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Thursday September 25 Rain Storm


IsentropicLift

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How bad were the US models on this? I mean the NAM and GFS were atrocious. GFS giving 1-2 inches even at 18z. When the GGEM schools you..something is inherently wrong

 

The issue most likely was convective parameterization on the models. While the GGEM was dry the RGEM was a soaker. The Euro Ensembles were also pretty bullish on getting rain in here. 

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The upper air flow is so weak in this system...it will not be comparable to a synoptic setup in the winter.

 

True - but I feel like this kind of system should be in the SREFs wheelhouse. Relatively (compared to winter) weak synoptic forecasting and some pockets of convection around.

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True - but I feel like this kind of system should be in the SREFs wheelhouse. Relatively (compared to winter) weak synoptic forecasting and some pockets of convection around.

 

Actually - going back and looking at the SREF plumes they did show a really really substantial amount of spread with yesterday's run. So I can't totally pan them. Even though the "mean" QPF was quite high there was really no clustering near any solution. 

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There were definitely red flags. There was drier air modeled, the flow kind of sheary and then helping to squash the low moving up from the south, and an overall weak low. The one thing is had going was a decent LLJ that quickly wrapped back to the west and not north. I thought the mid levels would be enough to help bring at least some -RA north of the pike, but fail.

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True - but I feel like this kind of system should be in the SREFs wheelhouse. Relatively (compared to winter) weak synoptic forecasting and some pockets of convection around.

 

 

I don't have any faith n the SREFs these days...they had a period of usefulness back in the 2008-2010 timeframe or roughly thereabouts, but whatever upgrades they did to it in the last couple of years has turned them into a useless winter forecasting tool.

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I don't have any faith n the SREFs these days...they had a period of usefulness back in the 2008-2010 timeframe or roughly thereabouts, but whatever upgrades they did to it in the last couple of years has turned them into a useless winter forecasting tool.

 

It's really a shame. You're right post 2010 it's been pretty much useless in the winter. It has some use I've found within 24 hours with spring/summer convection but that's about it. 

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The issue most likely was convective parameterization on the models. While the GGEM was dry the RGEM was a soaker. The Euro Ensembles were also pretty bullish on getting rain in here. 

 

All the ensembles (including the SREFS) were far too wet...but they are prone to doing that in sharp cut-off events.  You always have those big QPF members skewing things on the NW edge...doesn't matter snow or rain.

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I don't have any faith n the SREFs these days...they had a period of usefulness back in the 2008-2010 timeframe or roughly thereabouts, but whatever upgrades they did to it in the last couple of years has turned them into a useless winter forecasting tool.

 

I was reading some threads from 2007-2008 the other day (or a month ago) haha, and we used to hump the SREFS...it was like the next best thing to see what trends might happen in the next operational model run.

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I was reading some threads from 2007-2008 the other day (or a month ago) haha, and we used to hump the SREFS...it was like the next best thing to see what trends might happen in the next operational model run.

 

 

I'm not sure if they perform better in other seasons now at the expense of winter...or other types of events...but they definitely were more valuable in synoptic winter events back in that timeframe. If I was a model-guru, I might investigate why it is different now...but it involves too deep of an analysis to really interest me. I'm sure the QPF scores went up or they wouldn't have made the upgrades...but that doesn't mean it had to go up for synoptic cold season events...it could have improved in convection and such.

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They seem to do well in those heavy rain events that have sufficient modeled forcing. In previous heavy rains events, they've done a decent job hinting at the areas to get heavy rain and even the amounts. 

 

I'll have to see if I can find the image, they were absolutely atrocious in that tropical rainstorm over the summer where ISP got 12"... I remember they had widespread 2-3"+ amounts all the way through VT into NNY that ended up verifying over eastern New England.

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I'll have to see if I can find the image, they were absolutely atrocious in that tropical rainstorm over the summer where ISP got 12"... I remember they had widespread 2-3"+ amounts all the way through VT into NNY that ended up verifying over eastern New England.

 

Found it... this was actually one of the worst model forecasts I had seen in a while which is why I remember it.  Think back to that mid-August drenching where Ginxy got 4"+, ISP had 12", etc... Dendrite 3"+...BTV and NNY with more like 0.5-1.5". 

 

I mean this wasn't even close and it kept showing this for several days with big eastern NY rains.  ALB busted hard in this one too. 

 

Look at the Initial time of August 12th...so this was like 24-36 hours prior to the event.  And it ended up exactly the opposite of what this shows...heaviest SE areas and weakest NW areas.

 

post-352-0-98165700-1407886161.jpg

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