Composite Map Day 8-14

Experimental Probabilistic Outlooks Temperature Hazards Precipitation Hazards Wind Hazards Snow Hazards

Valid Friday March 14, 2025 to Thursday March 20, 2025

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST March 06 2025

Synopsis: Early in week-2, mid-level low pressure moving inland into the west-central contiguous U.S. favors the development of a large-scale surface cyclone across the Great Plains at the beginning of the period, tracking toward the Upper Mississippi Valley and Great Lakes, Widespread impacts are likely from this system ranging from heavy snow across the Northern Tier and potentially heavy frontally focused rainfall across the East. High winds are also a concern due to strong surface pressure gradients expected. Another mid-level low is predicted to amplify near the West Coast favoring renewed chances of heavy rain and high elevation snow. Above-normal temperatures, dry conditions, and high winds favor an increasing wildfire risk across portions of the south-central CONUS.

Hazards

• Moderate risk of heavy precipitation across portions of the Tennessee Valley, Appalachians, Southeast, Mid-Atlantic, and Northeast, Fri-Sun, Mar 14-16.
• Moderate risk of heavy precipitation across portions of western Oregon and northern California, Fri-Sun, Mar 14-16.
• Slight risk of heavy precipitation across much of the eastern third of the CONUS, Fri-Sun, Mar 14-16.
• Slight risk of heavy precipitation across coastal areas of the Pacific Northwest and northern California, Fri-Tue, Mar 14-18.
• Moderate risk of heavy snow across portions of the Northern Plains and Upper Mississippi Valley, Fri-Sat, Mar 14-15.
• Moderate risk of heavy snow across portions of the southern Cascades, Klamath, and northern Sierra Nevada Mountains, Fri-Sun, Mar 14-16.
• Slight risk of heavy snow across the Cascades, Klamath, and northern Sierra Nevada Mountains, Fri-Tue, Mar 14-18.
• Slight risk of heavy snow over portions of the Central Rockies, Northern and Central Plains, and Upper Midwest, Fri-Sat, Mar 14-15.
• Moderate risk of high winds across portions of the Central and Southern Rockies, Great Plains, Great Lakes, and the Upper and Middle Mississippi, Ohio, and Tennessee Valleys, Fri-Sat, Mar 14-15.
• Moderate risk of episodic high winds across coastal portions of Oregon and northern California, Fri-Sun, Mar 14-16.
• Slight risk of episodic high winds across most of the central and eastern CONUS, Fri-Sun, Mar 14-16.
• Slight risk of episodic high winds along portions of the West Coast, Fri-Tue, Mar 14-18.
• Slight risk of much above normal temperatures across the Rio Grande Valley, Fri, Mar 14.
• Rapid onset drought risk across portions of the Southern Plains.
• Possible flooding for parts of southwestern Oregon and northern California.

Detailed Summary

For Sunday March 09 - Thursday March 13: WPC Days 3-7 U.S. Hazards

For Friday March 14 - Thursday March 20: A highly amplified mid-level shortwave trough is forecast to progress across the CONUS during week-2 favoring lee cyclogenesis across the Great Plains with the 0z ECENS, GEFS, and CMCE dynamical models in very good agreement depicting a strengthening surface low pressure system across the central CONUS during the early to middle part of the period, with several of the last deterministic runs from the GFS and ECMWF depicting a sub 980-hPa low. While the Probabilistic Extremes Tools (PETs) are more modest, the synoptic set-up looks favorable for a large-scale impactful event, with increased chances for a snowstorm across the Northern Plains and Upper Midwest and heavy rain and potentially thunderstorms across the East. A slight risk of heavy precipitation is issued for Mar 14-16 across much of the eastern third of the CONUS, with an embedded moderate risk across parts of the Tennessee Valley, Appalachians, Southeast, Mid-Atlantic, and Northeast for the same period, consistent with stronger signals in the uncalibrated precipitation guidance. The initial focus for heavy rain is favored across the South on Mar 14-15, then shifting more toward the Mid-Atlantic and Northeast on Mar 15-16. Antecedent temperatures are forecast to be very warm across parts of the Northeast (up to 20 deg F above-normal) further enhancing precipitable water values ahead of a potent cold front. Due to the increased precipitation risk and antecedent saturated conditions over portions of the Mississippi Valley associated with enhanced precipitation favored during week-1 (based on WPC QPF), localized flooding is possible within the highlighted region. On the backside of the surface low, heavy snow is possible across the northern periphery of this system, with the uncalibrated 0z ECENS depicting parts of the north-central CONUS having at least a 40 percent chance of snowfall totals exceeding 4 inches. As with the precipitation forecast, the snow forecast leans more bullish due to the impressive agreement in the models regarding surface low placement and strength, with a moderate risk of heavy snow highlighted over portions of the Northern Plains and Upper Midwest, Mar 14-15. A broader slight risk for heavy snow surrounds the moderate risk area and is also valid for Mar 14-15.

There is some indication of another system ejecting out of the Rockies toward the end of week-2 (Mar 19-20) and taking a similar track. This potential will continue to be monitored as additional heavy rainfall across portions of the east-central U.S. would continue to exacerbate the flooding potential.

Due to potentially strong surface low pressure and strengthening pressure gradients, a broad area is highlighted with a slight risk of episodic high winds, covering much of the eastern two-thirds of the CONUS, Mar 14-16. Within this slight risk area, the PETs depict at least a 20 percent chance of wind speeds exceeding the 85th percentile and 20-mph over some locations. A moderate risk of high winds is also posted (Mar 14-15) over much of the Central and Southern Rockies, Great Plains, Great Lakes, and the Upper and Middle Mississippi, Ohio, and Tennessee Valleys tied to the forecast track of the surface low. A period of anomalously warm temperatures is possible across the Rio Grande Valley at the outset of week-2, with the uncalibrated 0z ECENS showing some areas with maximum temperatures exceeding 95 deg F (closer to 90 deg F in the GEFS) along with increasing signals in the corresponding PETs. A slight risk of much above normal temperatures is posted across the region, Mar 14, and in combination with the high winds, may increase the wildfire risk, where below-normal precipitation is predominately favored and drought conditions ranging from D0 to D4 are being registered. The continuation of above-normal temperatures and little to no precipitation forecast support the addition of an elevated risk for rapid drought onset across portions of the Southern Plains.

Another trough is forecast to amplify near the West Coast leading to renewed chances of impactful weather across the region following a brief lull at the end of week-1. The ECENS PET depicts at least a 40 percent chance of 3-day precipitation exceeding the 85th climatological percentile across portions of the Pacific Northwest and northern California early in week-2. Probabilities are slightly lower in the GEFS PET, but there is good agreement in the uncalibrated guidance for 24-hour precipitation totals to potentially exceed 1-inch in some locations. Areas impacted will be more susceptible to flooding compared to southern California due to high soil moisture anomalies associated with antecedent wet conditions. Due to the stronger signals, a moderate risk of heavy precipitation is posted across portions of western Oregon and northern California, Mar 14-16, with an accompanying moderate risk of heavy snow across portions of the southern Cascades, Klamath, and northern Sierra Nevada Mountains. A flooding risk remains over the more saturated areas of southwestern Oregon and northern California. In addition to the heavy precipitation, high winds are anticipated along the coast, with a moderate risk of high winds across coastal portions of Oregon and northern California, Mar 14-16. Slight risks of heavy precipitation, heavy snow, and high winds continue through Mar 18, after which there appears to be some evidence of ridging building near the West Coast, particularly in the 0z ECENS and CMCE, which would favor relatively drier conditions.

No hazards are posted over Alaska. Below-normal temperatures are generally favored for much of the Mainland with near to above-normal precipitation forecast across the southern Mainland and the Southeast.

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