Composite Map Day 8-14

Experimental Probabilistic Outlooks Temperature Hazards Precipitation Hazards Wind Hazards Snow Hazards

Valid Saturday May 03, 2025 to Friday May 09, 2025

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT April 25 2025

Synopsis: At the outset of week-2 surface low pressure is forecast to move from New England into southern Quebec, with a trailing cold front extending across the east-central contiguous U.S. (CONUS) and the Southern Plains. This front is forecast to become stationary, which favors enhanced chances of heavy precipitation and thunderstorms across portions of the south-central CONUS continuing through most of week-2. Broad mid-level high pressure is forecast to develop across the CONUS later in week-2, favoring increased chances for above-normal temperatures over many areas.

Hazards

• Moderate risk of heavy precipitation for much of Oklahoma and Texas, Sat-Wed, May 3-7.
• Slight risk of heavy precipitation for portions of the Southern and Central Plains, Sat-Fri, May 3-9.
• Possible flooding for the Southern Plains.
• Possible flooding for the Lower Mississippi River.

Detailed Summary

For Monday April 28 - Friday May 02: WPC Days 3-7 U.S. Hazards

For Saturday May 03 - Friday May 09: At the beginning of week-2, as surface low pressure departs New England and moves into southern Quebec, an associated trailing cold front is predicted to extend across the east-central CONUS and the Southern Plains, serving as a focus for continued increased chances of localized enhanced precipitation and thunderstorms. As the baroclinic zone stalls, the heavier precipitation amounts are favored over portions of the Southern and Central Plains, where a slight risk of heavy precipitation is posted for May 3-9. The GEFS and ECENS Probabilistic Extremes Tools (PETs) indicate at least a 20 percent chance of rainfall amounts exceeding the 85th climatological percentile and 1-inch across the highlighted risk area. A moderate risk (40-60% chance) is introduced today over much of Oklahoma and Texas from May 3-7, primarily based on higher probabilities in the ECENS PET, good model run consistency in ECENS precipitation forecasts, and the 12Z GEFS showing increasing potential for heavier amounts.

A possible flooding hazard remains posted across the Lower Mississippi River given the potential for new and renewed rises in water levels during week-2 tied to any additional rainfall over the region associated with the stationary front, as well as runoff from rainfall upstream. Main channels are already very high, and thus are unlikely to have large responses to additional precipitation. Regardless, tributaries and streams across this region (including the Southern Plains) will continue to be susceptible to renewed flooding or flash flooding if additional rainfall occurs. A risk of possible flooding is introduced for northern Texas and Oklahoma in today’s outlook, where there are the most vulnerable top soils to flooding where there is a moderate risk of heavy precipitation highlighted during the period. Late spring is the peak time for flash flooding in Texas, due in part to slow-moving thunderstorms.

Though no wind hazards are posted today, one area of concern is the Southwest, in advance of a mid-level, southern stream trough. Typically during the spring, as the deserts heat up, stronger winds rounding the base of approaching mid-level troughs are mixed down to the surface resulting in very gusty winds that occasionally produce significant damage. The ECENS and GEFS PETs depict wind speeds of at least 20 mph in parts of the Southwest, which may be underdone given the inherent nature of ensemble smoothing and challenges of wind predictability.

A cold front moving off the Northeast coast early in week-2 favors a reduction in temperatures over the Great Lakes and Northeast. High temperatures are forecast to range from the upper 50’s near the Great Lakes to around 80 degrees F near the Nation’s Capital. The National Blend of Models (NBM) does not show any widespread areas of record or near-record temperatures anywhere over the CONUS during at least the first half of week-2. A general trend toward more broad ridging and a pattern typical of late-Spring is forecast to emerge over much of the CONUS later in week-2.

Troughing forecast across Alaska favors increased chances for increased onshore flow and above-normal precipitation over the southeastern part of the state, though forecasted precipitation amounts of 1-2 inches fall short of hazards thresholds. Below-normal temperatures predicted over many areas may favor a slight delay in seasonal river ice breakup. However, as temperatures continue to warm, the eventual river ice breakup may lead to ice jams and associated upstream flooding in the coming weeks.

Forecaster: Anthony Artusa

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

Resources

Week-2 Probabilistic Extremes Tool

GFS Ensemble Forecasts