Thursday, December 15, 2011

City Forecast Discussion: Erie, Pennsylvania

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A city that sits in the Northeast right on Lake Erie is the beautiful city of Erie.  A peaceful city with an old-fashion sense to it with beautiful country sides and beautiful neighborhoods.  Too bad the weather cannot be explained the same way.  Erie is as tricky as Miami and Juneau for forecasting since it sits right next to a body of water.  Every factor in the air plays an important role in determining how warm, cool, windy, dry, or wet it will be.  The temperatures for the city is highly dependent on the wind.  An important thing to keep in mind for Erie is that the highest sustained wind for each day is rather uncommon to go below 10 mph.  If the wind blows from the land to Erie it will warm up and cool off as the rest of the land warms and cools.  When the wind does this it has been noticed that Erie will reach its warmest and coolest days.  If the wind blows from Lake Erie then its a different animal.  Erie will have more of a small temperature change with winds blowing from the lake since before winter really kicks in it stays unfrozen.  From experience, there was a day where the high reached 41 and the low was 38 with the wind coming off the water that entire day.  That is only a 3 degree temperature change for an entire day.  Quite crazy.  Clouds were in the area, but the clouds primarily affect the temperature of the city if the wind is coming from the land blowing towards Erie.  Clouds have little affect when the wind is from the lake.

Precipitation amount is just as challenging as the high and low for Erie.  It boils down to how far north or south the low pressure system is, how cold the air is, and the direction it is moving with respect to wind.  Because of Erie's location it typically gets a piece of most systems that near it, but sometimes a low pressure system may not be near it and they will still receive rain or snow.  How is that?  An interesting phenomenan called lake effect.  It can be in the form of rain or snow, but most of the time it will be in the form of snow.  Snow is a funny and tricky form of precip to forecast for.  Not really in its form, but how much will fall and converting it to liquid.  Typically, you can use a 1:10 ratio meaning for every 1 inch of liquid water there will be 10 inches of snow and vice versa.  This however does not always follow through as it can be as little as 1:5 or as much as 1:50, figuratively speaking.  If this isn't tricky enough then keep in mind that if there were lake effect snow or rain it doesn't mean it will fall over Erie.

Finally, the wind is always hard to predict no matter what city you are in, but Erie is a little different.  Wind from bouys in the lake can be as high as 30 to 40 mph sustained, but just on land it could be 10 to 20 mph all due to friction.  The Erie International Airport is very close to Lake Erie, but there is still enough land to create enough friction with the wind to slow it down some.  For the short period of time that Erie was forecasted for the wind ranged from 13 to 22 mph depending upon how tight of a pressure gradient there is and whether the wind is coming off the water or land.

Overall, very tricky forecast city with the 2 weeks spent on it which allows for high respect for the meteorologists forecasting for the area.  Now Christmas break is in session and will have a resting period until the next forecast city starts in late January.  Here is a hint: It is known as The Big Easy and not located in any county, but another kind of geographic subdivision of a state; well known for a French phrase that occurs on a Tuesday every year before lent starts; and well known for a very famous street that has the same name as a type of whiskey.

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