Interaction of an Intense Pacific Low Pressure System with a Strong Arctic Outbreak over British Columbia: Forecast Challenges of the Early December 2007 Storm
Bibliographic record
Abstract
The interaction of a warm moist air mass from an intense Pacific low pressure system with a cold air mass from a strong Arctic outbreak during 1-5 December 2007 produced a record number of high-impact weather events across British Columbia, including heavy snow, freezing rain, heavy rain, strong winds and extreme wind chill.The unusual concurrence of these two strong weather systems caused many forecast challenges for both the Canadian numerical weather prediction (NWP) models and meteorologists at the Pacific Storm Prediction Centre (PSPC) of Environment Canada.In this study, the evolution of the weather systems and the observed severe weather events during the 1-5 December 2007 storm are analyzed.Weather forecasts by the NWP models and PSPC meteorologists are compared with the observed high-impact weather events.It is shown that the Canadian NWP models forecast the storm reasonably well.Meteorologists at PSPC further improved the model forecasts by considering various local effects of the complex terrain over British Columbia that the model has difficulty resolving and model biases caused by inadequacies in its boundary layer parameterizations.RSUM [Traduit par la rdaction] L'interaction d'une masse d'air chaud et humide issue d'une forte dpression dans le Pacifique avec une masse d'air froid gnre par une forte coule polaire entre le 1 er et le 5 dcembre 2007 a engendr un nombre record d'vnements mtorologiques fort impact en Colombie-Britannique : neige abondante, pluie verglaante, pluie forte, vents forts et indice extrmement lev de refroidissement olien.Pour les modles canadiens de prvision numrique du temps (NWP) et les mtorologues du Centre de prvision des temptes du Pacifique (PSPC) d'Environnement Canada, la concidence inhabituelle de ces deux systmes mtorologiques forts a pos de nombreux dfis.Dans la prsente tude, nous analysons l'volution des systmes mtorologiques et les intenses vnements mtorologiques observs au cours de la tempte survenue entre le 1 er et le 5 dcembre 2007.Nous comparons les prvisions de la mto tablies partir des rsultats des modles NWP et par les mtorologues du PSPC avec les vnements mtorologiques fort impact qui ont t observs.Nous dmontrons que les modles canadiens de NWP, ont prdit raisonnablement bien l'volution de la tempte.Les mtorologues au PSPC ont rajust leur tour les prvisions tablies par ces modles en intgrant les divers effets locaux des terrains accidents en Colombie-Britannique, qui sont difficiles rsoudre par ces modles, et leurs biais attribuables au manque de prcision des paramtrages de la couche limite.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".