073 FXUS21 KWNC 271820 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT March 27 2026 SYNOPSIS: Mid-level low pressure is favored to develop over the western contiguous U.S. (CONUS) next week, which is expected to promote cooler and more seasonable temperatures following an exceptionally warm March for many parts of the western U.S. However, surface low development in the lee of the Rockies and accompanying frontal activity brings an elevated risk for high winds and heavy precipitation early in week-2. The elevated risk of high winds is expected to promote wildfire risks particularly in areas not affected by heavy rainfall across the Plains during the period. The synoptic pattern also supports the potential for thunderstorm activity across the south-central CONUS, with the possibility of localized flooding across parts of the Ohio Valley. In Alaska, mid-level high pressure located over the Bering Strait is expected to bring a continuation of near to below-normal temperatures over the southern Mainland and the Southeast. HAZARDS Moderate risk of high winds for portions of the lower Four Corners and the Great Plains, Sat, Apr 4. Slight risk of high winds for much of the CONUS extending from the Desert Southwest northeastward to the Great Lakes, Sat-Sun, Apr 4-5. Moderate risk of heavy precipitation from portions of the Southern Plains, Middle and Lower Mississippi, Ohio and Tennessee Valleys and adjacent Great Lakes Region, Sat-Sun, Apr 4-5. Slight risk of heavy precipitation from much of the Great Plains to the Appalachians and central Gulf Coast, Sat-Tue, Apr 4-7. DETAILED SUMMARY FOR MONDAY MARCH 30 - FRIDAY APRIL 03: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR SATURDAY APRIL 04 - FRIDAY APRIL 10: By late next week, 500-hPa height forecasts from the 0z GEFS and ECMWF ensembles generally feature shortwave troughing over the western CONUS, with amplified ridging overspreading the eastern U.S. While these models have come into slightly better agreement in regards to this former mid-level feature, and in the associated surface low development in the lee of the Rockies since yesterday, the ECMWF continues to favor a deeper and less progressive mean trough than the GEFS, leading to a stronger precipitation response across the south-central CONUS early in week-2. As this mean troughing deamplifies towards the middle of the period, the GEFS remains eager to build heights over the Interior West, whereas the ECMWF ensemble maintains more cyclonic flow downstream of an amplifying ridge center over the northeastern Pacific. In addition, the GEFS is also beginning to favor more longwave trough development over the eastern CONUS, whereas the ECMWF maintains more ridging over the southeastern U.S. during the back half of week-2. As a result of these differences in the predicted pattern, there continues to be added uncertainty in the hazards outlook beyond the early portion of the period. Tied to the mid-level troughing late next week, the GEFS, ECMWF and Canadian ensembles have come into better agreement featuring a mean surface low development mainly over eastern Colorado on day 7 (Apr 3). With the mean surface low favored to be situated over the eastern Great Lakes by day 8 (Apr 4), enhanced precipitation amounts are depicted along a large cold frontal boundary, extending from the mean low center into the Southern Plains and Lower Mississippi Valley. Compared to the ECMWF and Canadian, the GEFS remains the weakest with the mean low and precipitation totals, however there continues to be support in the uncalibrated tools showing at least 30% chances for 3-day amounts exceeding an inch along the boundary. Therefore, a moderate risk of heavy precipitation remains issued and valid through Apr 5, with added coverage over eastern Texas where the ECMWF Probabilistic Extreme Tool (PET) indicates 40-50% chances for 3-day amounts exceeding the 85th percentile and 1 inch. Given the favorable synoptic setup of ample moisture and forcing, and the uncalibrated ECMWF showing >60% (>30%) for 3-day amounts exceeding an inch (two inches), a high risk of heavy precipitation was considered, however the drier GEFS and discrepancies in the pattern aloft preclude this risk designation at this time. A broader slight risk area of heavy precipitation remained posted where both raw and calibrated probabilities for precipitation exceedance are less, and valid through day 11 (Apr 7) where tools show a lingering heavy precipitation potential through the middle of week-2. Within the highlighted risk areas, there is also the threat of thunderstorm activity particularly across the ArkLaTex region where dewpoints are likely to reach the upper 60s (deg F), as well as the possibility for localized flooding further north over parts of the Ohio Valley where there is a limited risk of flooding due to enhanced precipitation forecast during week-1. Following unseasonably warm weather in March throughout the western and central CONUS, the favored troughing will usher colder temperatures into the West, along with higher mean surface pressure to potentially induce episodes of high winds. Despite the GEFS having shallower troughing than the ECMWF, stronger mean high pressure is depicted in the wake of the surface low throughout the West and the high Plains relative to yesterday, supportive of maintaining an elevated risk of high winds. Based on fair agreement in the uncalibrated tools depicting increased chances for wind gusts exceeding 34 knots, a moderate risk of high winds remains issued from extending from the lower Four Corners and into the Upper Midwest for Apr 4. A broader slight risk area remains posted and valid through Apr 5. Antecedent conditions are likely to be unseasonably warm during the final week of March, which will continue the ongoing trend of declining surface moisture across the central and western CONUS. The elevated risk of high winds is expected to promote wildfire danger through much of this region at least into the middle of week-2, particularly in areas not affected by heavy rainfall. The predicted mid-level trough in the West may create enough instability to induce dry thunderstorms over the parts of the West, which could serve as triggers for fire development. The Morrill wildfire in southwestern Nebraska recently became the largest in state history, consuming more than 600,000 acres. The year-to-date total over the western half of the CONUS exceeds 920,000 acres, compared to the 10-year average of about 650,000 acres across the entire CONUS. Over Alaska, prevailing northwesterly mid-level flow downstream of a persistent 500-hPa mean ridge established over the Bering Strait is expected to lead to near to below normal temperatures for much of the southern Mainland, Aleutians and the Southeast. No temperature hazards are posted. Across Hawaii, persistent Kona Low activity brought heavy rainfall and flooding to the state during mid-March. Guidance shows a return to a more seasonable trade wind regime, and although above-normal precipitation is favored, any heavy precipitation risk looks to be kept to the south closer to the equator in the PETs, at least through the middle of week-2. FORECASTER: Nick Novella $$