Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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452 FXUS21 KWNC 071805 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT May 07 2024 SYNOPSIS: Mid-level high pressure over the West Coast and mostly zonal flow over the contiguous U.S. (CONUS) results in a relatively tranquil period of weather for week-2. Early in the period, a stalled frontal boundary over the Gulf Coast leads to the potential for heavy precipitation for portions of the Southeast U.S. HAZARDS Slight risk for heavy precipitation for portions of eastern Texas, Lower Mississippi Valley, Tennessee Valley, Southern Appalachians, Mid-Atlantic, and Southeast U.S., Wed-Fri, May 15-17. DETAILED SUMMARY FOR FRIDAY MAY 10 - TUESDAY MAY 14: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR WEDNESDAY MAY 15 - TUESDAY MAY 21: At the outset of week-2, ensemble models favor moderate ridging (troughing) over the West Coast (Great Plains) as depicted by 500-hPa height anomalies. The GEFS favors a broad trough, while the ECMWF features a narrower trough over the Great Plains. Model solutions move this trough eastward quickly, and favor the development of a mid-level ridge over the Great Plains by the end of the forecast period. This emerging ridge may lead to a risk for excessive heat for the southern CONUS late in week-2, however there is still too much uncertainty regarding this outcome so no heat-related hazard is posted at this time. Ensemble models have come into better agreement today regarding the timing and location of potentially heavy precipitation associated with a stalled frontal boundary along the Gulf Coast. Both the GEFS and ECMWF Probabilistic Extremes Tools (PETs) indicate at least a 20% probability of 3-day accumulated precipitation exceeding the 85th percentile and 1 inch for portions of the southeastern CONUS for May 15-17. The ECMWF is especially bullish, with much wider coverage of the area indicated for 1 inch total and over 2 inches possible for portions of the Louisiana coast. Therefore a slight risk for heavy precipitation is posted for portions of eastern Texas, Lower Mississippi Valley, Tennessee Valley, Southern Appalachians, Mid-Atlantic, and Southeast U.S. for the above dates. In Alaska, as we move into the middle of May snowmelt season is underway and frozen rivers are beginning to break up. This leads to the potential for river flooding related to ice-jams. We continue to monitor the situation but currently there are no indications of impending major river break-ups or serious threat of ice-jamming so no flooding-related hazards are posted at this time. Caution should be exercised however; river break-up can be unpredictable and local conditions can change quickly. FORECASTER: Danny Barandiaran $$