Fig. 1: The overnight day 11-15 temperature anomaly forecast by the GFS for North America.
Discussion: The GFS OP is volatile, excitable and frequently (very) wrong in the 11-15 day period. The GFS OP routinely scores poorly in the 11-15 day period and almost always ranks last among the major forecast models. However, because of the volatile nature of this model in the extended-range it can be the first model to see a pattern change. The overnight 11-15 day forecast indicates a fantastic arctic outbreak into the U.S. (Fig. 1). The outbreak is poorly supported by climate diagnostics. However, the model projects a whopping 288 HDD for Feb. 5-11 (Fig. 2). While the model is overdone it certainly will attract the attention of natural gas markets. (The just-arrived 0600 GMT GFS OP is similar.
Fig. 2: The U.S. gas population weight HDD forecast by all models including the super cold GFS for Feb. 5-11.
Fig. 3: Current NOAA/NWS weather watch, warning and advisory areas.
Short-term high impact weather discussion: While the overnight GFS is an attention-grabber the short-term weather is also dramatic. California long-term drought continues to receive significant benefit from heavy precipitation which is causing flooding near the central and south coast particularly mountain ranges where mudslides are likely and also for mountain areas where blizzard warnings remain in effect for the Sierra Nevada near Tahoe and south (Fig. 3). High wind continues to accompany the storm. In the East an area of moderate snow moves across the coastal Mid-Atlantic States today. And later today and tonight a cold arctic wind arrives in New York/New England.
Today’s forecast indicates the California storm expands inland today and is re-invigorated tomorrow (Fig. 4-5). By Saturday the western storm shifts to the Great Plains featuring heavy rain and thunderstorms for the Mid-south U.S. while snows spread across the Midwest (Fig. 6). The storm moves into the East mainly as a rainstorm on Sunday except moderate snows northern Ohio Valley to the northern Mid-Atlantic (Fig. 7). Storminess is concentrated on the Northeast and the Northwest (again) early next week (Fig. 8-9).
Fig. 4-5: NOAA/WPC depiction of U.S. fronts/storms today and tomorrow at 7AM.
Fig. 6-7: NOAA/WPC depiction of U.S. fronts/storms Saturday/Sunday at 7AM.
Fig. 8-9: NOAA/WPC depiction of U.S. fronts/storms Monday/Tuesday at 7AM.