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Things that make you say “ugh”

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Most weather forecasters like a good challenge. When you live in the Piedmont of North Carolina, challenges abound.

We have the mountains, foothills, and ocean. We have all four seasons — sometimes all in one week, as the joke goes. Our latitude and our geography both play a role in our weather for better or worse.

This week, our challenge is a stationary front. The boundary between cool air and warm air is just draped across the state from northwest to southeast creating a headache for meteorologists who are trying to publish forecasts for the Triangle area — yours truly included.

forecast high temp map

The NAM model’s forecast high temperatures across the country for Thursday, May 10, 2017

I think I said “ugh” at least 10 times this morning while writing the forecast for the Wake Forest Weekly and the Butner-Creedmoor News. While the towns aren’t very far apart, the forecast could be quite different in a case like the one we have this week. I settled on similar expected temperatures for both, but reality could play out differently than the virtual computer models are showing.

The map above shows one model’s forecast high temperatures for Thursday. The northeastern corner of North Carolina could have high temperatures in the 50s, while the southern portion of the state might see a high in the upper 80s. That’s a 30 degree temperature spread over just one state!

Any little waver in that frontal boundary could make a huge change in the forecast. If it moves a little to the north, we could see warmer temperatures. If it moves a little to the south, it could be much cooler.

Disturbances in the atmosphere are riding along the boundary from northwest to southeast bringing rain and the chance for strong to severe storms over the next couple of days as well. The timing of those showers and storms changes a little with each model run, so a forecaster really has to play it safe and just say “chance of showers and storms” for the whole 24-hour period.

QPF Map

Quantitative Precipitation Forecast map for May 10 – May 15, 2017

The amount of precipitation each location receives over the next few days also depends upon the position of the front. The QPF (Quantitative Precipitation Forecast) map shows a pretty wide range from south to north. The southern tip of the state may only receive a quarter of an inch while the northeastern corner  of North Carolina could get nearly two inches.

Happily, the last disturbance and the frontal boundary will finally exit late Saturday as a low pressure system develops off the Atlantic Coast and moves toward New England, leaving us sunshine and a chance to warm up and dry out on Sunday.