913 FXUS21 KWNC 201825 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT March 20 2026 SYNOPSIS: Lingering mid-level high pressure is depicted over the western Contiguous U.S. (CONUS) early in the forecast period, potentially extending ongoing unseasonably warm temperatures over much of the Interior West and Desert Southwest into early week-2. Surface high pressure is favored to build from the north into the Ohio Valley and Mid-Atlantic at the outset of week-2, bringing lower temperatures across the northeastern CONUS and potential freeze conditions in areas where emerging vegetation may be vulnerable. Tight pressure gradients along the western margin of surface high pressure over the eastern CONUS bring the potential for enhanced winds over portions of the Southern and Central Plains. HAZARDS Slight risk of much above-normal temperatures for portions of the Desert Southwest, Great Basin, and California, Sat-Sun, Mar 28-29. Slight risk of much below-normal temperatures for portions of the Mid-Atlantic, Southern Appalachians, and Tennessee Valley, Sat-Sun, Mar 28-29. Slight risk of high winds for portions of the Southern and Central Plains, Sat-Wed, Mar 28-Apr 1. DETAILED SUMMARY FOR MONDAY MARCH 23 - FRIDAY MARCH 27: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR SATURDAY MARCH 28 - FRIDAY APRIL 03: Ensemble mean 500-hPa height anomaly forecasts from the 0z ECENS and GEFS are in reasonable agreement through about the middle of week-2, and depict amplified ridging over the West early in week-1, which then weakens and shifts eastward by the middle of the forecast period as troughing begins to emerge over the North Pacific. At this point the ensemble solutions diverge significantly, with the ECENS indicating a shortwave trough emerging and moving over the Interior West by the middle of week-2, while the GEFS prefers a stronger trough over the North Pacific with slower eastward progression. Regardless of the evolution of the Pacific trough, its development and the concurrent shift eastward of ridging over the Desert Southwest results in a moderation of temperatures after an unusually early heat wave over much of the West. That said, record-breaking high temperatures are still indicated by the National Blend of Models for March 28-29 across many locations in the southwestern CONUS. This is further supported by the ECENS and GEFS Probabilistic Extremes Tools (PETs), which both indicate at least a 20% chance of high temperatures to exceed the 85th climatological percentile for the same days, warranting a continuation of a slight risk for much above-normal temperatures across portions of the Desert Southwest, Great Basin, and California for March 28-29. Meanwhile, both the ECENS and GEFS 500-hPa height anomalies depict deep troughing over Hudson Bay and strong cyclonic flow over the Yukon early in week-2, providing upper-level support for a cold surge to move into the eastern CONUS. These features quickly deamplify leading to a rapid moderation of cold temperatures, but uncalibrated daily minimum temperature forecasts reach near to below freezing as far south as the Mid-Atlantic and Tennessee Valley. This is further supported by the ECENS PET, which shows a 20% chance of minimum temperatures falling below freezing at the outset of the forecast period. The GEFS is less bullish but still shows some modest signal for potential sub-freezing temperatures. While this does not meet cold-weather criteria, given the time of year, such conditions may be damaging to emerging vegetation. Therefore, a slight risk of much below-normal temperatures remains posted for portions of the Mid-Atlantic, Southern Appalachians, and Tennessee Valley for Mar 28-29. The cold surge described above is accompanied by a strong surface high pressure center that moves across the Ohio Valley and Mid-Atlantic during the forecast period. Both the ECENS and GEFS depict sharp pressure gradients along the western margin of this feature for much of the forecast period, along with potential lee cyclogenesis later in week-2. This is favored to result in high winds over much of the Southern and Central Plains, where both the GEFS and ECENS indicate winds often nearing or exceeding 20mph. There is less support from the PETs regarding high wind, but synoptic pattern recognition along with modeled mean wind speeds warrants a slight risk of high winds for portions of the Southern and Central Plains, valid Mar 28-Apr 1. 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: Danny Barandiaran $$