Clear skies, high heat expected for Sunday; storms move in Monday

WASHINGTON - We hit 87 degrees on Saturday in D.C. with comfortable humidity and clear skies and Sunday will be even warmer as high pressure shifts east. 

Winds flow clockwise around high pressure, meaning winds turn southerly on a high's back side. That will ramp temperatures up into the 90º to 93º range for most folks. Remember the water if you're heading out and about to parades or festivities and the sunscreen too.

A few clouds may enter from the west late in the day ahead of a storm system approaching from the Ohio Valley. The muggy conditions make a return overnight too, with a more humid air mass briefly building in on Monday morning. Highs Monday only reach about 80 degrees in most spots, with a cold front knocking on our doorstep. That cold front will bring showers and thunderstorms.

Jet stream winds overhead could foster a change of wind speed and/or direction with height, known as wind shear, that could encourage severe weather. The wild card, at this point, remains the timing of the cold front.

If the cold front slips through around lunchtime, severe weather odds would be relegated to the Delmarva Peninsula, where the frontal passage would coincide with peak afternoon heating. If the cold front is delayed, it would cross Interstate 95 when the atmosphere was fully juiced up from afternoon sunshine. 

Where storms do occur, especially east of town near the Chesapeake Bay, a couple could become strong or severe. Wind and perhaps some hail are the main concerns, though an isolated spin-up can't entirely be ruled out. We'll refine that forecast going forward.

Otherwise, the flow turns west-northwesterly behind the front on Tuesday, ushering in a dry and comfortable air mass. Highs remain in the 80s for the remainder of the week.