has already happened. By late this afternoon, when we generally would hit a daytime high, we'll be dropping into the 40s, and with the winds picking up, it will feel like the 30s.

A NEXT Weather alert is in effect because of the cold conditions on Tuesday. Here's what to expect around the region: 

• Philadelphia, South Jersey and Delaware: Morning temperatures around 27-32 degrees, feels like 18-23 degrees; afternoon temps around 40-45 degrees, feels like 32-36 degrees
• Lehigh Valley: Morning temperatures around 24-29 degrees, feels like 15 to 20 degrees; afternoon temperatures around 37-42 degrees, feels like 27-35 degrees
• Jersey Shore: Morning temperatures around 30-35 degrees, feels like 20-25 degrees; afternoon temperatures around 40-45 degrees; feels like 33-37 degrees

That colder air deepens Monday night into Tuesday, bringing lows below freezing across nearly all areas except the immediate coast. 

The only good news is that we get a quick rebound back to normal with highs returning to the mid and upper 50s with dry weather expected through the end of the week and into the weekend.

Here's your 7-day forecast:

Monday: Turning colder. High 49.

Tuesday/Veterans Day: The big chill; NEXT Weather alert for cold. High 46, Low 31.

Wednesday: Much milder. High 56, Low 37.

Thursday: Mostly sunny. High 56, Low 43.

Friday: Partly cloudy. High 59, Low 37.  

Saturday: Partly cloudy. High 52, Low 36.

Sunday: Partly cloudy. High 63, Low 40.

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