Renato's Weather Blog

Good afternoon everyone,

Well I know people really don't want more rain after what Irene did to the area but we have a very complicated forecast coming up so this is just a preeliminary discussion until we get more details to forecast this potential rainmaker. We have a upper level low that will start to develop across the Upper Midwest and will stall itself for the next couple of days, creating waves of low pressure along the frontal boundary.

Before I go into specific details about the waves, I will go into the question everyone will ask, "How much Rain will we get?". Well the Hydrometeorological Prediction Center (HPC) has released this interesting 5 day precipitation map:

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The red and orange colors that are under the region show 3-4" inches of rain with 6-7" just offshore!

It seems like most of the forecasters I have talked to are not really to confident with their forecasts with this storm. A closed low with no where to go can create a very tricky pattern for the models to analyze so timing and precipitation amounts are varying on the models right now. The North American Model (NAM) is a little too amplified probably with its runs but compared to the Global Forecasting System (GFS), I can tell you to stick with the NAM. The European Center for Medium Range Forecasting (ECMWF) or European model at 12z (noon England time, 7AM EST), shows something similar to NAM so I will stick with a NAM/European solution.

We can split this rain event into three sequences:

Part 1: Weak Cold front arrives within the next 12-24 hrs giving us minimum precip, but would not be surprised to see some downpours at time (but it will be quick)

Part 2: As the upper low stalls in the Midwest, a coastal low forms along the atlantic with tropical moisture in it. This is the one that might be the most dangerous of all of them and might give us the most precipitation out of all of the sequences. This is supposed to be a Fri night-Saturday event and can create flooding with continuous heavy rains for hours and with a very wet ground still too from all the rain we have been receiving.

Part 3: The upper low starts to move eastward towards our area and another cold front/weak low pressure develops along the boundary and might create some additional rainfall too but thats still a little bit too far out for me to discuss at this time.

I'll try to give you another update later tonight, so have a nice day everyone!