Composite Map Day 8-14

Experimental Probabilistic Outlooks Temperature Hazards Precipitation Hazards Wind Hazards Snow Hazards

Valid Friday April 11, 2025 to Thursday April 17, 2025

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT April 03 2025

Synopsis: Mid-level low pressure is forecast across the eastern contiguous U.S. (CONUS) early in week-2, with dynamical models continuing to indicate an area of surface low pressure forming along the Eastern Seaboard bringing enhanced chances of heavy precipitation to portions of the Mid-Atlantic and Northeast. While below-normal temperatures continue to be likely across much of the East during the first half of the period, relatively warmer temperatures are likely compared to the late week-1 period, and it is less likely minimum temperatures will cause any additional impacts to vegetation. Mid-level high pressure is forecast to shift across the central CONUS, with models trending stronger with mid-level low pressure upstream across the Northwest. This favors increasing pressure gradients and elevated wind speeds across much of the Great Plains and Upper and Middle Mississippi Valley, which in combination with above-normal temperatures and dry soils, may increase the wildfire risk over some of these areas.

Hazards

• Slight risk of heavy precipitation across coastal portions of the Northeast and Mid-Atlantic, Fri-Sun, Apr 11-13.
• Slight risk of high winds across portions of California, Fri-Mon, Apr 11-14.
• Slight risk of high winds across much of the Great Plains and Upper and Middle Mississippi Valley, Sat-Mon, Apr 12-14.

Detailed Summary

For Sunday April 06 - Thursday April 10: WPC Days 3-7 U.S. Hazards

For Friday April 11 - Thursday April 17: Troughing is forecast to reload across the eastern CONUS early in week-2. As a result, below-normal temperatures are likely to persist through the first half of the period. However, minimum temperatures are forecast to be warmer compared to late in week-1, with the uncalibrated 0z GEFS and ECENS depicting areas with susceptible vegetation remaining above 40 deg F. Therefore, the much below-normal temperatures hazard is discontinued across the East.

Models continue to depict a wave of surface low pressure developing along the East Coast ahead of the trough at the start of week-2. The ECENS and GEFS Probabilistic Extremes Tools (PETs) depict at least a 20 percent chance 3-day precipitation totals exceed the 85th climatological percentile along the Eastern Seaboard north of the Carolinas, with probabilities for precipitation totals exceeding 1-inch only exceeding 20 percent over parts of coastal New England. However, the uncalibrated 0z ECENS depicts these enhanced probabilities extending further inland across New England and the coastal Mid-Atlantic. While the potential is marginal, a slight risk of heavy precipitation is posted for coastal portions of the Northeast and Mid-Atlantic, Apr 11-13. The 0z and 6z deterministic GFS solutions depict a more robust surface low compared to the ensemble means. These stronger solutions would favor heavier precipitation extending further inland along with some risk for a period of dynamically driven snow depending on the track of the low. Given the increased uncertainty and lack of ensemble support, no related snow hazard is posted at this time.

Compared to yesterday, the 0z GEFS, ECENS, and CMCE have all trended stronger with shortwave troughing moving into the northwestern CONUS early in week-2, with anomalous ridging shifting further downstream over the central CONUS. Despite some increased onshore flow, the PETs remain unimpressive with probabilities for hazardous precipitation. An increased risk of high winds is more of a concern, with the PETs depicting broad areas of the western and central CONUS having probabilities above 20 percent for wind speeds exceeding the 85th climatological percentile and 20-mph. Synoptically, the strongest pressure gradients are forecast to set up across the Great Plains and Upper and Middle Mississippi Valley beginning on day-9 (Apr 12) due to surface high pressure forecast across the Gulf Coast and surface low pressure moving into the West. As a result, a slight risk of high winds is posted across these areas, Apr 12-14. There is additional concern for increased wildfire potential due to drier than normal conditions along with forecast temperatures at least 10 deg F above-normal. Additionally, an offshore flow pattern is forecast to develop across California, with the uncalibrated 0z ECENS and GEFS depicting high probabilities for wind speeds exceeding 20-mph just offshore. Based on this, and the likely extension for higher winds across low elevation inland areas, a slight risk of high winds is posted across portions of California, Apr 11-14, with wildfires again being a primary concern, especially across drier areas of southern California.

No hazards are indicated across Alaska underneath weak troughing and a variable temperature pattern. Slightly elevated chances for above normal precipitation are forecast across Southeast Alaska, with near- to below normal precipitation chances increased across the rest of the state.

Forecaster: Thomas Collow

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

Resources

Week-2 Probabilistic Extremes Tool

GFS Ensemble Forecasts