Composite Map Day 8-14

Experimental Probabilistic Outlooks Temperature Hazards Precipitation Hazards Wind Hazards Snow Hazards

Valid Thursday April 10, 2025 to Wednesday April 16, 2025

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT April 02 2025

Synopsis: Mid-level low pressure across the eastern contiguous U.S. (CONUS) is forecast to peak in magnitude late in week-1 and weaken at the outset of week-2. This feature favors an increased risk for much below normal temperatures coinciding with emerging springtime vegetation lingering into day-8 (Apr 10). Following a brief moderation, mid-level low pressure is forecast to reload across the East, potentially ushering in another round of relatively cooler temperatures, in addition to cyclogenesis across the northeastern U.S, although confidence remains low regarding these outcomes. Upstream, mean mid-level high pressure is forecast to keep much of the western CONUS free of weather related hazards.

Hazards

• Slight risk of much below normal temperatures for portions of the eastern CONUS, Thu, Apr 10.

Detailed Summary

For Saturday April 05 - Wednesday April 09: WPC Days 3-7 U.S. Hazards

For Thursday April 10 - Wednesday April 16: Amplified troughing is forecast across the eastern CONUS late in week-1, along with an associated area of surface high pressure across the Tennessee Valley and Southeast. While this favors a welcome drying trend, a period of anomalously colder temperatures is forecast, with some areas experiencing frosts or freezes coinciding with susceptible emerging springtime vegetation. The coldest temperatures are favored prior to the start of week-2, with moderation likely as the period begins. However, the ECENS Probabilistic Extremes Tool (PET) continues to depict probabilities of at least 20 percent for minimum temperatures falling below the 15th climatological percentile across portions of the eastern CONUS on day-8 (Apr 10), with higher probabilities (above 40 percent) across the Southeast. Minimum temperatures potentially falling below 40 deg F support a continuation of the slight risk for much below normal temperatures on day-8 (Apr 10) due to an enhanced risk of frost. An increase in vegetation coverage across portions of the Ohio Valley, Mid-Atlantic, and lower Northeast is possible due to above-normal temperatures forecast early in week-1, justifying the northward extent of the slight risk. As the trough reloads across the East, there are some signals for another round of potentially hazardous temperatures across parts of the Southeast around the middle of the period. However, the PETs are more sporadic and weaker with below-normal temperature probabilities compared to the preceding event, with the uncertainty precluding a related addition of the hazard at this time.

Both the 0z GEFS and ECENS depict an area of surface low pressure developing off the northeast coast on days 9 and 10 (Apr 11-12) ahead of the reloading trough. The GEFS is more pronounced with this feature compared to yesterday, and both the GEFS and ECENS PETs depict at least a 20 percent chance 3-day precipitation totals exceed the 85th climatological percentile along the Eastern Seaboard early in week-2. However, probabilities for precipitation totals exceeding 1-inch only exceed 20 percent over parts of coastal New England, indicating the system may remain too far off the coast or too weak for widespread impacts. This potential will continue to be monitored, and associated precipitation hazards may be needed in tomorrow’s outlook for parts of the Northeast depending on model trends.

Strong mid-level ridging forecast across the western CONUS during week-2 favors unseasonably warmer and drier conditions compared to week-1, resulting in no weather related hazards for the western CONUS for week-2. However, as the ridge shifts slightly eastward with time, heights are forecast to trend closer to normal near the West Coast, with a greater tendency for shortwave troughs to move into the Northwest. The models are generally weak with these features, with the PETs unimpressive with hazardous precipitation probabilities. While the ECENS PET depicts elevated chances for wind speeds exceeding the 85th climatological percentile and 20-mph across portions of the Great Basin and Northern Plains, the synoptic set-up is not indicative of a widespread high wind event. Therefore no related wind hazard is posted, although occasional episodes of high winds cannot be ruled out, especially if shortwave troughing moves closer to the area.

No hazards are indicated across Alaska underneath a variable temperature pattern along with near- to below-normal precipitation forecast during week-2.

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