179 FXUS21 KWNC 041715 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT April 04 2026 SYNOPSIS: Mid-level low (high) pressure across the western (eastern) contiguous U.S. (CONUS) increases chances for heavy precipitation across most of the Plains, the Mississippi and Tennessee Valleys, much of the Ohio Valley, and the Great Lakes Region during the first half of week-2. Heavy rain appears most likely across northeastern Texas, eastern Oklahoma, and the adjacent Lower Mississippi Valley, and a high risk of heavy precipitation is posted there. Flooding is possible across and near the high risk area. Around the middle of week-2, pressure gradients between a surface low pressure moving out of the Plains and higher pressure to the east and could be sufficient to induce strong winds at times from the east-central and southeastern Great Plains northeastward through the Great Lakes and Northeast. Unusually strong trade winds and possible Kona Low activity may bring additional heavy precipitation to Hawaii during the first half of week-2. HAZARDS High risk of heavy precipitation over parts of the southeastern Great Plains and adjacent Lower Mississippi Valley, Sun, Apr 12. Moderate risk of heavy precipitation from the Southern Plains northeastward across much of the Mississippi Valley, adjacent parts of the Ohio and Tennessee Valleys, and the Great Lakes, Sun-Mon, Apr 12-13. Slight risk of heavy precipitation for much of the Plains, the Mississippi Valley, much of the Ohio Valleys, the Tennessee Valley, and the Great Lakes, Sun-Tue, Apr 12-14. Slight risk of high winds from the east-central and southeastern Great Plains through the Great Lakes and Northeast, Tue-Fri, Apr 14-17. Flooding possible over parts of the southeastern Great Plains and adjacent Lower Mississippi Valley. DETAILED SUMMARY FOR TUESDAY APRIL 07 - SATURDAY APRIL 11: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR SUNDAY APRIL 12 - SATURDAY APRIL 18: Models are in good agreement establishing mid-level ridging over the eastern CONUS and upstream troughing across the interior West late week-1. This trough slowly lifts northeastward, with one or more vorticity centers potentially moving through the system during the first half of week-2. The predicted strength of the trough is similar to yesterday, slowly weakening as the period progresses, at which point models start to diverge. This pattern elevates the chances for heavy precipitation across a large part of the central and interior eastern CONUS. Isolated high wind gusts are possible in stronger thunderstorms, but model support for more widespread high winds has shifted to the middle of week-2, especially in the dynamical European model (ECMWF). Low surface pressure is expected to develop over the Plains and move northeastward into southern Canada. Areas of high pressure are expected both ahead of this system and in its wake, potentially creating enough of a pressure gradient to produce strong winds. This supports a slight risk of high winds effective later in the period than yesterday's hazard (around the middle of week-2). By the start of week-2, increased low-level Gulf moisture is forecast to overspread most areas between the Rockies and the Appalachians as surface high pressure centered over the western Atlantic extends into the southeastern CONUS. Farther west, the mid-level trough is expected to induce lower surface pressure over the central CONUS, setting the stage for surface low pressure center(s) and associated frontal complex(es) to pass through the region. The influx of low-level moisture into a region of cyclonic mid-level flow and wavering frontal boundaries increases the odds for heavy precipitation over a large part of the central and interior northeastern CONUS during at least the first half of week-2. Guidance has consistently forecast the heaviest amounts over northeastern Texas, eastern Oklahoma, and the adjacent Mississippi Valley early week-2. Although amounts are not expected to be excessive, the consistency with which guidance has favored moderate to heavy amounts across this region justifies a high risk of heavy precipitation there for the first day of the period (Sun, Apr 12). There is somewhat more divergence among the guidance elsewhere regarding the location, timing, and intensity of heavy precipitation, but most tools generally agree that one or more rounds of locally heavy rain are possible along a swath from Texas through the Great Lakes Region, supporting a moderate risk of heavy precipitation there extending through Mon, Apr 13. There is considerably more uncertainty to the west and east of this primary threat area, but the situation could trigger heavy precipitation as far west as the Great Plains and Upper Mississippi Valley, and as far east as the central Gulf Coast, the western Appalachians, and the Great Lakes Region at times during the first half of week-2. This potential supports a slight risk of heavy precipitation across this broad area for the first part of week-2 (Sun-Tue Apr 12-14). Continuous heavy precipitation throughout this region and time period seems unlikely, but the synoptic situation is favorable for the development of periodic, locally heavy rain from heavy thunderstorms to affect different parts of this region at varying times, whenever there is a combination of unusual strong low-level moisture influx, a focusing frontal boundary, and surface instability. The Probabilistic Extremes Tools (PETs) derived from the GEFS, European ensemble (ECENS), and Canadian ensemble (CMCE) are not particularly bullish on the potential for heavy precipitation, with only the ECENS showing any areas with a greater than 40 percent chances for 3-day precipitation totals above the 15th percentile climatological threshold (centered over Texas and adjacent locales). However, at least a couple inches of rain are depicted on the deterministic European (ECMWF) and AIGFS models as well as the ECENS and CMCE means across different parts of the slight risk area, with the heavier amounts mostly centered over northeastern Texas, eastern Oklahoma, and adjacent Arkansas and Louisiana. A few tools show at least some risk of additional heavy precipitation later week-2 over the southern reaches of the slight risk region, but there is too much uncertainty and model disparity to justify posting any additional heavy precipitation risks at this time. Any heavy week-2 precipitation falling in the high risk region will be on top of heavy amounts expected during the next few days. According to the National Water Center (NWC), this will increase the potential for flooding in this area during week-2 even though drought has been entrenched for the past few months in many portions of the southern Great Plains and Lower Mississippi Valley. The area at risk of flooding extends farther north than the area at high risk of heavy precipitation due to somewhat increased support for heavier amounts there. The PETs for high winds are not impressive, but the probabilities for wind gusts over 39 mph approach 40 percent in the ECENS and CMCE around the middle of week-2 mostly from the east-central and southeastern Great Plains into the Mississippi Valley Tue Apr 14. Thereafter, the high wind risk expands northeastward through the Great Lakes and Northeast Wed-Fri Apr 15-17. The ECMWF forecasts spotty wind gusts exceeding 50 mph, with the greatest threat shifting farther northeast with time. No hazards are issued over Alaska, but flooding can occur this time of year with little or no notice during river ice breakup season. Check with the Alaska Pacific River Forecast Center for the latest conditions or advisories. Across Hawaii, Kona Low activity brought heavy rainfall and flooding during mid-March, and strong trade winds have helped keep precipitation totals above normal for the past few weeks. Ensemble guidance shows a mid-level trough to the north of the island chain early week-2, which may trigger additional heavy precipitation. PETs from the GEFS and ECENS show increased chances (20 to 40 percent) for 3-day amounts exceeding the 85th percentile early week-2, with declining chances for heavy precipitation thereafter. Any heavy precipitation during week-2 will be falling on saturated ground, potentially triggering additional localized flooding. FORECASTER: Rich Tinker $$