125 FXUS21 KWNC 151841 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT March 15 2026 SYNOPSIS: Strong mid-level high pressure across the west-central CONUS during week-1 is forecast to flatten and become more elongated across the contiguous U.S. (CONUS) in week-2. Above-normal temperatures continue to remain favored during the period, but the magnitude of heat is predicted to decrease compared to week-1. Continued frontal activity across the Northeast favors increased winds and relatively cooler temperatures. Persistent mid-level high pressure over the western Aleutians favors colder than normal temperatures across Alaska, with surface low pressure over the Gulf of Alaska leading to enhanced winds along the southern coastal Mainland and Southeast Alaska. HAZARDS Slight risk of much above normal temperatures across the Desert Southwest, Four Corners, and Central and Southern Plains, Mon-Tue, Mar 23-24. Slight risk of high winds across the Northeast, Mon, Mar 23. Slight risk of much below normal temperatures over much of central and southern Mainland Alaska, Mon-Fri, Mar 23-27. Slight risk of high winds over portions of coastal southern Mainland Alaska and Southeast Alaska, Mon-Fri, Mar 23-27. DETAILED SUMMARY FOR WEDNESDAY MARCH 18 - SUNDAY MARCH 22: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR MONDAY MARCH 23 - SUNDAY MARCH 29: Dynamical models remain in very good agreement regarding exceptionally warm temperatures across the western and central CONUS during week-1 tied to an anomalously strong mid-level ridge axis over the Four Corners. The latest Weather Prediction Center forecast indicates widespread positive maximum temperature anomalies of +20 to +30 deg F over the western CONUS into the Great Plains. By day-8 (Mar 23), the GEFS and ECMWF ensembles depict decreasing positive temperature anomalies, a sign that that most substantial warmth is beginning to wane. Therefore, the moderate risk for much above normal temperatures is discontinued, with a slight risk remaining in place through day-9 (Mar 24) across the Desert Southwest, Four Corners, and Central and Southern Plains. Early in the period, there remains some signal in the National Blend of Models (NBM) for daily record high temperatures, although spatial coverage is reduced considerably compared to week-1 and focused mainly across the Four Corners and Southern Plains. The GEFS and ECMWF Probabilistic Extremes Tools (PETs) continue to depict elevated chances of maximum temperatures exceeding the 95th climatological percentile across the highlighted slight risk area early in week-2, but probabilities fall below 20 percent in both tools on day-10 (Mar 25). Actual temperatures range from the 70s deg F across the Great Basin to the 80s and 90s deg F over the Southwest and Southern Plains. Triple digit temperatures are possible across some of the climatologically hottest areas of the Desert Southwest. During week-2, troughing is forecast across the northeastern Pacific. The 0z GEFS continues to dig this feature more across the West Coast of the CONUS, and the 0z ECMWF and Canadian ensembles are a bit more amplified compared to yesterday. This would result in relatively cooler temperatures across the Northwest along with increasing precipitation chances, with the more amplified GEFS extending this potential farther south along the West Coast. There are also elevated signals for increased wind speeds in the GEFS and ECMWF PETs and uncalibrated guidance along the West Coast tied to increasing onshore flow. However, model uncertainty regarding the pattern evolution precludes any additional hazards across the West. While the western and central CONUS are predicted to experience warm temperatures, a relatively colder pattern is anticipated across the northeastern U.S. tied to a trough centered over southeastern Canada and the northwest Atlantic, along with a blocking ridge developing near Greenland. This emerging pattern resembles a negative phase of the North Atlantic Oscillation (-NAO), which would favor a greater likelihood of below normal temperatures during week-2 over portions of the Northeast, Great Lakes, and northern Mid-Atlantic. The 0z GEFS, ECMWF, and Canadian ensembles all depict surface low pressure developing along the trough axis across the Canadian Maritimes late in week-1, with a tightening pressure gradient extending into the Northeast at the start of the period as the system departs. With added support from both the GEFS and ECMWF wind PETs, which depict at least a 20 percent chance wind speeds exceed the 85th climatological percentile and 20-mph, a slight risk for high winds is posted across portions of the Northeast on Mar 23. Ridging and positive 500-hPa height anomalies to the west of Alaska combined with troughing and surface low pressure over the Gulf of Alaska favor increased probabilities for below normal temperatures over much of Alaska. Given the time of year, it is becoming harder to reach hazardous cold temperatures across the state. However, the GEFS and ECMWF PETs continue to depict portions of central and southern Alaska having probabilities of at least 20 percent for temperatures falling below the 10th climatological percentile through the middle of the period, with the highest probabilities (greater than 40 percent) focused farther to the southwest where the corresponding uncalibrated guidance indicates temperatures 15-25 deg F below normal. These signals support a continued slight risk of much below normal temperatures across central and southern Mainland Alaska into the Alaska Peninsula, Mar 23-27. Surface low pressure over the Gulf of Alaska results in a tight pressure gradient extending from Southeast Alaska across the southern coastal Mainland, with the PETs supporting a slight risk of high winds, Mar 23-27. While this system favors increased precipitation across Southeast Alaska, amounts are forecast to remain below hazards thresholds. The 0z GEFS, ECMWF, and Canadian ensembles depict mid-level troughing amplifying to the northwest of Hawaii late in week-1, likely bringing another round of enhanced precipitation to the state. Some of this moisture is likely to linger into week-2, although probabilities for precipitation totals exceeding the 85th climatological percentile in the GEFS and ECMWF PETs are reduced compared to yesterday given the timing. However, probabilities still exceed 20 percent over most areas, with a stronger signal across the southeastern islands early in the period. Any additional heavy rainfall will exacerbate flooding ongoing at the start of the period from previous events. FORECASTER: Thomas Collow $$