Extended Forecast Discussion NWS Weather Prediction Center College Park MD 202 AM EST Fri Jan 28 2022 Valid 12Z Mon Jan 31 2022 - 12Z Fri Feb 04 2022 ...Overview... A weak shortwave moving through the southern Plains on Monday should shear out pretty quickly as it moves out of the Plains Tuesday-Wednesday due to a building ridge over the western Atlantic. This shortwave should at least generate enhanced rainfall along/north of the Gulf Coast on Monday. After this, another shortwave is forecast to amplify out of the West, sending an amplified and elongated trough into the central U.S. by Thursday. By Friday, broad longwave troughing should cover much of the CONUS as strong ridging builds over the East Pacific and Western Atlantic. This evolution is expected to bring widespread precipitation along a leading frontal boundary into the eastern third of the country mid-late next week, with potential for wintry weather on the backside of the system. ...Guidance Evaluation/Predictability Assessment... For the most part, the guidance shows pretty good agreement on the overall large scale pattern, but plenty of continued uncertainty in the details. The 27/12z UKMET remained a notable outlier for the initial shortwave through the Southern Plains/Gulf Coast on Monday, but the 28/00z run trended a little slower and more in line with the rest of the guidance. For the next system digging into the Western/Central U.S. Tuesday-Thursday, the operational models seem to be trending towards less separation of northern/southern stream energy compared to previous runs, though the UKMET again is problematic with maintaining more separation between streams. For the first half of the period, WPC leaned towards a non-UKMET deterministic model run consensus. Larger differences across the board begin to arise during the second half of the period. First concerning energy lifting towards the Great Lakes/Northeast where the GFS is noticeably faster than the ECMWF, which affects deepening low pressure into the Lower Great Lakes/Northeast on Friday. Out West, uncertainties remain with strength of upstream energy dropping into the mean trough on Thursday. The past few runs of the ECMWF have been consistently much weaker and faster with the energy as it rounds out the base of the trough by Friday. The GFS had been consistently more amplified/slower though the 27/18z run looked a lot like the ECMWF, and the 00z run again a tad more amplified than the previous run. The CMC is also stronger/slower. A look at individual ensemble members and the means, suggest a more amplified solution is possible (more so evident in the GEFS than the ECENS members). Given the lingering uncertainties both with the Northeast energy and the Western energy, the WPC forecast for days 6 and 7 trended towards the means, but continued about 50 percent contribution from the latest available GFS/ECMWF for some added definition to individual systems. ...Weather Highlights/Threats... The upper shortwave/low into the Southern Plains by Monday will bring a threat for locally moderate to heavy rainfall from eastern Texas across parts of the Gulf Coast region during the first half of next week. Best potential at this time appears to be over eastern Texas with lower confidence in details farther east. Some aspects of this event may hinge on small-scale details not easily resolved very far in advance. The northeastern Pacific upper trough digging into the West Monday-Tuesday will spread moderate amounts of rain and mountain snow from the Pacific Northwest eastward and southeastward into much of the Rockies. Highest totals are likely to be in the Pacific Northwest but should not be too extreme. In general, the forecast remains on track for a significant increase of coverage and intensity of precipitation over the east-central U.S. the second half of the week as the upper trough emerges from the Rockies and the leading cold front interacts with a strong low level feed of Gulf moisture. At this time the best chance for heaviest rainfall extends across the lower half of the Mississippi Valley into parts of the Ohio/Tennessee Valleys and the East. Wintry weather will be possible on the northwest side of the moisture shield, with at least some potential for meaningful snow from the central/south-central Plains northeastward through the Great Lakes. While confidence in a heavy rain area appears better than average, details with the wintry precipitation in the colder air may be more dependent on lower-confidence details of ejecting shortwave energy and frontal waves. Above average temperatures initially over the Plains on Monday should spread eastward Tuesday-Thursday as upper ridging builds in. Behind this, arctic high pressure dives into the Central U.S. midweek bringing chilly and much below normal temperatures all the way from the northern Rockies/High Plains southward into Texas. Widespread daytime highs (and slightly less extreme overnight lows) as much as 10-20 degrees below normal are possible. Locally higher values as much as 25 below normal are possible across the far northern Plains. The below normal temps should moderate slightly as they shift east into the Ohio Valley/Gulf Coast states next Friday. Much of the West Coast states should be near normal through much of next week owing to amplified ridging across the East Pacific. Santorelli 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, winter weather outlook probabilities and heat indices are at: 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/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml