Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 PM EST Sat Feb 8 2025 Valid 12Z Tue Feb 11 2025 - 12Z Sat Feb 15 2025 ...Active weather pattern on tap for the medium range period with periods of heavy rain and winter weather across parts of the West and the Central-Eastern U.S.... ...Overview... Models and ensembles continue to advertise a very active pattern during the Tuesday-Saturday period. Shortwave energy emerging from the West/Plains and associated frontal waves will likely focus an axis of heavy rainfall and flooding concerns over parts of the southeastern quarter of the lower 48 early-mid week with snow farther north from the central Plains into the Northeast Tuesday into Thursday. A wintry mix will be possible between the rain/snow areas. Then during the latter half of the week a Pacific system should bring areas of significant rain and mountain snow to parts of the West. This system may reach far enough east to develop precipitation over the central/eastern U.S. once again by next Saturday. Expect well below normal temperatures to persist over the Northwest and into the northern-central Plains Tuesday-Thursday. The West should see some moderation late week into the weekend as the region sees greater influence from Pacific flow. The central/southern Plains will briefly trend warmer late in the week but expect the cold air still over the northern Plains to push southward again on Saturday. The greatest number of days with above normal temperatures will likely be over the Gulf Coast and far Southeast. ...Guidance/Predictability Assessment... The latest model guidance continues to show overall good agreement on the large scale pattern, but plenty of uncertainty in the details. Early on, the 00z CMC was faster and sharper with leading energy into the Northwest around Wednesday, and faster with the surface low into the Mid-Atlantic/Northeast later in the week. The 12z run today though did slow down but is still on the stronger/sharper side. It was not preferred for the early morning medium range blend, so the WPC progs are a blend of the ECMWF and GFS with the UKMET. Otherwise, the next shortwave moves into the West late week and into the southern Plains next weekend. Guidance agrees on the presence, but some disagreement in the details and strength which could take until the shortrange to resolve these details. Prefered a blend of the ECMWF and GFS with the ensemble means to help smooth the differences for the later period WPC forecast blend. ...Weather/Hazards Highlights... Rapid progression of a leading wave and the approach of a stronger shortwave from the West will maintain a wavy frontal boundary over the South during Tuesday-Wednesday, essentially parallel to southwesterly flow aloft, and interacting with anomalous moisture. Guidance has been signaling the potential for excessive rainfall with flash flood potential during this time frame in recent days and continues to refine the expected axis of heaviest rainfall in successive runs. The Day 4 Excessive Rainfall Outlook valid on Tuesday continues an expansive slight risk from the Lower Mississippi Valley into the Tennessee Valley/southern Appalachians with only slight adjustments needed this cycle. Did extend the marginal risk north and eastward more into the southern Mid- Atlantic. The favored area for heavy rainfall on Day 5 Wednesday comes close to overlapping this region, shifting only a fraction east/northeast, with a Slight Risk again indicated. Rainfall from the previous day would make this region increasingly sensitive to additional rainfall. Eastern U.S. low pressure tracking northeastward on Thursday should drag a cold front through the Southeast, with associated rain trending less intense. The northern side of the precipitation shield may contain rounds of potentially disruptive wintry precipitation next week. The favored band for winter weather should extend from the central Plains through the Middle Mississippi Valley, Ohio Valley, central Appalachians, and Mid-Atlantic/Northeast where moisture overrunning southern tier fronts will interact with cold air. 50+ percent probabilities for a quarter inch of liquid equivalent snow/sleet remain in place for the Central Appalachians to Mid- Atlantic but with some slight southern shift of the overall probabilities for Tuesday to Wednesday morning. Meanwhile sleet and freezing rain are possible between the chances for heavy rain to the south and snow to the north. Stay tuned for refinements to the forecast as the placement, amount, and type of precipitation remains uncertain at any individual location. The next wave, reaching the East on Thursday, should produce a somewhat farther northward band of snow, from the Midwest into the northern Mid- Atlantic and Northeast. After a fairly dry period early in the week, expect a Pacific system to spread potentially significant rain and mountain snow into the West after midweek. For the Day 5 ERO period Wednesday- Wednesday night, models continue to show some variability in precipitation amounts reaching California. Maintained a Marginal Risk area along the northern half to two-thirds of the California coast and extended it into Southern California given increased sensitivities. After early Thursday expect moisture to continue through the West, with this system likely emerging into the Plains next Saturday and developing another area of various precipitation types over the central/eastern U.S. Northwestern and north-central parts of the lower 48 will see colder than average temperatures next week. The cold will be especially pronounced across Montana and North Dakota early in the week, with lows forecast to be in the -10s and -20s, along with some below zero highs. Colder than average temperatures will spread south behind a cold front next week, displacing unseasonable warmth across the southern tier during the weekend. Warmer than average temperatures should be limited to Florida and the adjacent Southeast by midweek. Introduction of Pacific flow should promote a moderating trend over the western-central U.S. by next Friday (but remaining quite cold over the northern Plains). Low pressure emerging over the Plains by next Saturday will help to pull down the lingering northern Plains cold air back down into the central Plains. At the same time, parts of the East should begin to trend somewhat warmer. Rausch 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