089 FXUS21 KWNC 191819 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT March 19 2026 SYNOPSIS: Persistent mid-level high pressure favored across much of the western and central contiguous U.S. is expected to lead to a continuation of above-normal temperatures from week-1 into week-2. While excessive heat conditions are less of a concern during the period, the anomalous warmth is likely to continue driving early springtime snowmelt for the higher elevations of the West, where many locations have registered well below normal snowpack over the winter. Surface low development and an accompanying frontal system tracking into southeastern Canada supports an increased risk of high winds over the northeastern contiguous U.S. (CONUS), while potentially strong surface high pressure in the wake of the front may bring below-normal, subfreezing temperatures to impact emerging springtime vegetation for parts of the southeastern CONUS. HAZARDS Slight risk of high winds for the northeastern CONUS, Fri-Sat, Mar 27-28. Slight risk of much below normal temperatures for parts of the Tennessee and Ohio Valleys, Southern Appalachians, and Southeast, Sat-Sun, Mar 28-29. Slight risk of much above-normal temperatures for the Desert Southwest, Rockies, Great Basin and the Central and Southern Plains, Fri-Mon, Mar 27-30. DETAILED SUMMARY FOR SUNDAY MARCH 22 - THURSDAY MARCH 26: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR FRIDAY MARCH 27 - THURSDAY APRIL 02: The mean week-2 500-hPa height forecasts from the GEFS and ECMWF feature a broad coverage of positive height departures overspreading the CONUS, with amplified troughing over central and eastern Canada. With this latter mean mid-level feature having shifted closer to Greenland in the updated guidance, this pattern has become more consistent with a positive North Atlantic Oscillation (+NAO). Historically during spring, this mode typically favors widespread above-normal springtime temperatures throughout the CONUS, with the strongest positive temperature anomalies over the Interior West and near normal temperatures over parts of the northeastern CONUS in proximity to the mean troughing to the north. By late next week, the GEFS and ECMWF ensembles have come into better agreement with this realization, both favoring a shortwave trough diving into the Great Lakes to usher in a period of anomalous cold into the northeastern CONUS. In addition, better agreement exists in the models regarding ridging favored upstream which is expected to keep much of the central and western CONUS on the warmer side following an unprecedented warm event during week-1 particularly over the southwestern CONUS. Later in week-2, models have become better aligned in favoring an eastward shift of the anomalous ridge center to allow for the development of more mid-level troughing over the West. Such a pattern evolution would become more favorable for lee cyclogenesis and promote the transition for wetter conditions unfolding over the Plains and Mississippi Valley late in March. Tied to the shortwave propagating above the anomalous ridge center in the West, surface low development remains favored in the lee of the Rockies late in week-1. While there is not much of a precipitation response, tools continue to point to an increased potential for elevated winds associated with the mean low and accompanying frontal system tracking into the Canadian Maritimes early in week-2. The strongest wind potential appears to have timed off over the High Plains, but a slight risk of winds is posted (Mar 27-28) where Probabilistic Extremes Tools (PETs) maintain some support for wind speeds exceeding the 85th percentile, and uncalibrated ECMWF show increased chances for gusts exceeding 40mph over the northeastern CONUS. Elevated wind speeds still remain possible over the High Plains heading into the period, and enhanced winds combined with above-normal temperatures and dry fuels could increase the risk of wildfire activity. In the wake of the departing surface low, potentially strong surface high pressure is favored to descend from southern Canada and bring a shot of colder air into the Northern Plains, Upper Mississippi Valley, Great Lakes, and the Northeast. Based on both raw and calibrated temperature tools, better agreement exists between the GEFS and ECMWF in regards to the strength and coverage of anomalous cold air since yesterday. The coldest temperatures are likely to be concentrated over the northeastern CONUS, but PETs show at least 20% chances for minimum temperatures falling below the 15th percentile and below freezing reaching south into parts of the Tennessee Valley, Southern Appalachians and the Carolinas. While these temperatures are not cold enough for winter hazards criteria, any early spring cold air bringing nighttime frost and/or freezes may adversely impact emerging springtime vegetation. Therefore, a slight risk of much below normal temperatures is highlighted over a narrow area in the southeastern CONUS for Mar 28-29 to capture this risk before temperatures begin to moderate later in the period. Upstream, the prevailing positive 500-hPa height departures are expected to prolong much of the above-normal temperatures from week-1 into week-2 throughout many parts of the western CONUS. Compared to yesterday, there is less of a warm signal in the raw and calibrated temperatures tools over the Great Plains, as the strongest positive temperatures departures becoming more focused over the Interior West and into parts of California late next week. A slight risk of much above-normal temperatures remains issued, but now extends through day 11 (Mar 30), with its coverage also reduced (expanded) over the High Plains (Northern Intermountain) in the updated outlook where PETs show 20-40% chances for maximum temperatures exceeding the 95th climatological percentile. Within the highlighted region, the National Blend of Models (NBM) continues to show an increased number of locations nearing record breaking daytime temperatures. While tools are less supportive of temperatures reaching excessive heat thresholds (upper 90s to lower 100s deg F in the Southwest, upper 70s in the Rockies and Great Basin), the anomalous warmth is likely to continue driving early springtime snowmelt for the higher elevations of the West, where many locations have registered well below normal snowpack over the winter. With much of the mid-level ridging favored to deamplify and shift eastward later in the period, the positive anomalous temperatures are likewise favored to follow this evolution towards the end of March. PETs are unsupportive of any temperature related hazard risk, but the combination of continued anomalous warmth and dryness sparks concerns on the potential development of Rapid Onset Drought (ROD) particularly over the Central High Plains and Middle Mississippi Valley where soil moisture is on sharp decline. A corresponding ROD risk was considered, however the aforementioned potential for falling mid-level heights in the West and surface low development in lee of the Rockies to bring increased precipitation during the back half of week-2 looks to quell this risk. This potential will be reevaluated in upcoming hazard outlooks. Over Alaska, models have been impressively consistent in maintaining amplified ridging to the west of the Bering Strait and downstream troughing over the Mainland and Southeast. This stable pattern has brought and continues to bring below-normal temperatures throughout much of the state. While PETs maintain elevated chances for minimum temperatures falling below the 15th percentile, actual temperatures look to remain above advisory thresholds due to rapidly increasing springtime sun angles at the higher latitudes, and no temperature hazards are posted. Over Hawaii, persistent Kona low activity has led to heavy rainfall and flooding throughout the state. Ensembles do not show much change in the mid-level pattern with troughing favored to persist over the Central Pacific later in March. PETs continue to indicate elevated chances for 3-day amounts exceeding the 85th percentile, with 3-day total accumulations exceeding an inch for some locations throughout week-2. The continuation of above-normal and potentially heavy precipitation is likely to worsen already saturated ground conditions and may trigger additional localized flooding in the state. FORECASTER: Nick Novella $$