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HOME> Expert Assessments>Hazards Outlook

For 3-7 day hazards see Weather Prediction Center's: WPC 3-7 Day Hazards

U.S. Week-2 Hazards Outlook - Made December 24, 2024 | About the Hazards Outlook

ATTENTION:
For more information on the addition of the Rapid Onset Drought hazard type to the Climate Prediction Center's 8-14 Day Hazards Outlook (Contiguous U.S. and Alaska), please click HERE.

Type and Period Temperature Precipitation Snow Wind Rapid Onset
Drought
Composite Days 8-14 Map No HazardsNo HazardsNo HazardsNo HazardsNo Hazards
Probabilistic Days 8-14 Map No Hazards

Composite Map
Experimental Probabilistic Outlooks

Valid Wednesday January 01, 2025 to Tuesday January 07, 2025

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST December 24 2024

Synopsis: An area of surface low pressure and associated cold front is forecast to ring in the new year across the East Coast with slight chances of heavy precipitation along coastal New England, with heavy snow possible for the interior Northeast, and potential high winds for much of the East Coast. In the Pacific Northwest, there may be another storm that will move into the area bringing rain, high elevation snow, and a period of high winds. One or more storm systems could increase snow chances for much of the Rockies western Great Plains.

Hazards
  • Slight risk of heavy precipitation for portions of coastal Northeast and Mid-Atlantic, Wed-Thu, Jan 1-2.
  • Slight risk of heavy heavy snow for the interior Northeast and downwind of Lakes Erie and Ontario, Wed-Thu, Jan 1-2.
  • Slight risk of high winds for the Northeast, Mid-Atlantic, and parts of the Southeast Wed-Thu, Jan 1-2.
  • Slight risk of heavy precipitation for portions of the Pacific Northwest, Wed-Fri, Jan 1-3.
  • Slight risk of heavy snow for high elevations of the Cascades, Wed-Fri, Jan 1-3.
  • Slight risk of high winds for portions of the Northwest, Wed-Fri, Jan 1-3.
  • Slight risk of heavy snow for much of the Rockies and western Great Plains, Wed-Sun, Jan 1-5.
Detailed Summary

For Friday December 27 - Tuesday December 31: WPC Days 3-7 U.S. Hazards

For Wednesday January 01 - Tuesday January 07: The forecast mid-level height pattern over the contiguous U.S. is rather uncertain today. The main driver of the uncertainty is the evolution of a weak mid-level trough near the West Coast prior to the week-2 period. The ECENS is more progressive, bringing this trough to the eastern CONUS by the onset of week-2, while the GEFS is slower, maintaining the negative 500-hPa height anomalies across the Rockies and western Plains. A more progressive pattern would favor increased chances for a stronger surface low pressure across the northeastern CONUS and strong mid-level ridging across the West. A slower pattern would increase precipitation chances across the Rockies and Plains early in the period.

The more progressive ECENS trough is forecast to undercut a mid-level ridge over eastern Canada and promote a strong surface low over the eastern CONUS. This storm system, early in week-2, would bring chances for heavy rain along portions of coastal New England. Therefore, a slight risk of heavy precipitation is posted for portions of coastal New England for Jan 1 & 2. The ECENS and GEFS Probabilistic Extremes Tools (PETs) indicate a 20-40% chance of 3-day accumulated precipitation exceeding the 85th climatological percentile and .75 inches in the hazard area. Further inland, the raw ECENS forecasts elevated chances for 3 day snow totals to exceed 6 inches. Therefore an associated risk of heavy snow is posted for portions of interior New England for the same period. Finally, this area of surface low pressure may increase wind speeds across much of the Northeast and Mid-Atlantic as the cold front pushes through. This is consistent with the ECENS and Canadian PETs which both have increased chances of wind speeds exceeding the 85th climatological percentile. Therefore, a slight risk of high winds is posted for Jan 1 & 2 for much of the Northeast, Mid-Atlantic, and parts of the Southeast.

In the Pacific Northwest, one or more shortwaves are forecast to progress through the region along the periphery of a mid-level ridge forecast across the western CONUS early in the week-2 period. This increases chances for heavy precipitation, high elevation snow, and episodic high winds. There is a fair amount of uncertainty regarding the strength of these shortwaves and available moisture. The GEFS and ECENS PETs indicate chances for precipitation to exceed the 85th climatological percentile and 2 inches across much of the region along and west of the Cascades. Therefore, a slight risk of heavy precipitation is posted for areas west of the mountains, with a slight risk of heavy snow for the higher elevations of the Cascades for Jan 1-3. A corresponding slight risk of high winds is posted for areas along and west of the Cascades with the ECENS PET forecasting strong chances of winds exceeding the 85th percentile, again for Jan 1-3.

The slower progression of a mid-level trough in the GEFS increases chances for heavy snow across portions of the central and southern Rockies early in the week-2 period. The GEFS PETs precipitation and Snow Water Equivalent (SWE) tool highlight this risk along with the potential for a surface low to eject out of the southern Rockies. The GEFS PET forecast increased chances for 3 day precipitation amounts to exceed the 85th percentile and 1 inch across parts of the lower Mississippi Valley associated with this wave of low pressure but with no support from the ECENS there is no hazard posted at this time. Further north, the shortwave troughs will progress inland and likewise increases chances for heavy snow across the Northern Rockies. Therefore, a broad slight risk of heavy snow is posted for the Rockies and western Great Plains for Jan 1-5 due to the general uncertainty of how the pattern will evolve but with the potential for an impactful storm to develop.

Across the Northern Plains and Upper Mississippi Valley, the GEFS PET shows at least a 20% chance of minimum temperatures falling below the 15th percentile and 0 degF. The ECENS PET has increased chances of temperatures falling below the 15th percentile today relative to yesterday. However, advisory level cold hazards require apparent temperatures near -30 degF in these regions and apparent temperatures seem unlikely to reach these thresholds at this time. Therefore, no corresponding hazard is posted but this area will continue to be monitored.

In southern California, there is some suggestion of an inverted trough near the coast in some of the ensemble guidance. However, most of the model guidance does not indicate strong high pressure forming over the Great Basin at this time which would limit the potential of any Santa Ana wind threat at this time.

In Alaska, above-normal precipitation is forecast across the southern Mainland. However, PETs do not indicate elevated chances for precipitation to exceed 2 inches during any 3 day period during week-2. Thus, no corresponding hazard is forecast at this time. Similarly, the ECENS PET shows signals for winds to exceed the 85th percentile in southern Mainland Alaska, but the highest wind speeds are likely to remain offshore resulting in no associated hazard being posted.

Forecaster: Ryan Bolt

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

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