From the ABC 7 Weather team

Rain and the chance for snow back in the D.C. area one last time?

March 14, 2013 - 02:13 PM
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It's been dry now for the past few days but this will be short-lived, with rain back in the D.C. area for the weekend.

Yes you ready the headline correctly, please don't throw your shoe at me. Who throws a shoe, honestly? After a brief lull in the wet weather, it appears the pattern will change once more, bringing back the chance for precipitation to the D.C. area from Saturday through next Tuesday. If that's not enough to make you mad at me, parts of the region will be cold enough for some snow to mix in. Happy mid-March everyone.

GFS 500mb Voriticity Forecast for Friday Afternoon

Above is a look at the 500mb vorticity plot for Friday early afternoon. I have circled the region of unsettled weather over the Northern Plains. This unsettled weather will travel along those constant lines of height (black lines aka isohyse) and right into the D.C. area through the weekend. Unfortunately, there is another larger area of storminess in the Pacific that will continue to bring this chance for rain to the region through early next week.

5-day Precipitation Outlook from HPC

Take a look at the rainfall potential for the next 5 days. Up to an inch of rain is forecast for the D.C. area with the potential for isolated higher amounts. The best chances for rain will be here Saturday morning, Monday and again Tuesday morning. A cold front will finally move into the region Tuesday afternoon bringing dry air back to the region.

You're getting off subject Alex, you said snow in your headline. Yes I did. The chance for snow exists through the area Saturday and again Monday morning. With that being said, I highly doubt (with 95% confidence) anyone will see snow in the D.C. Metro. The chance will exist northwest of the city at higher elevations, where enough cold air is expected to slip in to change precipitation to snow Saturday morning.

Sounding for Saturday morning in Hagerstown, MD

Above is a look at the Bufkit GFS forecast sounding for Saturday morning, showing the chance for snow as colder air filters in when the low passes to the south. Precipitation should actually start as rain on Saturday before sunrise and actually change over to snow, so now accumulations will be expected with wet and warm surface temperatures. Closer to D.C., there shouldn't be nearly enough cold air for a changeover, so rain will be the primary precip-type. Other models such as the latest run of the ECMWF do not even bring the chance for snow, so keep that in mind.

Monday, high pressure will be located over Eastern Canada and the Northeast. This will ensure cool air filtering into the region ahead of the next area of low pressure. As precipitation enters the area Monday morning, precipitation may start as snow along the Blue Ridge and points west. Changes will take place through the remainder of the day, however, with much warmer air filtering in by the afternoon changing all precipitation back to rain. Chances for rain will continue on Tuesday before finally exiting the area.

Now I'm waiting for the boo-birds to come out in the comment section below. Just remember there is a fair amount of uncertainty with this forecast still with an increasing amount later in time (Monday), so changes will occur. Temperatures will be the hardest part of the forecast as the D.C. area lies along the frontal boundary Sunday and a lot will lie on the strength of the high going into Monday morning. We'll continue to do our best to keep you informed, just know it will be wet through at least Tuesday!

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