For the rain lovers, the trend is definitely not our friend since last nights 00z runs. Forecast guidance has strengthened the high pressure a bit more and is holding back the precipitation longer, by the time the high pressure weakens and shifts northeast the bulk of the support for heavier precipitation is gone. Really a tricky scenario for models and I don't think anyone expected anything more than an awful performance from guidance in this one. A few days ago the high pressure was the dominant force on guidance, keeping most measurable precipitation to our south. Yesterday, the models ingested data that weakened the high pressure in time to allow an influx of moisture to slide northwest in off the ocean. Today, the trend has buckled back towards less precipitation; though it still appears that at least 0.50" will fall in much of the area. Latest SREF forecast precipitation percentages can be accessed by clicking this link (in an effort to avoid too many images in this post) with the latest weathertap radar to your top left. The SREF image details the percentage chance of 0.10" of accumulated precipitation, 0.25" of accumulated precipitation, 0.50" of accumulated precipitation, and 1.00" of accumulated precipitation as forecasted by the large number of SREF ensembles.


In other news, it seems as if we are finally beginning to make some headway in the long range forecasts. Long range GFS ensembles are beginning to grab on to the idea of large negative anomalies over Alaska and the west coast retrograding westward towards the Aleutians. This is highly important for anybody who wants to see a chance at negative departures and/or a colder pattern across the Eastern 1/3 of the nation as we head towards the end of November. The current positioning of the vortex in Alaska is awful and probably one of the worst patterns we could ever see the Pacific in. The -PNA/West coast troughing leads to the downstream ridge over the Eastern 1/3 of the US. The ensembles over the past few days are beginning to show a
favorable signal with the vortex retrograding towards the Aleutian Islands, with a resultant downstream +PNA ridge on the west coast and support for negative anomalies in the Central and Eastern US. Keep in mind there is quite a spread in the long range, but the GFS hints at the retrograding vortex as early as Day 5-7 on it's ensembles which is certainly a very good sign. We've included an image to the left with two separate images on it. The first image is the 168 hr GFS 500mb anomalies showing the aforementioned poor pattern in place, and on the right is the long range GFS showing the improved pattern aloft. To your right are the long range temperature anomalies advertised, a result of the aforementioned improved pattern aloft. Also, you can use this link to check out the positive phase of the PNA both at 500mb and resulting surface temperatures.


John