Think Snow, Tweet Snow !!!

Saturday, February 8, 2014

"Model Hugging Syndrome" and a might be storm late in the upcoming week

I have been getting some comments, tweets, emails asking or referring to a specific model at a specific time. It's actually great to see so much nuts and bolts interest in weather forecasting which I know has existed for some time. That being said, weather enthusiasts and closet weather enthusiasts (me included) can be at times stricken with "model hugging syndrome" or "MHS". The "glass half empty" guy will send me a doom and gloom email regarding some model showing rain while the "glass half full" buy will ask me about some model forecasting a 2 foot storm 10 days out. There is so much model to model variability with the output that "MHS" is capable of sending someone to the loony bin. It didn't help when NCEP decided to run the American GFS model 4 times a day even though concrete upper air data is only collected twice a day. The GFS in particular is chaotic even beyond day 5 and the biases and issues with the model need to be corrected by way of improving the physics in the model as opposed to running it a zillion times a day. This however is not a model bashing rant. In spite of biases and flaws, models are capable of performing a massive amount of atmospheric calculations that humans are incapable of and powder hounds certainly should use them to help plan sick days. These calculations can differ quite greatly however because a models run 6 or 12 or 24 hours can interpret either the same or different rounds of upper air data quite differently. It is thus important to look at a collection of data, try to establish a consensus of what the data is showing, making additional adjustments based on known biases, factor in any observations that models might be failing to account for and finally reach some sort of conclusion as to what might happen. In the end, there are lots of moving parts and it always best to expect these parts to move over time.

The decaying piece of the massive Rocky Mountain storm will approach the region Sunday and spread some light snow into most of Vermont Sunday night. The storm will try and get energized off the New England coast but too little too late I think for a big event. A little event is still welcome though and we could squeeze 2-4 inches out of this by the end of the day Monday which should be blustery and chilly with temperatures in the teens. Tuesday will be crisp and cold with sub zero readings in the morning. It should feel nice by the afternoon however with plenty of sunshine and temperatures inching toward 20 degrees. We should see more of the same for Wednesday only a little warmer and perhaps more high clouds late in the day.

The weather map later in the week consists of a southern branch storm that will intensify and move up the Atlantic Coast while a clipper system slowly approaches from the west. We had hoped these two systems might combine to form a monster noreaster by Friday but this may be a stretch. The southern branch storm however should track close to Cape Cod, it appears to be a more compact event but system is certainly capable of bringing a healthy period of snow to MRG and surroundings Thursday. The clipper then arrives Friday with a nice cool pool or instability pool which should kick the snow shower machine into action later Friday into Saturday. Different models are still producing different results Friday; in fact, there is less consensus Saturday than there was 48 hours ago. Still, we do have some consensus for some decent snow leading up to the weekend 15th and 16th.

Ensembles are still indicating a tightening of the jet in the Pacific beyond the 16th. The region has some tepid support from the AO and NAO but recent ensemble data has shifted the core of coldest and most unsettled weather into the western states. That is not a good trend as of this morning but below freezing temperatures should keep any fallen powder, powdery at least through around the 18th of the month. We have to open the door for the possibility of a thaw in the days that follow that.

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