917 FXUS21 KWNC 141830 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT May 14 2026 SYNOPSIS: Mid-level low pressure undercutting mid-level high pressure over the eastern Pacific is anticipated to build into parts of the western contiguous U.S. (CONUS) at the start of week-2. This reduces chances for extreme heat across the California Central Valley. There are some lingering chances for high winds along parts of the West Coast early in week-2, as the mid-level low pressure moves into the region. Meanwhile, southerly return flow into the Southern Plains and Lower Mississippi Valley increases chances for heavy precipitation. HAZARDS Slight risk of heavy precipitation for portions of the Southern Plains and Lower Mississippi Valley, Fri-Mon, May 22-25. Slight risk of high winds for portions of the Oregon and California coast, Fri, May 22. DETAILED SUMMARY FOR SUNDAY MAY 17 - THURSDAY MAY 21: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR FRIDAY MAY 22 - THURSDAY MAY 28: Across North America, ensemble guidance from the 0Z runs continues to exhibit significant spread throughout the week-2 timeframe. While positive 500-hPa height anomalies are favored for much of the eastern CONUS, slight discrepancies persist between the GEFS, ECENS, and CMCE concerning the precise core of this mid-level feature; current indications place the mean center over the Great Lakes. Conversely, negative 500-hPa height anomalies are favored across the West, undercutting a mid-level ridge over the eastern Pacific. Surface high pressure is anticipated to develop underneath the mid-level ridge situated over the eastern U.S., potentially initiating a phase of increased southerly return flow into the Southern Plains and Lower Mississippi Valley. While mean ensemble guidance does not currently indicate a robust flow, discrete ensemble members suggest the possibility of stronger moisture flow into this area. Uncalibrated GEFS and ECENS forecasts denote 30-50% probabilities of three-day rainfall totals surpassing one inch during the 8-10 and 10-12 day windows. This is corroborated by the Probabilistic Extremes Tools (PETs), with both the GEFS and ECENS PETs showing at least a 20% chance of exceeding these thresholds; the ECENS is notably stronger, suggesting 30-50% chances during both periods. Given the prevailing drought conditions, these rains may prove beneficial. However, isolated flash and urban flooding is possible and river rises are also possible in parts of eastern Texas. Consequently, a slight risk of heavy precipitation is valid for May 22-25 across portions of the Southern Plains and Lower Mississippi Valley. A slight risk of high winds is valid for May 22 across portions of the Oregon and California coast. Current ensemble guidance indicates cyclonic mid-level flow positioned south of an anomalous ridge over the northeastern Pacific, while surface guidance suggests periods of intensifying pressure gradients throughout the region. The ECENS uncalibrated and PETs guidance has been quite consistent in bringing a 20-40% chance of 1 inch of precipitation to portions of the Carolinas and Mid-Atlantic associated with a weak area of low pressure. The GEFS has not been as supportive of this potential but continues to bring some chances into portions of the Carolinas. No associated hazard is posted today but does bear watching for the Memorial Day weekend. Further north, surface high pressure may bring enhanced onshore flow into portions of the northern Mid-Atlantic elevating surf along the coast. In Alaska, the typical peak of the river ice breakup season is approaching, and ice jam flooding can occur this time of year with little or no notice as conditions on frozen rivers can change quickly. Please check with the Alaska Pacific River Forecast Center for the latest conditions and advisories. FORECASTER: Ryan Bolt $$