High resolution models initiate convection in the early afternoon hours, roughly around 4 PM Central time. Model probabilities for derecho formation tomorrow afternoon into the evening hours are pretty high, with upwards of a 70 percent chance of derecho formation across nearly all of the moderate risk area. The Storm Prediction Center has issued a moderate risk of severe weather for much of Illinois, nearly all of Indiana and the western half of Ohio in anticipation of a potentially significant weather event tomorrow. Evolution of this significant weather event should commence with multiple cells in northern and western Illinois before coagulation of these cells brings about a line segment of storm cells. Derecho formation is most likely to commence in east-central Illinois, throughout Indiana and into western Ohio. Increased ‘digging’ from this negative tilt will enhance building of the high pressure ridge over the Midwest, Great Lakes and Ohio Valley, as evidenced by the large arcing formation over the aforementioned regions. While the environment is not conducive for an incredibly damaging derecho like the one observed last year, it is very possible we could see a weaker derecho move through Indiana and Ohio after commencing in Illinois. We also see an upper level low in the Bering Sea, which is expected to contribute some energy to our pattern over the next week or two.

The SLP map (brown lines) and 500mb contours (blue lines) show our upper level low finally moving off into Canada, with the cold front continuing east into the East US, as infrared satellite presentation shows. For some of our recent down years, the cold has been the missing ingredient in the weather pattern. This pattern is conducive to cooler conditions in the United States (Phase 8-1 MJO). Heading into mid-December, tropical forcing should re-organize in a pattern more favorable for cooler weather in the United States. Current tropical forcing imagery over the globe shows strong divergence across Central America into the United States. The central bankers and their policies are a major part of the problem with current high commodity prices. Moisture values still not really high but much better than recently. Until today, many of these provinces are still submerged in flood which is expected to recede in less than 2 weeks.

But as I described in previous blogs, their tests were not forward looking, mainly using the old physics and the model resolution of today, rather than the situation of the future. The likelihood for a derecho is on the rise tomorrow, as new model data and an upgrade from the Storm Prediction Center launch Wednesday into a significant weather event status. Both the Storm Prediction Center and Weather Prediction Center charts will change, but due to the uncertainty at this point, I am not willing to elaborate on this day’s set-up. Due to the large difference between the ECMWF and GFS models, the idea of turning to the Canadian model looks like the safest bet at this time. This effect may not hold true for a very small number of analog ensemble members, due to sampling errors, or for a very large number of members in which analogs become extremely unrepresentative.

Require all members of Congress and the Presidential administration to take and pass a course on basic economic theory to try to address Bill Clinton’s insight above. All the members have about the same forecast for North America. The ensemble-average 500 mb forecast (above) for 5 pm MST on Tuesday the 19th indicates a deep trough along the west coast. The chart is actually the NAM analysis of 500 mb winds, heights and vorticity (and as indicated on the graphic it is actually an analysis of geostrophic absolute vorticity). Storm system will dig into the Plains to round out the workweek, with highest vorticity values tilting to the southeast to declare the development of a negative tilt in the storm system. A strong storm system is currently moving out of the United States, showing the reasoning behind that small swath of negative anomalies in the Plains. Over the last seven days, we’ve seen strong negative geopotential height anomalies over the Gulf of Alaska, leading to ridging in Canada and a warmer pattern here in the U.S. Pattern should quiet down over Thanksgiving, with tropical forcing moving into areas more favorable for warmer weather for much of the country into the opening 5-10 days of December.

More active day than anticipated yesterday for local area, especially higher elevations from north-east-south. There were 53 ALERT stations with rainfall during past 24-hours (58% areal coverage) – 12 sites had 1/2″ or more and 4 sites had over 1″. Greatest amount was near Arivaca in the far southwest corner of the network. Figure 11. Example of the partitioning of uncertainty in projections of southeast England rainfall for the (a) 2020s and (b) 2080s from UKCP09. Figure 3 shows the number of transcription factors in each genome compared to their total number of genes. Plot above shows the Catalina Mountains sector of the network, with high amounts extending from near the crest northward into Pinal County. Latest reasoning from the SPC cites abundant and high instability in the highlighted areas, as well as high moisture content in the lower levels of the atmosphere as supportive for a significant damaging wind event. In general, GAMER performs well in our research. An NWP ensemble, no matter how well designed, cannot sample from the true forecast PDF given the challenges of simulating both analysis and model uncertainties.