August 11th, 2014

Heavy rain event to unfold Tue - Early Wed.  Just an update on Sat's post. 

This system is very juicy, slow moving, and has great dynamics, low level jet, and instability to give some convective elements to the coming rain.  This means heavy to torrential downpours will be likely at times. 

Forecast Rain Amount: widespread 2" with locally up to 3" 

The picture above shows the Precipitable Water (PW) values off the SPC's website mesoanalysis page. (PW: amount of water in square inch column of air if it were emptied out). Anything over 1.5 gives heavy rain. Over 2 gives torrential flash flooding type rains. Right now we are below 1" which is why we were dry and cool last night. But notice in Ohio it surges to 1.9" and in the Carolina's its above 2". This moisture will surge toward our area. If we go to 2" or higher rainfall amounts will increase by 1" over my current forecast with locally even higher amounts possible. 

Factors in Forecast: 

1. North-south movement of showers/storms within eastward area of rainfall Tue-early Wed. 
2. High PW to going near 2" leading to very heavy rainfall at times. 
3. Triple point low developing along coast helping slow down system and maintain moisture flow into our region 
4. Some clearing on Wed could lead to milder temps to even near 80, but that could ignite more storms in the afternoon. 

This is a big ticket weather event. We've had them before, and will have them again. But this is bigger than many not because of the amount of rain, but because of the rain and the pattern change that it will help bring. Next week at this time we might be staring in the face a coming heatwave??? 

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