Composite Map Day 8-14

Experimental Probabilistic Outlooks Temperature Hazards Precipitation Hazards Wind Hazards Snow Hazards

Valid Tuesday January 13, 2026 to Monday January 19, 2026

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST January 05 2026

Synopsis: At the start of week-2, a tight gradient between high surface pressure over the interior West and low pressure farther south increases the odds for periodic high winds over the Southwest through the middle of the period, with Santa Ana winds possible near the southern California coast. Meanwhile, east of the high pressure center, strong downsloping winds are possible in the lee of the Rockies. Later in the period, surface high pressure is expected over the Canadian Prairies while the southern Rockies and adjacent High Plains see lower pressures. This is favorable for heavy snow along the eastern tier of the Rockies and the western High Plains, with upsloping low-level flow enhancing totals. Farther north, a potentially potent storm near southern Alaska may bring high winds and heavy precipitation to south-central and southeastern Alaska, but there is too much uncertainty to post any related hazards.

Hazards

• Slight risk of high winds in the Southwest from Arizona through southern California, Tue-Sat, Jan 13-17
• Slight risk of high winds along the east-central and northeastern Rockies and the adjacent High Plains, Tue-Thu, Jan 13-15.
• Slight risk of heavy snow along the eastern tier of the Rockies and the adjacent High Plains, Fri-Mon, Jan 16-19.

Detailed Summary

For Thursday January 08 - Monday January 12: WPC Days 3-7 U.S. Hazards

For Tuesday January 13 - Monday January 19: Early week-2, multiple model ensemble means favor a moderately amplified pattern with a sharp mid-level trough stretching from western Alaska into the central North Pacific, a strong downstream mid-level ridge over the western Contiguous United States (CONUS), and a weaker mid-level trough across the eastern CONUS. The Canadian ensemble (CMCE) mean indicates the strongest mid-level ridge across the western CONUS, showing 500-hPa height anomalies over +24 dm in the Pacific Northwest, while the GEFS and European ensemble (ECENS) are somewhat weaker by about 5 dm. This pattern is anticipated to remain in place with some amplification of the mid-level trough over the eastern CONUS for the first couple days of week-2, followed by retrograding of this feature. By the end of the period, the ensemble means show a strong mid-level ridge over the upper North Pacific, resulting in mid-level heights building over Alaska, but dropping over the western CONUS. This results in a relatively weak positively-tilted mid-level trough stretching from south-central or southeastern Canada interior West. The CMCE mean remains the strongest with the repositioned mid-level ridge, depicting 500-hPa anomalies exceeding +30 dm just south of the Gulf of Alaska. The other two ensemble means are a bit weaker, with the GEFS mean keeping positive height anomalies under +24 dm. A compromise of the 3 ensemble means is favored here, although the differences wouldn't result in much change to the sensible weather. Meanwhile, the ensemble means all establish a weak, positively-tilted mid-level trough across the western CONUS that extends into the Pacific off the southern California coast. The ECENS and CMCE all depict a secondary 500-hPa negative anomaly center in or over the Southwest while the GEFS mean keeps significant anomalies farther north. The deterministic models tend to favor the secondary height minimum on the southern extension of the mid-level trough, so that solution is favored. The CMCE and ECENS means would result in a pattern favoring heavier precipitation over and near the southeastern Rockies. Across the eastern half of the CONUS, the mid-level trough is expected to diminish and retreat northwestward later in the week as a flat mid-level ridge becomes established across the Lower Mississippi Valley and the Southeast, although this feature is weaker today than yesterday in most of the guidance. While the ensemble means are in decent agreement overall, a few deterministic model runs show mid-level features that are more amplified and/or persistent, introducing uncertainty into the week-2 Hazards Forecast.

At the start of week-2, the mid-level ridge over the interior West is expected to establish a strong surface high pressure system centered over the Rockies. The deterministic Canadian model is strongest with this feature, showing surface pressures topping out near 1054 mb from northeastern Nevada through the central Rockies, but this looks unreasonably high. Other guidance shows surface pressures peaking in the 1035 to 1045 mb range, which is still much higher than usual. Meanwhile, mid-level heights are forecast to be closer to normal farther south toward Mexico and the adjacent Pacific, resulting in lower surface pressures over the Southwest. Most model solutions show surface pressures below 1024 mb in parts of southern Arizona and southern California at the beginning of the period. This results in a tight pressure gradient over portions of the Southwest, increasing the odds for periods of high winds across the region. The Probabilistic Extremes Tool (PET) from the ECENS and CMCE show elevated odds for winds reaching the top 15 percent of climatology, peaking near 35 percent chances in parts of Arizona early in the period. Near coastal southern California, this pattern could result in periodic Santa Ana wind episodes. Fortunately, the recent wetness there should squelch any significant increase in fire danger. The bottom line is that these factors support a slight risk of high winds in the Southwest, which is posted from Arizona westward through the southern California coast until mid-week, when the mid-level ridge has retrograded sufficiently to pull the surface high pressure northward and northwestward away from the Rockies.

Meanwhile, on the eastern side of the high surface pressure system over the Rockies, a tight pressure gradient with significantly lower pressures just to the east in the central and northern High Plains could result in one or more episodes of strong downsloping winds near the northern half of the Front Range and in the adjacent High Plains. This set-up is depicted by most of the guidance, although the strength and duration of these conditions are uncertain.. The PETs from all three ensemble means show elevated chances for winds to exceed the upper 15 percentile threshold of the climatological envelope, supporting a slight risk of high winds in this region for the first few days of week-2. As the surface high pressure retreats northward and northwestward with time, both the reduced pressure gradient and the change in wind direction is expected to bring an end to the high wind risk.

Later in week-2, 500-hPa heights begin to build a weak flat ridge over the south-central and southeastern CONUS, pushing the eastern CONUS mid-level trough northward into southern Canada. At the same time, the mid-level ridge initially over the western CONUS begins to retrograde, building toward the central North Pacific and into Alaska. This results in lowering 500-hPa heights over the western CONUS, establishing an positively-tilted anomalous mid-level trough with an axis reaching from southern Canada through the interior West to near or off the California coast. The CMCE and ECENS means show a weak secondary 500-hPa height minimum near the far southwestern CONUS later week-2 which retrogrades slightly as the period ends. In concert with the retrograding mid-level ridge centered in the North Pacific toward the end of the period, this pattern is anticipated to establish relatively high surface pressures above the trough axis in the Canadian Prairies, and lower surface pressures over the southern to central High Plains upstream from the secondary 500-hPa height anomaly center. This pattern increases the likelihood of heavy snow along the Front Range and adjacent High Plains. Easterly upsloping low level flow could further enhance snowfall. The raw deterministic and ensemble mean snowfall forecasts remain generally unremarkable, but the GEFS PET shows increased odds for snow water equivalent totals among the top 15 percent of the climatological envelope for the last few days of week-2 along the southeastern Rockies and adjacent High Plains. There are no snow water equivalent PETs derived from either the ECENS or CMCE, but the pattern forecast by their ensemble means would be more favorable for heavy snow in the region than the GEFS mean, boosting forecast confidence somewhat. Downstream from the 500-hPa height minimum near the southwestern CONUS, the PETs from all three ensembles show slightly elevated odds for precipitation totals in the 85th percentile across the southern Rockies and some adjacent areas. In addition, some of the deterministic models show impressive if not overwhelming precipitation totals in this region later week-2, but too much uncertainty remains to post any related hazards at this time.

There are no hazards posted for Alaska again today, but some model guidance shows a limited potential for a few hazards. However, there is a great deal of model spread and the preponderance of the tools keep conditions below hazards thresholds. A sharp mid-level trough initially along the western tier of the state could result in much below normal temperatures over some of the central and western sections of the Mainland. Early week-2, some deterministic models and ensemble means depict temperatures reaching 10 to almost 30 deg. F below normal for at least some portion of the west-central or southwestern parts of the state, but most guidance has warmed up a bit relative to yesterday. The most extreme model solutions show temperature dropping as low as -45 deg. F below normal, but the majority of the tools favor milder conditions, which represents a shift toward normal relative to yesterday. Given the wide range of model solutions and the shift away from extreme cold in most tools, no related hazards are posted at this time.

There is also uncertainty regarding the potential for a potent storm system to affect some of the southern parts of Alaska. Most model solutions indicate low surface pressure starting the week over or near the Gulf of Alaska with higher surface pressures across the interior of Alaska and western Canada. However, the strength and location of any storm system that forms and the high surface pressures to the north and east are highly uncertain. The 0z deterministic ECMWF depicts a 962 hPa low pressure center in the Gulf of Alaska early in week-2 while surface pressures approach 1020 hPa in far southeastern Alaska. This pattern would engender high winds and heavy precipitation across south-central and southeastern Alaska, along with heavy snowfall away from the immediate coast. In contrast, the ensemble means all keep the surface low pressure center above 990 mb, with most members being weaker than depicted yesterday. In addition, several tools place a relatively weak low pressure center inland at the start of week-2, which would be less favorable for unsettled weather. The PETs derived from the ECENS and CMCE show enhanced odds for winds reaching the top 15th percentile, but the raw wind forecasts from the ensemble means and most deterministic models keep precipitation and winds below hazards thresholds. Given the broad array of model solutions, no wind or precipitation hazards are posted in Alaska at this time.

Forecaster: Rich Tinker

$$ Please consult local NWS Forecast Offices for short range forecasts and region-specific information.

Resources

Week-2 Probabilistic Extremes Tool

GFS Ensemble Forecasts