Extended Forecast Discussion NWS Weather Prediction Center College Park MD 158 AM EST Fri Jan 24 2025 Valid 12Z Mon Jan 27 2025 - 12Z Fri Jan 31 2025 ...General Overview... The forecast period for next week begins with a slow moving closed low over California and broad cyclonic flow aloft from the Northern Plains to the Northeast states, with a split upper level flow pattern in place for the beginning of the week. The closed low makes slow eastward progress through the middle of the week, with a ridge axis building north to the Pacific Northwest region, and a trough remaining over the northeastern quadrant of the country. It appears likely that surface cyclogenesis will take place over the Southern Plains in response to the approaching upper low, and this will likely fuel an increase in rain from Texas to portions of the Deep South for the end of the week. ...Guidance/Predictability Assessment... The 00Z model guidance suite is initially in good overall synoptic scale agreement across the Continental U.S. for the beginning of the week, but the CMC starts to differ across Ontario and Quebec going into Tuesday, and depicts a surface low over western Ontario that does not have much model support. The guidance becomes much more murky with location and extent of surface cyclogenesis over Texas and vicinity by Thursday. Given the overall upper air pattern and AI guidance, the ECMWF probably has the most reasonable depiction, whereas the CMC and GFS are much more suppressed. With forecast confidence dropping to below average by Thursday into Friday, the ensemble means accounted for about 2/3rds of the forecast blend by that time. ...Weather/Hazards Highlights... The slow moving upper low through California Sunday and into Monday will continue to allow for much needed rain to southern California. Most of the noteworthy rainfall with this event should be tapering off Monday morning, with just a few lingering showers remaining during the 12Z Monday to 00Z Tuesday time period. Therefore, no risk areas appear warranted in the Day 4 or Day 5 excessive rainfall outlooks at this time. The upper low that slowly approaches the Southern Plains by late Wednesday is likely to result in numerous showers and a few thunderstorms developing from central Texas to the lower Mississippi River valley through Friday morning. There has been a general upward trend in expected rainfall totals compared to the previous WPC forecast over the ArkLaTex region to the western Gulf Coast, with the potential for 1 to 3 inches for this region. Models still don't agree on the main QPF axis, so there will be updates on this as we get closer in time. Much of the East should finally be back up towards normal temperatures early next week, though readings a few degrees below normal are possible across the Southeast on Monday. Anomalously cold temperatures will also develop across the southwestern U.S. under the influence of upper troughing/closed low. The Northeast U.S. should also cool back down to slightly below average by the end of next week after another cold frontal passage. Hamrick Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw